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Sample records for reinforced concrete shear

  1. Direct Shear Failure in Reinforced Concrete Beams under Impulsive Loading

    DTIC Science & Technology

    1983-09-01

    failures in reinforced concrete under static loads are realized in specimens for which the ratio of shear span to effective depth (M/Vd) is less than O.Z...AFWL-TR-83-84 AFWL-TR- Ŝ, 83-84 000 DIRECT SHEAR FAILURE IN REINFORCED CONCRETE BEAMS UNDER IMPULSIVE LOADING Dr Timothy J. Ross September 1983...S TYP or 1116100 t PE& IGO 1OVRC DIRECT SHEAR FAILURE IN REINFORCED CONCRETE BEAMS Final Report UNDER IMPULSIVE LOADING 4. PEROMING.,OO.qEPORT NUMSER

  2. Prediction of residual shear strength of corroded reinforced concrete beams

    NASA Astrophysics Data System (ADS)

    Imam, Ashhad; Azad, Abul Kalam

    2016-09-01

    With the aim of providing experimental data on the shear capacity and behavior of corroded reinforced concrete beams that may help in the development of strength prediction models, the test results of 13 corroded and four un-corroded beams are presented. Corrosion damage was induced by accelerated corrosion induction through impressed current. Test results show that loss of shear strength of beams is mostly attributable to two important damage factors namely, the reduction in stirrups area due to corrosion and the corrosion-induced cracking of concrete cover to stirrups. Based on the test data, a method is proposed to predict the residual shear strength of corroded reinforced concrete beams in which residual shear strength is calculated first by using corrosion-reduced steel area alone, and then it is reduced by a proposed reduction factor, which collectively represents all other applicable corrosion damage factors. The method seems to yield results that are in reasonable agreement with the available test data.

  3. The Behaviour of Reinforced Concrete Subjected to Reversed Cyclic Shear

    NASA Astrophysics Data System (ADS)

    Ruggiero, David Michael Volpe

    Reversed cyclic loading, as may occur during seismic events, can cause sudden and brittle shear failures in reinforced concrete structural members. This thesis presents both experimental and analytical investigations into the behaviour of members subjected to reversed cyclic shear loading, and culminates in the development of a new, rational model to describe this behaviour. In the experimental phase of the research, ten reinforced concrete shell elements were tested under reversed cyclic in-plane shear loads. Data collected by means of several acquisition systems allowed extensive analysis of the experiments, and provided insight into the behaviour of the crack interfaces. In comparison with existing models, such as the Modified Compression Field Theory, it was found that the shear strengths of these reversed cyclically loaded specimens were as much as 25% lower than monotonic predictions. The results of the experimental program informed the development of a new analytical model, the General Crack Component Model (GCCM). The central concept of the GCCM is that the reversed cyclic behaviour of a shear panel depends on the behaviour of multiple crack systems, each with its own constitutive properties. A rigorous framework based on the principles of compatibility and equilibrium was formulated in order to allow for the appropriate combination of the stiffnesses of the three components of the model: concrete, steel, and cracks. The GCCM was validated for reversed cyclic and monotonic loading by comparison with the experimental results as well as data from other researchers. It was shown that the model provides good estimates of the behaviour of reinforced concrete subjected to reversed cyclic loads, and that it can be used as part of a larger structural analysis, ultimately helping engineers to design safer structures and more accurately assess the safety of existing construction.

  4. Behaviour of reinforced concrete beams with confined concrete related to ultimate bending and shear strength

    NASA Astrophysics Data System (ADS)

    Tee, Horng Hean; Al-Sanjery, Kousay; Chiang, Jeffrey Choong Luin

    2017-03-01

    This research is to investigate the behaviour of over-balanced High Strength Reinforced Concrete Beams with the compression zone confined with spiral / helical steel reinforcements. The study covered beam behaviour with respect to flexural strength, shear strength, deflection and cracking related to confined concrete. Six 200mm (width) X 300mm (depth) X 3000mm (length) Reinforced Concrete (RC) Beams, the first three beams incorporating steel ratio of 1.42ρb and the remaining 1.64ρb were tested under a four point static load test. The confinement of the concrete was carried out using spiral reinforcements of diameter 6mm and yield stress of 406N/mm2 with pitches of 50mm and 100mm. Measurements of deflection, cracking, and strains on both main reinforcements and concrete of the beams were taken. At the same level of stress, beams with confined concrete strained less than control beams without confinement for both tensile strain at the main steel reinforcement and compressive strain across the compression zone of concrete. Deflections of beams with helical confinement were less than the control beams. All beams failed in shear / flexural mode and gave fair warning against failure, more specifically beams with 1.42ρb, which is not normally associated with shear-type failure of beams which are over reinforced. The early shear failure prevented the beams from achieving its full utilisation of the ultimate strength. It is recommended that for over-reinforced confined concrete beams, the shear strength of beams should be based on using the diagonal compressive strut angle (θ) of more than 22 degrees recommended in Eurocode 2 (EC2), hence giving the beam higher safety factor against shear failure. All samples exhibited flexure and shear cracks in a manner which gave a good warning against failure. The ratio of the failure load to the theoretical ultimate load for shear ranged between 0.98 and 1.25 while the ratio of the failure load to the ultimate flexural load ranged

  5. Behavior of reinforced concrete slabs subjected to combined punching shear and biaxial tension

    SciTech Connect

    Jau, W.C.; White, R.N.; Gergely, P.

    1982-09-01

    This investigation was a continuing study of peripheral (punching) shear strength of precracked, biaxially tensioned, orthogonally reinforced concrete slabs. This research was motivated by the need to determie the strength of a reinforced concrete containment vessel wall when subjected to combined internal pressure and punching shear loads normal to the wall. The study served to determine the effect of three major variables (shear span, size of loaded area, and reinforcing steel ratio) on punching shear strength of slabs that were precracked in biaxial tension and then held at one of the two tension levels (0 or 0.8f/sub y/) during shear load application.

  6. Application of bamboo for flexural and shear reinforcement in concrete beams

    NASA Astrophysics Data System (ADS)

    Schneider, Nathan Alan

    As the developing world is industrializing and people migrate to cities, the need for infrastructure is growing quickly and concrete has become one of the most widely used construction materials. One poor construction practice observed widely across the developing world is the minimal use of reinforcement for concrete structures due to the high cost of steel. As a low-cost, high-performance material with good mechanical properties, bamboo has been investigated as an alternative to steel for reinforcing concrete. The goal of this research is to add to the knowledge base of bamboo reinforced concrete (BRC) by investigating a unique stirrup design and testing the lap-splicing of flexural bamboo reinforcement in concrete beams. Component tests on the mechanical properties of Moso bamboo (Phyllostachys edulis) were performed, including tensile tests and pull-out tests. The results of the component tests were used to design and construct 13 BRC beams which were tested under monotonic gravity loading in 3 and 4-point bending tests. Three types of beams were designed and tested, including shear controlled, flexure controlled, and lap-spliced flexure controlled beams. The test results indicated that bamboo stirrups increased unreinforced concrete beam shear capacities by up to 259%. The flexural bamboo increased beam capacities by up to 242% with an optimal reinforcement ratio of up to 3.9%, assuming sufficient shear capacity. Limitations of the bamboo reinforcement included water absorption as well as poor bonding capability to the concrete. The test results show that bamboo is a viable alternative to steel as tensile reinforcement for concrete as it increases the ultimate capacity of the concrete, allows for high deflections and cracks, and provides warning of impending structural failure.

  7. Joint shear strength of FRP reinforced concrete beam-column joints

    NASA Astrophysics Data System (ADS)

    Saravanan, Jagadeesan; Kumaran, Ganapathy

    2011-03-01

    An assessment of the joint shear strength of exterior concrete beam-column joints reinforced internally with Glass Fibre Reinforced Polymer (GFRP) reinforcements under monotonically increasing load on beams keeping constant load on columns is carried out in this study. Totally eighteen numbers of specimens are cast and tested for different parametric conditions like beam longitudinal reinforcement ratio, concrete strength, column reinforcement ratio, joint aspect ratio and influence of the joint stirrups at the joint. Also finite element analysis is performed to simulate the behaviour of the beam-column joints under various parametric conditions. Based on this study, a modified design equation is proposed for assessing the joint shear strength of the GFRP reinforced beam-column specimens based on the experimental results and the review of the prevailing design equations.

  8. Parametric Study of Shear Strength of Concrete Beams Reinforced with FRP Bars

    NASA Astrophysics Data System (ADS)

    Thomas, Job; Ramadass, S.

    2016-09-01

    Fibre Reinforced Polymer (FRP) bars are being widely used as internal reinforcement in structural elements in the last decade. The corrosion resistance of FRP bars qualifies its use in severe and marine exposure conditions in structures. A total of eight concrete beams longitudinally reinforced with FRP bars were cast and tested over shear span to depth ratio of 0.5 and 1.75. The shear strength test data of 188 beams published in various literatures were also used. The model originally proposed by Indian Standard Code of practice for the prediction of shear strength of concrete beams reinforced with steel bars IS:456 (Plain and reinforced concrete, code of practice, fourth revision. Bureau of Indian Standards, New Delhi, 2000) is considered and a modification to account for the influence of the FRP bars is proposed based on regression analysis. Out of the 196 test data, 110 test data is used for the regression analysis and 86 test data is used for the validation of the model. In addition, the shear strength of 86 test data accounted for the validation is assessed using eleven models proposed by various researchers. The proposed model accounts for compressive strength of concrete ( f ck ), modulus of elasticity of FRP rebar ( E f ), longitudinal reinforcement ratio ( ρ f ), shear span to depth ratio ( a/ d) and size effect of beams. The predicted shear strength of beams using the proposed model and 11 models proposed by other researchers is compared with the corresponding experimental results. The mean of predicted shear strength to the experimental shear strength for the 86 beams accounted for the validation of the proposed model is found to be 0.93. The result of the statistical analysis indicates that the prediction based on the proposed model corroborates with the corresponding experimental data.

  9. Constitutive Behavior of Reinforced Concrete Membrane Elements under Tri-directional Shear

    NASA Astrophysics Data System (ADS)

    Labib, Moheb

    The two-dimensional behavior of typical reinforced concrete (RC) structures has been extensively studied in the past several decades by investigating the constitutive behavior of full-scale reinforced concrete elements subjected to a bi-axial state of stress. In order to understand the true behavior of many large complex structures, the goal of this investigation is to develop new constitutive relationships for RC elements subjected to tri-directional shear stresses. Recently, additional out-of-plane jacks were installed on the panel tester at University of Houston so that concrete elements could be subjected to tri-directional shear stresses. This upgrade makes the panel tester the only one of its kind in the US that is capable of applying such combinations of stresses on full-scale reinforced concrete elements. This dissertation presents the details of the mounting and installation of the additional hydraulic jacks on the universal panel tester. The experimental program includes a series of seven reinforced concrete elements subjected to different combinations of in-plane and out-of-plane shear stresses. Increasing the applied out-of-plane shear stresses reduced the membrane shear strength of the elements. The effect of applying out-of-plane shear stresses on the in-plane shear strength was represented by modifying the softening coefficient in the compression stress strain curve of concrete struts. The modified model was able to capture the behavior and the ultimate capacity of the tested elements. The effect of the in-plane shear reinforcement ratio on the interaction between in-plane and out-of-plane shear stresses was evaluated. The model was implemented in the Finite Element package FEAP and was used to predict the ultimate capacity of many structures subjected to a combination of in-plane and out-of-plane shear stresses. The results of the analytical model were used to develop simplified design equations for members subjected to bi-directional shear loads

  10. Shear Behavior Models of Steel Fiber Reinforced Concrete Beams Modifying Softened Truss Model Approaches

    PubMed Central

    Hwang, Jin-Ha; Lee, Deuck Hang; Ju, Hyunjin; Kim, Kang Su; Seo, Soo-Yeon; Kang, Joo-Won

    2013-01-01

    Recognizing that steel fibers can supplement the brittle tensile characteristics of concrete, many studies have been conducted on the shear performance of steel fiber reinforced concrete (SFRC) members. However, previous studies were mostly focused on the shear strength and proposed empirical shear strength equations based on their experimental results. Thus, this study attempts to estimate the strains and stresses in steel fibers by considering the detailed characteristics of steel fibers in SFRC members, from which more accurate estimation on the shear behavior and strength of SFRC members is possible, and the failure mode of steel fibers can be also identified. Four shear behavior models for SFRC members have been proposed, which have been modified from the softened truss models for reinforced concrete members, and they can estimate the contribution of steel fibers to the total shear strength of the SFRC member. The performances of all the models proposed in this study were also evaluated by a large number of test results. The contribution of steel fibers to the shear strength varied from 5% to 50% according to their amount, and the most optimized volume fraction of steel fibers was estimated as 1%–1.5%, in terms of shear performance. PMID:28788364

  11. Shear Behavior Models of Steel Fiber Reinforced Concrete Beams Modifying Softened Truss Model Approaches.

    PubMed

    Hwang, Jin-Ha; Lee, Deuck Hang; Ju, Hyunjin; Kim, Kang Su; Seo, Soo-Yeon; Kang, Joo-Won

    2013-10-23

    Recognizing that steel fibers can supplement the brittle tensile characteristics of concrete, many studies have been conducted on the shear performance of steel fiber reinforced concrete (SFRC) members. However, previous studies were mostly focused on the shear strength and proposed empirical shear strength equations based on their experimental results. Thus, this study attempts to estimate the strains and stresses in steel fibers by considering the detailed characteristics of steel fibers in SFRC members, from which more accurate estimation on the shear behavior and strength of SFRC members is possible, and the failure mode of steel fibers can be also identified. Four shear behavior models for SFRC members have been proposed, which have been modified from the softened truss models for reinforced concrete members, and they can estimate the contribution of steel fibers to the total shear strength of the SFRC member. The performances of all the models proposed in this study were also evaluated by a large number of test results. The contribution of steel fibers to the shear strength varied from 5% to 50% according to their amount, and the most optimized volume fraction of steel fibers was estimated as 1%-1.5%, in terms of shear performance.

  12. Damage Evaluation in Shear-Critical Reinforced Concrete Beam using Piezoelectric Transducers as Smart Aggregates

    NASA Astrophysics Data System (ADS)

    Chalioris, Constantin E.; Papadopoulos, Nikos A.; Angeli, Georgia M.; Karayannis, Chris G.; Liolios, Asterios A.; Providakis, Costas P.

    2015-10-01

    Damage detection at early cracking stages in shear-critical reinforced concrete beams, before further deterioration and their inevitable brittle shear failure is crucial for structural safety and integrity. The effectiveness of a structural health monitoring technique using the admittance measurements of piezoelectric transducers mounted on a reinforced concrete beam without shear reinforcement is experimentally investigated. Embedded "smart aggregate" transducers and externally bonded piezoelectric patches have been placed in arrays at both shear spans of the beam. Beam were tested till total shear failure and monitored at three different states; healthy, flexural cracking and diagonal cracking. Test results showed that transducers close to the critical diagonal crack provided sound and graduated discrepancies between the admittance responses at the healthy state and thedamage levels.Damage assessment using statistical indices calculated from the measurements of all transducers was also attempted. Rational changes of the index values were obtained with respect to the increase of the damage. Admittance responses and index values of the transducers located on the shear span where the critical diagonal crack formed provided cogent evidence of damage. On the contrary, negligible indication of damage was yielded by the responses of the transducers located on the other shear span, where no diagonal cracking occurred.

  13. Shear strength of non-shear reinforced concrete elements. Part 3: Prestressed hollow-core slabs

    SciTech Connect

    Hoang, L.C.

    1997-12-31

    This paper deals with the shear strength of prestressed hollow-core slabs determined by the theory of plasticity. Two failure mechanisms are considered in order to derive the solutions. In the case of sliding failure in a diagonal crack, the shear strength is determined by means of the crack sliding model developed by Jin-Ping Zhang. The model takes into account the resistance against the formation of cracks due to prestressing as well as the variation of the prestressing force in the transfer zone. Due to the fact that the anchorage of the reinforcement takes place by bond, a rotation failure, which is indeed by a crack formed at the support with subsequent slip of the reinforcement, is also considered. This failure mode is likely to occur in cases with a high prestressing force combined with a short shear span. The theoretical calculations are compared with test results form the literature. A good agreement has been found.

  14. Experimental studies on behavior of fully grouted reinforced-concrete masonry shear walls

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Wang, Fenglai

    2015-12-01

    An experimental study is conducted on fully grouted reinforced masonry shear walls (RMSWs) made from concrete blocks with a new configuration. Ten RMSWs are tested under reversed cyclic lateral load to investigate the influence of different reinforcements and applied axial stress values on their seismic behavior. The results show that flexural strength increases with the applied axial stress, and shear strength dominated by diagonal cracking increases with both the amount of horizontal reinforcement and applied axial stress. Yield displacement, ductility, and energy dissipation capability can be improved substantially by increasing the amount of horizontal reinforcement. The critical parameters for the walls are derived from the experiment: displacement ductility values corresponding to 15% strength degradation of the walls reach up to 2.6 and 4.5 in the shear and flexure failure modes, respectively; stiffness values of flexure- and shear-dominated walls rapidly degrade to 17%-19% and 48%-57% of initial stiffness at 0.50 D max (displacement at peak load). The experiment suggests that RMSWs could be assigned a higher damping ratio (˜14%) for collapse prevention design and a lower damping value (˜7%) for a fully operational limit state or serviceability limit state.

  15. Pushover analysis of reinforced concrete frames considering shear failure at beam-column joints

    NASA Astrophysics Data System (ADS)

    Sung, Y. C.; Lin, T. K.; Hsiao, C. C.; Lai, M. C.

    2013-09-01

    Since most current seismic capacity evaluations of reinforced concrete (RC) frame structures are implemented by either static pushover analysis (PA) or dynamic time history analysis, with diverse settings of the plastic hinges (PHs) on such main structural components as columns, beams and walls, the complex behavior of shear failure at beam-column joints (BCJs) during major earthquakes is commonly neglected. This study proposes new nonlinear PA procedures that consider shear failure at BCJs and seek to assess the actual damage to RC structures. Based on the specifications of FEMA-356, a simplified joint model composed of two nonlinear cross struts placed diagonally over the location of the plastic hinge is established, allowing a sophisticated PA to be performed. To verify the validity of this method, the analytical results for the capacity curves and the failure mechanism derived from three different full-size RC frames are compared with the experimental measurements. By considering shear failure at BCJs, the proposed nonlinear analytical procedures can be used to estimate the structural behavior of RC frames, including seismic capacity and the progressive failure sequence of joints, in a precise and effective manner.

  16. Composite Behavior of a Novel Insulated Concrete Sandwich Wall Panel Reinforced with GFRP Shear Grids: Effects of Insulation Types.

    PubMed

    Kim, JunHee; You, Young-Chan

    2015-03-03

    A full-scale experimental program was used in this study to investigate the structural behavior of novel insulated concrete sandwich wall panels (SWPs) reinforced with grid-type glass-fiber-reinforced polymer (GFRP) shear connectors. Two kinds of insulation-expanded polystyrene (EPS) and extruded polystyrene (XPS) with 100 mm thickness were incased between the two concrete wythes to meet the increasing demand for the insulation performance of building envelope. One to four GFRP shear grids were used to examine the degree of composite action of the two concrete wythes. Ten specimens of SWPs were tested under displacement control subjected to four-point concentrated loads. The test results showed that the SWPs reinforced with GFRP grids as shear connectors developed a high degree of composite action resulting in high flexural strength. The specimens with EPS foam exhibited an enhanced load-displacement behavior compared with the specimens with XPS because of the relatively stronger bond between insulation and concrete. In addition, the ultimate strength of the test results was compared to the analytical prediction with the mechanical properties of only GRFP grids. The specimens with EPS insulation presented higher strength-based composite action than the ones with XPS insulation.

  17. Composite Behavior of a Novel Insulated Concrete Sandwich Wall Panel Reinforced with GFRP Shear Grids: Effects of Insulation Types

    PubMed Central

    Kim, JunHee; You, Young-Chan

    2015-01-01

    A full-scale experimental program was used in this study to investigate the structural behavior of novel insulated concrete sandwich wall panels (SWPs) reinforced with grid-type glass-fiber-reinforced polymer (GFRP) shear connectors. Two kinds of insulation-expanded polystyrene (EPS) and extruded polystyrene (XPS) with 100 mm thickness were incased between the two concrete wythes to meet the increasing demand for the insulation performance of building envelope. One to four GFRP shear grids were used to examine the degree of composite action of the two concrete wythes. Ten specimens of SWPs were tested under displacement control subjected to four-point concentrated loads. The test results showed that the SWPs reinforced with GFRP grids as shear connectors developed a high degree of composite action resulting in high flexural strength. The specimens with EPS foam exhibited an enhanced load-displacement behavior compared with the specimens with XPS because of the relatively stronger bond between insulation and concrete. In addition, the ultimate strength of the test results was compared to the analytical prediction with the mechanical properties of only GRFP grids. The specimens with EPS insulation presented higher strength-based composite action than the ones with XPS insulation. PMID:28787978

  18. Effects of Shear Stirrup Details on Ultimate Capacity and Tensile Membrane Behavior of Reinforced Concrete Slabs

    DTIC Science & Technology

    1985-08-01

    were not due to reinforcement strain hardening, tensile strength of concrete, or catenary actions. It was concluded that the increase in load capacity...was due to the development of inplane compressive forces, termed " arching " or "dome action." Experimental research using uniformly loaded beams or one...strength of the concrete governs and if the plate is " restrained, arching or compressive membrane behavior occurs. However, at large deformations, the

  19. Effects of shear stirrup details on ultimate capacity and tensile-membrane behavior of reinforced concrete slabs. Final report

    SciTech Connect

    Woodson, S.C.

    1985-08-01

    At the time this study was initiated, civil defense planning in the United States called for the evacuation of nonessential personnel to safe host areas when a nuclear attack is probable, requiring the construction of blasts shelters to protect the keyworkers remaining in the risk areas. The placement of shear stirrups in the one-way reinforced concrete roof slabs of the shelters will contribute significantly to project costs. Ten one-way reinforced concrete slabs were statically and uniformly loaded with water pressure, primarily to investigate the effect of stirrups and stirrup details on the load-response behavior of the slabs. The slabs had clear spans of 24.0 inches, span to effective depth ratios of 12.4, tensile reinforcement of 0.75%, and concrete strengths of approximately 5,000 psi. The test series significantly increased the data base for uniformly loaded one-way slabs. Support rotations between 13.1 and 20.6 degrees were observed. A more ductile behavior was observed in slabs with construction details, implying better concrete confinement due to more confining steel (i.e., closely spaced stirrups, double-leg stirrups, and closely spaced principal reinforcing bars). The parameters investigated did not appear to have a significant effect on ultimate load capacity.

  20. The Effect of Shear Wall Distribution on the Dynamics of Reinforced Concrete Structures

    SciTech Connect

    Helou, S. H.; Touqan, A. R.

    2008-07-08

    The inclusion of a soft storey in multistory concrete buildings is a feature gaining popularity in urban areas where land is of exorbitant cost. In earthquake prone zones, this feature has been observed in post earthquake investigations. Although engineers are prepared to accept the notion that a soft storey poses a weak link in Seismic Design, yet the idea demands better understanding. The following study illustrates the importance of the judicious distribution of shear walls. The selected building is analyzed through nine numerical models which address the behavior of framed structures. The parameters discussed include, inter alias, the fundamental period of vibration, lateral displacements, axial and shear forces. It is noticed that an abrupt change in stiffness between the soft storey and the level above is responsible for increasing the strength demand on first storey columns. Extending the elevator shafts throughout the soft storey is strongly recommended.

  1. The Effect of Shear Wall Distribution on the Dynamics of Reinforced Concrete Structures

    NASA Astrophysics Data System (ADS)

    Helou, S. H.; Touqan, A. R.

    2008-07-01

    The inclusion of a soft storey in multistory concrete buildings is a feature gaining popularity in urban areas where land is of exorbitant cost. In earthquake prone zones, this feature has been observed in post earthquake investigations. Although engineers are prepared to accept the notion that a soft storey poses a weak link in Seismic Design, yet the idea demands better understanding. The following study illustrates the importance of the judicious distribution of shear walls. The selected building is analyzed through nine numerical models which address the behavior of framed structures. The parameters discussed include, inter alias, the fundamental period of vibration, lateral displacements, axial and shear forces. It is noticed that an abrupt change in stiffness between the soft storey and the level above is responsible for increasing the strength demand on first storey columns. Extending the elevator shafts throughout the soft storey is strongly recommended.

  2. Shear reinforcement effect of reinforced concrete tie-columns on the lateral resistance of confined masonry walls

    NASA Astrophysics Data System (ADS)

    Bouhedja, Samir; Bourzam, Abdelkrim; Boukhaled, Ahmed; Nechnech, Ammar

    2016-06-01

    Tie-columns improve significantly the lateral resistance of masonry bearing walls against persistent, transient and accidental loads. The research work described herein has been carried out to assess the lateral resistance of confined masonry walls, where contribution of the masonry panel is evaluated according to material mechanics and tie-columns effect is estimated by a proposed analytical formulation based on a model reported on previously. This approach takes into account the effect of dowel support on the reaction of its adjacent shear reinforcement: the conditions for the various contributions of transverse reinforcements are better defined following a clear evaluation of the participation ratio of these reinforcements. Lateral resistances of confined masonry walls measured in full-scale tests and gleaned from the literature are compared and checked with resistances calculated using the present approach.

  3. Reinforced Concrete Modeling

    DTIC Science & Technology

    1982-07-01

    AFWL-TR-82-9 AFWL-TR-82-9 REINFORCED CONCRETE MODELING H. L. Schreyer J. W. Jeter, Jr. New Mexico Engineering Reseprch Institute University of New...Subtitle) S. TYPE OF REPORT & PERIOD COVERED REINFORCED CONCRETE MODELING Final Report 6. PERFORMING OtG. REPORT NUMBER NMERI TA8-9 7. AUTHORg) S...loading were identified and used to evaluate current concrete models . Since the endochronic and viscoplastic models provide satisfactory descriptions

  4. Experimental and numerical investigations of higher mode effects on seismic inelastic response of reinforced concrete shear walls

    NASA Astrophysics Data System (ADS)

    Ghorbanirenani, Iman

    This thesis presents two experimental programs together with companion numerical studies that were carried out on reinforced concrete shear walls: static tests and dynamic (shake table) tests. The first series of experiments were monotonic and cyclic quasi-static testing on ductile reinforced concrete shear wall specimens designed and detailed according to the seismic provisions of NBCC 2005 and CSA-A23.3-04 standard. The tests were carried out on full-scale and 1:2.37 reduced scale wall specimens to evaluate the seismic design provisions and similitude law and determine the appropriate scaling factor that could be applied for further studies such as dynamic tests. The second series of experiments were shake table tests conducted on two identical 1:2.33 scaled, 8-storey moderately ductile reinforced concrete shear wall specimens to investigate the effects of higher modes on the inelastic response of slender walls under high frequency ground motions expected in Eastern North America. The walls were designed and detailed according to the seismic provisions of NBCC 2005 and CSA-A23.3-04 standard. The objectives were to validate and understand the inelastic response and interaction of shear, flexure and axial loads in plastic hinge zones of the walls considering the higher mode effects and to investigate the formation of second hinge in upper part of the wall due to higher mode responses. Second mode response significantly affected the response of the walls. This caused inelastic flexural response to develop at the 6th level with approximately the same rotation ductility compared to that observed at the base. Dynamic amplification of the base shear forces was also observed in both walls. Numerical modeling of these two shake table tests was performed to evaluate the test results and validate current modeling approaches. Nonlinear time history analyses were carried out by the reinforced concrete fibre element (OpenSees program) and finite element (VecTor2 program

  5. STRUCTURAL PERFORMANCE OF DEGRADED REINFORCED CONCRETE MEMBERS.

    SciTech Connect

    Braverman, J.I.; Miller, C.A.; Ellingwood, B.R.; Naus, D.J.; Hofmayer, C.H.; Bezler, P.; Chang, T.Y.

    2001-03-22

    This paper describes the results of a study to evaluate, in probabilistic terms, the effects of age-related degradation on the structural performance of reinforced concrete members at nuclear power plants. The paper focuses on degradation of reinforced concrete flexural members and shear walls due to the loss of steel reinforcing area and loss of concrete area (cracking/spalling). Loss of steel area is typically caused by corrosion while cracking and spalling can be caused by corrosion of reinforcing steel, freeze-thaw, or aggressive chemical attack. Structural performance in the presence of uncertainties is depicted by a fragility (or conditional probability of failure). The effects of degradation on the fragility of reinforced concrete members are calculated to assess the potential significance of various levels of degradation. The fragility modeling procedures applied to degraded concrete members can be used to assess the effects of degradation on plant risk and can lead to the development of probability-based degradation acceptance limits.

  6. Residual Strength of Blast Damaged Reinforced Concrete Columns

    DTIC Science & Technology

    2010-07-01

    both reinforced concrete columns and shear walls during seismic investigations [14]. 4.2.3. Effect of longitudinal reinforcement ratio As the...Residual strength of blast damaged reinforced concrete columns Xiaoli Bao, Bing Li* School of Civil and Environmental Engineering, Nanyang...DATES COVERED - 4. TITLE AND SUBTITLE Residual strength of blast damaged reinforced concrete columns 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

  7. Strength Design of Reinforced Concrete Hydraulic Structures: Report 8. Design of Buried Circular Conduits - Flexure and Shear

    DTIC Science & Technology

    1989-09-01

    American Concrete Pipe Association ( ACPA ) that will be discussed. The ACPA studies have resulted in design criteria for the effects of radial tension...7 (Gerstle, i988) for flexural strength with the radial tension and shear criteria developed by ACPA . The procedure uses the EM loading distribution... ACPA (Heger, Liepins, and Selig, 1985). The computer program called SPIDA (Soil-Pipe Interaction Design and Analysis) incorporates multiple finite

  8. Fiber reinforced concrete solar collector

    SciTech Connect

    Slemmons, A. J.; Newgard, P. J.

    1985-05-07

    A solar collector is disclosed comprising a glass member having a solar selective coating thereon, and a molded, glass-reinforced concrete member bonded to the glass member and shaped to provide a series of passageways between the glass member and the fiber-reinforced concrete member capable of carrying heat exchanging fluid therethrough. The fiber-reinforced concrete member may be formed by spraying a thin layer of concrete and chopped fibers such as chopped glass fibers onto a mold to provide an inexpensive and lightweight, thin-walled member. The fiber-reinforced concrete member may have a lightweight cellular concrete backing thereon for insulation purposes. The collector is further characterized by the use of materials which have substantially matching thermal coefficients of expansion over the temperature range normally encountered in the use of solar collectors.

  9. Optimization of reinforced concrete slabs

    NASA Technical Reports Server (NTRS)

    Ferritto, J. M.

    1979-01-01

    Reinforced concrete cells composed of concrete slabs and used to limit the effects of accidental explosions during hazardous explosives operations are analyzed. An automated design procedure which considers the dynamic nonlinear behavior of the reinforced concrete of arbitrary geometrical and structural configuration subjected to dynamic pressure loading is discussed. The optimum design of the slab is examined using an interior penalty function. The optimization procedure is presented and the results are discussed and compared with finite element analysis.

  10. Optimization of reinforced concrete slabs

    NASA Technical Reports Server (NTRS)

    Ferritto, J. M.

    1979-01-01

    Reinforced concrete cells composed of concrete slabs and used to limit the effects of accidental explosions during hazardous explosives operations are analyzed. An automated design procedure which considers the dynamic nonlinear behavior of the reinforced concrete of arbitrary geometrical and structural configuration subjected to dynamic pressure loading is discussed. The optimum design of the slab is examined using an interior penalty function. The optimization procedure is presented and the results are discussed and compared with finite element analysis.

  11. Shear Resistance between Concrete-Concrete Surfaces

    NASA Astrophysics Data System (ADS)

    Kovačovic, Marek

    2013-12-01

    The application of precast beams and cast-in-situ structural members cast at different times has been typical of bridges and buildings for many years. A load-bearing frame consists of a set of prestressed precast beams supported by columns and diaphragms joined with an additionally cast slab deck. This article is focused on the theoretical and experimental analyses of the shear resistance at an interface. The first part of the paper deals with the state-of-art knowledge of the composite behaviour of concrete-concrete structures and a comparison of the numerical methods introduced in the relevant standards. In the experimental part, a set of specimens with different interface treatments was tested until failure in order to predict the composite behaviour of coupled beams. The experimental part was compared to the numerical analysis performed by means of FEM basis nonlinear software.

  12. Corrosion control of steel-reinforced concrete

    NASA Astrophysics Data System (ADS)

    Chung, D. D. L.

    2000-10-01

    The methods and materials for corrosion control of steel-reinforced concrete are reviewed. The methods are steel surface treatment, the use of admixtures in concrete, surface coating on concrete, and cathodic protection.

  13. Prestressed concrete using KEVLAR reinforced tendons

    SciTech Connect

    Dolan, C.W.

    1989-01-01

    KEVLAR is a high strength, high modulus synthetic fiber manufactured by the E.I. DuPont de Nemours Company. The fiber is resistant to chloride and alkali attack. The resistance is enhanced when the fibers are assembled into a resin matrix and fabricated as rods. These properties suggest that KEVLAR reinforced rods may be a substitute for high strength steel prestress tendons in certain applications such as bridge decks and parking structures. This dissertation presents the background, theoretical development, and experimental investigations of KEVLAR reinforced rod strength, anchorage, fabrication and performance in prestressed concrete structures. The study concludes that KEVLAR has significant potential for these prestressed concrete applications. However, the reliability of the long term anchorage of the KEVLAR reinforced rods must be improved before production applications are undertaken. KEVLAR has a low shear strength compared to its tensile capacity. The anchorage of KEVLAR reinforced rods is sensitive to the shear forces generated in the anchorage assembly. Finite element analyses, using interface elements to simulate the addition of a mold release agent in a conic anchor, predict the behavior of resin socketed anchors. Test results confirm that mold release agents reduce the anchor shear stresses and suggest that moderate strength resins may be used in the anchor. KEVLAR is nearly linearly elastic to failure, yet ductility of a structure is an important design concern. Prestressed concrete beam tests using both bonded and unbonded tendons demonstrated that ductile structural behavior is obtained. Methods of predicting the strength and deflection behavior of the prestressed beams are presented and the theoretical predictions are compared to the experimental results. The overall correlation between predicted and theoretical results is satisfactory.

  14. Study on shear behavior of FRP strengthened concrete beams

    NASA Astrophysics Data System (ADS)

    Zhao, J. K.; Xu, X. S.

    2017-04-01

    There are many researches on concrete bending beams reinforced with FRP, and the beam section of the bending strength is enhanced, it is necessary to carry out an oblique section bearing capacity review, if the bearing capacity is insufficient, it is also necessary to strengthen, so as to ensure the ductility of the beam and meet the needs of Engineering safety. In this paper, four concrete beams strengthened with different fibers (CFRP, HFRP and GFRP) were used to study the stress characteristics, failure forms, reasonable reinforcement methods, beam strain conditions, bearing capacity, stiffness and deformation capacity of shear behavior of concrete beams strengthened with different fibers and different forms of reinforcement. The experimental results showed that the FRP reinforcement can not only improve the shear bearing capacity and ultimate deformation of beam, but also increase the stiffness of the beam, reduce the bending deformation under the same load beam, and delay the extension of diagonal cracks.

  15. Computed tomography assessment of reinforced concrete

    SciTech Connect

    Martz, H.E.; Schneberk, D.J.; Roberson, G.P.; Monteiro, J.M.

    1991-05-24

    Gamma-ray computed tomography (CT) is potentially powerful nondestructive method for assessing the degree of distress that exists in reinforced-concrete structures. In a study to determine the feasibility of using CT to inspect reinforced-concrete specimens, we verified that CT can quantitatively image the internal details of reinforced concrete. To assess the accuracy of CT in determining voids and cracks, we inspected two fiber-reinforced concrete cylinders (one loaded and one unloaded) and a third cylinder containing a single reinforcing bar (rebar). To evaluate the accuracy of CT in establishing the location of reinforcing bars, we also inspected a concrete block containing rebars with different diameters. The results indicate that CT was able to revolve the many different phases in reinforced concrete (voids, cracks, rebars, and concrete) with great accuracy. 15 refs., 10 figs.

  16. 10. CONCRETE BRIDGE, REINFORCED BEAM TYPE ON CONCRETE, SOUTH CAROLINA ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. CONCRETE BRIDGE, REINFORCED BEAM TYPE ON CONCRETE, SOUTH CAROLINA STATE HIGHWAY DEPARTMENT, COLUMBIA, SOUTH CAROLINA (photocopy of drawing) - Salkehatchie Bridge, State Route No. 64 spanning Salkehatchie River, Barnwell, Barnwell County, SC

  17. Behaviour of concrete beams reinforced withFRP prestressed concrete prisms

    NASA Astrophysics Data System (ADS)

    Svecova, Dagmar

    The use of fibre reinforced plastics (FRP) to reinforce concrete is gaining acceptance. However, due to the relatively low modulus of FRP, in comparison to steel, such structures may, if sufficient amount of reinforcement is not used, suffer from large deformations and wide cracks. FRP is generally more suited for prestressing. Since it is not feasible to prestress all concrete structures to eliminate the large deflections of FRP reinforced concrete flexural members, researchers are focusing on other strategies. A simple method for avoiding excessive deflections is to provide sufficiently high amount of FRP reinforcement to limit its stress (strain) to acceptable levels under service loads. This approach will not be able to take advantage of the high strength of FRP and will be generally uneconomical. The current investigation focuses on the feasibility of an alternative strategy. This thesis deals with the flexural and shear behaviour of concrete beams reinforced with FRP prestressed concrete prisms. FRP prestressed concrete prisms (PCP) are new reinforcing bars, made by pretensioning FRP and embedding it in high strength grout/concrete. The purpose of the research is to investigate the feasibility of using such pretensioned rebars, and their effect on the flexural and shear behaviour of reinforced concrete beams over the entire loading range. Due to the prestress in the prisms, deflection of concrete beams reinforced with this product is substantially reduced, and is comparable to similarly steel reinforced beams. The thesis comprises both theoretical and experimental investigations. In the experimental part, nine beams reinforced with FRP prestressed concrete prisms, and two companion beams, one steel and one FRP reinforced were tested. All the beams were designed to carry the same ultimate moment. Excellent flexural and shear behaviour of beams reinforced with higher prestressed prisms is reported. When comparing deflections of three beams designed to have the

  18. Structural Behavior of Concrete Beams Reinforced with Basalt Fiber Reinforced Polymer (BFRP) Bars

    NASA Astrophysics Data System (ADS)

    Ovitigala, Thilan

    The main challenge for civil engineers is to provide sustainable, environmentally friendly and financially feasible structures to the society. Finding new materials such as fiber reinforced polymer (FRP) material that can fulfill the above requirements is a must. FRP material was expensive and it was limited to niche markets such as space shuttles and air industry in the 1960s. Over the time, it became cheaper and spread to other industries such as sporting goods in the 1980-1990, and then towards the infrastructure industry. Design and construction guidelines are available for carbon fiber reinforced polymer (CFRP), aramid fiber reinforced polymer (AFRP) and glass fiber reinforced polymer (GFRP) and they are currently used in structural applications. Since FRP is linear elastic brittle material, design guidelines for the steel reinforcement are not valid for FRP materials. Corrosion of steel reinforcement affects the durability of the concrete structures. FRP reinforcement is identified as an alternative to steel reinforcement in corrosive environments. Although basalt fiber reinforced polymer (BFRP) has many advantages over other FRP materials, but limited studies have been done. These studies didn't include larger BFRP bar diameters that are mostly used in practice. Therefore, larger beam sizes with larger BFRP reinforcement bar diameters are needed to investigate the flexural and shear behavior of BFRP reinforced concrete beams. Also, shear behavior of BFRP reinforced concrete beams was not yet studied. Experimental testing of mechanical properties and bond strength of BFRP bars and flexural and shear behavior of BFRP reinforced concrete beams are needed to include BFRP reinforcement bars in the design codes. This study mainly focuses on the use of BFRP bars as internal reinforcement. The test results of the mechanical properties of BFRP reinforcement bars, the bond strength of BFRP reinforcement bars, and the flexural and shear behavior of concrete beams

  19. Behavior of reinforced concrete at elevated temperatures

    SciTech Connect

    Freskakis, G.N.

    1984-09-01

    A study is presented concerning the behavior of reinforced concrete sections at elevated temperatures. Material properties of concrete and reinforcing steel are discussed. Behavior studies are made by means of moment-curvature-axial force relationships. Particular attention is given to the load carrying capacity, thermal forces and moments, and deformation capacity. The effects on these properties of variations in the strength properties, the temperature level and distribution, the amount of reinforcing steel, and limiting values of strains are considered.

  20. REVERSAL CYCLIC LOADING TEST OF REINFORCED CONCRETE COLUMN WITH HIGH DENSITY LONGITUDINAL REINFORCEMENT CONFINED BY SPIRAL REINFORCEMENT

    NASA Astrophysics Data System (ADS)

    Ohba, Mitsuaki; Sato, Akiko; Ishibashi, Tadayoshi

    In case of that column diameter is restricted by the narrow construction space, Concrete filled steel tube column is used. Authors developed new arrangement of bars that the range of longitudinal reinforcement ratio is from 14.8% to 24.7% and the longitudinal reinforcements are reinforced by spiral reinforcement. For the confirmation of the damage form and the deformation performance of the column with new bar arrangement at the earthquake, static reversal cyclic loading test was carried out. The parameters are longitudinal reinforcement ratio, shear span ratio and strength ratio. As the result, the damage form showed different trends due to longitudinal reinforcement ratio, shear span ratio and flexural strength and shear strength ratio. And specimens with the new bar arrangement had a good ductility with rotation angle of the column more than 1/10 and no rapid decline of strength. And, it is possible to evaluate ultimate bending capacity by considering the damage situation at maximum load.

  1. Sectional analysis of reinforced concrete members

    NASA Astrophysics Data System (ADS)

    Bentz, Evan C.

    2000-10-01

    Four easy to use programs have been written that allow for state of the art sectional analysis of reinforced concrete blocks, plates, beams, columns and shells. Unlike most sectional analysis programs, these programs include the effects of shear on behaviour. They are based on the assumption that plane sections remain plane, that there is no transverse clamping stress, and that the biaxial behaviour can be modelled well by the Modified Compression Field Theory (MCFT). Each of these assumptions is shown to be reasonable. The programs are freely available on the World Wide Web at the listed addresses: http://www.ecf.utoronto.ca/ ˜bentz/m2k.htm Membrane-2000 for plates http://www.ecf.utoronto.ca/ ˜bentz/r2k.htm Response-2000 for beams and columns http://www.ecf.utoronto.ca/ ˜bentz/t2k.htm Triax-2000 for 3D blocks http://www.ecf.utoronto.ca/ ˜bentz/s2k.htm Shell-2000: shells with out-of-plane forces This thesis describes the MCFT in detail as implemented in the programs as well as explaining new constitutive relations employed for the behaviour of concrete in tension. The strongest feature of the new programs is the employment of the longitudinal stiffness method, developed for this thesis, which calculates the shear stress profile for a beam or shell much faster and with more numerical stability than the previous state of the art. The programs are verified against a set of experiments as well as against two new shear experiments performed for this thesis. They indicate the programs are good at predicting the behaviour of the elements. Response-2000 is compared to a database of 534 beams and shown to predict shear strengths with an average experimental over predicted shear strength ratio of 1.05 and with a coefficient of variation of 12%. This compares favourably to the ACI code prediction ratios that have an average of 1.20 and a coefficient of variation of 32%. It is suggested that the programs in this thesis represent a good first step in allowing rational

  2. Composite Grids for Reinforcement of Concrete Structures.

    DTIC Science & Technology

    1998-06-01

    spiral deformation to provide a good bond between reinforcement and concrete. Research conducted by Larralde et al. (1989) investigated the...the stiffness of the steel-reinforced beams. Larralde and Zervai (1991) took a different approach by comparing the flexural behavior of FRP grating...Cincinnati, OH, Jan 30- Feb 1,1995. Session 21C. Larralde , AM. and Zerva, A., (1991). "Load/deflection Performance of FRP Grating-Concrete Composites

  3. Durable fiber reinforced self-compacting concrete

    SciTech Connect

    Corinaldesi, V.; Moriconi, G

    2004-02-01

    In order to produce thin precast elements, a self-compacting concrete was prepared. When manufacturing these elements, homogenously dispersed steel fibers instead of ordinary steel-reinforcing mesh were added to the concrete mixture at a dosage of 10% by mass of cement. An adequate concrete strength class was achieved with a water to cement ratio of 0.40. Compression and flexure tests were carried out to assess the safety of these thin concrete elements. Moreover, serviceability aspects were taken into consideration. Firstly, drying shrinkage tests were carried out in order to evaluate the contribution of steel fibers in counteracting the high concrete strains due to a low aggregate-cement ratio. Secondly, the resistance to freezing and thawing cycles was investigated on concrete specimens in some cases superficially treated with a hydrophobic agent. Lastly, both carbonation and chloride penetration tests were carried out to assess durability behavior of this concrete mixture.

  4. Bond of fiber reinforced plastic (FRP) rods to concrete

    SciTech Connect

    Al-Zahrani, M.M.; Nanni, A.; Al-Dulaijan, S.U.; Bakis, C.E.

    1996-11-01

    The bond behavior between FRP rods and concrete is one of the most important aspects to predicting the short- and long-term performance of FRP reinforced concrete structures including development and transfer length. In this research, the direct pull-out test was used to study the FRP/concrete bond behavior. This method allows measurement of the loaded- and free-end slip of the FRP rod and placement of a strain probe inside the rod to measure internal strain distribution in both axial and radial directions along the bonded length without affecting the FRP/concrete interface. Knowledge of strain distribution is necessary to study the load transfer mechanism between FRP rod and concrete. The scope of this paper include experimental results obtained with the direct pull-out test using 12.7 mm glass and carbon FRP rods with smooth and axisymmetrical deformed surfaces. The typical results are given as nominal bond and shear stress vs. free- and loaded-end slip. Experimental results obtained from strain probes used during pull-out tests are also presented as nominal bond and shear stress vs. strain. For smooth rods, friction is the main controlling factor. For deformed rods, bond tends to be controlled by strength and mechanical action of the axisymmetrical deformations rather than adhesion and friction. The strength of concrete appears to have no effect on the bond strength and failure mechanism of these particular machined FRP rods when concrete splitting is avoided.

  5. Braided reinforced composite rods for the internal reinforcement of concrete

    NASA Astrophysics Data System (ADS)

    Gonilho Pereira, C.; Fangueiro, R.; Jalali, S.; Araujo, M.; Marques, P.

    2008-05-01

    This paper reports on the development of braided reinforced composite rods as a substitute for the steel reinforcement in concrete. The research work aims at understanding the mechanical behaviour of core-reinforced braided fabrics and braided reinforced composite rods, namely concerning the influence of the braiding angle, the type of core reinforcement fibre, and preloading and postloading conditions. The core-reinforced braided fabrics were made from polyester fibres for producing braided structures, and E-glass, carbon, HT polyethylene, and sisal fibres were used for the core reinforcement. The braided reinforced composite rods were obtained by impregnating the core-reinforced braided fabric with a vinyl ester resin. The preloading of the core-reinforced braided fabrics and the postloading of the braided reinforced composite rods were performed in three and two stages, respectively. The results of tensile tests carried out on different samples of core-reinforced braided fabrics are presented and discussed. The tensile and bending properties of the braided reinforced composite rods have been evaluated, and the results obtained are presented, discussed, and compared with those of conventional materials, such as steel.

  6. Behavior of Partially Restrained Reinforced Concrete Slabs.

    DTIC Science & Technology

    1986-09-01

    Experimental Deflections and Coupling Forces. ........ 72 3.4 Method of Approximating Support Rotations . . . 76 3.5 Free-Body Diagram Used in Computing...common types of structural elements. Slabs are found in practically every type of structural system, ’ whether steel or concrete, single -story or...Because of the nature of reinforced concrete slabs, accurate evaluations of stresses, strains, and deflections are difficult to make by elasticity

  7. Shear and shear friction of ultra-high performance concrete bridge girders

    NASA Astrophysics Data System (ADS)

    Crane, Charles Kennan

    Ultra-High Performance Concrete (UHPC) is a new class of concrete characterized by no coarse aggregate, steel fiber reinforcement, low w/c, low permeability, compressive strength exceeding 29,000 psi (200 MPa), tensile strength ranging from 1,200 to 2,500 psi (8 to 17 MPa), and very high toughness. These properties make prestressed precast UHPC bridge girders a very attractive replacement material for steel bridge girders, particularly when site demands require a comparable beam depth to steel and a 100+ year life span is desired. In order to efficiently utilize UHPC in bridge construction, it is necessary to create new design recommendations for its use. The interface between precast UHPC girder and cast-in-place concrete decks must be characterized in order to safely use composite design methods with this new material. Due to the lack of reinforcing bars, all shear forces in UHPC girders have to be carried by the concrete and steel fibers. Current U.S. codes do not consider fiber reinforcement in calculating shear capacity. Fiber contribution must be accurately accounted for in shear equations in order to use UHPC. Casting of UHPC may cause fibers to orient in the direction of casting. If fibers are preferentially oriented, physical properties of the concrete may also become anisotropic, which must be considered in design. The current research provides new understanding of shear and shear friction phenomena in UHPC including: (1) Current AASHTO codes provide a non-conservative estimate of interface shear performance of smooth UHPC interfaces with and without interface steel. (2) Fluted interfaces can be created by impressing formliners into the surface of plastic UHPC. AASHTO and ACI codes for roughened interfaces are conservative for design of fluted UHPC interfaces.(3) A new equation for the calculation of shear capacity of UHPC girders is presented which takes into account the contribution of steel fiber reinforcement. (4) Fibers are shown to preferentially

  8. Detection and Identification of Concrete Cracking in Reinforced Concrete by Acoustic Emission

    NASA Astrophysics Data System (ADS)

    Ohtsu, Masayasu

    2003-03-01

    Cracking in concrete due to corrosion of rebars in reinforced concrete is one of critical problems in concrete structures. To clarify cracking process, acoustic emission (AE) measurement is applied. In an accelerated corrosion test, AE events are detected and monitored continuously. Comparing with permeation of chloride ions, it is found that onset of corrosion and nucleation of cracking can be qualified from AE activity. Applying SiGMA procedure, nucleation mechanisms of cracks due to expansion of corrosive product are identified. During extension of the surface crack, tensile cracks are nucleated dominantly. For the spalling crack, both the tensile and the shear cracks are generated, as the former dominates the latter approaching to a stress-free surface. In contrast, it is found that the internal crack is nucleated mainly due to shear-crack motion.

  9. Aerated concrete with mineral dispersed reinforcing additives

    NASA Astrophysics Data System (ADS)

    Berdov, G. I.; Ilina, L. V.; Mukhina, I. N.; Rakov, M. A.

    2015-01-01

    To guarantee the production of aerated concrete with the lowest average density while ensuring the required strength it is necessary to use a silica component with a surface area of 250-300 m2 / kg. The article presents experimental data on grinding the silica component together with clinker to the optimum dispersion. This allows increasing the strength of non-autoclaved aerated concrete up to 33%. Furthermore, the addition to aerated concrete the mixture of dispersed reinforcing agents (wollastonite, diopside) and electrolytes with multiply charged cations and anions (1% Fe2 (SO4)3; Al2 (SO4)3) provides the growth of aerated concrete strength at 30 - 75%. As a cohesive the clinker, crushed together with silica and mineral supplements should be used. This increases the strength of aerated concrete at 65% in comparing with Portland cement.

  10. Numerical Study Of The Effects Of Preloading, Axial Loading And Concrete Shrinkage On Reinforced Concrete Elements Strengthened By Concrete Layers And Jackets

    SciTech Connect

    Lampropoulos, A. P.; Dritsos, S. E.

    2008-07-08

    In this study, the technique of seismic strengthening existing reinforced concrete columns and beams using additional concrete layers and jackets is examined. The finite element method and the finite element program ATENA is used in this investigation. When a reinforced jacket or layer is being constructed around a column it is already preloaded due to existing service loads. This effect has been examined for different values of the axial load normalized to the strengthened column. The techniques of strengthening with a concrete jacket or a reinforced concrete layer on the compressive side of the column are examined. Another phenomenon that is examined in this study is the shrinkage of the new concrete of an additional layer used to strengthen an existing member. For this investigation, a simply supported beam with an additional reinforced concrete layer on the tensile side is examined. The results demonstrate that the effect of preloading is important when a reinforced concrete layer is being used with shear connectors between the old and the new reinforcement. It was also found that the shrinkage of the new concrete reduces the strength of the strengthened beam and induces an initial sliding between the old and the new concrete.

  11. Numerical Study Of The Effects Of Preloading, Axial Loading And Concrete Shrinkage On Reinforced Concrete Elements Strengthened By Concrete Layers And Jackets

    NASA Astrophysics Data System (ADS)

    Lampropoulos, A. P.; Dritsos, S. E.

    2008-07-01

    In this study, the technique of seismic strengthening existing reinforced concrete columns and beams using additional concrete layers and jackets is examined. The finite element method and the finite element program ATENA is used in this investigation. When a reinforced jacket or layer is being constructed around a column it is already preloaded due to existing service loads. This effect has been examined for different values of the axial load normalized to the strengthened column. The techniques of strengthening with a concrete jacket or a reinforced concrete layer on the compressive side of the column are examined. Another phenomenon that is examined in this study is the shrinkage of the new concrete of an additional layer used to strengthen an existing member. For this investigation, a simply supported beam with an additional reinforced concrete layer on the tensile side is examined. The results demonstrate that the effect of preloading is important when a reinforced concrete layer is being used with shear connectors between the old and the new reinforcement. It was also found that the shrinkage of the new concrete reduces the strength of the strengthened beam and induces an initial sliding between the old and the new concrete.

  12. Seismic evaluation of an underground reinforced concrete tunnel

    SciTech Connect

    Huang, S.N.

    1993-02-01

    An underground reinforced concrete tunnel under the influence of seismic wave propagation was analyzed. Methods previously developed for underground steel pipes were extended to assess the structural integrity of the underground reinforced concrete tunnel.

  13. Fracture Toughness of Fiber Reinforced Concrete.

    DTIC Science & Technology

    1983-06-01

    14, 1979, pp. 443-449. 5 Mindess , S., Lawrence, F. V., and Kesler, C. E., "The J-Integral as a Fracture Criterion for Fiber Reinforced Concrete...34 Cement and Con- crete Research, Vol. 7, 1977 , pp. 731-742. 6 Velazco, G., Visalvanich, K., and Shah, S. P., "Fracture Behavior and Analysis of Fiber

  14. Retrofitting of Reinforced Concrete Beams using Reactive Powder Concrete (RPC)

    NASA Astrophysics Data System (ADS)

    Karthik, S.; Sundaravadivelu, Karthik

    2017-07-01

    Strengthening of existing damaged structures is one of the leading studies in civil engineering. The purpose of retrofitting is to structurally treat the member with an aim to restore the structure to its original strength. The focus of this project is to study the behaviour of damaged Reinforced Concrete beam retrofitted with Reactive Powder Concrete (RPC) Overlay. Reinforced concrete beams of length 1200 mm, width 100 mm and depth 200 mm were casted with M30 grade of concrete in the laboratory and cured for 28 days. One beam is taken as control and are tested under two point loading to find out ultimate load. Remaining beams are subjected to 90 % ultimate load of control beams. The partially damaged beams are retrofitted with Reactive Powder Concrete Overlay at the full tension face of the beam and side overlay depends upon the respectable retrofitting techniques with 10 mm and 20 mm thick layer to find optimum. Materials like steel fibres are added to enhance the ductility by eliminating coarse particle for homogeneity of the structure. Finally, the modes of failure for retrofitted beams are analysed experimentally under two point loading & compared the results with Control beam.

  15. Reinforced Concrete on Constitutive Relations

    DTIC Science & Technology

    1975-02-01

    elements, it can also be applied to homo - geneous elements of plain concrete or rock, etc., by eliminating from the analysis the terms...etc«» »■’)« «»(•BONDING kyrf.9 CRACX ECCao.Ol’fcC ir (ros.u.rt.) Ecc »E»eo^o*Ec KFTURM END KFH 1 HtU 2 Rtb ) RtH 4 HEB 5 REB 6 299

  16. A method for three-dimensional structural analysis of reinforced concrete containment

    SciTech Connect

    Kulak, R.F.; Fiala, C.

    1989-01-01

    A finite element method designed to assist reactor safety analysts in the three-dimensional numerical simulation of reinforced concrete containments to normal and off-normal mechanical loadings is presented. The development of a lined reinforced concrete plate element is described in detail, and the implementation of an empirical transverse shear failure criteria is discussed. The method is applied to the analysis of a 1/6th scale reinforced concrete containment model subjected to static internal pressurization. 11 refs., 14 figs., 1 tab.

  17. Seismic retrofitting of reinforced concrete frame structures using GFRP-tube-confined-concrete composite braces

    NASA Astrophysics Data System (ADS)

    Moghaddasi B., Nasim S.; Zhang, Yunfeng; Hu, Xiaobin

    2012-03-01

    This paper presents a new type of structural bracing intended for seismic retrofitting use in framed structures. This special composite brace, termed glass-fiber-reinforced-polymer (GFRP)-tube-confined-concrete composite brace, is comprised of concrete confined by a GFRP tube and an inner steel core for energy dissipation. Together with a contribution from the GFRP-tube confined concrete, the composite brace shows a substantially increased stiffness to control story drift, which is often a preferred feature in seismic retrofitting. An analysis model is established and implemented in a general finite element analysis program — OpenSees, for simulating the load-displacement behavior of the composite brace. Using this model, a parametric study of the hysteretic behavior (energy dissipation, stiffness, ductility and strength) of the composite brace was conducted under static cyclic loading and it was found that the area ratio of steel core to concrete has the greatest influence among all the parameters considered. To demonstrate the application of the composite brace in seismic retrofitting, a three-story nonductile reinforced concrete (RC) frame structure was retrofitted with the composite braces. Pushover analysis and nonlinear time-history analyses of the retrofitted RC frame structure was performed by employing a suite of 20 strong ground motion earthquake records. The analysis results show that the composite braces can effectively reduce the peak seismic responses of the RC frame structure without significantly increasing the base shear demand.

  18. CP systems for steel reinforced concrete bridges

    SciTech Connect

    Bullard, Sophie J.; Cramer, Stephen D.; Covino, Bernard S., Jr.; Holcomb, Gordon R.; Ziomek-Moroz, Margaret; Soltesz, Steven M.

    2004-01-01

    Thermal-sprayed zinc anodes are used for cathodic protection (CP) systems in Oregon?s reinforced concrete coastal bridges to prevent chloride-induced corrosion damage. Thermal-sprayed zinc performs well as an ICCP anode but the service life of the zinc anode is directly related to the average current density used to operate the systems. Oregon Department of Transportation (DOT) is investigating ways of monitoring the rebar corrosion in reinforced concrete bridges to identify conditions when protection of the rebar is needed. This approach reflects the fact that external protection may not be needed for all environmental conditions, leading Oregon DOT to examine the use of intermittent, galvanic, and constant voltage cathodic protection systems. Results from these types of systems are reported.

  19. Design guidelines for steel-reinforced polymer concrete using resins based on recycled PET

    SciTech Connect

    Rebeiz, K.S.; Fowler, D.W.

    1996-10-01

    Very little research has been done on the structural behavior of steel-reinforced polymer concrete (PC). In all the previous studies, it was generally assumed that the structural behavior of reinforced PC is similar to the structural behavior of reinforced portland cement concrete because both are composite materials consisting of a binder and inorganic aggregates. However, the design equations developed for steel-reinforced portland cement concrete yield very conservative results when applied to reinforced PC. The objective of this paper is to recommend simple, yet effective design guidelines in shear and flexure for steel-reinforced PC. The recommended design procedures are mostly based on test results performed on PC beams using resins based on recycled poly(ethyleneterephthalate), PET, plastic waste (the PET waste is mainly recovered from used beverage bottles). Previous studies have shown that polyester resins based on recycled PET can produce very good quality PC at a potentially lower cost.

  20. Cohesive fracture model for functionally graded fiber reinforced concrete

    SciTech Connect

    Park, Kyoungsoo; Paulino, Glaucio H.; Roesler, Jeffery

    2010-06-15

    A simple, effective, and practical constitutive model for cohesive fracture of fiber reinforced concrete is proposed by differentiating the aggregate bridging zone and the fiber bridging zone. The aggregate bridging zone is related to the total fracture energy of plain concrete, while the fiber bridging zone is associated with the difference between the total fracture energy of fiber reinforced concrete and the total fracture energy of plain concrete. The cohesive fracture model is defined by experimental fracture parameters, which are obtained through three-point bending and split tensile tests. As expected, the model describes fracture behavior of plain concrete beams. In addition, it predicts the fracture behavior of either fiber reinforced concrete beams or a combination of plain and fiber reinforced concrete functionally layered in a single beam specimen. The validated model is also applied to investigate continuously, functionally graded fiber reinforced concrete composites.

  1. Bond characteristics of reinforcing steel embedded in geopolymer concrete

    NASA Astrophysics Data System (ADS)

    Kathirvel, Parthiban; Thangavelu, Manju; Gopalan, Rashmi; Raja Mohan Kaliyaperumal, Saravana

    2017-07-01

    The force transferring between reinforcing steel and the surrounding concrete in reinforced concrete is influenced by several factors. Whereas, the study on bond behaviour of geopolymer concrete (GPC) is lagging. In this paper, an experimental attempt has been made to evaluate the geopolymer concrete bond with reinforcing steel of different diameter and embedded length using standard pull out test. The geopolymer concrete is made of ground granulated blast furnace slag (GGBFS) as geopolymer source material (GSM). The tests were conducted to evaluate the development of bond between steel and concrete of grade M40 and M50 with 12 and 16 mm diameter reinforcing steel for geopolymer and cement concrete mixes and to develop a relation between bond strength and compressive strength. From the experimental results, it has been observed that the bond strength of the geopolymer concrete mixes was more compared to the cement concrete mixes and increases with the reduction in the diameter of the bar.

  2. Compressive strength of dune sand reinforced concrete

    NASA Astrophysics Data System (ADS)

    Mohammed, Mani; Abdelouahed, Kriker; Allaoua, Belferrag

    2017-02-01

    Many areas of south Algeria suffer from the problem of accumulation of sand on constructions. In fact, the phenomenon of sand silting causes technical and economical problems. Besides, these areas and other regions in Algeria suffer from the problem of unavailability of suitable sand for building. The use of dune sand offers an alternative solution for construction. In the same context, many researches confirm the possibility of using dune sand in the composition of concrete. In this paper, concrete made with dune sand was studied. For correction of the granulometry of dune sand by river sand, the rates of 50% DS+50% RS and 40% DS+60% RS were used. Also, two types of fibers were used, with 45 and 30 mm lengths, and diameters of 1 and 0.5 mm respectively. The percentage of the used fibers in the sand concrete was 1% and 1.5%. In this work an improvement of the compressive strength for the metal fibers reinforced sand concrete compared to plain concrete was obtained.

  3. Modelling Dowel Action of Discrete Reinforcing Bars in Cracked Concrete Structures

    SciTech Connect

    Kwan, A. K. H.; Ng, P. L.; Lam, J. Y. K.

    2010-05-21

    Dowel action is one of the component actions for shear force transfer in cracked reinforced concrete. In finite element analysis of concrete structures, the use of discrete representation of reinforcing bars is considered advantageous over the smeared representation due to the relative ease of modelling the bond-slip behaviour. However, there is very limited research on how to simulate the dowel action of discrete reinforcing bars. Herein, a numerical model for dowel action of discrete reinforcing bars crossing cracks in concrete is developed. The model features the derivation of dowel stiffness matrix based on beam-on-elastic-foundation theory and the direct assemblage of dowel stiffness into the concrete element stiffness matrices. The dowel action model is incorporated in a nonlinear finite element programme with secant stiffness formulation. Deep beams tested in the literature are analysed and it is found that the incorporation of dowel action model improves the accuracy of analysis.

  4. LABORATORY INVESTIGATION OF PLASTIC-GLASS FIBER REINFORCEMENT FOR REINFORCED AND PRESTRESSED CONCRETE; PRESTRESSED CONCRETE.

    DTIC Science & Technology

    The investigation consisted of the evaluation of plastic-glass fiber elements, commonly called fiber glass, as prestressing tendons in concrete...reinforced, prestressed concrete beams with the following parameters held constant: cross- sectional area of prestressing tendons , prestress tension...applied to tendons , and beam dimensions. Several methods for anchoring the fiber-glass tendons were investigated, and a method using expanding cement was

  5. 7. Detail view of reinforced concrete archrings comprising dam's upstream ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Detail view of reinforced concrete arch-rings comprising dam's upstream face. Impressions of the wooden formwork used in construction are visible in the concrete. - Little Rock Creek Dam, Little Rock Creek, Littlerock, Los Angeles County, CA

  6. Cathodic protection of steel reinforced concrete facilitated by using carbon fiber reinforced mortar or concrete

    SciTech Connect

    Hou, J.; Chung, D.D.L.

    1997-05-01

    Due to the decrease in volume electrical resistivity associated with carbon fiber addition (0.35 vol.%) to concrete (embedding steel rebar), concrete containing carbon fibers and silica fume reduced by 18% the driving voltage required for cathodic protection compared to plain concrete, and by 28% compared to concrete with silica fume. Due to the decrease in resistivity associated with carbon fiber addition (1.1 vol.%) to mortar, overlay (embedding titanium wires for electrical contacts to steel reinforced concrete) in the form of mortar containing carbon fibers and latex reduced by the 10% the driving voltage required for cathodic protection, compared to plain mortar overlay. In spite of the low resistivity of mortar overlay with carbon fibers, cathodic protection required multiple metal electrical contacts embedded in the mortar at a spacing of 11 cm or less.

  7. Numerical Study on Mixed-mode Fracture in Reinforced Concrete

    SciTech Connect

    Yu, Rena C.; Saucedo, Luis; Ruiz, Gonzalo

    2010-05-21

    The object of this work is to model the propagation of fracture in mixed-mode in lightly reinforced concrete beams. When a notched beam does not have enough shear reinforcement, fracture can initiate and propagate unstably and lead to failure through diagonal tension. In order to study this phenomenon numerically, a model capable of dealing with both static and dynamic crack propagation as well as the natural transition of those two regimes is necessary. We adopt a cohesive model for concrete fracture and an interface model for the deterioration between concrete and steel re-bar, both combined with an insertion algorithm. The static process is solved by dynamic relaxation (DR) method together with a modified technique to enhance convergence rate. The same DR method is used to detect a dynamic process and switch to a dynamic calculation. The numerically obtained load-displacement curves, load-CMOD curves and crack patterns fit reasonably well with their experimental counterparts, having in mind that we fed the calculations only with parameters measured experimentally.

  8. Curvature ductility of reinforced and prestressed concrete columns

    SciTech Connect

    Suprenant, B.A.

    1984-01-01

    Engineers are concerned with the survival of reinforced and prestressed concrete columns during earthquakes. The prediction of column survival can be deduced from moment-curvature curves of the column section. An analytical approach is incorporated into a computer model. The computer program is based on assumed stress-strain relations for confined and unconfined concrete, nonprestressed and prestressing steel. The results of studies on reinforced and prestressed concrete columns indicate that reinforced concrete columns may be designed to resist earthquakes, while prestressed concrete columns may not. The initial reduction in moment capacity, after concrete cover spalling, of a prestressed concrete column could be as much as 50%. Analyses indicate that the bond between concrete and prestressing strand after concrete cover spalling is not critical.

  9. 150. Credit ER. Building reinforced concrete portion of Coleman Canal ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    150. Credit ER. Building reinforced concrete portion of Coleman Canal inverted siphon #2. Longitudinal steel reinforcing rods are visible at bottom. (ER, v. 64 1911 p. 702). - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

  10. Experimental investigation of reinforced concrete beams with and without CFRP wrapping

    NASA Astrophysics Data System (ADS)

    Venkatesha, K. V.; Dinesh, S. V.; Balaji Rao, K.; Bharatkumar, B. H.; Balasubramanian, S. R.; Iyer, Nagesh R.

    2012-11-01

    This paper presents the results of experimental investigations on six reinforced concrete beams, with three different shear span-to-depth ratios, which were tested under two-point loading. The aim of the work was to study the efficacy of Carbon Fibre Reinforced Polymer (CFRP) strips in enhancing shear capacity and/or changing the failure mode from brittle shear failure to ductile flexural failure. The results of the study indicate that while there is a marginal increase in first crack and ultimate loads, it is possible to achieve a change in the failure mode, and the monitored strain gauge data can be used to explain the failure pattern observed.

  11. A state of the art review on reinforced concrete beams with openings retrofitted with FRP

    NASA Astrophysics Data System (ADS)

    Osman, Bashir H.; Wu, Erjun; Ji, Bohai; S Abdelgader, Abdeldime M.

    2016-09-01

    The use of externally bonded fiber reinforced polymer (FRP) sheets, strips or steel plates is a modern and convenient way for strengthening of reinforced concrete (RC) beams. Several researches have been carried out on reinforced concrete beams with web openings that strengthened using fiber reinforced polymer composite. Majority of researches focused on shear strengthening compared with flexural strengthening, while others studied the effect of openings on shear and flexural separately with various loading. This paper investigates the impact of more than sixty articles on opening reinforced concrete beams with and without strengthening by fiber reinforcement polymers FRP. Moreover, important practical issues, which are contributed in shear strengthening of beams with different strengthening techniques, such as steel plate and FRP laminate, and detailed with various design approaches are discussed. Furthermore, a simple technique of applying fiber reinforced polymer contributed with steel plate for strengthening the RC beams with openings under different load application is concluded. Directions for future research based on the existing gaps of the present works are presented.

  12. Monitoring corrosion in reinforced concrete structures

    NASA Astrophysics Data System (ADS)

    Kung, Peter; Comanici, Maria I.

    2014-06-01

    Many defects can cause deterioration and cracks in concrete; these are results of poor concrete mix, poor workmanship, inadequate design, shrinkage, chemical and environmental attack, physical or mechanical damage, and corrosion of reinforcing steel (RS). We want to develop a suite of sensors and systems that can detect that corrosion is taking place in RS and inform owners how serious the problem is. By understanding the stages of the corrosion process, we can develop special a sensor that detects each transition. First, moisture ingress can be monitored by a fiber optics humidity sensor, then ingress of Chloride, which acts as a catalyst and accelerates the corrosion process by converting iron into ferrous compounds. We need a fiber optics sensor which can quantify Chloride ingress over time. Converting ferric to ferrous causes large volume expansion and cracks. Such pressure build-up can be detected by a fiber optic pressure sensor. Finally, cracks emit acoustic waves, which can be detected by a high frequency sensor made with phase-shifted gratings. This paper will discuss the progress in our development of these special sensors and also our plan for a field test by the end of 2014. We recommend that we deploy these sensors by visually inspecting the affected area and by identifying locations of corrosion; then, work with the designers to identify spots that would compromise the integrity of the structure; finally, drill a small hole in the concrete and insert these sensors. Interrogation can be done at fixed intervals with a portable unit.

  13. Numerical Investigations on a Blast Loaded Laced Reinforced Concrete Structure using an Equivalent Constitutive Property

    NASA Astrophysics Data System (ADS)

    Anandavalli, N.; Lakshmanan, N.; Prakash, Amar; Rajasankar, J.; Iyer, Nagesh R.

    2015-12-01

    A Laced Reinforced Concrete (LRC) structural element consists of continuously inclined shear reinforcement in the form of lacing that tie the longitudinal reinforcements on both faces of the structural element. LRC is used particularly in blast resistant construction. Conventional finite element modeling of reinforced concrete (RC) structures requires concrete and steel to be considered as separate entities and interaction between them to be defined through smeared, discrete or embedded approach. In this paper, a new approach for modeling RC structures is adopted to analyse a blast loaded LRC structure. Present approach considers RC/LRC as a homogenous material, whose constitutive property is derived based on the moment-curvature relationship of the structural component. An equivalent single-degree-of-freedom system obtained based on a proven technique is analysed to verify the results of the finite element analysis. Present approach significantly reduces the modeling effort and in turn, the computational demand for a given accuracy in the results.

  14. 19. Virginia Route 605 grade separation structure. This reinforced concrete ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. Virginia Route 605 grade separation structure. This reinforced concrete rigid frame structure. This reinforced concrete rigid frame structure was built in 1950. It is an example of the most common ornament used on the parkway where the headwall, wingwalls, and railing is faced rusticated stone, but not the interior abutment walls and the bottom of the arch are plain concrete. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  15. Bond tests of fiberglass-reinforced plastic bars in concrete

    SciTech Connect

    Larralde, J.; Silva-Rodriquez, R.; Burdette, J.; Harris, B. . Civil and Architectural Engineering Dept.)

    1994-07-01

    Fiberglass Reinforced Plastic (FRP) bars for concrete reinforcement have been commercially available for several years. The main advantage of such bar relative to the conventional steel reinforcing bars is their resistance to corrosion. The reinforced plastic bars are slightly different from the conventional steel bars both geometrically and mechanically. Thus, research is needed to understand their behavior and to be able to use them in concrete reinforcement with adequate reliability. Bond strength of reinforced plastic bars in concrete is one of the mechanical and behavioral differences with the steel bars. This paper presents the results of pullout and beam tests conducted to determine the bond stress-slip behavior of FRP bars in concrete.

  16. CREATION OF MUSIC WITH FIBER REINFORCED CONCRETE

    NASA Astrophysics Data System (ADS)

    Kato, Hayato; Takeuchi, Masaki; Ogura, Naoyuki; Kitahara, Yukiko; Okamoto, Takahisa

    This research focuses on the Fiber Reinforcement Concrete(FRC) and its performance on musical tones. Thepossibility of future musical instruments made of this concrete is discussed. Recently, the technical properties of FRC had been improved and the different production styles, such as unit weight of binding material and volume of fiber in the structure, hardly affects the results of the acoustics. However, the board thickness in the FRC instruments is directly related with the variety of musical tone. The FRC musical effects were compared with those produced with wood on wind instruments. The sounds were compared with those produced with woodwind instruments. The sound pressure level was affected by the material and it becomes remarkably notorious in the high frequency levels. These differences had great influence on the spectrum analysis of the tone in the wind instruments and the sensory test. The results from the sensory test show dominant performances of brightness, beauty and power in the FRC instruments compared with those made of wood.

  17. Active tendon control of reinforced concrete frame structures subjected to near-fault effects

    NASA Astrophysics Data System (ADS)

    Nigdeli, Sinan Melih; Boduroǧlu, M. Hasan

    2013-10-01

    A reinforced concrete (RC) frame structure was controlled with active tendons under the excitation of near-fault ground motions. Proportional Integral Derivative (PID) type controllers were used and the controller was tuned by using a numerical algorithm. In order to prevent brittle fracture of the structure, the aim of the control is to reduce maximum base shear force. The RC structure was investigated for different characteristic strengths of concrete and the approach is applicable for the structure with 14 MPa concrete strength or higher.

  18. Cracking Analysis of FRP-Reinforced Concrete Flexural Members

    NASA Astrophysics Data System (ADS)

    Aiello, M. A.; Ombres, L.

    2000-09-01

    The paper is dedicated to the cracking analysis of FRP (Fiber-Reinforced Polymer)-reinforced concrete elements. A general nonlinear calculation procedure, based on the slip and bond stresses, is described and adopted for the prediction of the crack width and crack spacing in FRP-reinforced concrete beams. An analytical expression of the bond-slip law is estimated using the corresponding experimental results available in the literature. A numerical investigation is carried out and the influence of the mechanical and geometrical parameters of the material (bond-slip law, reinforcement ratio, concrete strength, diameter of rebars, etc.) on the crack formation is investigated. Referring to glass-FRP-reinforced concrete beams, a comparison between the theoretical predictions and experimental results is made. The results obtained are presented and discussed.

  19. Investigation Into The Crack Development And Joint Rotation Of Reinforced Concrete Structures

    NASA Astrophysics Data System (ADS)

    Grob, Klaus-Peter; von Cramon, Wolfram

    1986-07-01

    The experimental investigation is described of the reinforced concrete construction pro blems mentioned in the title, making use of the Laser-Speckle-Photography optical measurement method- Proceeding from the material-conditional particularities and the high demands on the accuracy of the measurement values, a semi-automatically working device. was developed for analysing the Laser-Speckle photographs. The method of working with this device, the statistical routines applied in the process and the attainable accuracy are reported on. Moreover, reference is also made to the strains in a reinforced concrete member and the crack. formation. In the last section, the results of measurements of the joint rotation on the inner support of a two-span beam of reinforced micro-concrete, as well as the shear bearing behavior observed in this context, are discribed.

  20. Surface treated polypropylene (PP) fibres for reinforced concrete

    SciTech Connect

    López-Buendía, Angel M.; Romero-Sánchez, María Dolores; Climent, Verónica

    2013-12-15

    Surface treatments on a polypropylene (PP) fibre have contributed to the improvement of fibre/concrete adhesion in fibre-reinforced concrete. The treatments to the PP fibre were characterized by contact angle measurements, ATR-IR and XPS to analyse chemical alterations. The surface topography and fibre/concrete interaction were analysed by several microscopic techniques, namely optical petrographic, and scanning electron microscopy. Treatment modified the surface chemistry and topography of the fibre by introducing sodium moieties and created additional fibre surface roughness. Modifications in the fibre surface led to an increase in the adhesion properties between the treated fibres and concrete and an improvement in the mechanical properties of the fibre-reinforced concrete composite as compared to the concrete containing untreated PP fibres. Compatibility with the concrete and increased roughness and mineral surface was also improved by nucleated portlandite and ettringite mineral association anchored on the alkaline PP fibre surface, which is induced during treatment.

  1. Prediction of reinforced concrete strength by ultrasonic velocities

    NASA Astrophysics Data System (ADS)

    Sabbağ, Nevbahar; Uyanık, Osman

    2017-06-01

    This study was aimed to determine the strength of the reinforced concrete and to reveal the reinforcement effect on the concrete strength by Ultrasonic P and S wave velocities. Studies were conducted with prepared 9 different concrete designs of showing low, medium and high strength features. 4 kinds of cubic samples which unreinforced and including 10, 14 or 20 mm diameter reinforcement were prepared for these designs. Studies were carried out on total 324 samples including 9 samples for each design of these 4 kinds. The prepared samples of these designs were subjected to water curing. On some days of the 90-day period, P and S wave measurements were repeated to reveal the changes in seismic velocities of samples depending on whether reinforced or unreinforced of samples and diameter of reinforcement. Besides, comparisons were done by performing uniaxial compressive strength test with crushing of 3 samples on 7th, 28th and 90th days. As a result of studies and evaluations, it was seen that values of seismic velocities and uniaxial compressive strength increased depending on reinforcement and diameter of reinforcement in low strength concretes. However, while the seismic velocities were not markedly affected from reinforcement or reinforcement diameter in high strength concrete, uniaxial compressive strength values were negatively affected.

  2. Bond characteristics of steel fiber and deformed reinforcing steel bar embedded in steel fiber reinforced self-compacting concrete (SFRSCC)

    NASA Astrophysics Data System (ADS)

    Aslani, Farhad; Nejadi, Shami

    2012-09-01

    Steel fiber reinforced self-compacting concrete (SFRSCC) is a relatively new composite material which congregates the benefits of the self-compacting concrete (SCC) technology with the profits derived from the fiber addition to a brittle cementitious matrix. Steel fibers improve many of the properties of SCC elements including tensile strength, ductility, toughness, energy absorption capacity, fracture toughness and cracking. Although the available research regarding the influence of steel fibers on the properties of SFRSCC is limited, this paper investigates the bond characteristics between steel fiber and SCC firstly. Based on the available experimental results, the current analytical steel fiber pullout model (Dubey 1999) is modified by considering the different SCC properties and different fiber types (smooth, hooked) and inclination. In order to take into account the effect of fiber inclination in the pullout model, apparent shear strengths (τ (app)) and slip coefficient (β) are incorporated to express the variation of pullout peak load and the augmentation of peak slip as the inclined angle increases. These variables are expressed as functions of the inclined angle (ϕ). Furthurmore, steel-concrete composite floors, reinforced concrete floors supported by columns or walls and floors on an elastic foundations belong to the category of structural elements in which the conventional steel reinforcement can be partially replaced by the use of steel fibers. When discussing deformation capacity of structural elements or civil engineering structures manufactured using SFRSCC, one must be able to describe thoroughly both the behavior of the concrete matrix reinforced with steel fibers and the interaction between this composite matrix and discrete steel reinforcement of the conventional type. However, even though the knowledge on bond behavior is essential for evaluating the overall behavior of structural components containing reinforcement and steel fibers

  3. Bond characteristics of steel fiber and deformed reinforcing steel bar embedded in steel fiber reinforced self-compacting concrete (SFRSCC)

    NASA Astrophysics Data System (ADS)

    Aslani, Farhad; Nejadi, Shami

    2012-09-01

    Steel fiber reinforced self-compacting concrete (SFRSCC) is a relatively new composite material which congregates the benefits of the self-compacting concrete (SCC) technology with the profits derived from the fiber addition to a brittle cementitious matrix. Steel fibers improve many of the properties of SCC elements including tensile strength, ductility, toughness, energy absorption capacity, fracture toughness and cracking. Although the available research regarding the influence of steel fibers on the properties of SFRSCC is limited, this paper investigates the bond characteristics between steel fiber and SCC firstly. Based on the available experimental results, the current analytical steel fiber pullout model (Dubey 1999) is modified by considering the different SCC properties and different fiber types (smooth, hooked) and inclination. In order to take into account the effect of fiber inclination in the pullout model, apparent shear strengths ( τ ( app)) and slip coefficient ( β) are incorporated to express the variation of pullout peak load and the augmentation of peak slip as the inclined angle increases. These variables are expressed as functions of the inclined angle ( ϕ). Furthurmore, steel-concrete composite floors, reinforced concrete floors supported by columns or walls and floors on an elastic foundations belong to the category of structural elements in which the conventional steel reinforcement can be partially replaced by the use of steel fibers. When discussing deformation capacity of structural elements or civil engineering structures manufactured using SFRSCC, one must be able to describe thoroughly both the behavior of the concrete matrix reinforced with steel fibers and the interaction between this composite matrix and discrete steel reinforcement of the conventional type. However, even though the knowledge on bond behavior is essential for evaluating the overall behavior of structural components containing reinforcement and steel fibers

  4. Bond slip detection of concrete-encased composite structure using shear wave based active sensing approach

    NASA Astrophysics Data System (ADS)

    Zeng, Lei; Parvasi, Seyed Mohammad; Kong, Qingzhao; Huo, Linsheng; Lim, Ing; Li, Mo; Song, Gangbing

    2015-12-01

    Concrete-encased composite structure exhibits improved strength, ductility and fire resistance compared to traditional reinforced concrete, by incorporating the advantages of both steel and concrete materials. A major drawback of this type of structure is the bond slip introduced between steel and concrete, which directly reduces the load capacity of the structure. In this paper, an active sensing approach using shear waves to provide monitoring and early warning of the development of bond slip in the concrete-encased composite structure is proposed. A specimen of concrete-encased composite structure was investigated. In this active sensing approach, shear mode smart aggregates (SAs) embedded in the concrete act as actuators and generate desired shear stress waves. Distributed piezoceramic transducers installed in the cavities of steel plates act as sensors and detect the wave response from shear mode SAs. Bond slip acts as a form of stress relief and attenuates the wave propagation energy. Experimental results from the time domain analysis clearly indicate that the amplitudes of received signal by lead zirconate titanate sensors decreased when bond slip occurred. In addition, a wavelet packet-based analysis was developed to compute the received signal energy values, which can be used to determine the initiation and development of bond slip in concrete-encased composite structure. In order to establish the validity of the proposed method, a 3D finite element analysis of the concrete-steel bond model is further performed with the aid of the commercial finite element package, Abaqus, and the numerical results are compared with the results obtained in experimental study.

  5. Experimental Study on Voided Reinforced Concrete Beams with Polythene Balls

    NASA Astrophysics Data System (ADS)

    Sivaneshan, P.; Harishankar, S.

    2017-07-01

    The primary component in any structure is concrete, that exist in buildings and bridges. In present situation, a serious problems faced by construction industry is exhaustive use of raw materials. Recent times, various methods are being adopted to limit the use of concrete. In structural elements like beams, polythene balls can be induced to reduce the usage of concrete. A simply supported reinforced concrete beam has two zones, one above neutral axis and other below neutral axis. The region below neutral axis is in tension and above neutral axis is in compression. As concrete is weak in tension, steel reinforcements are provided in tension zone. The concrete below the neutral axis acts as a stress transfer medium between the compression zone and tension zone. The concrete above the neutral axis takes minimum stress so that we could partially replace the concrete above neutral axis by creating air voids using recycled polythene balls. Polythene balls of varying diameters of 75 mm, 65 mm and 35 mm were partially replaced in compression zone. Hence the usage of concrete in beams and self-weight of the beams got reduced considerably. The Load carrying capacity, Deflection of beams and crack patterns were studied and compared with conventional reinforced concrete beams.

  6. Investigation of rectangular concrete columns reinforced or prestressed with fiber reinforced polymer (FRP) bars or tendons

    NASA Astrophysics Data System (ADS)

    Choo, Ching Chiaw

    Fiber reinforced polymer (FRP) composites have been increasingly used in concrete construction. This research focused on the behavior of concrete columns reinforced with FRP bars, or prestressed with FRP tendons. The methodology was based the ultimate strength approach where stress and strain compatibility conditions and material constitutive laws were applied. Axial strength-moment (P-M) interaction relations of reinforced or prestressed concrete columns with FRP, a linearly-elastic material, were examined. The analytical results identified the possibility of premature compression and/or brittle-tension failure occurring in FRP reinforced and prestressed concrete columns where sudden and explosive type failures were expected. These failures were related to the rupture of FRP rebars or tendons in compression and/or in tension prior to concrete reaching its ultimate strain and strength. The study also concluded that brittle-tension failure was more likely to occur due to the low ultimate tensile strain of FRP bars or tendons as compared to steel. In addition, the failures were more prevalent when long term effects such as creep and shrinkage of concrete, and creep rupture of FRP were considered. Barring FRP failure, concrete columns reinforced with FRP, in some instances, gained significant moment resistance. As expected the strength interaction of slender steel or FRP reinforced concrete columns were dependent more on column length rather than material differences between steel and FRP. Current ACI minimum reinforcement ratio for steel (rhomin) reinforced concrete columns may not be adequate for use in FRP reinforced concrete columns. Design aids were developed in this study to determine the minimum reinforcement ratio (rhof,min) required for rectangular reinforced concrete columns by averting brittle-tension failure to a failure controlled by concrete crushing which in nature was a less catastrophic and more gradual type failure. The proposed method using rhof

  7. Detail view of the reinforced concrete viaduct over the Union ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view of the reinforced concrete viaduct over the Union Pacific Railroad corridor, view looking east - Grande Ronde River Bridge, Sprnning Grande Ronde River on Old Oregon Trail Highway (Oregon Route 6), La Grande, Union County, OR

  8. 57. Metz Run Viaduct. Detail of the reinforced concrete arched ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    57. Metz Run Viaduct. Detail of the reinforced concrete arched piers. Looking south-southeast. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  9. 3. View of reinforced concrete and through truss eleveated rightofway, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. View of reinforced concrete and through truss eleveated right-of-way, Shaker Rapid Transit, at E. 80th St in Cleveland. Constructed ca. 1920. - Shaker Heights Rapid Transit Line, Cleveland, Cuyahoga County, OH

  10. 4. EAST ELEVATION. TOWER, OF REINFORCED CONCRETE CONSTRUCTION, WAS BUILT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. EAST ELEVATION. TOWER, OF REINFORCED CONCRETE CONSTRUCTION, WAS BUILT IN 1944 TO SPEED UP THE FUELING OF LOCOMOTIVE TENDERS DURING WARTIME. - Collinwood Railroad Yard Coal Tipple, Between East 146th Street & East 152nd Street, Cleveland, Cuyahoga County, OH

  11. 7. REINFORCED CONCRETE SLAB ROOF FROM NORTHWEST EDGE, FLAME DEFLECTOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. REINFORCED CONCRETE SLAB ROOF FROM NORTHWEST EDGE, FLAME DEFLECTOR AT RIGHT, VIEW TOWARDS SOUTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, CaptiveTest Stand D-3, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  12. 11. REINFORCED CONCRETE SLAB ROOF, FLAME DEFLECTOR AT RIGHT, CONTROL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. REINFORCED CONCRETE SLAB ROOF, FLAME DEFLECTOR AT RIGHT, CONTROL BUILDING B AT FAR CENTER RIGHT. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-4, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  13. 2. FLAME DEFLECTOR FROM THE REINFORCED CONCRETE SLAB ROOF, VIEW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. FLAME DEFLECTOR FROM THE REINFORCED CONCRETE SLAB ROOF, VIEW TOWARDS SOUTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-2, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  14. 3. SOUTH FLAME DEFLECTOR FROM THE REINFORCED CONCRETE ROOF, VIEW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. SOUTH FLAME DEFLECTOR FROM THE REINFORCED CONCRETE ROOF, VIEW TOWARDS EAST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-2, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  15. 9. FLAME DEFLECTOR FROM REINFORCED CONCRETE SLAB ROOF, VIEW TOWARDS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. FLAME DEFLECTOR FROM REINFORCED CONCRETE SLAB ROOF, VIEW TOWARDS NORTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-1, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  16. Computational models for the nonlinear analysis of reinforced concrete plates

    NASA Technical Reports Server (NTRS)

    Hinton, E.; Rahman, H. H. A.; Huq, M. M.

    1980-01-01

    A finite element computational model for the nonlinear analysis of reinforced concrete solid, stiffened and cellular plates is briefly outlined. Typically, Mindlin elements are used to model the plates whereas eccentric Timoshenko elements are adopted to represent the beams. The layering technique, common in the analysis of reinforced concrete flexural systems, is incorporated in the model. The proposed model provides an inexpensive and reasonably accurate approach which can be extended for use with voided plates.

  17. Material and Flexural Properties of Fiber-reinforced Rubber Concrete

    NASA Astrophysics Data System (ADS)

    Helminger, Nicholas P.

    The purpose of this research is to determine the material properties of rubber concrete with the addition of fibers, and to determine optimal mixture dosages of rubber and fiber in concrete for structural applications. Fiber-reinforced concrete and rubberized concrete have been researched separately extensively, but this research intends to combine both rubber and fiber in a concrete matrix in order to create a composite material, fiber-reinforced rubber concrete (FRRC). Sustainability has long been important in engineering design, but much of the previous research performed on sustainable concrete does not result in a material that can be used for practical purposes. While still achieving a material that can be used for structural applications, economical considerations were given when choosing the proportions and types of constituents in the concrete mix. Concrete mixtures were designed, placed, and tested in accordance with common procedures and standards, with an emphasis on practicality. Properties that were investigated include compressive strength, tensile strength, modulus of elasticity, toughness, and ductility. The basis for determining the optimal concrete mixture is one that is economical, practical, and exhibits ductile properties with a significant strength. Results show that increasing percentages of rubber tend to decrease workability, unit weight, compressive strength, split tensile strength, and modulus of elasticity while the toughness is increased. The addition of steel needle fibers to rubber concrete increases unit weight, compressive strength, split tensile strength, modulus of elasticity, toughness, and ductility of the composite material.

  18. Evaluation of Simplified Methods for Estimating Shear Capacity Using JNES/NUPEC Low-Rise Concrete Shear Wall Cyclic Test Data.

    SciTech Connect

    Nie,J.; Braverman, J.; Hofmayer, C.; Ali, S.

    2008-06-01

    The simplified methods in current codes for determining the shear capacity of reinforced concrete shear walls had mostly been validated using the test results of single-element shear walls. Recently available JNES/NUPEC test data of reinforced concrete shear walls under multi-directional cyclic loadings provided a unique opportunity to investigate the adequacy of the simplified methods for use in situations with strong interaction effects. A total of 11 test specimens with aspect ratios between 0.47 and 0.87 have been used in the assessment. Two simplified methods from the ACI 349-01 standard [1] and one from the ASCE 43-05 standard [2] have been evaluated. This paper also presents the development of an adjustment factor to consider the aspect ratio and the development of two approaches to consider interaction effects for one of the simplified methods. It concludes with the insights on the applicability of the code methods when interaction effects exist.

  19. Analytical modeling of concrete box beams reinforced by GFRP rebars

    SciTech Connect

    Zhao, Y.; Pang, S.S.

    1998-12-31

    An FRP rebar reinforced concrete box beam has been studied in this paper. Static analysis has been performed on the beams subjected to tension, bending, and torsion, based on a conceptual box beam structure. Linear vibration analysis has been conducted to predict the natural frequencies of the structures. Three dimensional finite element analysis has also been carried out to predict the stress, strain, deflection, and natural frequencies of the box beam structures. The results show that an FRP rebar deforms more compatibly with surrounding concrete than a steel rebar does. The results suggest that the concrete beams with FRP reinforcement are much more likely to be subject to compression failure (breakage of concrete on compression side) when compared to the box beams reinforced with steel rebars under the same loading conditions.

  20. Monitoring corrosion of steel bars in reinforced concrete structures.

    PubMed

    Verma, Sanjeev Kumar; Bhadauria, Sudhir Singh; Akhtar, Saleem

    2014-01-01

    Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion.

  1. Inspection of reinforcement concrete structures with active infrared thermography

    NASA Astrophysics Data System (ADS)

    Szymanik, Barbara; Chady, Tomasz; Frankowski, Paweł

    2017-02-01

    In this article the reinforced concrete non-destructive evaluation using active thermography is discussed. There are several aspects of possible non-destructive testing of mentioned structures. One of them is the detection and assessment of the reinforcement itself. In case of active thermography, the external energy source has to be used to induce the thermal response of the inspected specimen. Here, authors propose two different techniques: microwave heating and induction heating. In this article authors will present several experimental results which will allow to compare mentioned two techniques of heating. suitability of each one to assess the reinforced concrete by using the active thermography will be discussed.

  2. Monitoring Corrosion of Steel Bars in Reinforced Concrete Structures

    PubMed Central

    Verma, Sanjeev Kumar; Bhadauria, Sudhir Singh; Akhtar, Saleem

    2014-01-01

    Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion. PMID:24558346

  3. Structural and seismic analyses of waste facility reinforced concrete storage vaults

    SciTech Connect

    Wang, C.Y.

    1995-07-01

    Facility 317 of Argonne National Laboratory consists of several reinforced concrete waste storage vaults designed and constructed in the late 1940`s through the early 1960`s. In this paper, structural analyses of these concrete vaults subjected to various natural hazards are described, emphasizing the northwest shallow vault. The natural phenomenon hazards considered include both earthquakes and tornados. Because these vaults are deeply embedded in the soil, the SASSI (System Analysis of Soil-Structure Interaction) code was utilized for the seismic calculations. The ultimate strength method was used to analyze the reinforced concrete structures. In all studies, moment and shear strengths at critical locations of the storage vaults were evaluated. Results of the structural analyses show that almost all the waste storage vaults meet the code requirements according to ACI 349--85. These vaults also satisfy the performance goal such that confinement of hazardous materials is maintained and functioning of the facility is not interrupted.

  4. Producing Durable Continuously Reinforced Concrete Pavement using Glass-ceramic Coated Reinforcing Steel

    DTIC Science & Technology

    2010-02-01

    BUILDING STRONG® Producing Durable Continuously Reinforced Concrete Pavement using Glass- ceramic Coated Reinforcing Steel Principal Investigator... ceramic Coated Reinforcing Steel 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER...Vitreous- Ceramic Coating  Ease of Application to Reinforcement Steel  Bond Strength and Corrosion-Resistance  Field Demonstration Program  Testing in

  5. Technical note on using CNTs as reinforcements in reinforced concrete structural elements

    NASA Astrophysics Data System (ADS)

    Babu, C. Ramesh

    2017-07-01

    The disasters whether man made or natural dominates all types of structures and has ever been attention to researchers, academicians and scientists. Concrete had been reinforced with steel, macro fibers and microfibers which bridges the cracks. The advantages of microfibers are to delay the development of cracks. Numerous researches focused on arresting the initiation of micro cracks and delay in the macro cracks. However the initiation of the cracks could not be avoided. It is quite fruitful and needy for the present scenario in a country like India to carry out research by reinforcing concrete with fibers/nanomaterials at nano scale which would provide crack free materials and structures. This technical note explores the possibilities of impregnating concrete with CNTs (Carbon Nano Tubes) and also as reinforcement bars at macro level in reinforced concrete structural elements.

  6. Effect of tree roots on a shear zone: modeling reinforced shear stress.

    Treesearch

    Kazutoki Abe; Robert R. Ziemer

    1991-01-01

    Tree roots provide important soil reinforcement that impoves the stability of hillslopes. After trees are cut and roots begin to decay, the frequency of slope failures can increase. To more fully understand the mechanics of how tree roots reinforce soil, fine sandy soil containing pine roots was placed in a large shear box in horizontal layers and sheared across a...

  7. Blast impact behaviour of concrete with different fibre reinforcement

    NASA Astrophysics Data System (ADS)

    Drdlová, Martina; Čechmánek, René; Řídký, Radek

    2015-09-01

    The paper summarizes the results of the development of special concrete intended for the explosion resistance applications, with the emphasis on minimal secondary fragments formation at the explosion. The fine-grained concrete matrix has been reinforced by various types of short dispersed fibers (metallic, mineral and polymer) of different sizes and by their combination and the effect of the fibre reinforcement on the physico-mechanical properties and blast resistance was observed. The concrete prism specimens have been subjected to the determination of mechanical parameters (compressive and flexural strength at quasi-static load). The blast tests were conducted on the slab specimens prepared from selected mixtures. The material characteristics and explosion test data have been used for numerical investigation, which defined the optimal wall composition and dimensions of the concrete element which should resist the explosion defined by type, size, weight and placement of the blast. In the next step the test elements resistance was verified by real explosion test.

  8. Maintenance methods for continuously reinforced concrete pavements

    NASA Astrophysics Data System (ADS)

    Yoder, E. J.

    1980-05-01

    Test sections were constructed on a section of 1-65 south of Indianapolis, Indiana to evaluate various maintenance techniques that might be adopted for this type of pavement. The road was stratified into similar sections using deflection, cracking and breakup as selection criteria. Maintenance methods used included concrete shoulders, undersealing, asphalt concrete overlay, subdrains at the pavement edge and various combinations of these methods. In every case the pavement was patched prior to installation of the maintenance.

  9. 7. View showing reinforced concrete arch, east approach. The 591 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. View showing reinforced concrete arch, east approach. The 591 foot three-hinge steel arch that spans the Cuyahoga River is flanked by twelve such approach arches. Each concrete arch consists of four arch ribs, which support the beam and slab streetcar deck on spandrel columns. As the photograph illustrates, the spandrel columns continue above the lower deck to support the roadway. - Detroit Superior High Level Bridge, Cleveland, Cuyahoga County, OH

  10. Polymer concrete reinforced with recycled-tire fibers: Mechanical properties

    NASA Astrophysics Data System (ADS)

    Martínez-Cruz, E.; Martínez-Barrera, G.; Martínez-López, M.

    2013-06-01

    Polymer Concrete was reinforced with recycled-tire fibers in order to improve the compressive and flexural strength. Polymer concrete specimens were prepared with 70% of silicious sand, 30% of polyester resin and various fiber concentrations (0.3, 0.6, 0.9 and 1.2 vol%). The results show increment of 50% in average of the compressive and flexural strength as well as on the deformation when adding 1.2 vol% of recycled-fibers.

  11. Reliability Analysis of a Reinforced Concrete Drainage Structure.

    DTIC Science & Technology

    1995-12-01

    Drainage Structure by Robert C. Patev, Mary Ann Leggett Approved For Public Release; Distribution Is Unlimited TpXIC QUALITY DJCPECTED1...PRINTED ON RECYCLED PAPER Technical Report ITL-95-13 December 1995 Reliability Analysis of a Reinforced Concrete Drainage Structure by Robert C...concrete drainage structure / by Robert C. Patev, Mary Ann Leggett; prepared for U.S. Army Engineer District Vicksburg. 38 p.: ill.; 28 cm

  12. Experimental testing of the fracture of concrete and reinforced concrete plates under impact

    NASA Astrophysics Data System (ADS)

    Konyaev, A. A.; Tolkachev, V. F.; Platova, T. M.

    2015-11-01

    This paper describes the results of experimental studies on penetration of cylindrical projectiles into concrete and reinforced concrete at impact velocities reaching 0.5 km/s. An algorithm is proposed for calculating the depth of penetration of a projectile, making it possible to find the depth of penetration of high-strength steel projectiles with a mass of up to 13.5 kg into concrete on the basis of measurements of the specific work required to remove concrete using projectiles with a mass of up to 8 g.

  13. Experimental assessment of air permeability in a concrete shear wall subjected to simulated seismic loading

    SciTech Connect

    Girrens, S.P.; Farrar, C.R.

    1991-07-01

    A safety concern for the proposed Special Nuclear Materials Laboratory (SNML) facility at the Los Alamos National Laboratory was air leakage from the facility if it were to experience a design basis earthquake event. To address this concern, a study was initiated to estimate air leakage, driven by wind-generated pressure gradients, from a seismically damaged concrete structure. This report describes a prototype experiment developed and performed to measure the air permeability in a reinforced concrete shear wall, both before and after simulated seismic loading. A shear wall test structure was fabricated with standard 4000-psi concrete mix. Static load-cycle testing was used to simulate earthquake loading. Permeability measurements were made by pressurizing one side of the shear wall above atmospheric conditions and recording the transient pressure decay. As long as the structure exhibited linear load displacement response, no variation in the air permeability was detected. However, experimental results indicate that the air permeability in the shear wall increased by a factor of 40 after the wall had been damaged (cracked). 17 figs., 8 tabs.

  14. Performance of Straight Steel Fibres Reinforced Alkali Activated Concrete

    NASA Astrophysics Data System (ADS)

    Faris, Meor Ahmad; Bakri Abdullah, Mohd Mustafa Al; Nizar Ismail, Khairul; Muniandy, Ratnasamy; Putra Jaya, Ramadhansyah

    2016-06-01

    This paper focus on the performance of alkali activated concrete produced by using fly ash activated by sodium silicate and sodium hydroxide solutions. These alkali activated concrete were reinforced with straight steel fibres with different weight percentage starting from 0 % up to 5 %. Chemical composition of raw material in the production alkali activated concrete which is fly ash was first identified by using X-ray fluorescence. Results reveal there have an effect of straight steel fibres inclusion to the alkali activated concrete. Highest compressive strength of alkali activated concrete which is 67.72 MPa was obtained when 3 % of straight fibres were added. As well as flexural strength, highest flexural strength which is 6.78 MPa was obtained at 3 % of straight steel fibres inclusions.

  15. Delamination detection in reinforced concrete using thermal inertia

    SciTech Connect

    Del Grande, N K; Durbin, P F

    1998-11-30

    We investigated the feasibility of thermal inertia mapping for bridge deck inspections. Using pulsed thermal imaging, we heat-stimulated surrogate delaminations in reinforced concrete and asphalt-concrete slabs. Using a dual-band infrared camera system, we measured thermal inertia responses of Styrofoam implants under 5 cm of asphalt, 5 cm of concrete, and 10 cm of asphalt and concrete. We compared thermal maps from solar-heated concrete and asphalt-concrete slabs with thermal inertia maps from flash-heated concrete and asphalt-concrete slabs. Thermal inertia mapping is a tool for visualizing and quantifying subsurface defects. Physically, thermal inertia is a measure of the resistance of the bridge deck to temperature change. Experimentally, it is determined from the inverse slope of the surface temperature versus the inverse square root of time. Mathematically, thermal inertia is the square root of the product of thermal conductivity, density, and heat capacity. Thermal inertia mapping distinguishes delaminated decks which have below-average thermal inertias from normal or shaded decks. Key Words: Pulsed Thermal Imaging, Thermal Inertia, Detection Of Concrete Bridgedeck Delaminations

  16. RC beams shear-strengthened with fabric-reinforced-cementitious-matrix (FRCM) composite

    NASA Astrophysics Data System (ADS)

    Loreto, Giovanni; Babaeidarabad, Saman; Leardini, Lorenzo; Nanni, Antonio

    2015-12-01

    The interest in retrofit/rehabilitation of existing concrete structures has increased due to degradation and/or introduction of more stringent design requirements. Among the externally-bonded strengthening systems fiber-reinforced polymers is the most widely known technology. Despite its effectiveness as a material system, the presence of an organic binder has some drawbacks that could be addressed by using in its place a cementitious binder as in fabric-reinforced cementitious matrix (FRCM) systems. The purpose of this paper is to evaluate the behavior of reinforced concrete (RC) beams strengthened in shear with U-wraps made of FRCM. An extensive experimental program was undertaken in order to understand and characterize this composite when used as a strengthening system. The laboratory results demonstrate the technical viability of FRCM for shear strengthening of RC beams. Based on the experimental and analytical results, FRCM increases shear strength but not proportionally to the number of fabric plies installed. On the other hand, FRCM failure modes are related with a high consistency to the amount of external reinforcement applied. Design considerations based on the algorithms proposed by ACI guidelines are also provided.

  17. 78 FR 55755 - Steel Concrete Reinforcing Bar From Mexico and Turkey; Institution of Antidumping and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-11

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Steel Concrete Reinforcing Bar From Mexico and Turkey; Institution of Antidumping and... from Mexico and Turkey of steel concrete reinforcing bar, primarily provided for in subheadings...

  18. Report on aging of nuclear power plant reinforced concrete structures

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

    1996-03-01

    The Structural Aging Program provides the US Nuclear Regulatory Commission with potential structural safety issues and acceptance criteria for use in continued service assessments of nuclear power plant safety-related concrete structures. The program was organized under four task areas: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technology, and Quantitative Methodology for Continued Service Determinations. Under these tasks, over 90 papers and reports were prepared addressing pertinent aspects associated with aging management of nuclear power plant reinforced concrete structures. Contained in this report is a summary of program results in the form of information related to longevity of nuclear power plant reinforced concrete structures, a Structural Materials Information Center presenting data and information on the time variation of concrete materials under the influence of environmental stressors and aging factors, in-service inspection and condition assessments techniques, repair materials and methods, evaluation of nuclear power plant reinforced concrete structures, and a reliability-based methodology for current and future condition assessments. Recommendations for future activities are also provided. 308 refs., 61 figs., 50 tabs.

  19. Analysis of polarization decay of reinforced concrete in saltwater

    SciTech Connect

    Kumar, A.; Boy, J.H.

    1996-11-01

    Electrochemical impedance spectroscopy (EIS), polarization resistance, and polarization decay measurements techniques were used to analyze uncoated steel reinforcing rods encased in concrete and exposed to saltwater. A nested equivalent circuit containing a Warburg impedance was utilized to analyze the results. When rust is present on the steel, the Warburg impedance dominated the impedance response.

  20. Solar-Array Substrate From Glass-Reinforced Concrete

    NASA Technical Reports Server (NTRS)

    Eirls, J. L.

    1985-01-01

    Design elminiates glass superstrate and associated metal framing. Panel has two trapezoidal stiffening ribs for structural support. Strategic placement of ribs with embedded support tubes (standard PVC tubing) minimizes bending moments and resulting stresses produced by installation and windloads. Glass-reinforced concrete panel has smooth flat surface suitable for solar substrate and includes structural bracing for rigidity and design adaptable to mass production.

  1. RETENTION BASIN. ERECTING REINFORCING STEEL FOR CONCRETE DECK. STACK RISES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    RETENTION BASIN. ERECTING REINFORCING STEEL FOR CONCRETE DECK. STACK RISES AT TOP LEFT. CAMERA FACES WEST. INL NEGATIVE NO. 2581. Unknown Photographer, 6/18/1951 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  2. Investigation of Mechanical Properties of Steel Fibre- Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Ryabchikov, A.; Tamme, V.; Laurson, M.

    2015-11-01

    Steel fibre-reinforced concrete (SFRC) is widely used in the structural elements of buildings: industrial floors, slabs, walls, foundation, etc. When a load is applied to a fibre- reinforced composite consisting of a low-modulus matrix reinforced with high-strength, high- modulus fibres, the plastic flow of the matrix under stress transfers the load to the fibre; this results in high-strength, high-modulus material which determines the stiffness and stress of the composite. In this study the equivalent flexural strength, equivalent flexural ratio Re,3 and the compressing strength of SFRC are investigated. Notched test specimens with five different dosages of steel fibres (20, 25, 30, 35, 40 kg/m3) were prepared using industrial concrete. Determination of flexural tension strength was carried out according to the EU norm EVS-EN 14651:2005+A1:2007. The equivalent flexural strength and subsequent equivalent flexural ratio Re,3 of SFRC with a dosage of 20, 25, 30, 35 kg/m3 similar to their average values and with a dosage of 40 kg/m3 were 31% higher than their average values. The compressive strength of the steel fibre-reinforced concrete was slightly higher compared to plain concrete, except specimens with the dosage of 40 kg/m3 where the increase was 30%.

  3. 3. DRAINING & DRYING BUILDING, REINFORCED CONCRETE MUSHROOM COLUMNS WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. DRAINING & DRYING BUILDING, REINFORCED CONCRETE MUSHROOM COLUMNS WITH DROP PANELS SUPPORTING DRAINING BINS (IRON VALVES OF DRAINING BINS ARE EMBEDDED IN THE CEILING), VIEW LOOKING WEST - Mill "C" Complex, Sand Draining & Drying Building, South of Dee Bennet Road, near Illinois River, Ottawa, La Salle County, IL

  4. 10. Interior view looking SE showing reinforced concrete structural system ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Interior view looking SE showing reinforced concrete structural system at ground floor of Paint Shop. - Central of Georgia Railway, Savannah Repair Shops & Terminal Facilities, Paint & Coach Barn, Bounded by West Broad, Jones, West Boundary & Hull Streets, Savannah, Chatham County, GA

  5. 15. DETAIL EXTERIOR VIEW LOOKING NORTH SHOWING REINFORCED CONCRETE PILLBOX ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. DETAIL EXTERIOR VIEW LOOKING NORTH SHOWING REINFORCED CONCRETE PILLBOX ON BRADFORD ISLAND END OF DAM/SPILLWAY; THE PILLBOX WAS BUILT DURING WORLD WAR II TO HELP PROTECT THE DAM/SPILLWAY FROM SABOTAGE. - Bonneville Project, Bonneville Dam, Columbia River, Bonneville, Multnomah County, OR

  6. 9. Photocopy of Reinforced Concrete Details drawing (from the BPA ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. Photocopy of Reinforced Concrete Details drawing (from the BPA Engineering Vault, Drawing C13-J2-342-D1, Sheet 6, 13 March 1939) - Bonneville Power Administration South Bank Substation, I-84, South of Bonneville Dam Powerhouse, Bonneville, Multnomah County, OR

  7. Perspective view. Fivestory reinforced concrete factory building reveals the structural ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Perspective view. Five-story reinforced concrete factory building reveals the structural frame on the exterior of the facade. Twelve bay facade facing onto Clay Avenue (north facade) has first floor openings bricked up. Mix of typical factory windows and glass block windows fill the majority of the openings on the rest of building - Russell Industrial Center, 1600 Clay Avenue, Detroit, MI

  8. Modeling Blast Loading on Buried Reinforced Concrete Structures with Zapotec

    DOE PAGES

    Bessette, Greg C.

    2008-01-01

    A coupled Euler-Lagrange solution approach is used to model the response of a buried reinforced concrete structure subjected to a close-in detonation of a high explosive charge. The coupling algorithm is discussed along with a set of benchmark calculations involving detonations in clay and sand.

  9. 3. Occident Terminal Elevator. Reinforced concrete. First total "electric" elevator ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. Occident Terminal Elevator. Reinforced concrete. First total "electric" elevator at Duluth. (Powered by electrical substation instead of steam generator). - Occident Terminal Elevator & Storage Annex, South side of second slip, north from outer end of Rice's Point, east of Garfield Avenue, Duluth, St. Louis County, MN

  10. 8. WEST FLAME DEFLECTOR FROM REINFORCED CONCRETE SLAB ROOF, FORMER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. WEST FLAME DEFLECTOR FROM REINFORCED CONCRETE SLAB ROOF, FORMER DRAINAGE AREA IN THE DISTANCE, VIEW TOWARDS NORTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-1, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  11. Solar-Array Substrate From Glass-Reinforced Concrete

    NASA Technical Reports Server (NTRS)

    Eirls, J. L.

    1985-01-01

    Design elminiates glass superstrate and associated metal framing. Panel has two trapezoidal stiffening ribs for structural support. Strategic placement of ribs with embedded support tubes (standard PVC tubing) minimizes bending moments and resulting stresses produced by installation and windloads. Glass-reinforced concrete panel has smooth flat surface suitable for solar substrate and includes structural bracing for rigidity and design adaptable to mass production.

  12. Fracture of concrete caused by the reinforcement corrosion products

    NASA Astrophysics Data System (ADS)

    Nguyen, Q. T.; Millard, A.; Caré, S.; L'Hostis, V.; Berthaud, Y.

    2006-11-01

    One of the most current degradations in reinforced concrete structures is related to the corrosion of the reinforcements. The corrosion products during active corrosion induce a mechanical pressure on the surrounding concrete that leads to cover cracking along the rebar. The objective of this work is to study the cracking of concrete due to the corrosion of the reinforcements. The phenomenon of corrosion/cracking is studied in experiments through tests of accelerated corrosion on plate and cylindrical specimens. A CCD camera is used to take images every hour and the pictures are analyzed by using the intercorrelation image technique (Correli^LMT) to derive the displacement and strain field. Thus the date of appearance of the first through crack is detected and the cinematic crack initiations are observed during the test. A finite element model that allows prediction of the mechanical consequences of the corrosion of steel in reinforced concrete structures is proposed. From the comparison between the test results and numerical simulations, it may be concluded that the model is validated in term of strains up to the moment when the crack becomes visible, and in terms of crack pattern.

  13. CORROSION PROCESS IN REINFORCED CONCRETE IDENTIFIED BY ACOUSTIC EMISSION

    NASA Astrophysics Data System (ADS)

    Kawasaki, Yuma; Kitaura, Misuzu; Tomoda, Yuichi; Ohtsu, Masayasu

    Deterioration of Reinforced Concrete (RC) due to salt attack is known as one of serious problems. Thus, development of non-destructive evaluation (NDE) techniques is important to assess the corrosion process. Reinforcement in concrete normally does not corrode because of a passive film on the surface of reinforcement. When chloride concentration at reinfo rcement exceeds the threshold level, the passive film is destroyed. Thus maintenance is desirable at an early stage. In this study, to identify the onset of corrosion and the nucleation of corrosion-induced cracking in concrete due to expansion of corrosion products, continuous acoustic emission (AE) monitoring is applied. Accelerated corrosion and cyclic wet and dry tests are performed in a laboratory. The SiGMA (Simplified Green's functions for Moment tensor Analysis) proce dure is applied to AE waveforms to clarify source kinematics of micro-cracks locations, types and orientations. Results show that the onset of corrosion and the nu cleation of corrosion-induced cracking in concrete are successfully identified. Additionally, cross-sections inside the reinforcement are observed by a scanning electron microscope (SEM). From these results, a great promise for AE techniques to monitor salt damage at an early stage in RC structures is demonstrated.

  14. 14. Reinforced Concrete Arch over Truckee River at Reno, Nevada. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. Reinforced Concrete Arch over Truckee River at Reno, Nevada. January 24, 1920. C. R. Hill, Consulting Engineer, Reno, Nevada. Various plan, section, and detail views. Paper (same as NV-10-13). Drawing No. B-72 (VB-10-25) - Riverside Bridge, Spanning Truckee River at Booth Street, Reno, Washoe County, NV

  15. 15. Reinforced Concrete Arch over Truckee River at Reno, Nevada. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. Reinforced Concrete Arch over Truckee River at Reno, Nevada. January 28, 1920. C. R. Hill, Consulting Engineer, Reno, Nevada. Various sectional and detail views of railings. lamp posts, and brackets. Paper (same as NV-10-13 and NV-10-14). Drawing No. B-73 (VB-10-26). - Riverside Bridge, Spanning Truckee River at Booth Street, Reno, Washoe County, NV

  16. 12. Reinforced Concrete Arch over Truckee River at Reno, Nevada. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. Reinforced Concrete Arch over Truckee River at Reno, Nevada. January 21, 1920. C. R. Hill, Consulting Engineer, Reno, Nevada. Plan and Elevation of East Side. Paper (white on blue). Drawing No. B-71 (VA-7-5). - Riverside Bridge, Spanning Truckee River at Booth Street, Reno, Washoe County, NV

  17. Computational simulation of reinforced concrete structures enhanced with fiber composites

    SciTech Connect

    Gotsis, P.K.; Chamis, C.C.

    1998-12-31

    Laminate analogy is applied in the structural sections by discretizing them in layers through the thickness. Different layers are used for the concrete, for the reinforcing steel in the concrete, and for the fiber composite laminates. The reinforced concrete structure is synthesized with finite elements where the element stiffness is obtained by using laminate theory to the discretized structural section mentioned earlier. The load carrying capacity of the structure is determined by progressive structural fracture. Results show that with relatively small laminate thickness, equal to 5% of the total thickness, the select arch structure enhanced with fiber composites, improved their strength in fracture, the buckling load and the natural frequencies due to the free vibration.

  18. 76 FR 48802 - Certain Steel Concrete Reinforcing Bars From Turkey; Notice of Amended Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-09

    ... International Trade Administration Certain Steel Concrete Reinforcing Bars From Turkey; Notice of Amended Final... antidumping duty order on certain steel concrete reinforcing bars (rebar) from Turkey. See Certain Steel Concrete Reinforcing Bars From Turkey; Final Results of Antidumping Duty Administrative Review...

  19. 78 FR 60831 - Steel Concrete Reinforcing Bar From Turkey: Initiation of Countervailing Duty Investigation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-02

    ... International Trade Administration Steel Concrete Reinforcing Bar From Turkey: Initiation of Countervailing Duty... (``CVD'') petition \\1\\ concerning imports of steel concrete reinforcing bar (``rebar'') from the Republic... Countervailing Duties on Imports of Steel Concrete Reinforcing Bar from the Republic of Turkey, dated September...

  20. 77 FR 64127 - Steel Concrete Reinforcing Bar From Belarus, China, Indonesia, Latvia, Moldova, Poland, and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-18

    ... COMMISSION Steel Concrete Reinforcing Bar From Belarus, China, Indonesia, Latvia, Moldova, Poland, and... determine whether revocation of the antidumping duty orders on steel concrete reinforcing bar from Belarus... concrete reinforcing bar from Latvia and Moldova. The Commission found that the respondent interested...

  1. 78 FR 60827 - Steel Concrete Reinforcing Bar From Mexico and Turkey: Initiation of Antidumping Duty Investigations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-02

    ... International Trade Administration Steel Concrete Reinforcing Bar From Mexico and Turkey: Initiation of... imports of steel concrete reinforcing bar (``rebar'') from Mexico and Turkey filed in proper form on... Duties on Steel Concrete Reinforcing Bar from Mexico and Turkey and the Imposition of...

  2. Influence of reinforcement mesh configuration for improvement of concrete durability

    NASA Astrophysics Data System (ADS)

    Pan, Chong-gen; Jin, Wei-liang; Mao, Jiang-hong; Zhang, Hua; Sun, Li-hao; Wei, Dong

    2017-08-01

    Steel bar in concrete structures under harsh environmental conditions, such as chlorine corrosion, seriously affects its service life. Bidirectional electromigration rehabilitation (BIEM) is a new method of repair technology for reinforced concrete structures in such chloride corrosion environments. By applying the BIEM, chloride ions can be removed from the concrete and the migrating corrosion inhibit can be moved to the steel surface. In conventional engineering, the concrete structure is often configured with a multi-layer steel mesh. However, the effect of the BIEM in such structures has not yet been investigated. In this paper, the relevant simulation test is carried out to study the migration law of chloride ions and the migrating corrosion inhibitor in a concrete specimen with complex steel mesh under different energizing modes. The results show that the efficiency of the BIEM increases 50% in both the monolayer steel mesh and the double-layer steel mesh. By using the single-sided BIEM, 87% of the chloride ions are removed from the steel surface. The different step modes can affect the chloride ion removal. The chloride ions within the range of the reinforcement protective cover are easier to be removed than those in the concrete between the two layers of steel mesh. However, the amount of migrating corrosion inhibitor is larger in the latter circumstances.

  3. Polarization Induced Deterioration of Reinforced Concrete with CFRP Anode

    PubMed Central

    Zhu, Ji-Hua; Wei, Liangliang; Zhu, Miaochang; Sun, Hongfang; Tang, Luping; Xing, Feng

    2015-01-01

    This paper investigates the deterioration of reinforced concrete with carbon fiber reinforced polymer (CFRP) anode after polarization. The steel in the concrete was first subjected to accelerated corrosion to various extents. Then, a polarization test was performed with the external attached CFRP as the anode and the steel reinforcement as the cathode. Carbon fiber reinforced mortar and conductive carbon paste as contact materials were used to adhere the CFRP anode to the concrete. Two current densities of 1244 and 2488 mA/m2, corresponding to the steel reinforcements were applied for 25 days. Electrochemical parameters were monitored during the test period. The deterioration mechanism that occurred at the CFRP/contact material interface was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The increase of feeding voltage and the failure of bonding was observed during polarization process, which might have resulted from the deterioration of the interface between the contact material and CFRP. The formation and accumulation of NaCl crystals at the contact material/CFRP interface were inferred to be the main causes of the failure at the interface. PMID:28793442

  4. Polarization Induced Deterioration of Reinforced Concrete with CFRP Anode.

    PubMed

    Zhu, Ji-Hua; Wei, Liangliang; Zhu, Miaochang; Sun, Hongfang; Tang, Luping; Xing, Feng

    2015-07-15

    This paper investigates the deterioration of reinforced concrete with carbon fiber reinforced polymer (CFRP) anode after polarization. The steel in the concrete was first subjected to accelerated corrosion to various extents. Then, a polarization test was performed with the external attached CFRP as the anode and the steel reinforcement as the cathode. Carbon fiber reinforced mortar and conductive carbon paste as contact materials were used to adhere the CFRP anode to the concrete. Two current densities of 1244 and 2488 mA/m², corresponding to the steel reinforcements were applied for 25 days. Electrochemical parameters were monitored during the test period. The deterioration mechanism that occurred at the CFRP/contact material interface was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The increase of feeding voltage and the failure of bonding was observed during polarization process, which might have resulted from the deterioration of the interface between the contact material and CFRP. The formation and accumulation of NaCl crystals at the contact material/CFRP interface were inferred to be the main causes of the failure at the interface.

  5. Experimental Studies on Behaviour of Reinforced Geopolymer Concrete Beams Subjected to Monotonic Static Loading

    NASA Astrophysics Data System (ADS)

    Madheswaran, C. K.; Ambily, P. S.; Dattatreya, J. K.; Ramesh, G.

    2015-06-01

    This work describes the experimental investigation on behaviour of reinforced GPC beams subjected to monotonic static loading. The overall dimensions of the GPC beams are 250 mm × 300 mm × 2200 mm. The effective span of beam is 1600 mm. The beams have been designed to be critical in shear as per IS:456 provisions. The specimens were produced from a mix incorporating fly ash and ground granulated blast furnace slag, which was designed for a compressive strength of 40 MPa at 28 days. The reinforced concrete specimens are subjected to curing at ambient temperature under wet burlap. The parameters being investigated include shear span to depth ratio (a/d = 1.5 and 2.0). Experiments are conducted on 12 GPC beams and four OPCC control beams. All the beams are tested using 2000 kN servo-controlled hydraulic actuator. This paper presents the results of experimental studies.

  6. Strain Rate Effects for Concrete and Fiber Reinforced Concrete Subjected to Impact Loading

    DTIC Science & Technology

    1987-10-01

    S. Mindess and S. P. Shah) MRS Symposia Proceedings, V67. 64, pp. 21-37, 1986. 9. Shah, S. P., "Concrete and Fiber Reinforced Concrete Subjected to...Impact Loading," in Cement Based Composites: Strain Rate Effects on Fracture (eds. S. Mindess and S. P. Shah) MRS Symposia Proceedings, Vol. 64, pp... Mindess (11), Sierakowski (12), aAd Reinhardt (13). Many investigators (see for example Ref. 6) have studied the rate sensitivity of fracture strength

  7. Experimental and analytical study on seismic behavior of steel-concrete multienergy dissipation composite shear walls

    NASA Astrophysics Data System (ADS)

    Dong, Hongying; Cao, Wanlin; Wu, Haipeng; Qiao, Qiyun; Yu, Chuanpeng

    2015-03-01

    In this paper, a steel-concrete multi-energy dissipation composite shear wall, comprised of steel-reinforced concrete (SRC) columns, steel plate (SP) deep beams, a concrete wall and energy dissipation strips, is proposed. In order to study the multi-energy dissipation behavior and restorability after an earthquake, two stages of low cyclic loading tests were carried out on ten test specimens. In the first stage, test on five specimens with different number of SP deep beams was carried out, and the test lasted until the displacement drift reached 2%. In the second stage, thin SPs were welded to both sides of the five specimens tested in the first stage, and the same test was carried out on the repaired specimens (designated as new specimens). The load-bearing capacity, stiffness, ductility, hysteretic behavior and failure characteristics were analyzed for both stages and the results are discussed herein. Extrapolating from these results, strength calculation models and formulas are proposed herein and simulations using ABAQUS carried out; they show good agreement with the test results. The study demonstrates that SRC columns, SP deep beams, concrete wall and energy dissipation strips cooperate well and play an important role in energy dissipation. In addition, this study shows that the shear wall has good recoverability after an earthquake, and that the welding of thin SP's to repair a deformed wall is a practicable technique.

  8. Code System for Analysis of 3-D Reinforced Concrete Structures.

    SciTech Connect

    ANDERSON, C. A.

    1999-11-22

    Version 00 NONSAP-C is a finite element program for determining the static and dynamic response of three-dimensional reinforced concrete structures. Long-term, or creep, behavior of concrete structures can also be analyzed. Nonlinear constitutive relations for concrete under short-term loads are incorporated in two time-independent models, a variable-modulus approach with orthotropic behavior induced in the concrete due to the development of different tangent moduli in different directions and an elastic-plastic model in which the concrete is assumed to be a continuous, isotropic, and linearly elastic-plastic strain-hardening-fracture material. A viscoelastic constitutive model for long-term thermal creep of concrete is included. Three-dimensional finite elements available in NONSAP-C include a truss element, a multinode tendon element for prestressed and post tensioned concrete structures, an elastic-plastic membrane element to represent the behavior of cavity liners, and a general isoparametric element with a variable number of nodes for analysis of solids and thick shells.

  9. Analytical Modeling of Reinforced Concrete in Tension

    DTIC Science & Technology

    1989-04-01

    microcracks having a blunt front. This concept was pioneered by Rashid (Ref 3), developed by Bazant et al. (Ref 4 through 7), and is also known as the...size. In order to circumvent this condition, Bazant and Cedolin (Ref 5) suggested linking the rela- tionship to the fracture energy, Gf, forcing the...analytical models which represent the nonlinear relationships between shear stress and slip are the Rough Crack Model of Bazant and Gambarova (Ref 19

  10. New Fiber Reinforced Waterless Concrete for Extraterrestrial Structural Applications

    NASA Technical Reports Server (NTRS)

    Toutanji, H.; Tucker, D.; Ethridge, E.

    2005-01-01

    Commercial use of sulfur concrete on Earth is well established, particularly in corrosive, e.g., acid and salt, environments. Having found troilite (FeS) on the Moon raises the question of using extracted sulfur as a lunar construction mate: iii an attractive alternative to conventional concrete as it does not require water For the purpose of this paper it is assumed that lunar ore is mined, refined, and the raw sulfur processed with appropriate lunar regolith to form, for example, brick and beam elements. Glass fibers produced from regolith were used as a reinforcement to improve the mechanical properties of the sulfur concrete. Glass fibers and glass rebar were produced by melting the lunar regolith simulant. Lunar regolith stimulant was melted in a 25 cc Pt-Rh crucible in a Sybron Thermoline 46100 high temperature MoSi2 furnace at melting temperatures of 1450 to 1600G. The glass melt wets the ceramic rod and long continuous glass fibers were easily hand drawn. The glass fibers were immediately coated with a protective polymer to maintain the mechanical strength. The viability of sulfur concrete as a construction material for extraterrestrial application is presented. The mechanical properties of the glass fiber reinforced sulfur concrete were investigated.

  11. Protection of reinforced concrete pipe against microbial induced corrosion

    SciTech Connect

    Kennedy, H.

    1997-12-01

    This paper evaluates the internal lining solutions to the problem of microbial induced corrosion in municipal wastewater applications as it relates to reinforced concrete pipe used in new or replacement construction. Microbial Induced Corrosion (MIC), commonly referred to as hydrogen sulfide (H{sub 2}S) corrosion, in Reinforced Concrete Pipe (RCP) is caused by sulfuric acid that is produced by bacteria known as Thiobacillus. Thiobacillus genus bacteria exist in the crown area of the pipe and metabolize the hydrogen sulfide (H{sub 2}S) into sulfuric acid (H{sub 2}SO{sub 4}). The sulfuric acid, in turn, corrodes the concrete. This destructive activity amounts to a multi-billion dollar annual cost to municipal wastewater systems around the world. Numerous solutions to MIC are available. The initial step in controlling MIC is to prevent the creation of H{sub 2}S through proper design of the wastewater system. Other solutions are to place anti-microbial agents in the system to prevent the growth of the bacteria or to provide an additional thickness of concrete that will take longer to corrode. If acid production cannot be prevented, the only solution left is to provide a barrier lining to protect the concrete from the acidic environment. The paper evaluates the common lining systems available in the market today including polyvinyl chloride, 100% solids polyurethane and coal tar epoxy. These materials are compared in terms of performance, application, safety and environmental implications.

  12. Study of Bond Characteristics of Reinforced Waste Glass Aggregate Concrete

    NASA Astrophysics Data System (ADS)

    Rajagopalan, P.; Balaji, V.; Unnikrishnan, N.; Jainul Haq, T.; Bhuvaneshwari, P.

    2017-07-01

    The conformity of properties of waste glass aggregate with conventional aggregate was found out. Nine cubes (150mm x 150mm x 150mm) were cast out of which three were used for control concrete, three were fully replaced with waste glass as coarse aggregate, three were partially replaced(50%) with waste glass as fine aggregate. Six cylinders (150mm x 300mm) were cast out of which two for control concrete, two cylinders with coarse aggregate fully replaced with waste glass aggregate(WGA) and remaining two cylinders with partially replaced (50%) fine aggregate with waste glass aggregate. Cured specimens were subjected to compression and split-tensile test to ascertain the characteristic compressive strength and split tensile strength. Since the surface of the coarse aggregate plays a significant role in bonding of the rebar in reinforced concrete, pull-out test on both control and Waste Glass Aggregate (WGA) cube specimens (150mm x 150mm with 20mm diameter steel rods) were conducted. Scanning Electron Microscopy (SEM) analysis has been done for better understanding of bonding properties in waste glass fine aggregate(WGFA) and waste glass coarse aggregate(WGCA) concrete. Comparison of the results with that of control specimens showed that waste glass could be effectively used as aggregates in reinforced concrete construction.

  13. New Fiber Reinforced Waterless Concrete for Extraterrestrial Structural Applications

    NASA Technical Reports Server (NTRS)

    Toutanji, H.; Tucker, D.; Ethridge, E.

    2005-01-01

    Commercial use of sulfur concrete on Earth is well established, particularly in corrosive, e.g., acid and salt, environments. Having found troilite (FeS) on the Moon raises the question of using extracted sulfur as a lunar construction mate: iii an attractive alternative to conventional concrete as it does not require water For the purpose of this paper it is assumed that lunar ore is mined, refined, and the raw sulfur processed with appropriate lunar regolith to form, for example, brick and beam elements. Glass fibers produced from regolith were used as a reinforcement to improve the mechanical properties of the sulfur concrete. Glass fibers and glass rebar were produced by melting the lunar regolith simulant. Lunar regolith stimulant was melted in a 25 cc Pt-Rh crucible in a Sybron Thermoline 46100 high temperature MoSi2 furnace at melting temperatures of 1450 to 1600G. The glass melt wets the ceramic rod and long continuous glass fibers were easily hand drawn. The glass fibers were immediately coated with a protective polymer to maintain the mechanical strength. The viability of sulfur concrete as a construction material for extraterrestrial application is presented. The mechanical properties of the glass fiber reinforced sulfur concrete were investigated.

  14. Behaviour of fibre reinforced polymer confined reinforced concrete columns under fire condition

    NASA Astrophysics Data System (ADS)

    Chowdhury, Ershad Ullah

    In recent years, fibre reinforced polymer (FRP) materials have demonstrated enormous potential as materials for repairing and retrofitting concrete bridges that have deteriorated from factors such as electro-chemical corrosion and increased load requirements. However, concerns associated with fire remain an obstacle to applications of FRP materials in buildings and parking garages due to FRP's sensitivity to high temperatures as compared with other structural materials and to limited knowledge on their thermal and mechanical behaviour in fire. This thesis presents results from an ongoing study on the fire performance of FRP materials, fire insulation materials and systems, and FRP wrapped reinforced concrete columns. The overall goal of the study is to understand the fire behaviour of FRP materials and FRP strengthened concrete columns and ultimately, provide rational fire safety design recommendations and guidelines for FRP strengthened concrete columns. A combined experimental and numerical investigation was conducted to achieve the goals of this research study. The experimental work consisted of both small-scale FRP material testing at elevated temperatures and full-scale fire tests on FRP strengthened columns. A numerical model was developed to simulate the behaviour of unwrapped reinforced concrete and FRP strengthened reinforced concrete square or rectangular columns in fire. After validating the numerical model against test data available in literature, it was determined that the numerical model can be used to analyze the behaviour of concrete axial compressive members in fire. Results from this study also demonstrated that although FRP materials experience considerable loss of their mechanical and bond properties at temperatures somewhat below the glass transition temperature of the resin matrix, externally-bonded FRP can be used in strengthening concrete structural members in buildings, if appropriate supplemental fire protection system is provided over

  15. Design and behavior of reinforced concrete beams strengthened with fiber-reinforced plastics (FRP)

    NASA Astrophysics Data System (ADS)

    El-Mihilmy, Mahmoud Tharwat

    A comprehensive investigation of the design and behavior of reinforced concrete beams strengthened with externally bonded FRP laminates has been conducted. The study has confirmed the applicability of the strain compatibility method for calculating the increased ultimate moment capacity of the repaired beams. An upper limit to the amount of FRP that can be added to a specific structure was recommended to ensure ductile behavior. Design charts to facilitate calculations of the ultimate moment capacity for reinforced concrete beams strengthened with FRP laminates were developed. The results of a subsequent parametric investigation indicate that strengthening reinforced concrete beams with FRP laminates can enhance their ultimate capacity by as much as three times the original strength, especially for beams with a low steel ratio. It was also determined that, increasing the concrete compressive strength and the FRP modulus of elasticity increases the beam ultimate flexural capacity significantly; however, the repaired beams are less ductile than the pre-repaired concrete beams. During the course of the study, it had been noticed that the current ACI recommended method for calculating deflections for ordinary reinforced concrete beams does not render an accurate estimate for reinforced concrete beams strengthened with FRP laminates. A simplified equation for predicting the deflection of reinforced concrete beams repaired with FRP was developed and verified with comparisons to experimental results. The effectiveness of strengthening an existing bridge with externally bonded FRP laminates was investigated through comprehensive static and dynamic finite element analyses. The results of these analyses correlate well with field load test results. The repaired girders exhibited an average reduction in reinforcing steel stresses of 11 percent and an average reduction in midspan girder deflections of 9 percent. The results of the study also indicated that existing methods for

  16. Crack-Arrest Techniques in Reinforced Concrete Structural Elements. Report 1. Laboratory Tests

    DTIC Science & Technology

    1974-11-01

    Control Charac-teristics of Various Types of Bar in Reinforced Concrete Beams," Research Report 18, Part 1, Dec 1966, Cement and Concrete Associa- tion...AD/A-002 661 CRACK-ARREST TECHNIQUES IN REINFORCED CONCRETE STRUCTURAL ELEMENTS. REPORT 1. LABORATORY TESTS Frank B. Cox Army Engineer Waterways...ACCESSION NO. 3. FECIPI§NT’S CATALOG NUMBER 4. TITLE (and Subtitle) S. TYPE OF REPORT &-PERIOD COVERED CRACK-ARREST TECHNIQUES IN REINFORCED CONCRETE

  17. The Use of Vitreous Enamel Coatings to Improve Bonding and Reduce Corrosion in Concrete Reinforcing Steel

    DTIC Science & Technology

    2009-02-01

    concrete apart • All normal reinforced concrete (cast-in-place and precast ) may have a short service life due to corrosion U S A r m y E n g i n e e...the Army, the Nation The Use of Vitreous Enamel Coatings to Improve Bonding and Reduce Corrosion in Concrete Reinforcing Steel Sean W. Morefield1...TITLE AND SUBTITLE The Use of Vitreous Enamel Coatings to Improve Bonding and Reduce Corrosion in Concrete Reinforcing Steel 5a. CONTRACT NUMBER

  18. Experimental study on the seismic response of braced reinforced concrete frame with irregular columns

    NASA Astrophysics Data System (ADS)

    Xiao, Jianzhuang; Li, Jie; Chen, Jun

    2011-12-01

    A 15-storey K-braced reinforced concrete model frame with irregular columns, i.e., T-shaped, L-shaped, as well as +-shaped columns, was constructed and tested on the six-degree-of-freedom shaking table at the State Key Laboratory for Disaster Reduction in Civil Engineering in Tongji, China. Two types of earthquake records, El-Centro wave (south-north direction) and Shanghai artifi cial wave (SHAW) with various peak accelerations and principal-secondary sequences, were input and experimentally studied. Based on the shaking table tests and theoretical analysis, several observations can be made. The failure sequence of the model structure is brace→beam→column→joints, so that the design philosophy for several lines of defense has been achieved. Earthquake waves with different spectrums not only infl uence the magnitude and distribution of the earthquake force and the storey shear force, but also obviously affect the magnitude of the displacement response. The aftershock seismic response of previously damaged reinforced concrete braced frames with irregular columns possesses the equivalent elastic performance characteristic. Generally speaking, from the aspects of failure features and drift ratio, this type of reinforced concrete structure provides adequate earthquake resistance and can be promoted for use in China.

  19. Seismic performance of steel reinforced ultra high-strength concrete composite frame joints

    NASA Astrophysics Data System (ADS)

    Yan, Changwang; Jia, Jinqing

    2010-09-01

    To investigate the seismic performance of a composite frame comprised of steel reinforced ultra high-strength concrete (SRUHSC) columns and steel reinforced concrete (SRC) beams, six interior frame joint specimens were designed and tested under low cyclically lateral load. The effects of the axial load ratio and volumetric stirrup ratio were studied on the characteristics of the frame joint performance including crack pattern, failure mode, ductility, energy dissipation capacity, strength degradation and rigidity degradation. It was found that all joint specimens behaved in a ductile manner with flexural-shear failure in the joint core region while plastic hinges appeared at the beam ends. The ductility and energy absorption capacity of joints increased as the axial load ratio decreased and the volumetric stirrup ratio increased. The displacement ductility coefficient and equivalent damping coefficient of the joints fell between the corresponding coefficients of the steel reinforced concrete (SRC) frame joint and RC frame joint. The axial load ratio and volumetric stirrup ratio have less influence on the strength degradation and more influence on the stiffness degradation. The stiffness of the joint degrades more significantly for a low volumetric stirrup ratio and high axial load ratio. The characteristics obtained from the SRUHSC composite frame joint specimens with better seismic performance may be a useful reference in future engineering applications.

  20. Advance study of fiber-reinforced self-compacting concrete

    SciTech Connect

    Mironova, M. Ivanova, M. Naidenov, V.; Georgiev, I.; Stary, J.

    2015-10-28

    Incorporation in concrete composition of steel macro- and micro – fiber reinforcement with structural function increases the degree of ductility of typically brittle cement-containing composites, which in some cases can replace completely or partially conventional steel reinforcement in the form of rods and meshes. Thus, that can reduce manufacturing, detailing and placement of conventional reinforcement, which enhances productivity and economic efficiency of the building process. In this paper, six fiber-reinforced with different amounts of steel fiber cement-containing self-compacting compositions are investigated. The results of some of their main strength-deformation characteristics are presented. Advance approach for the study of structural and material properties of these type composites is proposed by using the methods of industrial computed tomography. The obtained original tomography results about the microstructure and characteristics of individual structural components make it possible to analyze the effective macro-characteristics of the studied composites. The resulting analytical data are relevant for the purposes of multi-dimensional modeling of these systems. Multifactor structure-mechanical analysis of the obtained with different methods original scientific results is proposed. It is presented a conclusion of the capabilities and effectiveness of complex analysis in the studies to characterize the properties of self-compacting fiber-reinforced concrete.

  1. Advance study of fiber-reinforced self-compacting concrete

    NASA Astrophysics Data System (ADS)

    Mironova, M.; Ivanova, M.; Naidenov, V.; Georgiev, I.; Stary, J.

    2015-10-01

    Incorporation in concrete composition of steel macro- and micro - fiber reinforcement with structural function increases the degree of ductility of typically brittle cement-containing composites, which in some cases can replace completely or partially conventional steel reinforcement in the form of rods and meshes. Thus, that can reduce manufacturing, detailing and placement of conventional reinforcement, which enhances productivity and economic efficiency of the building process. In this paper, six fiber-reinforced with different amounts of steel fiber cement-containing self-compacting compositions are investigated. The results of some of their main strength-deformation characteristics are presented. Advance approach for the study of structural and material properties of these type composites is proposed by using the methods of industrial computed tomography. The obtained original tomography results about the microstructure and characteristics of individual structural components make it possible to analyze the effective macro-characteristics of the studied composites. The resulting analytical data are relevant for the purposes of multi-dimensional modeling of these systems. Multifactor structure-mechanical analysis of the obtained with different methods original scientific results is proposed. It is presented a conclusion of the capabilities and effectiveness of complex analysis in the studies to characterize the properties of self-compacting fiber-reinforced concrete.

  2. Optimum detailed design of reinforced concrete frames using genetic algorithms

    NASA Astrophysics Data System (ADS)

    Govindaraj, V.; Ramasamy, J. V.

    2007-06-01

    This article presents the application of the genetic algorithm to the optimum detailed design of reinforced concrete frames based on Indian Standard specifications. The objective function is the total cost of the frame which includes the cost of concrete, formwork and reinforcing steel for individual members of the frame. In order for the optimum design to be directly constructible without any further modifications, aspects such as available standard reinforcement bar diameters, spacing requirements of reinforcing bars, modular sizes of members, architectural requirements on member sizes and other practical requirements in addition to relevant codal provisions are incorporated into the optimum design model. The produced optimum design satisfies the strength, serviceability, ductility, durability and other constraints related to good design and detailing practice. The detailing of reinforcements in the beam members is carried out as a sub-level optimization problem. This strategy helps to reduce the size of the optimization problem and saves computational time. The proposed method is demonstrated through several example problems and the optimum results obtained are compared with those in the available literature. It is concluded that the proposed optimum design model can be adopted in design offices as it yields rational, reliable, economical, time-saving and practical designs.

  3. Effects of Reinforcement Configuration on Reserve Capacity of Concrete Slabs

    DTIC Science & Technology

    1985-08-01

    Reinforced concreted Tensile membrane,, Buried shelters/ Shelters/ ..i, Civil defense, Slab capacity, 120. A34TlRACT rCcnhma in~ r aidit noe..era aad...CHAPTER 1 I XTPODLCT, CI At the- iiti it io., of this Study civil d~efense plwlgcalled for the .;evacuation of nonessenrt*I51 pezrsonnel to safe (lower...lqbal and Derecho (Reference 10). The reinforcement ratio, p , was 0.0062 in "Christianscn’s te,;tts and varied from 0.0023 to 0.0093 in Roberts’ tests

  4. Mixed Consolidation Solution for a Reinforced Concrete Structure

    NASA Astrophysics Data System (ADS)

    Lute, M.

    2016-06-01

    During the last years, reinforced concrete structures become subject for rehabilitation due to two factors: their long life span and large change in norms that leaded to a large increase of seismic loads in Eastern Europe. These lead to a necessity for rehabilitation of existing building stock in order to use them during their entire life span at the maximum potential. The present paper proposes a solution for rehabilitation for three reinforced concrete building of a hospital, that consumed a half of their life span and do not correspond anymore to present norms. The chosen solution is a combination between CFRP rehabilitation and increase of structural elements cross section in order to achieve the stiffness balance in the structure nodes that is required by present norms. As a further matter, correction in stiffness of local elements diminished the lateral drifts of the structure and improved the global seismic response of the building.

  5. Glass fiber reinforced concrete for terrestrial photovoltaic arrays

    NASA Technical Reports Server (NTRS)

    Maxwell, H.

    1979-01-01

    The use of glass-fiber-reinforced concrete (GRC) as a low-cost structural substrate for terrestrial solar cell arrays is discussed. The properties and fabrication of glass-reinforced concrete structures are considered, and a preliminary design for a laminated solar cell assembly built on a GRC substrate is presented. A total cost for such a photovoltaic module, composed of a Korad acrylic plastic film front cover, an aluminum foil back cover, an ethylene/vinyl acetate pottant/adhesive and a cotton fabric electrical isolator in addition to the GRC substrate, of $9.42/sq m is projected, which is less than the $11.00/sq m cost goal set by the Department of Energy. Preliminary evaluations are concluded to have shown the design capabilities and cost effectiveness of GRC; however, its potential for automated mass production has yet to be evaluated.

  6. Glass fiber reinforced concrete for terrestrial photovoltaic arrays

    NASA Technical Reports Server (NTRS)

    Maxwell, H.

    1979-01-01

    The use of glass-fiber-reinforced concrete (GRC) as a low-cost structural substrate for terrestrial solar cell arrays is discussed. The properties and fabrication of glass-reinforced concrete structures are considered, and a preliminary design for a laminated solar cell assembly built on a GRC substrate is presented. A total cost for such a photovoltaic module, composed of a Korad acrylic plastic film front cover, an aluminum foil back cover, an ethylene/vinyl acetate pottant/adhesive and a cotton fabric electrical isolator in addition to the GRC substrate, of $9.42/sq m is projected, which is less than the $11.00/sq m cost goal set by the Department of Energy. Preliminary evaluations are concluded to have shown the design capabilities and cost effectiveness of GRC; however, its potential for automated mass production has yet to be evaluated.

  7. Reinforced concrete structures loaded by snow avalanches : numerical and experimental approaches.

    NASA Astrophysics Data System (ADS)

    Ousset, I.; Bertrand, D.; Brun, M.; Limam, A.; Naaim, M.

    2012-04-01

    Today, due to the extension of occupied areas in mountainous regions, new strategies for risk mitigation have to be developed. In the framework of risk analysis, these latter have to take into account not only the natural hazard description but also the physical vulnerability of the exposed structures. From a civil engineering point of view, the dynamic behavior of column or portico was widely investigated especially in the case of reinforced concrete and steel. However, it is not the case of reinforced concrete walls for which only the in-plan dynamic behavior (shear behavior) has been studied in detail in the field of earthquake engineering. Therefore, the aim of this project is to study the behavior of reinforced concrete civil engineering structures submitted to out-of-plan dynamic loadings coming from snow avalanche interaction. Numerical simulations in 2D or 3D by the finite element method (FEM) are presented. The approach allows solving mechanical problems in dynamic condition involving none linearities (especially none linear materials). Thus, the structure mechanical response can be explored in controlled conditions. First, a reinforced concrete wall with a L-like shape is considered. The structure is supposed to represent a French defense structure dedicated to protect people against snow avalanches. Experimental pushover tests have been performed on a physical model. The experimental tests consisted to apply a uniform distribution of pressure until the total collapse of the wall. A 2D numerical model has been developed to simulate the mechanical response of the structure under quasi-static loading. Numerical simulations have been compared to experimental datas and results gave a better understanding of the failure mode of the wall. Moreover, the influence of several parameters (geometry and the mechanical properties) is also presented. Secondly, punching shear experimental tests have also been carried out. Reinforced concrete slabs simply supported have

  8. Fiber-Reinforced Concrete For Hardened Shelter Construction

    DTIC Science & Technology

    1993-02-01

    not limited to, steel, nylon, polypropylene, carbon, glass , and steel fiber - mat matrices. Based on this literature review, areas where research is...reinforce concrete in a wide range of areas, from large size tanks such as swimming pools to roofing system tiles and shingles . 3. Polymeric Fibers ...Page 1 Steel Mat Fiber Matrix Used In Test Beam Types MI And M2 ................ 12 2 Test Beam Cross-Sections. Test Phases I And H

  9. Perspective view. The threestory reinforced concrete building faced with brick ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Perspective view. The three-story reinforced concrete building faced with brick has direct frontage onto neighboring railroad line. The facade says: "The Fairmont Creamery Company" in white stone. The facade is divided into bays by large brick piers capped with a square accent piece. A large stone band runs just above the windows and between the second and third floors - The Fairmont Creamery Company, 608 East Milwaukee Avenue, Detroit, MI

  10. View from intersection. Ninestory reinforced concrete building infilled with brick. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View from intersection. Nine-story reinforced concrete building infilled with brick. The street facades on beaubien and east grand are faced with stone accents and elaborate brick work. Brick pilasters run the entire height of the building. Steel tiebacks are apparent running up the height of the building on the east side. The large tower appears at the northeast and southeast corners - Detroit Storage Company, 2937 East Grand Boulevard, Detroit, MI

  11. Fatigue testing of reinforced-concrete steel bars

    NASA Astrophysics Data System (ADS)

    Maropoulos, S.; Fasnakis, D.; Voulgaraki, Ch; Papanikolaou, S.; Maropoulos, A.; Antonatos, A.

    2016-11-01

    A number of low-cycle fatigue tests were conducted on reinforced-concrete steel bars of various diameters to study their behaviour under axial loading according to EN 10080 and EN 1421-3. Scanning electron microscopy was used to study the specimen fracture surfaces. The problems faced during testing are presented and a specimen preparation method is described that will aid researchers on fatigue testing to obtain accurate test results and save on material and time.

  12. 83. ARAIII. A blast wall of reinforced concrete separated the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    83. ARA-III. A blast wall of reinforced concrete separated the GCRE control room from the reactor. Blast wall goes up at left of view. Camera stands at the southwest corner of the control building (ARA-607) and faces east. October 14, 1958. Ineel photo no. 58-5085. Photographer: Jack L. Anderson. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

  13. Interfacial chemistry of zinc anodes for reinforced concrete structures

    SciTech Connect

    Covino, B.S. Jr.; Bullard, S.J.; Cramer, S.D.; Holcomb, G.R.; McGill, G.E.; Cryer, C.B.; Stoneman, A.; Carter, R.R.

    1997-12-01

    Thermally-sprayed zinc anodes are used in both galvanic and impressed current cathodic protection systems for reinforced concrete structures. The Albany Research Center, in collaboration with the Oregon Department of Transportation, has been studying the effect of electrochemical aging on the bond strength of zinc anodes for bridge cathodic protection systems. Changes in anode bond strength and other anode properties can be explained by the chemistry of the zinc-concrete interface. The chemistry of the zinc-concrete interface in laboratory electrochemical aging studies is compared with that of several bridges with thermal-sprayed zinc anodes and which have been in service for 5 to 10 years using both galvanic and impressed current cathodic protection systems. The bridges are the Cape Creek Bridge on the Oregon coast and the East Camino Undercrossing near Placerville, CA. Also reported are interfacial chemistry results for galvanized steel rebar from the 48 year old Longbird Bridge in Bermuda.

  14. Crack detection and leakage monitoring on reinforced concrete pipe

    NASA Astrophysics Data System (ADS)

    Feng, Qian; Kong, Qingzhao; Huo, Linsheng; Song, Gangbing

    2015-11-01

    Reinforced concrete underground pipelines are some of the most widely used types of structures in water transportation systems. Cracks and leakage are the leading causes of pipeline structural failures which directly results in economic losses and environmental hazards. In this paper, the authors propose a piezoceramic based active sensing approach to detect the cracks and the further leakage of concrete pipelines. Due to the piezoelectric properties, piezoceramic material can be utilized as both the actuator and the sensor in the active sensing approach. The piezoceramic patch, which is sandwiched between protective materials called ‘smart aggregates,’ can be safely embedded into concrete structures. Circumferential and axial cracks were investigated. A wavelet packet-based energy analysis was developed to distinguish the type of crack and determine the further leakage based on different stress wave energy attenuation propagated through the cracks.

  15. Corrosion of reinforced concrete in the Persian Gulf region

    SciTech Connect

    Novokshchenov, V.

    1995-01-01

    The Kuwait liquefied gas/sulfur (LGS) plant is located on a small island in the southern part of the Persian Gulf. The plant was built in phases between 1973 and 1977. Designed to manufacture liquefied natural and petroleum gas and to extract sulfur, the LGS plant consists of two similar process unit trains served by a common boiler and utility plant. The major reinforced-concrete structures at the plant include the cooling water outfall, the cooling water intake, the operations building, structures supporting elevated pipe and equipment, boiler stack foundations, bridge over the flume, the loading jetty, sulfur plant structures, substations, and storage tank foundations. The first signs of distress in the plant structures were reported in 1980: cracking, spalling, and delamination of concrete cover and corrosion of reinforcing steel. In some cases, deterioration had progressed to the extent that safety and life expectancy of the structures were at risk. Subsequently, several investigations were conducted on various structures from 1980 to 1987 to identify the causes of the deterioration. The principal cause of the deterioration was corrosion of reinforcing steel caused by the presence of chlorides; marine salts were the main source. Construction-related contributing factors included insufficient concrete cover, use of sulfate-resistant (ASTM Type V) portland cement, and an elevated water-to-cement ratio.

  16. Influence of loading-rate and steel fibers on the shear strength of ultra high performance concrete

    NASA Astrophysics Data System (ADS)

    Bratislav, Lukic; Pascal, Forquin

    2015-09-01

    The paper describes quasi-static and dynamic experimental methods used to examine the confined shear strength of an Ultra High Performance Concrete, with and without the presence of steel fibers in the concrete composition. An experimental setup was created to investigate the concrete shear strength under quasi-static loading regime using a hydraulic press Schenk while dynamic shear strength was characterized by subjecting concrete samples to dynamic loading through a modified Split Hopkinson Pressure Bar. Both methods are based on a Punch Through Shear (PTS) test with a well-instrumented aluminum passive confinement ring that allows measuring the change of radial stress in the shear ligament throughout the test. Firstly, four equally distributed radial notches have been performed in order to deduce the radial stress by suppressing a self-confinement of the sample peripheral part. However, by analyzing the strain gauge data from the confinement ring, it has been noticed that these were apparently insufficient, especially for fiber-reinforced samples, resulting in subsequently practicing eight radial notches through the sample peripheral part. The results obtained from both procedures are reported and discussed.

  17. Numerical simulation of monitoring corrosion in reinforced concrete based on ultrasonic guided waves.

    PubMed

    Zheng, Zhupeng; Lei, Ying; Xue, Xin

    2014-01-01

    Numerical simulation based on finite element method is conducted to predict the location of pitting corrosion in reinforced concrete. Simulation results show that it is feasible to predict corrosion monitoring based on ultrasonic guided wave in reinforced concrete, and wavelet analysis can be used for the extremely weak signal of guided waves due to energy leaking into concrete. The characteristic of time-frequency localization of wavelet transform is adopted in the corrosion monitoring of reinforced concrete. Guided waves can be successfully used to identify corrosion defects in reinforced concrete with the analysis of suitable wavelet-based function and its scale.

  18. Numerical Simulation of Monitoring Corrosion in Reinforced Concrete Based on Ultrasonic Guided Waves

    PubMed Central

    Zheng, Zhupeng; Lei, Ying; Xue, Xin

    2014-01-01

    Numerical simulation based on finite element method is conducted to predict the location of pitting corrosion in reinforced concrete. Simulation results show that it is feasible to predict corrosion monitoring based on ultrasonic guided wave in reinforced concrete, and wavelet analysis can be used for the extremely weak signal of guided waves due to energy leaking into concrete. The characteristic of time-frequency localization of wavelet transform is adopted in the corrosion monitoring of reinforced concrete. Guided waves can be successfully used to identify corrosion defects in reinforced concrete with the analysis of suitable wavelet-based function and its scale. PMID:25013865

  19. Shear degradation in fiber reinforced laminates due to matrix damage

    NASA Astrophysics Data System (ADS)

    Salavatian, Mohammedmahdi

    The objective of this study was to develop and implement a shear modulus degradation model to improve the failure analysis of the fiber reinforced composite structures. Matrix damage, involving transverse and shear cracks, is a common failure mode for composite structures, yet little is known concerning their interaction. To understand the material behavior after matrix failure, the nonlinear response of the composite laminate was studied using pressure vessels made from a [+/-o] bias orientation, which tend to exhibit a matrix dominated failure. The result of this work showed laminate matrix hardening in shear and softening in the transverse direction. A modified Iosipescu coupon was proposed to study the evolution of shear and transverse damage and their mutual effects. The proposed method showed good agreement with tubular results and has advantages of simplified specimen fabrication using standard test fixtures. The proposed method was extended by introducing a novel experimental technique to study the shear degradation model under biaxial loading. Experimental results of the transverse modulus reduction were in good agreement with material degradation models, while the predicted shear modulus reduction was higher than experiment. The discrepancy between available models and observations was due to the presence of a traction between the crack surfaces. Accordingly, a closed form solution was proposed for the shear stress-strain field of a cracked laminate by replacing the cracks with cohesive zones. The constitutive equations of the crack laminate were derived including the effects of internal tractions and transverse stress on the shear modulus. The proposed analytical model was shown to be the most comprehensive model for shear modulus degradation reduction of the fiber reinforced laminates. A numerical implementation of the shear degradation model was done using continuum damage mechanics. Through this work it was shown the common assumption of a linear

  20. Fatigue and Fracture Characterization of GlasGridRTM Reinforced Asphalt Concrete Pavement

    NASA Astrophysics Data System (ADS)

    Safavizadeh, Seyed Amirshayan

    The purpose of this research is to develop an experimental and analytical framework for describing, modeling, and predicting the reflective cracking patterns and crack growth rates in GlasGridRTM-reinforced asphalt pavements. In order to fulfill this objective, the effects of different interfacial conditions (mixture and tack coat type, and grid opening size) on reflective cracking-related failure mechanisms and the fatigue and fracture characteristics of fiberglass grid-reinforced asphalt concrete beams were studied by means of four- and threepoint bending notched beam fatigue tests (NBFTs) and cyclic and monotonic interface shear tests. The digital image correlation (DIC) technique was utilized for obtaining the displacement and strain contours of specimen surfaces during each test. The DIC analysis results were used to develop crack tip detection methods that were in turn used to determine interfacial crack lengths in the shear tests, and vertical and horizontal (interfacial) crack lengths in the notched beam fatigue tests. Linear elastic fracture mechanics (LEFM) principles were applied to the crack length data to describe the crack growth. In the case of the NBFTs, a finite element (FE) code was developed and used for modeling each beam at different stages of testing and back-calculating the stress intensity factors (SIFs) for the vertical and horizontal cracks. The local effect of reinforcement on the stiffness of the system at a vertical crack-interface intersection or the resistance of the grid system to the deflection differential at the joint/crack (hereinafter called joint stiffness) for GlasGrid-reinforced asphalt concrete beams was determined by implementing a joint stiffness parameter into the finite element code. The strain level dependency of the fatigue and fracture characteristics of the GlasGrid-reinforced beams was studied by performing four-point bending notched beam fatigue tests at strain levels of 600, 750, and 900 microstrain. These beam

  1. 78 FR 73838 - Steel Concrete Reinforcing Bar From Turkey: Postponement of Preliminary Determination in the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-09

    ... International Trade Administration Steel Concrete Reinforcing Bar From Turkey: Postponement of Preliminary... Department of Commerce (the Department) initiated a countervailing duty investigation on steel concrete... December 16, 2013.\\3\\ \\1\\ See Steel Concrete Reinforcing Bar from Turkey: Initiation of Countervailing...

  2. 77 FR 71631 - Steel Concrete Reinforcing Bar From Belarus, China, Indonesia, Latvia, Moldova, Poland, and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-03

    ... COMMISSION Steel Concrete Reinforcing Bar From Belarus, China, Indonesia, Latvia, Moldova, Poland, and Ukraine; Scheduling of Full Five-Year Reviews Concerning the Antidumping Duty Orders on Steel Concrete...) to determine whether revocation of the antidumping duty orders on steel concrete reinforcing bar...

  3. Fibre Reinforced Polymers (FRP) as Reinforcement for Concrete According to German Approvals

    NASA Astrophysics Data System (ADS)

    Alex, R.

    2015-11-01

    This article demonstrates the possibility of the application of joint principles to develop test programs for national approval or European Technical Assessments of FRP reinforcement for concrete. The limits of different systems are shown, which until now have been approved in Germany.

  4. Impact Resistance Performance of Kenaf Fibre Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Che Muda, Zakaria; Liyana Mohd Kamal, Nur; Syamsir, Agusril; Sheng, Chiam Yung; Beddu, Salmia; Nasharuddin Mustapha, Kamal; Thiruchelvam, Sivadass; Usman, Fathoni; Ashraful Alam, Md; Birima, Ahmed H.; Zaroog, O. S.

    2016-03-01

    This paper investigate the performance of kenaf fibre mesh reinforced concrete (KFMRC) with varied kenaf fibre mesh reinforcement content for the concrete slab of 300mm × 300mm size reinforced with different mesh diameter at constant spacing with varied slab thickness subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.236 kg drop at 0.40 m height has been used in this research work. The main variables for the study is to find the relationship of the impact resistance against the amount of mesh reinforcement and slab thickness. A linear relationship has been established between first and ultimate crack resistance against kenaf fiber diameters by the experiment. The linear relationship has also been established between the service (first) crack and ultimate crack resistance against the slab thickness. The threshold (highest) values for service crack and ultimate crack is 47.9 N/mm2 and 130.58 N/mm2 respectively observed and computed for 50 mm slab with 7 mm diameter mesh.

  5. Hybrid fiber-reinforcement in mortar and concrete

    NASA Astrophysics Data System (ADS)

    Lawler, John Steven

    Performance of concrete and mortar is improved through use of discontinuous fibers because of the resulting fundamental changes in the failure mechanism. The role a specific type of fiber plays in this process is governed by the material and geometry of the fibers, the fiber-matrix bond and the matrix properties. Blending fiber types exhibiting complementary and additive properties in the composite is a means for maximizing the potential of fibers for the reinforcement of concrete. The specific blend pursued in this investigation is a combination of steel or PVA microfibers, that interact with developing cracks, and steel macrofibers, which become crucial once cracks develop. The objective of this investigation is to explore the mechanisms by which fibers interact with the composite matrix and to provide a rigorous characterization of performance achievable with hybrid reinforced concrete. The role of micro- and macrofibers in the failure of mortar is examined using Subregion Scanning Computer Vision. The fracture process occurs in three stages: microcrack formation, microcrack coalescence and finally the formation of macrocracks. Closely spaced microfibers bridge coalesced microcracks. This increases performance up to and around the peak load by delaying the initiation of macrocracking. Once macrocracks develop, macrofibers are most effective at imparting ductility to the composite. Hybrid reinforcing fibers reduce the water permeability of cracked mortar, which has implications for durability, through the induction of multiple cracking. An innovative method for measuring cracked permeability in uniaxial tension under load is presented. The workability of macro- and microfiber hybrids in concrete is governed by the high surface area of the microfibers. A mix design procedure is presented to determine the optimum paste volume to efficiently achieve the best flow and cohesion properties. The relationships between workability, fiber dispersion, and mechanical

  6. Strength Design of Reinforced Concrete Hydraulic Structures. Report 9. Analysis and Design of Reinforced Concrete Conduits

    DTIC Science & Technology

    1989-06-01

    American Concrete Pipe Association ( ACPA ) Approach 15. The "indirect method" of the ACPA (2-5) follows the D-load method of ASTM, but accounts for...been used on many occasions and is currently being converted from main frame to PC use. ACPA intends to distribute this program to designers, so there...Philadelphia, Pa., 1984. 2-5. American Concrete Pipe Association, "Concrete Pipe Handbook", Chap.4, ACPA , Vienna, Va. 1988. 2-6. Olander, H.C., U.S

  7. Ductility of nonmetallic hybrid fiber composite reinforcement for concrete

    NASA Astrophysics Data System (ADS)

    Tepfers, R.; Tamužs, V.; Apinis, R.; Vilks, U.; Modniks, J.

    1996-03-01

    Reinforcing units, FRP, of unidirectional fiber composites for concrete have elastic behavior up to tensile failure. For safety reasons an elongation of 3% at maximum load is usually required for the reinforcement. Ductile behavior with the necessary elongation and stress hardening could be obtained with braided fiber strands around a core of foam plastic, thin glass fiber cylindrical shell, or unidirectional carbon fibers. Braids around a porous core reveal the ductility when epoxy resin breaks up and collapse of core enables the braids to rotate. The same seems to happen at that cross section, where carbon fiber core breaks in tension. The best result is obtained using a cylindrical glass fiber reinforced core shell surrounded with aramid fiber braid.

  8. Performance and Characterization of Shear Ties for Use in Insulated Precast Concrete Sandwich Wall Panels

    DTIC Science & Technology

    2010-11-01

    AFRL-RX-TY-TP-2010-0082 PERFORMANCE AND CHARACTERIZATION OF SHEAR TIES FOR USE IN INSULATED PRECAST CONCRETE SANDWICH WALL PANELS...of Shear Ties for Use in Insulated Precast Concrete Sandwich Wall Panels (PREPRINT) FA8903-08-D-8768-0002 0909999F GOVT F0 QF101000 #Naito, Clay...PERFORMANCE AND CHARACTERIZATION OF SHEAR TIES FOR USE IN 1 INSULATED PRECAST CONCRETE SANDWICH WALL PANELS 2 Clay Naito1, John Hoemann2, Mark Beacraft3

  9. Flexural strengthening of Reinforced Concrete (RC) Beams Retrofitted with Corrugated Glass Fiber Reinforced Polymer (GFRP) Laminates

    NASA Astrophysics Data System (ADS)

    Aravind, N.; Samanta, Amiya K.; Roy, Dilip Kr. Singha; Thanikal, Joseph V.

    2015-01-01

    Strengthening the structural members of old buildings using advanced materials is a contemporary research in the field of repairs and rehabilitation. Many researchers used plain Glass Fiber Reinforced Polymer (GFRP) sheets for strengthening Reinforced Concrete (RC) beams. In this research work, rectangular corrugated GFRP laminates were used for strengthening RC beams to achieve higher flexural strength and load carrying capacity. Type and dimensions of corrugated profile were selected based on preliminary study using ANSYS software. A total of twenty one beams were tested to study the load carrying capacity of control specimens and beams strengthened with plain sheets and corrugated laminates using epoxy resin. This paper presents the experimental and theoretical study on flexural strengthening of Reinforced Concrete (RC) beams using corrugated GFRP laminates and the results are compared. Mathematical models were developed based on the experimental data and then the models were validated.

  10. Improvement in reinforcing bond strength in reinforced concrete with self-repairing chemical adhesives

    NASA Astrophysics Data System (ADS)

    Dry, Carolyn M.

    1997-05-01

    Self-healing concretes have embedded adhesives which are released from hollow fibers inside the concrete when and where cracking of the matrix and the fibers occurs. It was found that the adhesive improves the strength of the cracked portions of the concrete and increases its ability to deflect under load. Structural materials subjected to dynamic events such as earthquakes and impacts can have improved response by the noise of adhesive type which can impart improved damping, lateral stiffness, or deflection. Testing also assessed the improvement of the bond strength in structures. In laboratory tests the internal adhesive repair system improved the bond between the reinforcing steel and the concrete to prevent pullout failure or debonding at the interface.

  11. Intermittent cathodic protection for steel reinforced concrete bridges

    SciTech Connect

    Bullard, Sophie J.; Ziomek-Moroz, Margaret; Cramer, Stephen D.; Covino, Bernard S., Jr.; Holcomb, Gordon R.; Russell, James H.; Soltesz, S.M.

    2002-01-01

    Thermal-sprayed zinc anodes are used for impressed current cathodic protection (ICCP) systems on Oregon's reinforced concrete coastal bridges to prevent chloride-induced corrosion damage. Thermal-sprayed zinc performs well as an ICCP anode but the service life of the zinc anode is directly related to the average current density used to operate the systems. After a ICCP system is turned off, the rebar in the concrete remains passive and protected for a period of time. Intermittent operation of CP systems is possible when continuous corrosion rate monitoring is used to identify conditions when the CP system needs to be turned on to reestablish protection conditions for the rebar. This approach applies CP protection only when needed and reflects the fact that external protection may not be needed for a range of environmental conditions. In doing so, intermittent CP would lower the average current necessary to protect rebar, increase the anode service life, and reduce the lifetime costs for protecting reinforced concrete bridges.

  12. New NDE technologies for evaluating reinforced concrete masonry

    SciTech Connect

    Alexander, A.M.; Haskins, R.W.

    1999-07-01

    Researchers at the Waterways' Experiment Station (WES) have demonstrated that two new nondestructive evaluation technologies show promise in making a more accurate diagnosis of the structural condition of concrete masonry walls than prior technologies. Traditionally, sounding with a hammer has been used to determine the presence and quality of the grout fill around the reinforcing bars in concrete masonry units (CMU's). First, WES has developed a new grout detection system, which senses the reverberating energy in the CMU's with a microphone. This energy is introduced into the CMU by using a pistol to fire a metal BB against the face of the block. A microphone and spectrum analyzer replaces the function of the human ear to distinguish different pitches of sound through sounding. Since a technician is more likely to get consistent results with the new system, it is not as subjective as sounding. Next, WES has evaluated the new digital steel detectors. A reinforced concrete masonry structure can contain many combinations of steel: vertical bars, horizontal bars, size of bar, number of bars, splices, etc. Digital steel detectors with microprocessors have the potential to provide much more information than traditional analog types.

  13. Life cycle CO{sub 2} evaluation on reinforced concrete structures with high-strength concrete

    SciTech Connect

    Tae, Sungho; Baek, Cheonghoon Shin, Sungwoo

    2011-04-15

    The purpose of this study is to evaluate the environment performance of high-strength concrete used in super tall buildings as material of environmental load reduction. To this end, this study proposed a plan for the evaluation of energy consumption and CO{sub 2} emission throughout the life cycle of the building, and calculated the energy consumption and CO{sub 2} emission throughout the life cycle of tall apartment building that was actually constructed using this plan. Then, we evaluated the energy consumption and CO{sub 2} emission reduction performance for the life cycle of the building by the decrease of concrete and reinforced rebar quantities and the increase of building lifespan obtained through conversion of existing building's concrete compressive strength to 40 MPa high-strength concrete. As a result, the life cycle energy consumption in case 3, a high-strength concrete building, decreased 15.53% and 2.95% respectively compared with cases 1 and 2. The evaluation of the general strength concrete buildings and the life cycle CO{sub 2} emission also decreased 16.70% and 3.37% respectively, compared with cases 1 and 2.

  14. Evaluation of Glass Fiber Reinforced Concrete Panels for Use in Military Construction.

    DTIC Science & Technology

    1984-06-01

    AD-A158 134 UNCLASSIFIED EVALUATION OF GLASS FIBER REINFORCED CONCRETE PANELS FOR USE IN MILITARY. . (U) CONSTRUCTION ENGINEERING RESEARCH LAB...Construction Engineering Research Laboratory i=h-C=iU. TECHNICAL REPORT M-85/15 June 1985 AD-A158 134 0~- 8 Evaluation of Glass Fiber ...Reinforced Concrete Panels for Use in Military Construction by Gilbert R. Williamson Glass fiber reinforced concrete (GFRC) materials are investigated

  15. Characteristics and applications of high-performance fiber reinforced asphalt concrete

    NASA Astrophysics Data System (ADS)

    Park, Philip

    Steel fiber reinforced asphalt concrete (SFRAC) is suggested in this research as a multifunctional high performance material that can potentially lead to a breakthrough in developing a sustainable transportation system. The innovative use of steel fibers in asphalt concrete is expected to improve mechanical performance and electrical conductivity of asphalt concrete that is used for paving 94% of U. S. roadways. In an effort to understand the fiber reinforcing mechanisms in SFRAC, the interaction between a single straight steel fiber and the surrounding asphalt matrix is investigated through single fiber pull-out tests and detailed numerical simulations. It is shown that pull-out failure modes can be classified into three types: matrix, interface, and mixed failure modes and that there is a critical shear stress, independent of temperature and loading rate, beyond which interfacial debonding will occur. The reinforcing effects of SFRAC with various fiber sizes and shapes are investigated through indirect tension tests at low temperature. Compared to unreinforced specimens, fiber reinforced specimens exhibit up to 62.5% increase in indirect tensile strength and 895% improvements in toughness. The documented improvements are the highest attributed to fiber reinforcement in asphalt concrete to date. The use of steel fibers and other conductive additives provides an opportunity to make asphalt pavement electrically conductive, which opens up the possibility for multifunctional applications. Various asphalt mixtures and mastics are tested and the results indicate that the electrical resistivity of asphaltic materials can be manipulated over a wide range by replacing a part of traditional fillers with a specific type of graphite powder. Another important achievement of this study is development and validation of a three dimensional nonlinear viscoelastic constitutive model that is capable of simulating both linear and nonlinear viscoelasticity of asphaltic materials. The

  16. Modeling and Measurement of Sustained Loading and Temperature-Dependent Deformation of Carbon Fiber-Reinforced Polymer Bonded to Concrete.

    PubMed

    Jeong, Yoseok; Lee, Jaeha; Kim, WooSeok

    2015-01-29

    This paper aims at presenting the effects of short-term sustained load and temperature on time-dependent deformation of carbon fiber-reinforced polymer (CFRP) bonded to concrete and pull-off strength at room temperature after the sustained loading period. The approach involves experimental and numerical analysis. Single-lap shear specimens were used to evaluate temperature and short-term sustained loading effects on time-dependent behavior under sustained loading and debonding behavior under pull-off loading after a sustained loading period. The numerical model was parameterized with experiments on the concrete, FRP, and epoxy. Good correlation was seen between the numerical results and single-lap shear experiments. Sensitivity studies shed light on the influence of temperature, epoxy modulus, and epoxy thickness on the redistribution of interfacial shear stress during sustained loading. This investigation confirms the hypothesis that interfacial stress redistribution can occur due to sustained load and elevated temperature and its effect can be significant.

  17. Tipping point analysis of cracking in reinforced concrete

    NASA Astrophysics Data System (ADS)

    Perry, M.; Livina, V.; Niewczas, P.

    2016-01-01

    In this work, we demonstrate that tipping point analysis of strain data can provide reactive and predictive indicators of cracking and structural transitions in a reinforced concrete system. The method is able to detect trend-driven transitions in a short time series of approximately 2000 datapoints, providing a clear indication of when a concrete beam under gradual bending progresses from a linear to a nonlinear strain response. The method is also able to provide an early warning signal of the appearance of bifurcations, such as cracks, with a forewarning of 200-500 datapoints. The method, which was originally developed for applications in geophysics, shows promising results in the area of structural health monitoring, in particular, for real-time observations of civil constructions.

  18. Durability Studies on Confined Concrete using Fiber Reinforced Polymer

    NASA Astrophysics Data System (ADS)

    Ponmalar, V.; Gettu, R.

    2014-06-01

    In this study, 24 concrete cylinders with a notch at the centre were prepared. Among them six cylinders were wrapped using single and double layers of fiber reinforced polymer; six cylinders were coated with epoxy resin; the remaining cylinders were used as a control. The cylinders were exposed to wet and dry cycling and acid (3 % H2SO4) solution for the period of 120 days. Two different concrete strengths M30 and M50 were considered for the study. It is found that the strength, ductility and failure mode of wrapped cylinders depend on number of layers and the nature of exposure conditions. It was noticed that the damage due to wet and dry cycling and acid attack was severe in control specimen than the epoxy coated and wrapped cylinders.

  19. Processing and Mechanical Properties of Macro Polyamide Fiber Reinforced Concrete.

    PubMed

    Jeon, Joong Kyu; Kim, WooSeok; Jeon, Chan Ki; Kim, Jin Cheol

    2014-11-26

    This study developed a macro-sized polyamide (PA) fiber for concrete reinforcement and investigated the influence of the PA fiber on flexural responses in accordance with ASTM standards. PA fibers are advantageous compared to steel fibers that are corrosive and gravitated. The macro-sized PA fiber significantly improved concrete ductility and toughness. Unlike steel fibers, the PA fibers produced two peak bending strengths. The first-peaks occurred near 0.005 mm of deflection and decreased up to 0.5 mm of deflection. Then the bending strength increased up to second-peaks until the deflections reached between 1.0 and 1.5 mm. The averaged flexural responses revealed that PA fiber content did not significantly influence flexural responses before L/600, but had significant influence thereafter. Toughness performance levels were also determined, and the results indicated more than Level II at L/600 and Level IV at others.

  20. Processing and Mechanical Properties of Macro Polyamide Fiber Reinforced Concrete

    PubMed Central

    Jeon, Joong Kyu; Kim, WooSeok; Jeon, Chan Ki; Kim, Jin Cheol

    2014-01-01

    This study developed a macro-sized polyamide (PA) fiber for concrete reinforcement and investigated the influence of the PA fiber on flexural responses in accordance with ASTM standards. PA fibers are advantageous compared to steel fibers that are corrosive and gravitated. The macro-sized PA fiber significantly improved concrete ductility and toughness. Unlike steel fibers, the PA fibers produced two peak bending strengths. The first-peaks occurred near 0.005 mm of deflection and decreased up to 0.5 mm of deflection. Then the bending strength increased up to second-peaks until the deflections reached between 1.0 and 1.5 mm. The averaged flexural responses revealed that PA fiber content did not significantly influence flexural responses before L/600, but had significant influence thereafter. Toughness performance levels were also determined, and the results indicated more than Level II at L/600 and Level IV at others. PMID:28788265

  1. A damage detection technique for reinforced concrete structures

    NASA Astrophysics Data System (ADS)

    Wu, Ai-Lun; Yang, Jann N.; Loh, Chin-Hsiung

    2012-04-01

    Civil engineering structures, such as reinforced concrete frames, exhibit nonlinear hysteretic behavior when subject to dynamic loads, such as earthquakes. The ability to detect damages in structures after a major earthquake will ensure their reliability and safety. Innovative analysis techniques for damage detection of structures have been extensively studied recently. However, practical and effective damage identification techniques remain to be developed for nonlinear structures, in particular hysteretic reinforced concrete (RC) structures. In this paper, a smooth hysteretic model with stiffness and strength degradations and with the pinching effect is used to represent the dynamic characteristics of reinforced concrete (RC) frames. A system identification method capable of detecting damages in nonlinear structures, referred to as the adaptive quadratic sum-square error with unknown inputs (AQSSE-UI), is used to detect damages in hysteretic RC frames. The performance of the AQSSE-UI technique is demonstrated by the experimental data. A 1/3 scale 2-story RC frame has been tested experimentally on the shake table at NCREE, Taiwan. This 2-story RC frame was subject to different levels of ground excitations back to back. The RC frame is firstly considered as a linear model with rotational springs and the tracking of the degradation of the stiffness parameters is carried out using the AQSSE-UI technique. Then the same RC frame is considered as a nonlinear structure with plastic hinges following a smooth hysteretic model. Experimental results show that the AQSSE-UI technique is quite effective for tracking of : (i) the stiffness degradation of linear structures, and (ii) the non-linear hysteretic parameters with stiffness and strength degradations.

  2. CONCRETE POURS HAVE PRODUCED A REINFORCED SUPPORT BASE FOR MTR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CONCRETE POURS HAVE PRODUCED A REINFORCED SUPPORT BASE FOR MTR REACTOR. PIPE TUNNEL IS UNDER CONSTRUCTION AT CENTER OF VIEW. PIPES WILL CARRY RADIOACTIVE WATER FROM REACTOR TO WATER PROCESS BUILDING. CAMERA LOOKS SOUTH INTO TUNNEL ALONG WEST SIDE OF REACTOR BASE. TWO CAISSONS ARE AT LEFT SIDE OF VIEW. NOTE "WINDOW" IN SOUTH FACE OF REACTOR BASE AND ALSO GROUP OF PENETRATIONS TO ITS LEFT. INL NEGATIVE NO. 733. Unknown Photographer, 10/6/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  3. Postcrack creep of polymeric fiber-reinforced concrete in flexure

    SciTech Connect

    Kurtz, S.; Balaguru, P.

    2000-02-01

    Results of an experimental investigation of the creep-time behavior of polypropylene and nylon fiber-reinforced concrete (FRC) are presented. Gravity loads were applied in flexure to precracked low volume fraction (0.1%) polypropylene and nylon FRC beams. Beams were tested at a range of stress levels to produce three outcomes: load sustained indefinitely (low stress), creep failure (intermediate stress), and rapid failure (high stress). Emphasis was placed on determining the maximum flexural stress that is sustainable indefinitely. The results indicate that polypropylene FRC has higher initial strength but nylon FRC can sustain a higher stress level. For both groups the sustainable stress is much lower than the postcrack strength.

  4. Perspective view of threestory reinforced concrete factory. The factory is ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Perspective view of three-story reinforced concrete factory. The factory is painted pink with factory windows infilling the structural frame exposed on the exterior facade. On the east facade of the three-story factory is a two-story, seven bay addition that is painted the same tone as the larger factory. The last two bays of the two-story addition are newer. A brick base surrounds both the factory and the addition and runs the entire length of the building on Clay Ave. and Morrow St - Ivan Doverspike Company, 1925 Clay Avenue, Detroit, MI

  5. Perspective view of threestory reinforced concrete factory. The factory is ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Perspective view of three-story reinforced concrete factory. The factory is painted pink with factory windows infilling the structural frame exposed on the exterior facade. On the east facade of the three-story factory is a two-story, seven bay addition that is painted the same tone as the larger factory. The last two bays of the two-story addition are newer. A brick base surrounds both the factory and the addition and runs the entire length of the building on Clay Ave. and Morrow St. (Duplicate Color view of HAER MI-334-1) - Ivan Doverspike Company, 1925 Clay Avenue, Detroit, MI

  6. Strengthening of Existing Bridge Structures for Shear and Bending with Carbon Textile-Reinforced Mortar

    PubMed Central

    Herbrand, Martin; Classen, Martin; Kueres, Dominik; Hegger, Josef

    2017-01-01

    Increasing traffic loads and changes in code provisions lead to deficits in shear and flexural capacity of many existing highway bridges. Therefore, a large number of structures are expected to require refurbishment and strengthening in the future. This projection is based on the current condition of many older road bridges. Different strengthening methods for bridges exist to extend their service life, all having specific advantages and disadvantages. By applying a thin layer of carbon textile-reinforced mortar (CTRM) to bridge deck slabs and the webs of pre-stressed concrete bridges, the fatigue and ultimate strength of these members can be increased significantly. The CTRM layer is a combination of a corrosion resistant carbon fiber reinforced polymer (CFRP) fabric and an efficient mortar. In this paper, the strengthening method and the experimental results obtained at RWTH Aachen University are presented. PMID:28925962

  7. Modeling of a reinforced concrete beam using shape memory alloy as reinforcement bars

    NASA Astrophysics Data System (ADS)

    Bajoria, Kamal M.; Kaduskar, Shreya S.

    2017-04-01

    In this paper the structural behavior of reinforced concrete (RC) beams with smart rebars under three point loading system has been numerically studied, using Finite Element Method. The material used in this study is Superelastic Shape Memory Alloy (SE SMA) which contains nickel and titanium. Shape memory alloys (SMAs) are a unique class of materials which have ability to undergo large deformation and also regain their un-deformed shape by removal of stress or by heating. In this study, a uniaxial SMA model is able to reproduce the pseudo-elastic behavior for the reinforcing SMA wires. Finite element simulation is developed in order to study the load-deflection behavior of smart concrete beams subjected to three-point bending tests.

  8. Size effect of concrete column retrofitted by fiber-reinforced polymer (FRP)

    NASA Astrophysics Data System (ADS)

    Zhang, Pengpeng; Xu, Xinsheng

    2017-04-01

    At present, the research on the size effect of fiber-reinforced polymer (FRP) reinforced concrete members is not enough, besides the conclusions about size effect are different. It is of great theoretical significance and engineering application value to study the size effect of FRP reinforced concrete members in this field. In this paper, the study status from two aspects containing plain concrete columns and reinforced concrete columns for the retrofitted effect were analyzed and some new problems were put forward in this field. Also the paper mainly discussed the size effect of FRP constraint ratio and column slenderness ratio on FRP retrofitted concrete columns, and the effects of different load forms of FRP reinforced concrete columns under eccentric loading, repeated loading and unloading, and horizontal cyclic loading on the size effect of FRP reinforced concrete columns, and the influence of the single factor change of FRP paste way, type, package type and the concrete strength on the FRP reinforced concrete column. Besides, the changing tendency and regularity of the size effect of FRP strengthened concrete columns under the condition of muti-factors were given.

  9. Assessment of concrete damage and strength degradation caused by reinforcement corrosion

    NASA Astrophysics Data System (ADS)

    Nepal, Jaya; Chen, Hua-Peng

    2015-07-01

    Structural performance deterioration of reinforced concrete structures has been extensively investigated, but very limited studies have been carried out to investigate the effect of reinforcement corrosion on time-dependent reliability with consideration of the influence of mechanical characteristics of the bond interface due to corrosion. This paper deals with how corrosion in reinforcement creates different types of defects in concrete structure and how they are responsible for the structural capacity deterioration of corrosion affected reinforced concrete structures during their service life. Cracking in cover concrete due to reinforcement corrosion is investigated by using rebar-concrete model and realistic concrete properties. The flexural strength deterioration is analytically predicted on the basis of bond strength evolution due to reinforcement corrosion, which is examined by the experimental data available. The time-dependent reliability analysis is undertaken to calculate the life time structural reliability of corrosion damaged concrete structures by stochastic deterioration modelling of reinforced concrete. The results from the numerical example show that the proposed approach is capable of evaluating the damage caused by reinforcement corrosion and also predicting the structural reliability of concrete structures during their lifecycle.

  10. Antiplane shear wave propagation in fiber-reinforced composites.

    PubMed

    Kim, Jin-Yeon

    2003-05-01

    A self-consistent method for analyzing antiplane shear wave propagation in two-dimensional inhomogeneous media is presented. For applications in the high-frequency range, the self-consistent condition for the effective medium is solved being supplemented with the theory of quasidynamic effective density. Comparisons with other theoretical calculations and experimental data for fiber-reinforced composites demonstrate the merits of using the present method.

  11. Acoustic emission of fire damaged fiber reinforced concrete

    NASA Astrophysics Data System (ADS)

    Mpalaskas, A. C.; Matikas, T. E.; Aggelis, D. G.

    2016-04-01

    The mechanical behavior of a fiber-reinforced concrete after extensive thermal damage is studied in this paper. Undulated steel fibers have been used for reinforcement. After being exposed to direct fire action at the temperature of 850°C, specimens were subjected to bending and compression in order to determine the loss of strength and stiffness in comparison to intact specimens and between the two types. The fire damage was assessed using nondestructive evaluation techniques, specifically ultrasonic pulse velocity (UPV) and acoustic emission (AE). Apart from the strong, well known, correlation of UPV to strength (both bending and compressive), AE parameters based mainly on the frequency and duration of the emitted signals after cracking events showed a similar or, in certain cases, better correlation with the mechanical parameters and temperature. This demonstrates the sensitivity of AE to the fracture incidents which eventually lead to failure of the material and it is encouraging for potential in-situ use of the technique, where it could provide indices with additional characterization capability concerning the mechanical performance of concrete after it subjected to fire.

  12. Probabilistic Flexural Fatigue in Plain and Fiber-Reinforced Concrete.

    PubMed

    Ríos, José D; Cifuentes, Héctor; Yu, Rena C; Ruiz, Gonzalo

    2017-07-07

    The objective of this work is two-fold. First, we attempt to fit the experimental data on the flexural fatigue of plain and fiber-reinforced concrete with a probabilistic model (Saucedo, Yu, Medeiros, Zhang and Ruiz, Int. J. Fatigue, 2013, 48, 308-318). This model was validated for compressive fatigue at various loading frequencies, but not for flexural fatigue. Since the model is probabilistic, it is not necessarily related to the specific mechanism of fatigue damage, but rather generically explains the fatigue distribution in concrete (plain or reinforced with fibers) for damage under compression, tension or flexion. In this work, more than 100 series of flexural fatigue tests in the literature are fit with excellent results. Since the distribution of monotonic tests was not available in the majority of cases, a two-step procedure is established to estimate the model parameters based solely on fatigue tests. The coefficient of regression was more than 0.90 except for particular cases where not all tests were strictly performed under the same loading conditions, which confirms the applicability of the model to flexural fatigue data analysis. Moreover, the model parameters are closely related to fatigue performance, which demonstrates the predictive capacity of the model. For instance, the scale parameter is related to flexural strength, which improves with the addition of fibers. Similarly, fiber increases the scattering of fatigue life, which is reflected by the decreasing shape parameter.

  13. Probabilistic Flexural Fatigue in Plain and Fiber-Reinforced Concrete

    PubMed Central

    Ríos, José D.

    2017-01-01

    The objective of this work is two-fold. First, we attempt to fit the experimental data on the flexural fatigue of plain and fiber-reinforced concrete with a probabilistic model (Saucedo, Yu, Medeiros, Zhang and Ruiz, Int. J. Fatigue, 2013, 48, 308–318). This model was validated for compressive fatigue at various loading frequencies, but not for flexural fatigue. Since the model is probabilistic, it is not necessarily related to the specific mechanism of fatigue damage, but rather generically explains the fatigue distribution in concrete (plain or reinforced with fibers) for damage under compression, tension or flexion. In this work, more than 100 series of flexural fatigue tests in the literature are fit with excellent results. Since the distribution of monotonic tests was not available in the majority of cases, a two-step procedure is established to estimate the model parameters based solely on fatigue tests. The coefficient of regression was more than 0.90 except for particular cases where not all tests were strictly performed under the same loading conditions, which confirms the applicability of the model to flexural fatigue data analysis. Moreover, the model parameters are closely related to fatigue performance, which demonstrates the predictive capacity of the model. For instance, the scale parameter is related to flexural strength, which improves with the addition of fibers. Similarly, fiber increases the scattering of fatigue life, which is reflected by the decreasing shape parameter. PMID:28773123

  14. Stiffening of short small-size circular composite steel–concrete columns with shear connectors

    PubMed Central

    Younes, Sherif M.; Ramadan, Hazem M.; Mourad, Sherif A.

    2015-01-01

    An experimental program was conducted to investigate the effect of shear connectors’ distribution and method of load application on load–displacement relationship and behavior of thin-walled short concrete-filled steel tube (CFT) columns when subjected to axial load. The study focused on the compressive strength of the CFT columns and the efficiency of the shear stud in distribution of the load between the concrete core and steel tube. The study showed that the use of shear connectors enhanced slightly the axial capacity of CFT columns. It is also shown that shear connectors have a great effect on load distribution between the concrete and steel tubes. PMID:27222757

  15. Earthquake Response of Reinforced Concrete Building Retrofitted with Geopolymer Concrete and X-shaped Metallic Damper

    NASA Astrophysics Data System (ADS)

    Madheswaran, C. K.; Prakash vel, J.; Sathishkumar, K.; Rao, G. V. Rama

    2017-06-01

    A three-storey half scale reinforced concrete (RC) building is fixed with X-shaped metallic damper at the ground floor level, is designed and fabricated to study its seismic response characteristics. Experimental studies are carried out using the (4 m × 4 m) tri-axial shake-table facility to evaluate the seismic response of a retrofitted RC building with open ground storey (OGS) structure using yielding type X-shaped metallic dampers (also called as Added Damping and Stiffness-ADAS elements) and repairing the damaged ground storey columns using geopolymer concrete composites. This elasto-plastic device is normally incorporated within the frame structure between adjacent floors through chevron bracing, so that they efficiently enhance the overall energy dissipation ability of the seismically deficient frame structure under earthquake loading. Free vibration tests on RC building without and with yielding type X-shaped metallic damper is carried out. The natural frequencies and mode shapes of RC building without and with yielding type X-shaped metallic damper are determined. The retrofitted reinforced concrete building is subjected to earthquake excitations and the response from the structure is recorded. This work discusses the preparation of test specimen, experimental set-up, instrumentation, method of testing of RC building and the response of the structure. The metallic damper reduces the time period of the structure and displacement demands on the OGS columns of the structure. Nonlinear time history analysis is performed using structural analysis package, SAP2000.

  16. Non-linear finite element-based material constitutive law for zero slump steel fiber reinforced concrete pipe structures

    NASA Astrophysics Data System (ADS)

    Mikhaylova, Alena

    This study presents a comprehensive investigation of performance and behavior of steel-fiber reinforced concrete pipes (SFRCP). The main goal of this study is to develop the material constitutive model for steel fiber reinforced concrete used in dry-cast application. To accomplish this goal a range of pipe sizes varying from 15 in. (400 mm) to 48 in. (1200 mm) in diameter and fiber content of 0.17%, 0.25%, 0.33%, 0.5%, 0.67% and 83% by volume were produced. The pipes were tested in three-edge bearing condition to obtain the load-deformation response and overall performance of the pipe. The pipes were also subjected to hydrostatic joint and joint shear tests to evaluate the performance of the fiber-pipe joints for water tightness and under differential displacements, respectively. In addition, testing on hardened concrete was performed to obtain the basic mechanical material properties. High variation in the test results for material testing was identified as a part of experimental investigation. A three-dimensional non-linear finite element model of the pipe under the three edge bearing condition was developed to identify the constitutive material relations of fiber-concrete composite. A constitutive model of concrete implementing the concrete plasticity and continuum fracture mechanics was considered for defining the complex non-linear behavior of fiber-concrete. Three main concrete damage algorithms were examined: concrete brittle cracking, concrete damaged plasticity with adaptive meshing technique and concrete damaged plasticity with visco-plastic regularization. The latter was identified as the most robust and efficient to model the post-cracking behavior of fiber reinforced concrete and was used in the subsequent studies. The tension stiffening material constitutive law for composite concrete was determined by converging the FEM solution of load-deformation response with the results of experimental testing. This was achieved by iteratively modifying the non

  17. Hysteretic behavior of special shaped columns composed of steel and reinforced concrete (SRC)

    NASA Astrophysics Data System (ADS)

    Chen, Zongping; Xu, Jinjun; Xue, Jianyang

    2015-06-01

    This paper describes a series of experimental investigations on seventeen specimens of steel reinforced concrete special shaped (SRCSS) columns under low cyclic reversed loading using parallel crosshead equipment. Nine T-shaped SRC columns, four L-shaped SRC columns and four +-shaped SRC columns were tested to examine the effects of shape steel configuration, loading angle, axial compressive ratio and shear-span ratio on the behavior (strength, stiffness, energy dissipation, ductility, etc.) of SRCSS column specimens. The failure modes and hysteretic performance of all the specimens were obtained in the tests. Test results demonstrate that the shear-span ratio is the main parameter affecting the failure modes of SRCSS columns. The specimens with small shear-span ratio are prone to shear failure, and the primary failure planes in SRCSS columns are parallel to the loading direction. As a result, there is a symmetry between positive and negative loading directions in the hysteretic curves of the SRCSS columns. The majority of displacement ductility coefficients for all the specimens are over 3.0, so that the SRCSS columns demonstrate a better deformation capacity. In addition, the equivalent viscous damping coefficients of all the specimens are greater than 0.2, indicating that the seismic behavior of SRCSS columns is adequate. Finally, the superposition theory was used to calculate the limits of axial compressive ratio for the specimens, and it is found that the test axial compressive ratio is close to or smaller than the calculated axial compressive ratio limit.

  18. Non-traditional shape GFRP rebars for concrete reinforcement

    NASA Astrophysics Data System (ADS)

    Claure, Guillermo G.

    The use of glass-fiber-reinforced-polymer (GFRP) composites as internal reinforcement (rebars) for concrete structures has proven to be an alternative to traditional steel reinforcement due to significant advantages such as magnetic transparency and, most importantly, corrosion resistance equating to durability and structural life extension. In recent years, the number of projects specifying GFRP reinforcement has increased dramatically leading the construction industry towards more sustainable practices. Typically, GFRP rebars are similar to their steel counterparts having external deformations or surface enhancements designed to develop bond to concrete, as well as having solid circular cross-sections; but lately, the worldwide composites industry has taken advantage of the pultrusion process developing GFRP rebars with non-traditional cross-sectional shapes destined to optimize their mechanical, physical, and environmental attributes. Recently, circular GFRP rebars with a hollow-core have also become available. They offer advantages such as a larger surface area for improved bond, and the use of the effective cross-sectional area that is engaged to carry load since fibers at the center of a solid cross-section are generally not fully engaged. For a complete understanding of GFRP rebar physical properties, a study on material characterization regarding a quantitative cross-sectional area analysis of different GFRP rebars was undertaken with a sample population of 190 GFRP specimens with rebar denomination ranging from #2 to #6 and with different cross-sectional shapes and surface deformations manufactured by five pultruders from around the world. The water displacement method was applied as a feasible and reliable way to conduct the investigation. In addition to developing a repeatable protocol for measuring cross-sectional area, the objectives of establishing critical statistical information related to the test methodology and recommending improvements to

  19. Flexural retrofitting of reinforced concrete structures using Green Natural Fiber Reinforced Polymer plates

    NASA Astrophysics Data System (ADS)

    Cervantes, Ignacio

    An experimental study will be carried out to determine the suitability of Green Natural Fiber Reinforced Polymer plates (GNFRP) manufactured with hemp fibers, with the purpose of using them as structural materials for the flexural strengthening of reinforced concrete (RC) beams. Four identical RC beams, 96 inches long, are tested for the investigation, three control beams and one test beam. The first three beams are used as references; one unreinforced, one with one layer of Carbon Fiber Reinforced Polymer (CFRP), one with two layers of CFRP, and one with n layers of the proposed, environmental-friendly, GNFRP plates. The goal is to determine the number of GNFRP layers needed to match the strength reached with one layer of CFRP and once matched, assess if the system is less expensive than CFRP strengthening, if this is the case, this strengthening system could be an alternative to the currently used, expensive CFRP systems.

  20. Prediction of reinforcement corrosion using corrosion induced cracks width in corroded reinforced concrete beams

    SciTech Connect

    Khan, Inamullah; François, Raoul; Castel, Arnaud

    2014-02-15

    This paper studies the evolution of reinforcement corrosion in comparison to corrosion crack width in a highly corroded reinforced concrete beam. Cracking and corrosion maps of the beam were drawn and steel reinforcement was recovered from the beam to observe the corrosion pattern and to measure the loss of mass of steel reinforcement. Maximum steel cross-section loss of the main reinforcement and average steel cross-section loss between stirrups were plotted against the crack width. The experimental results were compared with existing models proposed by Rodriguez et al., Vidal et al. and Zhang et al. Time prediction models for a given opening threshold are also compared to experimental results. Steel cross-section loss for stirrups was also measured and was plotted against the crack width. It was observed that steel cross-section loss in the stirrups had no relationship with the crack width of longitudinal corrosion cracks. -- Highlights: •Relationship between crack and corrosion of reinforcement was investigated. •Corrosion results of natural process and then corresponds to in-situ conditions. •Comparison with time predicting model is provided. •Prediction of load-bearing capacity from crack pattern was studied.

  1. 78 FR 68090 - Steel Concrete Reinforcing Bar from Mexico and Turkey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-13

    ... COMMISSION Steel Concrete Reinforcing Bar from Mexico and Turkey Determinations On the basis of the record \\1... injured by reason of imports from Mexico and Turkey of steel concrete reinforcing bar, provided for in... alleged to be sold in the United States at less than fair value (LTFV), and by imports of steel...

  2. Seismic response of reinforced concrete frames at different damage levels

    NASA Astrophysics Data System (ADS)

    Morales-González, Merangeli; Vidot-Vega, Aidcer L.

    2017-03-01

    Performance-based seismic engineering is focused on the definition of limit states to represent different levels of damage, which can be described by material strains, drifts, displacements or even changes in dissipating properties and stiffness of the structure. This study presents a research plan to evaluate the behavior of reinforced concrete (RC) moment resistant frames at different performance levels established by the ASCE 41-06 seismic rehabilitation code. Sixteen RC plane moment frames with different span-to-depth ratios and three 3D RC frames were analyzed to evaluate their seismic behavior at different damage levels established by the ASCE 41-06. For each span-to-depth ratio, four different beam longitudinal reinforcement steel ratios were used that varied from 0.85 to 2.5% for the 2D frames. Nonlinear time history analyses of the frames were performed using scaled ground motions. The impact of different span-to-depth and reinforcement ratios on the damage levels was evaluated. Material strains, rotations and seismic hysteretic energy changes at different damage levels were studied.

  3. 221-U Facility concrete and reinforcing steel evaluations specification for the canyon disposition initiative (CDI)

    SciTech Connect

    Baxter, J.T.

    1998-05-28

    This describes a test program to establish the in-situ material properties of the reinforced concrete in Building 221-U for comparison to the original design specifications. Field sampling and laboratory testing of concrete and reinforcing steel structural materials in Building 221-U for design verification will be undertaken. Forty seven samples are to be taken from radiologically clean exterior walls of the canyon. Laboratory testing program includes unconfined compressive strength of concrete cores, tensile strength of reinforcing steel, and petrographic examinations of concrete cores taken from walls below existing grade.

  4. Test study on the impact damage performance of stainless steel reinforced concrete

    NASA Astrophysics Data System (ADS)

    Zhang, Guoxue; Xu, Shixiang

    2017-04-01

    In this study, in order to research the damage performance of stainless steel reinforced concrete under the action of repeated horizontal impact, an ultra-high drop hammer impact tester system was used for impact tests on ordinary reinforced concrete bridge piers and stainless steel reinforced concrete bridge piers with equal longitudinal bar diameter. In addition, ultrasonic waves were adopted for damage testing. The results show that, after each impact, the elastic modulus of the specimen was decreased. With the improvement of impact energy, the damage degrees of the two groups of specimens were also increased. Under the same impact energy, the damage degrees of the stainless steel reinforced concrete bridge pier specimens were lower than those of the ordinary reinforced concrete bridge pier specimens with equal longitudinal bar diameters.

  5. Polymer concrete for precast repair of continuously reinforced concrete pavement on IH 30, near Mt. Pleasant

    NASA Astrophysics Data System (ADS)

    Meyer, A. M.; McCullough, B. F.; Fowler, D. W.

    1981-08-01

    Two punchout repairs made in a continuously reinforced concrete pavement (CRCP) using precast portland cement panels are described. The two repairs, one 1.44 sq. ft., the other 36 sq. ft., were completed and opened to traffic in one afternoon. This technique provides a rapid method of repair that produces a repair that is structurally as good or better than the surrounding pavement. With a trained crew, the repair time can be reduced and thus reducing lane closure time. Since lane closure time is a critical consideration in high volume highways, this method is cost effective in those areas.

  6. Optimization of a Hybrid-Fiber-Reinforced High-Strength Concrete

    NASA Astrophysics Data System (ADS)

    Ferreira, L. E. T.; de Hanai, J. B.; Ferrari, V. J.

    2016-07-01

    The fracture performance of a high-strength concrete reinforced with steel fibers was studied. Tests of notched beams subjected to fracture in the three-point bend configuration were conducted in accordance with RILEM recommendations TC 162-TDF. The R-curve concepts based on load-CMOD responses and the RILEM criteria were used for the performance evaluation of concrete beams reinforced with steel fiber mixtures and loaded up to fracture. Steel fibers of different types (regular and microfibers), in different proportions were employed as the reinforcement. The hybrid-fiber-reinforced concrete demonstrated a superior performance regarding their resistance and toughness properties as a result of interaction between the fibers.

  7. Detection of Bond Defects in Carbon Fiber Reinforced Polymer Strengthened Concrete Using Pulse Phase Thermography

    NASA Astrophysics Data System (ADS)

    Mabry, Nehemiah James

    As externally bonded fiber-reinforced polymers (FRP) are finding regular use in the strengthening of existing concrete structures, common installation practices still allow for the likelihood of defects forming at the interface of these bond-critical systems. Though published guidelines exist to provide recommendations for handling this issue in the field, significant research is still needed to determine critical defects, their identification using rapid methods of nondestructive evaluation (NDE) techniques, and the effect of such defects on the overall performance. This dissertation examines the use of pulsed phase infrared thermography (PPT) as a method to determine the location, size and depth of bond defects in wet lay-up carbon FRP (CFRP) systems. A series of small scale, single lap shear pull-tests were also performed to examine the effect detectable defects have on the strength of the CFRP strengthened concrete joints. Environmental conditioning protocols, namely submersion and freeze-thaw cycles, were also subjected to a subsample of specimens in order to observe durability effects on ultimate loads and strains. Results from PPT inspection and structural tests were then compared to present an effective approach for monitoring and evaluation. Finally a set of conclusions were presented regarding PPT inspection and the criticality of defects found in CFRP strengthened concrete governed by the common debonding mechanism.

  8. Shaking table experimental study of recycled concrete frame-shear wall structures

    NASA Astrophysics Data System (ADS)

    Zhang, Jianwei; Cao, Wanlin; Meng, Shaobin; Yu, Cheng; Dong, Hongying

    2014-06-01

    In this study, four 1/5 scaled shaking table tests were conducted to investigate the seismic performance of recycled concrete frame-shear wall structures with different recycled aggregates replacement rates and concealed bracing detail. The four tested structures included one normal concrete model, one recycled coarse aggregate concrete model, and two recycled coarse and fine aggregate concrete models with or without concealed bracings inside the shear walls. The dynamic characteristics, dynamic response and failure mode of each model were compared and analyzed. Finite element models were also developed and nonlinear time-history response analysis was conducted. The test and analysis results show that the seismic performance of the recycled coarse aggregate concrete frame-shear wall structure is slightly worse than the normal concrete structure. The seismic resistance capacity of the recycled concrete frame-shear wall structure can be greatly improved by setting up concealed bracings inside the walls. With appropriate design, the recycled coarse aggregate concrete frame-shear wall structure and recycled concrete structure with concealed bracings inside the walls can be applied in buildings.

  9. Evaluating cover depth of steel fiber reinforced concrete using impact-echo testing

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Feng

    2014-04-01

    The purpose of this research is to estimate of the cover depth of steel fiber reinforced concrete using the impact-echo testing. In order to evaluate the security of the construction, usually need to estimate the cover depth of the reinforced concrete. At present, the examination technique of the cover depth of the reinforced concrete without the steel fiber is mainly applied in the magnetic and electrical methods, its rapid detection and good results. But the research of the reactive powder concrete be gradually progress, with the steel fiber concrete structure will be increased, if should still operate the examination with the magnetic and electrical methods, theoretically the steel fiber will have the interference to its electromagnetism field. Therefore, this research designs four kinds of reinforced concrete plate that include different steel fiber contents, to evaluate test results of estimate of the cover depth of the reinforcing bar. The results showed that: estimate of the cover depth of steel fiber reinforced concrete reinforcing bar using the impact-echo testing, the variety of the steel fiber content does not have much influence, the test measurement error within ± 10%, and the most important source of uncertainty is the velocity of concrete.

  10. Drying shrinkage of fibre-reinforced lightweight aggregate concrete containing fly ash

    SciTech Connect

    Kayali, O.; Haque, M.N.; Zhu, B.

    1999-11-01

    Lightweight aggregate concretes containing fly ash with a compressive strength between 61 to 67 NPa were produced. The lightweight aggregate used was sintered fly ash. The concretes were reinforced with either polypropylene or steel fibres. The fibres did not affect the compressive strength, but did increase the tensile strength of these concretes. The modulus of elasticity of all the lightweight concretes tested was about 21 GPa, compared to 35 GPa for the normal-weight concrete. Fibre reinforcement did not affect the value of the elastic modulus. This type of lightweight concrete, containing fly ash as 23% of the total cementitious content, resulted in long-term shrinkage that is nearly twice as large as normal-weight concrete of somewhat similar strength. Polypropylene fibre reinforcement did not reduce drying shrinkage, while steel fibres did. Early shrinkage behavior of this type of lightweight concrete was similar to normal-weight concrete. However, the rate of shrinkage of the lightweight concrete remained constant until nearly 100 days of drying. This is different from normal-weight concrete that showed appreciably after 56 days. Shrinkage of normal-weight concrete stabilized after 400 days, which shrinkage of lightweight concrete did not appear to stabilize after a similar period of continuous drying.

  11. Tensile Characterization of FRP Rods for Reinforced Concrete Structures

    NASA Astrophysics Data System (ADS)

    Micelli, F.; Nanni, A.

    2003-07-01

    The application of FRP rods as an internal or external reinforcement in new or damaged concrete structures is based on the development of design equations that take into account the mechanical properties of FRP material systems.The measurement of mechanical characteristics of FRP requires a special anchoring and protocol, since it is well known that these characteristics depend on the direction and content of fibers. In this study, an effective tensile test method is described for the mechanical characterization of FRP rods. Twelve types of glass and carbon FRP specimens with different sizes and surface characteristics were tested to validate the procedure proposed. In all, 79 tensile tests were performed, and the results obtained are discussed in this paper. Recommendations are given for specimen preparation and test setup in order to facilitate the further investigation and standardization of the FRP rods used in civil engineering.

  12. Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection

    PubMed Central

    Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

    2016-01-01

    In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering. PMID:27999245

  13. Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection.

    PubMed

    Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

    2016-12-16

    In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering.

  14. 75 FR 7562 - Certain Steel Concrete Reinforcing Bars From Turkey: Notice of Court Decision Not in Harmony With...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-22

    ... International Trade Administration Certain Steel Concrete Reinforcing Bars From Turkey: Notice of Court Decision... certain steel concrete reinforcing bars (rebar) from Turkey covering the period of review (POR) of April 1, 2003, through March 31, 2004. See Certain Steel Concrete Reinforcing Bars From Turkey; Final...

  15. 75 FR 22552 - Certain Steel Concrete Reinforcing Bars from Turkey; Notice of Amended Final Results Pursuant to...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-29

    ... International Trade Administration Certain Steel Concrete Reinforcing Bars from Turkey; Notice of Amended Final... Department) in the 2003-2004 administrative review of certain steel concrete of reinforcing bars (rebar) from...) of April 1, 2003, through March 31, 2004. See Certain Steel Concrete Reinforcing Bars From...

  16. 75 FR 47260 - Certain Steel Concrete Reinforcing Bars from Turkey: Notice of Amended Final Results Pursuant to...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-05

    ... International Trade Administration (A-489-807) Certain Steel Concrete Reinforcing Bars from Turkey: Notice of...) in the 2005-2006 administrative review of certain steel concrete reinforcing bars (rebar) from Turkey..., through March 31, 2006. See Certain Steel Concrete Reinforcing Bars From Turkey; Final Results of...

  17. Seismic analysis of a reinforced concrete containment vessel model

    SciTech Connect

    RANDY,JAMES J.; CHERRY,JEFFERY L.; RASHID,YUSEF R.; CHOKSHI,NILESH

    2000-02-03

    Pre-and post-test analytical predictions of the dynamic behavior of a 1:10 scale model Reinforced Concrete Containment Vessel are presented. This model, designed and constructed by the Nuclear Power Engineering Corp., was subjected to seismic simulation tests using the high-performance shaking table at the Tadotsu Engineering Laboratory in Japan. A group of tests representing design-level and beyond-design-level ground motions were first conducted to verify design safety margins. These were followed by a series of tests in which progressively larger base motions were applied until structural failure was induced. The analysis was performed by ANATECH Corp. and Sandia National Laboratories for the US Nuclear Regulatory Commission, employing state-of-the-art finite-element software specifically developed for concrete structures. Three-dimensional time-history analyses were performed, first as pre-test blind predictions to evaluate the general capabilities of the analytical methods, and second as post-test validation of the methods and interpretation of the test result. The input data consisted of acceleration time histories for the horizontal, vertical and rotational (rocking) components, as measured by accelerometers mounted on the structure's basemat. The response data consisted of acceleration and displacement records for various points on the structure, as well as time-history records of strain gages mounted on the reinforcement. This paper reports on work in progress and presents pre-test predictions and post-test comparisons to measured data for tests simulating maximum design basis and extreme design basis earthquakes. The pre-test analyses predict the failure earthquake of the test structure to have an energy level in the range of four to five times the energy level of the safe shutdown earthquake. The post-test calculations completed so far show good agreement with measured data.

  18. Analyses of a Reinforced Concrete Containment with Liner Corrosion Damage

    SciTech Connect

    Cherry, J.L.; Smith, J.A.

    1998-11-19

    Incidents of liner corrosion in nuclear power containment structures have been recorded. These incidents and concerns of other possible liner corrosion in containment have prompted an interest in determining g the capacity of a degraded containment. Finite element analyses of a typical pressurized water reactor (PWR) reinforced concrete containment with liner corrosion were conducted using the A13AQUS finite element code with the ANACAP-U nonlinear concrete constitutive model. The effect of liner corrosion on containment capacity was investigated. A loss of coolant accident was simulated by applying pressure and temperature changes to the structure without corrosion to determine baseline failure limits, followed by multiple analyses of the containment with corrosion at different locations and varying degrees of liner degradation. The corrosion locations were chosen at the base of the containment wall, near the equipment hatch, and at the midheight of the containment wall. Using a strain-based failure criterion the different scenarios were evaluated to prioritize their effect on containment capacity

  19. Matrix cracking of fiber-reinforced ceramic composites in shear

    NASA Astrophysics Data System (ADS)

    Rajan, Varun P.; Zok, Frank W.

    2014-12-01

    The mechanics of cracking in fiber-reinforced ceramic matrix composites (CMCs) under general loadings remains incomplete. The present paper addresses one outstanding aspect of this problem: the development of matrix cracks in unidirectional plies under shear loading. To this end, we develop a model based on potential energy differences upstream and downstream of a fully bridged steady-state matrix crack. Through a combination of analytical solutions and finite element simulations of the constituent stresses before and after cracking, we identify the dominant stress components that drive crack growth. We show that, when the axial slip lengths are much larger than the fiber diameter and when interfacial slip precedes cracking, the shear stresses in the constituents are largely unaffected by the presence of the crack; the changes that do occur are confined to a 'core' region within a distance of about one fiber diameter from the crack plane. Instead, the driving force for crack growth derives mainly from the axial stresses-tensile in the fibers and compressive in the matrix-that arise upon cracking. These stresses are well-approximated by solutions based on shear-lag analysis. Combining these solutions with the governing equation for crack growth yields an analytical estimate of the critical shear stress for matrix cracking. An analogous approach is used in deriving the critical stresses needed for matrix cracking under arbitrary in-plane loadings. The applicability of these results to cross-ply CMC laminates is briefly discussed.

  20. Acoustic emission monitoring of concrete columns and beams strengthened with fiber reinforced polymer sheets

    NASA Astrophysics Data System (ADS)

    Ma, Gao; Li, Hui; Zhou, Wensong; Xian, Guijun

    2012-04-01

    Acoustic emission (AE) technique is an effective method in the nondestructive testing (NDT) field of civil engineering. During the last two decades, Fiber reinforced polymer (FRP) has been widely used in repairing and strengthening concrete structures. The damage state of FRP strengthened concrete structures has become an important issue during the service period of the structure and it is a meaningful work to use AE technique as a nondestructive method to assess its damage state. The present study reports AE monitoring results of axial compression tests carried on basalt fiber reinforced polymer (BFRP) confined concrete columns and three-point-bending tests carried on BFRP reinforced concrete beams. AE parameters analysis was firstly utilized to give preliminary results of the concrete fracture process of these specimens. It was found that cumulative AE events can reflect the fracture development trend of both BFRP confined concrete columns and BFRP strengthened concrete beams and AE events had an abrupt increase at the point of BFRP breakage. Then the fracture process of BFRP confined concrete columns and BFRP strengthened concrete beams was studied through RA value-average frequency analysis. The RA value-average frequency tendencies of BFRP confined concrete were found different from that of BFRP strengthened concrete beams. The variation tendency of concrete crack patterns during the loading process was revealed.

  1. Research on deformation characteristics and design method of concrete beams reinforced with GFRP bars

    NASA Astrophysics Data System (ADS)

    Pan, M. X.; Xu, X. S.

    2017-04-01

    Two different glass fiber reinforced polymer (GFRP) bars were produced to reinforce concrete beams, including plain GFRP bars and ribbed surface GFRP bars. The flexural property of GFRP reinforced concrete beams was studied by testing four specimen beams under two point vertical loads. The crack development and stain distribution of beam cross section during loading were recorded, and the deformation characteristics and failure mode were also analyzed in this experiment. According to the test results, the bond property of plain GFRP bars was too poor to serve as reinforcement bars, while the ribbed surface GFRP bars showed good bond performance and worked well with concrete before final failure. The test beam reinforced with ribbed surface GFRP bars exhibited a uniform crack distribution, and the strain agreed with the assumption of plane cross section. Moreover, calculation method for bending capacity of concrete beam strengthened with GFRP bars was deducted based on this experiment.

  2. Application of Cu-Al-Mn superelastic alloy bars as reinforcement elements in concrete beams

    NASA Astrophysics Data System (ADS)

    Shrestha, Kshitij C.; Araki, Yoshikazu; Nagae, Takuya; Yano, Hayato; Koetaka, Yuji; Omori, Toshihiro; Sutou, Yuji; Kainuma, Ryosuke; Ishida, Kiyohito

    2012-04-01

    Experimental works are done to assess the seismic behavior of concrete beams reinforced with superelastic alloy (SEA) bars. Applicability of newly developed Cu-Al-Mn SEA bars, characterized by large recovery strain, low material cost, and high machinability, have been proposed as partial replacements for conventional steel bars in order to reduce residual deformations in structures during and after intense earthquakes. Four-point reverse-cyclic bending tests were done on 1/3 scale concrete beams comprising three different types of specimens - conventional steel reinforced concrete (ST-RC), SEA reinforced concrete (SEA-RC), and SEA reinforced concrete with pre-tensioning (SEA-PC). The results showed that SEA reinforced concrete beams demonstrated significant enhancement in crack recovery capacity in comparison to steel reinforced beam. Average recovery of cracks for each of the specimens was 21% for ST-RC, 84% for SEA-RC, and 86% for SEA-PC. In addition, SEA-RC and SEA-PC beams demonstrated strong capability of recentering with comparable normalized strength and ductility relative to conventional ST-RC beam specimen. ST-RC beam, on the other hand, showed large residual cracks due to progressive reduction in its re-centering capability with each cycle. Both the SEA-RC and SEA-PC specimens demonstrated superiority of Cu-Al-Mn SEA bars to conventional steel reinforcing bars as reinforcement elements.

  3. Preparation and characterization of glass fibers - polymers (epoxy) bars (GFRP) reinforced concrete for structural applications

    NASA Astrophysics Data System (ADS)

    Alkjk, Saeed; Jabra, Rafee; Alkhater, Salem

    2016-06-01

    The paper presents some of the results from a large experimental program undertaken at the Department of Civil Engineering of Damascus University. The project aims to study the ability to reinforce and strengthen the concrete by bars from Epoxy polymer reinforced with glass fibers (GFRP) and compared with reinforce concrete by steel bars in terms of mechanical properties. Five diameters of GFRP bars, and steel bars (4mm, 6mm, 8mm, 10mm, 12mm) tested on tensile strength tests. The test shown that GFRP bars need tensile strength more than steel bars. The concrete beams measuring (15cm wide × 15cm deep × and 70cm long) reinforced by GFRP with 0.5 vol.% ratio, then the concrete beams reinforced by steel with 0.89 vol.% ratio. The concrete beams tested on deflection test. The test shown that beams which reinforced by GFRP has higher deflection resistance, than beams which reinforced by steel. Which give more advantage to reinforced concrete by GFRP.

  4. Structural Aspects of Railway Truss Bridges Affecting Transverse Shear Forces in Steel-Concrete Composite Decks

    NASA Astrophysics Data System (ADS)

    Siekierski, Wojciech

    2015-03-01

    At the steel-concrete interface, the horizontal shear forces that are transverse to cross beams occur due to joint action of the steel-concrete composite deck and the truss girders. Numerical analysis showed that values of the forces are big in comparison to the longitudinal shear forces. In both cases extreme force values occur near side edges of a slab. The paper studies possibilities of reduction of these shear forces by structural alterations of the following: rigidity of a concrete slab, arrangement of a wind bracing, arrangement of concrete slab expansion joints. An existing railway truss bridge span has been analysed. Numerical analysis shows that it is possible to reduce the values of shear forces transverse to cross beams. It may reach 20% near the side edges of slabs and 23% in the centre of slab width.

  5. The effect of recycled concrete aggregate properties on the bond strength between RCA concrete and steel reinforcement

    SciTech Connect

    Butler, L. West, J.S.; Tighe, S.L.

    2011-10-15

    The purpose of this study was to investigate the influence that replacing natural coarse aggregate with recycled concrete aggregate (RCA) has on concrete bond strength with reinforcing steel. Two sources of RCA were used along with one natural aggregate source. Numerous aggregate properties were measured for all aggregate sources. Two types of concrete mixture proportions were developed replacing 100% of the natural aggregate with RCA. The first type maintained the same water-cement ratios while the second type was designed to achieve the same compressive strengths. Beam-end specimens were tested to determine the relative bond strength of RCA and natural aggregate concrete. On average, natural aggregate concrete specimens had bond strengths that were 9 to 19% higher than the equivalent RCA specimens. Bond strength and the aggregate crushing value seemed to correlate well for all concrete types.

  6. Experimental, numerical, and analytical studies on the seismic response of steel-plate concrete (SC) composite shear walls

    NASA Astrophysics Data System (ADS)

    Epackachi, Siamak

    The seismic performance of rectangular steel-plate concrete (SC) composite shear walls is assessed for application to buildings and mission-critical infrastructure. The SC walls considered in this study were composed of two steel faceplates and infill concrete. The steel faceplates were connected together and to the infill concrete using tie rods and headed studs, respectively. The research focused on the in-plane behavior of flexure- and flexure-shear-critical SC walls. An experimental program was executed in the NEES laboratory at the University at Buffalo and was followed by numerical and analytical studies. In the experimental program, four large-size specimens were tested under displacement-controlled cyclic loading. The design variables considered in the testing program included wall thickness, reinforcement ratio, and slenderness ratio. The aspect ratio (height-to-length) of the four walls was 1.0. Each SC wall was installed on top of a re-usable foundation block. A bolted baseplate to RC foundation connection was used for all four walls. The walls were identified to be flexure- and flexure-shear critical. The progression of damage in the four walls was identical, namely, cracking and crushing of the infill concrete at the toes of the walls, outward buckling and yielding of the steel faceplates near the base of the wall, and tearing of the faceplates at their junctions with the baseplate. A robust finite element model was developed in LS-DYNA for nonlinear cyclic analysis of the flexure- and flexure-shear-critical SC walls. The DYNA model was validated using the results of the cyclic tests of the four SC walls. The validated and benchmarked models were then used to conduct a parametric study, which investigated the effects of wall aspect ratio, reinforcement ratio, wall thickness, and uniaxial concrete compressive strength on the in-plane response of SC walls. Simplified analytical models, suitable for preliminary analysis and design of SC walls, were

  7. Evaluation of passivation method and corrosion inhibitors for steel-reinforced concrete structures

    NASA Astrophysics Data System (ADS)

    Brown, Richard; Lee, K. Wayne; Cao, Yong

    1999-02-01

    Corrosion of reinforcing steel due to the ingression of chloride ions from deicing salt and/or seawater has been a major cause of the deterioration of reinforced concrete structures. Typically reinforcing steel is protected from corrosion by the formation of passive film because of highly alkaline concrete environment. The film can be damaged with the introduction of chloride ions to concrete, then corrosion occurs. There are mainly three approaches to tackle this problem, i.e., protective coating, cathodic protection and corrosion inhibitors.

  8. Vertical impedance measurements on concrete bridge decks for assessing susceptibility of reinforcing steel to corrosion.

    PubMed

    Bartholomew, Paul D; Guthrie, W Spencer; Mazzeo, Brian A

    2012-08-01

    Corrosion is a pressing problem for aging concrete infrastructure, especially bridge decks. Because of its sensitivity to factors that affect corrosion of reinforcing steel in concrete, resistivity is an important structural health indicator for reinforced concrete structures. In this research, an instrument was developed to measure vertical impedance on concrete bridge decks. Measurements of vertical impedance on slabs prepared in the laboratory, on slabs removed from decommissioned bridge decks, and on an in-service bridge deck in the field demonstrate the utility of the new apparatus.

  9. Vertical impedance measurements on concrete bridge decks for assessing susceptibility of reinforcing steel to corrosion

    NASA Astrophysics Data System (ADS)

    Bartholomew, Paul D.; Guthrie, W. Spencer; Mazzeo, Brian A.

    2012-08-01

    Corrosion is a pressing problem for aging concrete infrastructure, especially bridge decks. Because of its sensitivity to factors that affect corrosion of reinforcing steel in concrete, resistivity is an important structural health indicator for reinforced concrete structures. In this research, an instrument was developed to measure vertical impedance on concrete bridge decks. Measurements of vertical impedance on slabs prepared in the laboratory, on slabs removed from decommissioned bridge decks, and on an in-service bridge deck in the field demonstrate the utility of the new apparatus.

  10. Strut deformation in CFRP-strengthened reinforced concrete deep beams.

    PubMed

    Panjehpour, Mohammad; Chai, Hwa Kian; Voo, Yen Lei

    2014-01-01

    Strut-and-tie model (STM) method evolved as one of the most useful designs for shear critical structures and discontinuity regions (D-regions). It provides widespread applications in the design of deep beams as recommended by many codes. The estimation of bottle-shaped strut dimensions, as a main constituent of STM, is essential in design calculations. The application of carbon fibre reinforced polymer (CFRP) as lightweight material with high tensile strength for strengthening D-regions is currently on the increase. However, the CFRP-strengthening of deep beam complicates the dimensions estimation of bottle-shaped strut. Therefore, this research aimed to investigate the effect of CFRP-strengthening on the deformation of RC strut in the design of deep beams. Two groups of specimens comprising six unstrengthened and six CFRP-strengthened RC deep beams with the shear span to the effective depth ratios (a/d) of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were constructed in this research. These beams were tested under four-point bending configuration. The deformation of struts was experimentally evaluated using the values of strain along and perpendicular to the strut centreline. The evaluation was made by the comparisons between unstrengthened and CFRP-strengthened struts regarding the widening and shortening. The key variables were a/d ratio and applied load level.

  11. Strut Deformation in CFRP-Strengthened Reinforced Concrete Deep Beams

    PubMed Central

    Panjehpour, Mohammad; Chai, Hwa Kian; Voo, Yen Lei

    2014-01-01

    Strut-and-tie model (STM) method evolved as one of the most useful designs for shear critical structures and discontinuity regions (D-regions). It provides widespread applications in the design of deep beams as recommended by many codes. The estimation of bottle-shaped strut dimensions, as a main constituent of STM, is essential in design calculations. The application of carbon fibre reinforced polymer (CFRP) as lightweight material with high tensile strength for strengthening D-regions is currently on the increase. However, the CFRP-strengthening of deep beam complicates the dimensions estimation of bottle-shaped strut. Therefore, this research aimed to investigate the effect of CFRP-strengthening on the deformation of RC strut in the design of deep beams. Two groups of specimens comprising six unstrengthened and six CFRP-strengthened RC deep beams with the shear span to the effective depth ratios (a/d) of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were constructed in this research. These beams were tested under four-point bending configuration. The deformation of struts was experimentally evaluated using the values of strain along and perpendicular to the strut centreline. The evaluation was made by the comparisons between unstrengthened and CFRP-strengthened struts regarding the widening and shortening. The key variables were a/d ratio and applied load level. PMID:25197698

  12. Study on crack development of concrete beams in bending reinforced with FRP bars

    NASA Astrophysics Data System (ADS)

    Pan, M. X.; Xu, X. S.

    2017-04-01

    The comparatively high tensile strength and low elastic modulus of fiber reinforced polymer (FRP) bars result in deflection and crack width requirements controlling the design of concrete beams reinforced with FRP bars. Consequently, when it comes to the design of such members, the deflection and crack width are first calculated at serviceability limit state, and then are checked at ultimate limit state. In this paper, five concrete beams reinforced with different FRP reinforcement ratios were tested and the crack development and pattern as well as the effect of reinforcement ratio on crack width and spacing were analyzed. The experimental results were compared with the calculation results using design guidelines recommended by Japan JSCE code, American ACI440.1R-03 code and China GB50608-2010 code. Several design suggestions were proposed for bending concrete beams reinforced with FRP bars.

  13. Investigation of radial shear in the wall-base juncture of a 1:4 scale prestressed concrete containment vessel model

    SciTech Connect

    Dameron, R.A.; Rashid, Y.R.; Luk, V.K.; Hessheimer, M.F.

    1998-04-01

    Construction of a prestressed concrete containment vessel (PCCV) model is underway as part of a cooperative containment research program at Sandia National Laboratories. The work is co-sponsored by the Nuclear Power Engineering Corporation (NUPEC) of Japan and US Nuclear Regulatory Commission (NRC). Preliminary analyses of the Sandia 1:4 Scale PCCV Model have determined axisymmetric global behavior and have estimated the potential for failure in several areas, including the wall-base juncture and near penetrations. Though the liner tearing failure mode has been emphasized, the assumption of a liner tearing failure mode is largely based on experience with reinforced concrete containments. For the PCCV, the potential for shear failure at or near the liner tearing pressure may be considerable and requires detailed investigation. This paper examines the behavior of the PCCV in the region most susceptible to a radial shear failure, the wall-basemat juncture region. Prediction of shear failure in concrete structures is a difficult goal, both experimentally and analytically. As a structure begins to deform under an applied system of forces that produce shear, other deformation modes such as bending and tension/compression begin to influence the response. Analytically, difficulties lie in characterizing the decrease in shear stiffness and shear stress and in predicting the associated transfer of stress to reinforcement as cracks become wider and more extensive. This paper examines existing methods for representing concrete shear response and existing criteria for predicting shear failure, and it discusses application of these methods and criteria to the study of the 1:4 scale PCCV.

  14. Bond variability of glass-fiber-reinforcing-plastic reinforcement in concrete

    SciTech Connect

    Hanus, J.P.

    1998-12-01

    This report summarizes an experimental program that investigated the bond variability of glass-fiber-reinforced-polymer (GFRP) reinforcement in concrete. The variables in the study were manufacturer (Marshall Industries Composites, Incorporated M1 and Corrosion Proof Products/Hughes Brothers M2), bar size (Number 5 and 6), cover (2 and 3 bar diameters), and embedment length (10 through 47 inch). Tensile tests were also performed on the GFRP rebar for comparison to bond tests that exhibited bar failure. Eighty-four inverted half-beam bond specimens were tested while monitoring load, loaded-end slip, free-end slip, cracking, and acoustic emissions on the embedded bar and concrete. Three to six replicate tests were conducted for each set of variables. The results of each test within a series were examined to investigate the relative variability with respect to the failure types. The M1 rebar was observed to rely primarily on mechanical interlock to develop bond strength. This conclusion was based on investigations of the rebar surface condition, bar deformation geometry, slip curves, AE results, crack patterns and forensic investigations. Additionally, the ultimate loads for the bond tests with the Ml rebar were affected by changes in embedment lengths but did not vary for tests with 2 and 3d(b) cover. Overall, the M1 rebar had coefficients of variation (COV) of 14.3 and 8.9% for bond tests that exhibited bar failure and tensile test bar failures, respectively. The bond tests that failed in concrete splitting had COVs from 5.2 to 5.9%.

  15. Fracture Behavior and Properties of Functionally Graded Fiber-Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Roesler, Jeffery; Bordelon, Amanda; Gaedicke, Cristian; Park, Kyoungsoo; Paulino, Glaucio

    2008-02-01

    In concrete pavements, a single concrete mixture design is selected to resist mechanical loading without attempting to adversely affect the concrete pavement shrinkage, ride quality, or noise attenuation. An alternative approach is to design distinct layers within the concrete pavement surface which have specific functions thus achieving higher performance at a lower cost. The objective of this research was to address the structural benefits of functionally graded concrete materials (FGCM) for rigid pavements by testing and modeling the fracture behavior of different combinations of layered plain and synthetic fiber-reinforced concrete materials. Fracture parameters and the post-peak softening behavior were obtained for each FGCM beam configuration by the three point bending beam test. The peak loads and initial fracture energy between the plain, fiber-reinforced, and FGCM signified similar crack initiation. The total fracture energy indicated improvements in fracture behavior of FGCM relative to full-depth plain concrete. The fracture behavior of FGCM depended on the position of the fiber-reinforced layer relative to the starter notch. The fracture parameters of both fiber-reinforced and plain concrete were embedded into a finite element-based cohesive zone model. The model successfully captured the experimental behavior of the FGCMs and predicted the fracture behavior of proposed FGCM configurations and structures. This integrated approach (testing and modeling) demonstrates the viability of FGCM for designing layered concrete pavements system.

  16. Statistical variations in impact resistance of steel fiber-reinforced concrete subjected to drop weight test

    SciTech Connect

    Nataraja, M.C.; Dhang, N.; Gupta, A.P.

    1999-07-01

    The variation in impact resistance of steel fiber-reinforced concrete and plain concrete as determined from a drop weight test is reported. The observed coefficients of variation are about 57 and 46% for first-crack resistance and the ultimate resistance in the case of fiber concrete and the corresponding values for plain concrete are 54 and 51%, respectively. The goodness-of-fit test indicated poor fitness of the impact-resistance test results produced in this study to normal distribution at 95% level of confidence for both fiber-reinforced and plain concrete. However, the percentage increase in number of blows from first crack to failure for both fiber-reinforced concrete and as well as plain concrete fit to normal distribution as indicated by the goodness-of-fit test. The coefficient of variation in percentage increase in the number of blows beyond first crack for fiber-reinforced concrete and plain concrete is 51.9 and 43.1%, respectively. Minimum number of tests required to reliably measure the properties of the material can be suggested based on the observed levels of variation.

  17. Fracture Behavior and Properties of Functionally Graded Fiber-Reinforced Concrete

    SciTech Connect

    Roesler, Jeffery; Bordelon, Amanda; Gaedicke, Cristian; Park, Kyoungsoo; Paulino, Glaucio

    2008-02-15

    In concrete pavements, a single concrete mixture design is selected to resist mechanical loading without attempting to adversely affect the concrete pavement shrinkage, ride quality, or noise attenuation. An alternative approach is to design distinct layers within the concrete pavement surface which have specific functions thus achieving higher performance at a lower cost. The objective of this research was to address the structural benefits of functionally graded concrete materials (FGCM) for rigid pavements by testing and modeling the fracture behavior of different combinations of layered plain and synthetic fiber-reinforced concrete materials. Fracture parameters and the post-peak softening behavior were obtained for each FGCM beam configuration by the three point bending beam test. The peak loads and initial fracture energy between the plain, fiber-reinforced, and FGCM signified similar crack initiation. The total fracture energy indicated improvements in fracture behavior of FGCM relative to full-depth plain concrete. The fracture behavior of FGCM depended on the position of the fiber-reinforced layer relative to the starter notch. The fracture parameters of both fiber-reinforced and plain concrete were embedded into a finite element-based cohesive zone model. The model successfully captured the experimental behavior of the FGCMs and predicted the fracture behavior of proposed FGCM configurations and structures. This integrated approach (testing and modeling) demonstrates the viability of FGCM for designing layered concrete pavements system.

  18. An experiment on the use of disposable plastics as a reinforcement in concrete beams

    NASA Technical Reports Server (NTRS)

    Chowdhury, Mostafiz R.

    1992-01-01

    Illustrated here is the concept of reinforced concrete structures by the use of computer simulation and an inexpensive hands-on design experiment. The students in our construction management program use disposable plastic as a reinforcement to demonstrate their understanding of reinforced concrete and prestressed concrete beams. The plastics used for such an experiment vary from plastic bottles to steel reinforced auto tires. This experiment will show the extent to which plastic reinforcement increases the strength of a concrete beam. The procedure of using such throw-away plastics in an experiment to explain the interaction between the reinforcement material and concrete, and a comparison of the test results for using different types of waste plastics are discussed. A computer analysis to simulate the structural response is used to compare the test results and to understand the analytical background of reinforced concrete design. This interaction of using computers to analyze structures and to relate the output results with real experimentation is found to be a very useful method for teaching a math-based analytical subject to our non-engineering students.

  19. Self-sensing CF-GFRP rods as mechanical reinforcement and sensors of concrete beams

    NASA Astrophysics Data System (ADS)

    Nanni, F.; Auricchio, F.; Sarchi, F.; Forte, G.; Gusmano, G.

    2006-02-01

    In this paper testing carried out on concrete beams reinforced with self-sensing composite rods is presented. Such concrete beams, whose peculiarity is to be reinforced by self-sensing materials able to generate an alarm signal when fixed loads are reached, were designed, manufactured and tested. The reinforcing rods were manufactured by pultrusion and consisted of self-sensing hybrid composites containing both glass and carbon fibres in an epoxy resin. The experimentation was carried out by performing simultaneously mechanical tests on the reinforced beams and electrical measurements on the composite rods. The results showed that the developed system reached the target proposed, giving an alarm signal.

  20. A vision-based technique for damage assessment of reinforced concrete structures

    NASA Astrophysics Data System (ADS)

    Farhidzadeh, Alireza; Ebrahimkhanlou, Arvin; Salamone, Salvatore

    2014-03-01

    The most common damage assessment technique for concrete structures is visual inspection (VI). Condition assessed by VI is subjective in nature, meaning it depends on the experience, knowledge, expertise, measurement accuracy, mental attention, and judgment of the inspector carrying out the assessment. In many post-event assessments, cracks data including width and pattern provide the most indicative information about the health or damage state of the structure. Residual cracks are sometimes the only available data for VI. However, due to adjacent elastic members, earthquake displacement spectrum, or re-centering systems, these measurements may lead to erroneous decisions. To overcome this problem, this paper proposes a novel damage index based upon Fractal Dimension (FD) analysis of residual cracks as a complementary method for VI. FD can quantify crack patterns and enhance the routine inspection procedure by establishing a crack pattern recognition system. This algorithm was validated through an experimental study on a large scale reinforced concrete shear wall (RCSW). The results demonstrate the novel technique as a quite accurate estimator for damage grades and stiffness loss of the wall.

  1. Natural Corrosion Inhibitors for Steel Reinforcement in Concrete — a Review

    NASA Astrophysics Data System (ADS)

    Raja, Pandian Bothi; Ghoreishiamiri, Seyedmojtaba; Ismail, Mohammad

    2015-04-01

    Reinforced concrete is one of the widely used construction materials for bridges, buildings, platforms and tunnels. Though reinforced concrete is capable of withstanding a large range of severe environments including marine, industrial and alpine conditions, there are still a large number of failures in concrete structures for many reasons. Either carbonation or chloride attack is the main culprit which is due to depassivation of reinforced steel and subsequently leads to rapid steel corrosion. Among many corrosion prevention measures, application of corrosion inhibitors play a vital role in metal protection. Numerous range of corrosion inhibitors were reported for concrete protection that were also used commercially in industries. This review summarizes the application of natural products as corrosion inhibitors for concrete protection and also scrutinizes various factors influencing its applicability.

  2. Durability of adhesive joints between concrete and FRP reinforcement in aggressive environments

    NASA Astrophysics Data System (ADS)

    Park, Soojae

    The durability of the bondline between concrete and its fiber-reinforced polymer reinforcement was characterized at various temperature and humidity levels. The bondline consisted of an epoxy primer, an epoxy putty and an epoxy saturant. In principle, fracture could occur anywhere in this bondline, but attention was focused on the concrete/primer interface in this study because preliminary experiments indicated that this was the dominant failure mechanism. The initial part of the constitutive modeling of the epoxy primer was conducted using linear viscoelastic experiments. Confined compression experiments determined two linear material functions simultaneously. Because this was a relatively new experiment, the results were validated by conducting bulk compliance experiments. The viscoelastic region of the bulk modulus was as wide as that of the tensile and shear relaxation moduli. This result contradicts previous conceptions but is agreement with some other recent observations. Thermal and hygral expansions were also measured and used in a hybrid nonlinear viscoelastic constitutive model. The hybrid model captured the hygrothermal nonlinear viscoelastic deformation of the epoxy primer. This model is a combination of Schapery's model and Popelar's shear modified free volume model. Torsion tests were conducted and used to calibrate the distortional parameters in the free volume model. Tension experiments were performed at four different temperature and humidity levels and were used to calibrate the dilatational, thermal and hygral parameters in the hybrid model. The linear and hygrothermal nonlinear viscoelastic constitutive models were used in the analysis of time-dependent interfacial fracture between concrete and epoxy primer. A generalized time-dependent J integral was used as a fracture parameter for characterizing the time-dependent interfacial fracture. This was used instead of the strain energy release rate and the stress intensity factor because of the

  3. Atmospheric rusting of rebars and its effect on reinforced concrete corrosion

    SciTech Connect

    Mehmood, T.; Absan, S.N.; Al-Mughidi, M.S.

    1998-12-31

    Steel concrete reinforcing bars are known to rust on open storage, particularly in humid environments. Rebar manufactured through different technologies exhibit varying rusting tendency and hence have increased the confusion about their use in concrete. Published literature mainly deals with effect of rust on rebars` mechanical properties and concrete bond strength. Little work has been reported on the corrosion behavior of rusted rebars in concrete, Present paper compares the atmospheric rusting behavior of rebars produced through different processes and effect of degree of rust on rebars` corrosion behavior in concrete.

  4. Micromechanics Solution for the Elastic Moduli of Fiber-Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Huan, Yu Jia; Yang, Liu; Jin, Yu; Guang, Jia Lian; Ming, Liu

    2014-09-01

    The overall elastic moduli of fiber-reinforced concrete composite materials are investigated by employing the theory of micromechanics. A method based on the Mori-Tanaka theory and triple inhomogeneities is found to provide a sufficiently accurate evaluation of the average elastic properties of fiber-reinforced concrete composite materials. The inhomogeneities of the materials are divided into three groups: a fine aggregate, a coarse aggregate, and fibers (steel or polymer). The elastic moduli of fiber-reinforced concrete composite materials are determined as functions of the physical properties and volume fraction of sand, gravel, fibers (steel or polymer), and cement paste as a matrix. The theoretical results obtained are compared with published experimental data. The parameters affecting the elastic moduli of fiber-reinforced concrete are discussed in detail.

  5. Monitoring the Corrosion Process of Reinforced Concrete Using BOTDA and FBG Sensors

    PubMed Central

    Mao, Jianghong; Chen, Jiayun; Cui, Lei; Jin, Weiliang; Xu, Chen; He, Yong

    2015-01-01

    Expansion and cracking induced by the corrosion of reinforcement concrete is the major factor in the failure of concrete durability. Therefore, monitoring of concrete cracking is critical for evaluating the safety of concrete structures. In this paper, we introduce a novel monitoring method combining Brillouin optical time domain analysis (BOTDA) and fiber Bragg grating (FBG), based on mechanical principles of concrete expansion cracking. BOTDA monitors concrete expansion and crack width, while FBG identifies the time and position of cracking. A water-pressure loading simulation test was carried out to determine the relationship between fiber strain, concrete expansion and crack width. An electrical accelerated corrosion test was also conducted to evaluate the ability of this novel sensor to monitor concrete cracking under practical conditions. PMID:25884790

  6. Monitoring the corrosion process of reinforced concrete using BOTDA and FBG sensors.

    PubMed

    Mao, Jianghong; Chen, Jiayun; Cui, Lei; Jin, Weiliang; Xu, Chen; He, Yong

    2015-04-15

    Expansion and cracking induced by the corrosion of reinforcement concrete is the major factor in the failure of concrete durability. Therefore, monitoring of concrete cracking is critical for evaluating the safety of concrete structures. In this paper, we introduce a novel monitoring method combining Brillouin optical time domain analysis (BOTDA) and fiber Bragg grating (FBG), based on mechanical principles of concrete expansion cracking. BOTDA monitors concrete expansion and crack width, while FBG identifies the time and position of cracking. A water-pressure loading simulation test was carried out to determine the relationship between fiber strain, concrete expansion and crack width. An electrical accelerated corrosion test was also conducted to evaluate the ability of this novel sensor to monitor concrete cracking under practical conditions.

  7. Peridynamic modeling of plain and reinforced concrete structures.

    SciTech Connect

    Silling, Stewart Andrew; Gerstle, Walter H.; Sau, Nicolas

    2005-08-01

    The peridynamic model was introduced by Silling in 1998. In this paper, we demonstrate the application of the quasistatic peridynamic model to two-dimensional, linear elastic, plane stress and plane strain problems, with special attention to the modeling of plain and reinforced concrete structures. We consider just one deviation from linearity--that which arises due to the irreversible sudden breaking of bonds between particles. The peridynamic model starts with the assumption that Newton's second law holds true on every infinitesimally small free body (or particle) within the domain of analysis. A specified force density function, called the pairwise force function, (with units of force per unit volume per unit volume) between each pair of infinitesimally small particles is postulated to act if the particles are closer together than some finite distance, called the material horizon. The pairwise force function may be assumed to be a function of the relative position and the relative displacement between the two particles. In this paper, we assume that for two particles closer together than the specified 'material horizon' the pairwise force function increases linearly with respect to the stretch, but at some specified stretch, the pairwise force function is irreversibly reduced to zero.

  8. Radiation exposure inside reinforced concrete buildings at Nagasaki

    SciTech Connect

    Rhoades, W.A.; Childs, R.L.; Ingersoll, D.T.

    1989-05-01

    The biological effects on the residents of Hiroshima and Nagasaki due to initial-irradiation exposure during the nuclear attacks of World War II was recognized immediately as an important source of information. After the war, an extensive effort gathered data concerning the locations of individuals at the time of the attack and their subsequent medical histories. The data from personnel located in reinforced concrete buildings are particularly significant, since large groups of occupants received radiation injury without complications due to blast and thermal effects. In order to correlate the radiation dose with physiological effects, the dose to each individual must be calculated. Enough information about the construction of the buildings was available after the war to allow a radiation transport model to be constructed, but the accurate calculation of penetration into such large, thick-walled three dimensional structures was beyond the scope of computing technology until recently. Now, the availability of Cray vector computers and the development of a specially-constructed discrete ordinates transport code, TORT, have combined to allow the successful completion of such a study. This document describes the radiation transport calculations and tabulates the resulting doses by source component and individual case location. An extensive uncertainty analysis is also included. These data are to be used in another study as input to a formal statistical analysis, resulting in a new value for the LD50 dose, i.e., the dose at which the mortality risk is 50%. 55 refs., 67 figs., 70 tabs.

  9. High-temperature testing of high performance fiber reinforced concrete

    NASA Astrophysics Data System (ADS)

    Fořt, Jan; Vejmelková, Eva; Pavlíková, Milena; Trník, Anton; Čítek, David; Kolísko, Jiří; Černý, Robert; Pavlík, Zbyšek

    2016-06-01

    The effect of high-temperature exposure on properties of High Performance Fiber Reinforced Concrete (HPFRC) is researched in the paper. At first, reference measurements are done on HPFRC samples without high-temperature loading. Then, the HPFRC samples are exposed to the temperatures of 200, 400, 600, 800, and 1000 °C. For the temperature loaded samples, measurement of residual mechanical and basic physical properties is done. Linear thermal expansion coefficient as function of temperature is accessed on the basis of measured thermal strain data. Additionally, simultaneous difference scanning calorimetry (DSC) and thermogravimetry (TG) analysis is performed in order to observe and explain material changes at elevated temperature. It is found that the applied high temperature loading significantly increases material porosity due to the physical, chemical and combined damage of material inner structure, and negatively affects also the mechanical strength. Linear thermal expansion coefficient exhibits significant dependence on temperature and changes of material structure. The obtained data will find use as input material parameters for modelling the damage of HPFRC structures exposed to the fire and high temperature action.

  10. Rupture Directivity Effect on Seismic Vulnerability of Reinforced Concrete Bridge

    NASA Astrophysics Data System (ADS)

    Shirazian, Shadi; Nouri, Gholamreza; Ghayamghamian, Mohamadreza

    2017-04-01

    Earthquake catastrophes menace humans` lives and assets. Although earthquakes are inevitable, damage is not. To remedy this situation, significant amount of research is conducted in order to assess the performance of existent man-made structures, particularly infrastructures such as bridges which play a vital role in post earthquake services. The results can be used for assessing retrofit prioritization for structures and as a basis for economic loss estimations. The research presented here determines the vulnerability of a common typical two-span reinforced concrete bridge by generating fragility curves. Near-fault ground motions are different from ordinary ground motions, often containing strong coherent dynamic long-period pulses and permanent ground displacements. Here special attention is given to this type of ground motions, and their effects on the seismic behavior of structure are compared with ordinary motions. The results show near-fault ground motions exacerbate the seismic vulnerability of a bridge by about 68% in comparison with near-field ground motions. In other words, near-source ground motions with forward directivity effect are more dangerous.

  11. Aftershock collapse vulnerability assessment of reinforced concrete frame structures

    USGS Publications Warehouse

    Raghunandan, Meera; Liel, Abbie B.; Luco, Nicolas

    2015-01-01

    In a seismically active region, structures may be subjected to multiple earthquakes, due to mainshock–aftershock phenomena or other sequences, leaving no time for repair or retrofit between the events. This study quantifies the aftershock vulnerability of four modern ductile reinforced concrete (RC) framed buildings in California by conducting incremental dynamic analysis of nonlinear MDOF analytical models. Based on the nonlinear dynamic analysis results, collapse and damage fragility curves are generated for intact and damaged buildings. If the building is not severely damaged in the mainshock, its collapse capacity is unaffected in the aftershock. However, if the building is extensively damaged in the mainshock, there is a significant reduction in its collapse capacity in the aftershock. For example, if an RC frame experiences 4% or more interstory drift in the mainshock, the median capacity to resist aftershock shaking is reduced by about 40%. The study also evaluates the effectiveness of different measures of physical damage observed in the mainshock-damaged buildings for predicting the reduction in collapse capacity of the damaged building in subsequent aftershocks. These physical damage indicators for the building are chosen such that they quantify the qualitative red tagging (unsafe for occupation) criteria employed in post-earthquake evaluation of RC frames. The results indicated that damage indicators related to the drift experienced by the damaged building best predicted the reduced aftershock collapse capacities for these ductile structures.

  12. Experimental data of the static behavior of reinforced concrete beams at room and low temperature.

    PubMed

    Mirzazadeh, M Mehdi; Noël, Martin; Green, Mark F

    2016-06-01

    This article provides data on the static behavior of reinforced concrete at room and low temperature including, strength, ductility, and crack widths of the reinforced concrete. The experimental data on the application of digital image correlation (DIC) or particle image velocimetry (PIV) in measuring crack widths and the accuracy and precision of DIC/PIV method with temperature variations when is used for measuring strains is provided as well.

  13. Experimental data of the static behavior of reinforced concrete beams at room and low temperature

    PubMed Central

    Mirzazadeh, M. Mehdi; Noël, Martin; Green, Mark F.

    2016-01-01

    This article provides data on the static behavior of reinforced concrete at room and low temperature including, strength, ductility, and crack widths of the reinforced concrete. The experimental data on the application of digital image correlation (DIC) or particle image velocimetry (PIV) in measuring crack widths and the accuracy and precision of DIC/PIV method with temperature variations when is used for measuring strains is provided as well. PMID:27158650

  14. Feasibility research report of villa constructed of glass fiber reinforced concrete

    NASA Astrophysics Data System (ADS)

    Li, Shengli; Lu, Yu; Wang, Dongwei

    2011-04-01

    With the development of economy and improvement degree of modernization, the villa project design program tend to focus on the green, high-tech, humanities, and more emphasis on the integrity of space, noble and elegant feeling. Therefore, based on the study of literatures, this paper discussed the present situation and issue and features of Glass Fiber Reinforced Concrete and the feature of assembly house, and confirmed that the villa of assemble house is feasible by built of Glass Fiber Reinforced Concrete.

  15. Evaluation of post-fire strength of concrete flexural members reinforced with glass fiber reinforced polymer (GFRP) bars

    NASA Astrophysics Data System (ADS)

    Ellis, Devon S.

    Owing to their corrosion resistance and superior strength to weight ratio, there has been, over the past two decades, increased interest in the use of fiber-reinforced polymer (FRP) reinforcing bars in reinforced concrete structural members. The mechanical behavior of FRP reinforcement differs from that of steel reinforcement. For example, FRP reinforcement exhibit a linear stress-strain behavior until the bar ruptures and the strength, stiffness and bond properties of FRP reinforcement are affected more adversely by elevated temperatures. All structures are subject to the risk of damage by fire and fires continue to be a significant cause of damage to structures. Many structures do not collapse after being exposed to fire. The safety of the structure for any future use is dependent on the ability to accurately estimate the post-fire load capacity of the structure. Assuming that the changes, due to fire exposure, in the mechanical behavior of the GFRP reinforcing bar and concrete, and the bond between the reinforcing bar and the concrete are understood, an analytical procedure for estimating the post-fire strength of GFRP reinforced concrete flexural elements can be developed. This thesis investigates the changes in: a) tensile properties and bond of GFRP bars; and b) the flexural behavior of GFRP reinforced concrete beams flexural after being exposed to elevated temperatures up to 400°C and cooled to ambient temperature. To this end, twelve tensile tests, twelve pullout bond tests and ten four-point beam tests were performed. The data from the tests were used to formulate analytical procedures for evaluating the post-fire strength of GFRP reinforced concrete beams. The procedure produced conservative results when compared with the experimental data. In general, the residual tensile strength and modulus of elasticity of GFRP bars decrease as the exposure temperature increases. The loss in properties is however, smaller than that observed by other researchers when

  16. Modeling the dynamic stiffness of cracked reinforced concrete beams under low-amplitude vibration loads

    NASA Astrophysics Data System (ADS)

    Xu, Tengfei; Castel, Arnaud

    2016-04-01

    In this paper, a model, initially developed to calculate the stiffness of cracked reinforced concrete beams under static loading, is used to assess the dynamic stiffness. The model allows calculating the average inertia of cracked beams by taking into account the effect of bending cracks (primary cracks) and steel-concrete bond damage (i.e. interfacial microcracks). Free and forced vibration experiments are used to assess the performance of the model. The respective influence of bending cracks and steel-concrete bond damage on both static and dynamic responses is analyzed. The comparison between experimental and simulated deflections confirms that the effects of both bending cracks and steel-concrete bond loss should be taken into account to assess reinforced concrete stiffness under service static loading. On the contrary, comparison of experimental and calculated dynamic responses reveals that localized steel-concrete bond damages do not influence significantly the dynamic stiffness and the fundamental frequency.

  17. Refinement of Strut-and-Tie Model for Reinforced Concrete Deep Beams.

    PubMed

    Panjehpour, Mohammad; Chai, Hwa Kian; Voo, Yen Lei

    2015-01-01

    Deep beams are commonly used in tall buildings, offshore structures, and foundations. According to many codes and standards, strut-and-tie model (STM) is recommended as a rational approach for deep beam analyses. This research focuses on the STM recommended by ACI 318-11 and AASHTO LRFD and uses experimental results to modify the strut effectiveness factor in STM for reinforced concrete (RC) deep beams. This study aims to refine STM through the strut effectiveness factor and increase result accuracy. Six RC deep beams with different shear span to effective-depth ratios (a/d) of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were experimentally tested under a four-point bending set-up. The ultimate shear strength of deep beams obtained from non-linear finite element modeling and STM recommended by ACI 318-11 as well as AASHTO LRFD (2012) were compared with the experimental results. An empirical equation was proposed to modify the principal tensile strain value in the bottle-shaped strut of deep beams. The equation of the strut effectiveness factor from AASHTTO LRFD was then modified through the aforementioned empirical equation. An investigation on the failure mode and crack propagation in RC deep beams subjected to load was also conducted.

  18. Multifractal analysis of two-dimensional images for damage assessment of reinforced concrete structures

    NASA Astrophysics Data System (ADS)

    Ebrahimkhanlou, Arvin; Farhidzadeh, Alireza; Salamone, Salvatore

    2015-03-01

    The most common assessment technique for reinforced concrete shear walls (RCSW) is Visual Inspection (VI). The current practice suffers from subjective and labor intensive nature as it highly relies on judgment and expertise of the inspectors. In post-earthquake events where urgent and objective decisions are crucial, failure of the conventional VI could be catastrophic. Conventional VI is mainly based on width of residual cracks. Given that cracks could close partially (e.g., due to weight of the structure, behavior of adjacent elastic members, earthquake displacement spectrum, etc.), methods based on crack width may lead to underestimating the state of damage and eventually an erroneous decision. This paper proposes a novel method to circumvent the aforementioned limitations by utilizing the information hidden in crack patterns. Crack patterns from images of the surface cracks on RCSW are extracted automatically, and Multifractal Analysis (MFA) are applied on them. Images were taken from two large scale low aspect ratio RCSW under quasi-static cyclic loading, and MFA showed clear correlation with tri-linear shear controlled behavior of walls which was observed in their backbone curves.

  19. Refinement of Strut-and-Tie Model for Reinforced Concrete Deep Beams

    PubMed Central

    Panjehpour, Mohammad; Chai, Hwa Kian; Voo, Yen Lei

    2015-01-01

    Deep beams are commonly used in tall buildings, offshore structures, and foundations. According to many codes and standards, strut-and-tie model (STM) is recommended as a rational approach for deep beam analyses. This research focuses on the STM recommended by ACI 318-11 and AASHTO LRFD and uses experimental results to modify the strut effectiveness factor in STM for reinforced concrete (RC) deep beams. This study aims to refine STM through the strut effectiveness factor and increase result accuracy. Six RC deep beams with different shear span to effective-depth ratios (a/d) of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were experimentally tested under a four-point bending set-up. The ultimate shear strength of deep beams obtained from non-linear finite element modeling and STM recommended by ACI 318-11 as well as AASHTO LRFD (2012) were compared with the experimental results. An empirical equation was proposed to modify the principal tensile strain value in the bottle-shaped strut of deep beams. The equation of the strut effectiveness factor from AASHTTO LRFD was then modified through the aforementioned empirical equation. An investigation on the failure mode and crack propagation in RC deep beams subjected to load was also conducted. PMID:26110268

  20. Fiber-reinforced concretes with a high fiber volume fraction — a look in future. Can a design determine the fiber amount in concrete in real time in every part of a structure in production?

    NASA Astrophysics Data System (ADS)

    Tepfers, R.

    2010-09-01

    addition is to be preferred? The target point where the concrete comes to rest into a structure has to be electronically noted and sent to the FEM system. The FEM analysis should then immediately send back the information for the correct amount of fibers at that point. This requires the elaboration of an appropriate signal system, which should not be impossible. An integrated system for the design and production of concrete structures could be developed excluding the heavy and time-consuming work with steel reinforcing bars. The result could be: no evaluation of moments and shear forces from a FEM analysis for determining the bar reinforcement; no bar anchorage requirements and reinforcement detailing; no reinforcement drawings; no reinforcing bars; no heavy work with the reinforcement. Finally, investigations have to be performed concerning the demolition of fiber-reinforced concrete structures and the reuse of the material. The fragments of fiber-reinforced concrete might be sticky and cause problems for nature. The recirculation of material has also to be solved.

  1. Experimental investigation of bond in concrete members reinforced with shape memory alloy bars

    NASA Astrophysics Data System (ADS)

    Daghash, S. M.; Sherif, M. M.; Ozbulut, O. E.

    2015-04-01

    Conventional seismic design of reinforced concrete structures relies on yielding of steel reinforcement to dissipate energy while undergoing residual deformations. Therefore, reinforced concrete structures subjected to strong earthquakes experience large permanent displacements and are prone to severe damage or collapse. Shape memory alloys (SMAs) have gained increasing acceptance in recent years for use in structural engineering due to its attractive properties such as high corrosion resistance, excellent re-centering ability, good energy dissipation capacity, and durability. SMAs can undergo large deformations in the range of 6-8% strain and return their original undeformed position upon unloading. Due to their appealing characteristics, SMAs have been considered as an alternative to traditional steel reinforcement in concrete structures to control permanent deformations. However, the behavior of SMAs in combination with concrete has yet to be explored. In particular, the bond strength is important to ensure the composite action between concrete and SMA reinforcements. This study investigates the bond behavior between SMA bars and concrete through pull-out tests. To explore the size effect on bond strength, the tests are performed using various diameters of SMA bars. For the same diameter, the tests are also conducted with different embedment length to assess the effect of embedment length on bond properties of SMA bars. To monitor the slippage of the SMA reinforcement, an optical Digital Image Correlation method is used and the bond-slip curves are obtained.

  2. 77 FR 39254 - Steel Concrete Reinforcing Bar From Belarus, China, Indonesia, Latvia, Moldova, Poland, and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-02

    ... Ukraine; Institution of Five-Year Reviews Concerning the Antidumping Duty Orders on Steel Concrete... determine whether revocation of the antidumping duty orders on steel concrete reinforcing bar from Belarus..., 2001, the Department of Commerce (``Commerce'') issued antidumping duty orders on imports of steel...

  3. Shrinkage modeling of concrete reinforced by palm fibres in hot dry environments

    NASA Astrophysics Data System (ADS)

    Akchiche, Hamida; Kriker, Abdelouahed

    2017-02-01

    The cement materials, such as concrete and conventional mortar present very little resistance to traction and cracking, these hydraulic materials which induces large withdrawals on materials and cracks in structures. The hot dry environments such as: the Saharan regions of Algeria, Indeed, concrete structures in these regions are very fragile, and present high shrinkage. Strengthening of these materials by fibers can provide technical solutions for improving the mechanical performance. The aim of this study is firstly, to reduce the shrinkage of conventional concrete with its reinforcement with date palm fibers. In fact, Algeria has an extraordinary resources in natural fibers (from Palm, Abaca, Hemp) but without valorization in practical areas, especially in building materials. Secondly, to model the shrinkage behavior of concrete was reinforced by date palm fibers. In the literature, several models for still fiber concrete were founded but few are offers for natural fiber concretes. To do so, a still fiber concretes model of YOUNG - CHERN was used. According to the results, a reduction of shrinkage with reinforcement by date palm fibers was showed. A good ability of molding of shrinkage of date palm reinforced concrete with YOUNG - CHERN Modified model was obtained. In fact, a good correlation between experimental data and the model data was recorded.

  4. 78 FR 41079 - Steel Concrete Reinforcing Bar From Belarus, China, Indonesia, Latvia, Moldova, Poland, and Ukraine

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-09

    ... COMMISSION Steel Concrete Reinforcing Bar From Belarus, China, Indonesia, Latvia, Moldova, Poland, and... Tariff Act of 1930 (19 U.S.C. 1675(c)), that revocation of the antidumping duty orders on steel concrete... views of the Commission are contained in USITC Publication 4409 (July 2013), entitled Steel...

  5. 78 FR 43858 - Steel Concrete Reinforcing Bars From Belarus, Indonesia, Latvia, Moldova, Poland, the People's...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-22

    ...] Steel Concrete Reinforcing Bars From Belarus, Indonesia, Latvia, Moldova, Poland, the People's Republic... Department of Commerce (``Department'') that revocation of the antidumping duty orders \\1\\ on steel concrete... of the continuation of the antidumping duty orders. \\1\\ See Antidumping Duty Orders: Steel...

  6. Experimental Investigation of the Fracture of Hybrid-Fiber-Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Krūmiņš, J.; Zesers, A.

    2015-03-01

    The effects of polypropylene fibers on the fracture of concrete and steel-fiber-reinforced concrete (SFRC) are studied. Properties of the composites were investigated by conducting four-point bending tests. The experimental data obtained showed a good overall improvement in SFRC properties with addition of polypropylene fibers.

  7. Seismic Performance of Composite Shear Walls Constructed Using Recycled Aggregate Concrete and Different Expandable Polystyrene Configurations

    PubMed Central

    Liu, Wenchao; Cao, Wanlin; Zhang, Jianwei; Qiao, Qiyun; Ma, Heng

    2016-01-01

    The seismic performance of recycled aggregate concrete (RAC) composite shear walls with different expandable polystyrene (EPS) configurations was investigated. Six concrete shear walls were designed and tested under cyclic loading to evaluate the effect of fine RAC in designing earthquake-resistant structures. Three of the six specimens were used to construct mid-rise walls with a shear-span ratio of 1.5, and the other three specimens were used to construct low-rise walls with a shear-span ratio of 0.8. The mid-rise and low-rise shear walls consisted of an ordinary recycled concrete shear wall, a composite wall with fine aggregate concrete (FAC) protective layer (EPS modules as the external insulation layer), and a composite wall with sandwiched EPS modules as the insulation layer. Several parameters obtained from the experimental results were compared and analyzed, including the load-bearing capacity, stiffness, ductility, energy dissipation, and failure characteristics of the specimens. The calculation formula of load-bearing capacity was obtained by considering the effect of FAC on composite shear walls as the protective layer. The damage process of the specimen was simulated using the ABAQUS Software, and the results agreed quite well with those obtained from the experiments. The results show that the seismic resistance behavior of the EPS module composite for shear walls performed better than ordinary recycled concrete for shear walls. Shear walls with sandwiched EPS modules had a better seismic performance than those with EPS modules lying outside. Although the FAC protective layer slightly improved the seismic performance of the structure, it undoubtedly slowed down the speed of crack formation and the stiffness degradation of the walls. PMID:28773274

  8. Seismic Performance of Composite Shear Walls Constructed Using Recycled Aggregate Concrete and Different Expandable Polystyrene Configurations.

    PubMed

    Liu, Wenchao; Cao, Wanlin; Zhang, Jianwei; Qiao, Qiyun; Ma, Heng

    2016-03-02

    The seismic performance of recycled aggregate concrete (RAC) composite shear walls with different expandable polystyrene (EPS) configurations was investigated. Six concrete shear walls were designed and tested under cyclic loading to evaluate the effect of fine RAC in designing earthquake-resistant structures. Three of the six specimens were used to construct mid-rise walls with a shear-span ratio of 1.5, and the other three specimens were used to construct low-rise walls with a shear-span ratio of 0.8. The mid-rise and low-rise shear walls consisted of an ordinary recycled concrete shear wall, a composite wall with fine aggregate concrete (FAC) protective layer (EPS modules as the external insulation layer), and a composite wall with sandwiched EPS modules as the insulation layer. Several parameters obtained from the experimental results were compared and analyzed, including the load-bearing capacity, stiffness, ductility, energy dissipation, and failure characteristics of the specimens. The calculation formula of load-bearing capacity was obtained by considering the effect of FAC on composite shear walls as the protective layer. The damage process of the specimen was simulated using the ABAQUS Software, and the results agreed quite well with those obtained from the experiments. The results show that the seismic resistance behavior of the EPS module composite for shear walls performed better than ordinary recycled concrete for shear walls. Shear walls with sandwiched EPS modules had a better seismic performance than those with EPS modules lying outside. Although the FAC protective layer slightly improved the seismic performance of the structure, it undoubtedly slowed down the speed of crack formation and the stiffness degradation of the walls.

  9. User’s Guide: Fracture Mechanics Analysis of Reinforced Concrete Beams (FMARCB)

    DTIC Science & Technology

    2008-01-01

    prediction by analysis of existing data. ACI Journal 65 (11): 943-951. Zwoyer, E.M., and C. Siess. 1954. Ultimate strength in shear of simply...process, strength , and deformation characteristics (Van Den Berg 1962a,b,and c). The successful application of nonlinear finite element systems to...an improved concrete plasticity model, a multiaxial fracture criterion for concrete, a smeared model for concrete cracking, and modeling of post

  10. Analysis of concrete targets with different kinds of reinforcements subjected to blast loading

    NASA Astrophysics Data System (ADS)

    Oña, M.; Morales-Alonso, G.; Gálvez, F.; Sánchez-Gálvez, V.; Cendón, D.

    2016-05-01

    In this paper we describe an experimental campaign carried out to study and analyse the behaviour of concrete slabs when subjected to blast loading. Four different types of concrete have been tested: normal strength concrete with steel rebar, normal strength concrete with steel rebar retrofitted with Kevlar coating, steel fibre reinforced concrete (SFRC) and polypropylene fibre reinforced concrete (PFRC). The major asset of the experimental setup used is that it allows to subject up to four specimens to the same blast load what, besides being cost effective, makes possible to have a measure of the experimental scatter. The results of SFRC and PFRC concretes have been analysed by using a previously developed material model for the numerical simulation of concrete elements subjected to blast. The experimental campaign and preliminary results of this numerical analysis show how the high strain rates, in spite of improving the mechanical properties of these kinds of fibre reinforced concretes, lead to an embrittlement of the material, which may be dangerous from the point of view of the structural behaviour.

  11. Development of a Skewed Pipe Shear Connector for Precast Concrete Structures

    PubMed Central

    Kim, Sang-Hyo; Choi, Jae-Gu; Park, Sejun; Lee, Hyunmin; Heo, Won-Ho

    2017-01-01

    Joint connection methods, such as shear key and loop bar, improve the structural performance of precast concrete structures; consequently, there is usually decreased workability or constructional efficiency. This paper proposes a high-efficiency skewed pipe shear connector. To resist shear and pull-out forces, the proposed connectors are placed diagonally between precast concrete segments and a cast-in-place concrete joint part on a girder. Design variables (such as the pipe diameter, length, and insertion angle) have been examined to investigate the connection performance of the proposed connector. The results of our testing indicate that the skewed pipe shear connectors have 50% higher ductility and a 15% higher ratio of maximum load to yield strength as compared to the corresponding parameters of the loop bar. Finite element analysis was used for validation. The resulting validation indicates that, compared to the loop bar, the skewed pipe shear connector has a higher ultimate shear and pull-out resistance. These results indicate that the skewed pipe shear connector demonstrates more idealized behavior than the loop bar in precast concrete structures. PMID:28772887

  12. Development of a Skewed Pipe Shear Connector for Precast Concrete Structures.

    PubMed

    Kim, Sang-Hyo; Choi, Jae-Gu; Park, Sejun; Lee, Hyunmin; Heo, And Won-Ho

    2017-05-13

    Joint connection methods, such as shear key and loop bar, improve the structural performance of precast concrete structures; consequently, there is usually decreased workability or constructional efficiency. This paper proposes a high-efficiency skewed pipe shear connector. To resist shear and pull-out forces, the proposed connectors are placed diagonally between precast concrete segments and a cast-in-place concrete joint part on a girder. Design variables (such as the pipe diameter, length, and insertion angle) have been examined to investigate the connection performance of the proposed connector. The results of our testing indicate that the skewed pipe shear connectors have 50% higher ductility and a 15% higher ratio of maximum load to yield strength as compared to the corresponding parameters of the loop bar. Finite element analysis was used for validation. The resulting validation indicates that, compared to the loop bar, the skewed pipe shear connector has a higher ultimate shear and pull-out resistance. These results indicate that the skewed pipe shear connector demonstrates more idealized behavior than the loop bar in precast concrete structures.

  13. Application of artificial neural networks to predict the deflections of reinforced concrete beams

    NASA Astrophysics Data System (ADS)

    Kaczmarek, Mateusz; Szymańska, Agnieszka

    2016-06-01

    Nonlinear structural mechanics should be taken into account in the practical design of reinforced concrete structures. Cracking is one of the major sources of nonlinearity. Description of deflection of reinforced concrete elements is a computational problem, mainly because of the difficulties in modelling the nonlinear stress-strain relationship of concrete and steel. In design practise, in accordance with technical rules (e.g., Eurocode 2), a simplified approach for reinforced concrete is used, but the results of simplified calculations differ from the results of experimental studies. Artificial neural network is a versatile modelling tool capable of making predictions of values that are difficult to obtain in numerical analysis. This paper describes the creation and operation of a neural network for making predictions of deflections of reinforced concrete beams at different load levels. In order to obtain a database of results, that is necessary for training and testing the neural network, a research on measurement of deflections in reinforced concrete beams was conducted by the authors in the Certified Research Laboratory of the Building Engineering Institute at Wrocław University of Science and Technology. The use of artificial neural networks is an innovation and an alternative to traditional methods of solving the problem of calculating the deflections of reinforced concrete elements. The results show the effectiveness of using artificial neural network for predicting the deflection of reinforced concrete beams, compared with the results of calculations conducted in accordance with Eurocode 2. The neural network model presented in this paper can acquire new data and be used for further analysis, with availability of more research results.

  14. Fracture analysis of a high-strength concrete and a high-strength steel-fiber-reinforced concrete

    NASA Astrophysics Data System (ADS)

    Ferreira, L. E. T.

    2007-09-01

    This paper addresses the use of R-curves to study the fracture behavior of high-strength concrete and steel-fiber-reinforced concrete subjected to crack ing in a three-point bending configuration. The R-curves are modeled through an effective approach based on the equations of linear-elastic fracture mechanics (LEFM), which relates the applied load to the fundamental displacements of notched-through beams loaded monotonically. It is initially shown that, for quasi-brittle materials, the R-curves responses can be evaluated in a quasi-analytical way, using the load-crack mouth opening, the load-load line displacement, or exclusively the displacement responses obtained experimentally. Afterward, the methodology is used to obtain the fracture responses of high-strength and fiber-reinforced concretes, up to the final stages of rupture.

  15. Tensile properties of glass/natural jute fibre-reinforced polymer bars for concrete reinforcement

    NASA Astrophysics Data System (ADS)

    Han, J. W.; Lee, S. K.; Kim, K. W.; Park, C. G.

    2015-12-01

    The tensile performance of glass/natural jute fibre-reinforced polymer (FRP) bar, intended for concrete reinforcement was evaluated as a function of volume fraction of natural jute fibre. Natural jute fibre, mixed at a ratio of 7:3 with vinyl ester, was surface-treated with a silane coupling agent and used to replaced glass fibre in the composite in volume fractions of 0%, 30%, 50%, 70%, and 100%. The tensile load-displacement curve showed nearly linear elastic behaviour up to 50% natural jute fibre, but was partially nonlinear at a proportion of 70%. However, the glass/natural jute FRP bars prepared using 100% natural jute fibre showed linear elastic behaviour. Tensile strength decreased as the natural jute fibre volume fraction increased because the tensile strength of natural jute fibre is much lower than that of glass fibre (about 1:8.65). The degree of reduction was not proportional to the natural jute fibre volume fraction due to the low density of natural jute fibre (1/2 that of glass fibre). Thus, as the mix proportion of natural jute fibre increased, the amount (wt%) and number of fibres used also increased.

  16. Strengthening of beam - column joint with steel fibre reinforced concrete under seismic loading

    NASA Astrophysics Data System (ADS)

    Prasanna, K.; Ramasubramani, R.; Anandh, K. S.; Saisabarish; Krupaker Maddu, Vijay

    2017-07-01

    Earthquakes not only kill the human beings but the structures too. Considering this above fact, there is a necessity to take care of the beam column joint region in a structure. Under seismic excitation, the bar segment joint district is subjected to even and the vertical shear force extents are normally commonly greater than those in the adjoining bits of the structural segments. In the event that the joint is not precisely nitty gritty, the shaft segment joint may end up plainly frail. To keep this, an adequate control ought to be given in the joint area. The seismic examination and outline technique ought to be utilised as a part of the plan of the building structures and their segments ought to be recommended in the segment. The building structures incorporate finish sidelong and vertical drive opposing frameworks fit for giving satisfactory quality. Stiffness and the vitality dissemination ability to withstand the outline ground movements inside the recommended furthest reaches of twisting and quality request. The plan ground movements are accepted to happen along any even headings of a building structure. This work focuses on behaviour of M20 concrete in beam-column joint subjected to seismic loading, by using steel fibre (1.5%). The specimens detailed as per IS: 456-2000 and IS: 13920-1993 were casted and tested under cyclic and reverse cyclic loading. The parameters analysed were ductility, energy dissipation, load v/s displacement curve, beam-column reinforcement strain and crack pattern. From the experimental investigation, it is found that the fibre reinforced beam-column joint with fibre (1.50% of steel fibre) performs better ductility, load carrying capacity, energy dissipation and strength by 10% more than conventional reinforced beam-column joint.

  17. Effect of hot-dry environment on fiber-reinforced self-compacting concrete

    NASA Astrophysics Data System (ADS)

    Tioua, Tahar; Kriker, Abdelouahed; Salhi, Aimad; Barluenga, Gonzalo

    2016-07-01

    Drying shrinkage can be a major reason for the deterioration of concrete structures. Variation in ambient temperature and relative humidity cause changes in the properties of hardened concrete which can affect their mechanical and drying shrinkage characteristics. The present study investigated mechanical strength and particularly drying shrinkage properties of self-compacting concretes (SCC) reinforced with date palm fiber exposed to hot and dry environment. In this study a total of nine different fibers reinforced self compacting concrete (FRSCC) mixtures and one mixture without fiber were prepared. The volume fraction and the length of fibers reinforcement were 0.1-0.2-0.3% and 10-20-30 mm. It was observed that drying shrinkage lessened with adding low volumetric fraction and short length of fibers in curing condition (T = 20 °C and RH = 50 ± 5 %), but increased in hot and dry environment.

  18. Long-term deflections of reinforced concrete elements: accuracy analysis of predictions by different methods

    NASA Astrophysics Data System (ADS)

    Gribniak, Viktor; Bacinskas, Darius; Kacianauskas, Rimantas; Kaklauskas, Gintaris; Torres, Lluis

    2013-08-01

    Long-term deflection response of reinforced concrete flexural members is influenced by the interaction of complex physical phenomena, such as concrete creep, shrinkage and cracking, which makes their prediction difficult. A number of approaches are proposed by design codes with different degrees of simplification and accuracy. This paper statistically investigates accuracy of long-term deflection predictions made by some of the most widely used design codes ( Eurocode 2, ACI 318, ACI 435, and the new Russian code SP 52-101) and a numerical technique proposed by the authors. The accuracy is analyzed using test data of 322 reinforced concrete members from 27 test programs reported in the literature. The predictions of each technique are discussed, and a comparative analysis is made showing the influence of different parameters, such as sustained loading duration, compressive strength of concrete, loading intensity and reinforcement ratio, on the prediction accuracy.

  19. Strain Sharing Assessment in Woven Fiber Reinforced Concrete Beams Using Fiber Bragg Grating Sensors.

    PubMed

    Montanini, Roberto; Recupero, Antonino; De Domenico, Fabrizio; Freni, Fabrizio

    2016-09-22

    Embedded fiber Bragg grating sensors have been extensively used worldwide for health monitoring of smart structures. In civil engineering, they provide a powerful method for monitoring the performance of composite reinforcements used for concrete structure rehabilitation and retrofitting. This paper discusses the problem of investigating the strain transfer mechanism in composite strengthened concrete beams subjected to three-point bending tests. Fiber Bragg grating sensors were embedded both in the concrete tensioned surface and in the woven fiber reinforcement. It has been shown that, if interface decoupling occurs, strain in the concrete can be up to 3.8 times higher than that developed in the reinforcement. A zero friction slipping model was developed which fitted very well the experimental data.

  20. Strain Sharing Assessment in Woven Fiber Reinforced Concrete Beams Using Fiber Bragg Grating Sensors

    PubMed Central

    Montanini, Roberto; Recupero, Antonino; De Domenico, Fabrizio; Freni, Fabrizio

    2016-01-01

    Embedded fiber Bragg grating sensors have been extensively used worldwide for health monitoring of smart structures. In civil engineering, they provide a powerful method for monitoring the performance of composite reinforcements used for concrete structure rehabilitation and retrofitting. This paper discusses the problem of investigating the strain transfer mechanism in composite strengthened concrete beams subjected to three-point bending tests. Fiber Bragg grating sensors were embedded both in the concrete tensioned surface and in the woven fiber reinforcement. It has been shown that, if interface decoupling occurs, strain in the concrete can be up to 3.8 times higher than that developed in the reinforcement. A zero friction slipping model was developed which fitted very well the experimental data. PMID:27669251

  1. Infilled masonry walls contribution in mitigating progressive collapse of multistory reinforced concrete structures according to UFC guidelines

    NASA Astrophysics Data System (ADS)

    Helmy, Huda; Hadhoud, Hamed; Mourad, Sherif

    2015-09-01

    A structure is subjected to progressive collapse when an element fails, resulting in failure of adjoining structural elements which, in their turn, cause further structural failure leading eventually to partial or total collapse. The failure of a primary vertical support might occur due to extreme loadings such as bomb explosion in a terrorist attack, gas explosion and huge impact of a car in the parking area. Different guidelines such as the General Services Administration (GSA 2003) and the Unified Facilities Criteria (UFC 2009) addressed the structural progressive collapse due to the sudden loss of a main vertical support. In the current study, a progressive collapse assessment according to the UFC guidelines is carried out for a typical ten-story reinforced concrete framed structure designed according to codes [(ACI 318-08) and (ASCE 7-10)] for minimum design loads for buildings and other structures. Fully nonlinear dynamic analysis for the structure was carried out using Applied Element Method (AEM). The investigated cases included the removal of a corner column, an edge column, an edge shear wall, internal columns and internal shear wall. The numerical analysis showed that simplification of the problem into 3D bare frames would lead to uneconomical design. It was found for the studied case that, the infilled masonry walls have a valuable contribution in mitigating progressive collapse of the reinforced concrete framed structures. Neglecting these walls would lead to uneconomical design.

  2. Shear Strength of Partially Bonded Concrete-Rock Interfaces for Application in Dam Stability Analyses

    NASA Astrophysics Data System (ADS)

    Krounis, Alexandra; Johansson, Fredrik; Larsson, Stefan

    2016-07-01

    The shear strength of the concrete-rock interface has a substantial influence on the sliding stability of concrete gravity dams founded on rock. While several studies have been done on concrete-rock contacts, there remains uncertainty regarding the peak shear strength of partially bonded interfaces. There exists, in particular, an uncertainty regarding the contribution from surface roughness of the unbonded parts to the peak shear strength of the interface due to the dependency of mobilized strength on shear displacement. In this study, a series of 24 direct shear tests are performed under CNL conditions on concrete-rock samples with different bonding conditions. Tests on samples with fully bonded and unbonded interfaces are conducted to study the strain compatibility of the different contacts, while the results of samples with partially bonded interfaces are evaluated in the context of linking the joint roughness of the unbonded parts to the peak shear strength of the interface. The results indicate that a significant part of the surface roughness of the unbonded parts is mobilized prior to degradation of bond strength, in particular for interfaces with low bonding percentages. It is recommended that further research should be conducted to understand how the contribution from roughness change with an increase in scale and degree of matedness.

  3. Experimental and Numerical Analysis of the Shear Behaviour of Cemented Concrete-Rock Joints

    NASA Astrophysics Data System (ADS)

    Tian, H. M.; Chen, W. Z.; Yang, D. S.; Yang, J. P.

    2015-01-01

    The shear behaviour of cemented concrete-rock joints is a key factor affecting the shear resistance of dam foundations, arch bridge foundations, rock socketed piles and rock bolts in rock engineering. This paper presents an experimental and numerical investigation of the shear behaviour of cemented concrete-rock joints by direct shear tests. In this study we focused on the bond strength of cemented concrete-rock joints, so limestone with smooth surfaces was used for samples preparation to reduce the roughness effect. The experimental results show that the shear strength of joints with good adhesion is strongly dependent on the bond strength of the cohesive interfaces when the applied normal stress is less than 6 MPa. In addition, the sudden and gradual bond failure processes of the cohesive interfaces were observed with an increase of the normal stress. A simple, yet realistic, model of cemented concrete-rock joint is proposed to simulate the observed behaviour, including elastic behaviour of the bond before peak shear stress and post-peak behaviour due to bond failure and friction increase. Finally, the parameters analysis and calibration of the proposed model are presented.

  4. Study on evaluation of corrosion condition of reinforcing bar embedded concrete using infrared thermal imaging camera

    NASA Astrophysics Data System (ADS)

    Ruiko, Watanabe; Toshiaki, Mizobuchi

    2017-04-01

    Rapid aging of many concrete structures, which have been developed during rapid economic growth period in Japan, has become a serious problem for us these days. And thus, there is an urgent need to prolong their service life expectancies. For this purpose, the deterioration of reinforcing bars in the concrete structures should be detected quickly and correctly at the early stages. Nevertheless, conventional testing methods such as destructive and nondestructive testing have disadvantages: partial damages on concrete structures; difficulty with quantitative evaluation, etc. Many preceding studies have examined to estimate the deterioration of reinforcing bars based on the temperature of the concrete specimen surfaces. According to those papers, the differences in corrosion degree of reinforcing bars have a certain effect on the temperature of concrete specimen surfaces. In this study, firstly, the quantitative evaluation of the corrosion degree was conducted with 3D scanner which could measure the volume, coverage area and cross-sectional area. Secondly, the surface of the concrete specimen was cooled down with liquid nitrogen, and thirdly, thermographic change was observed up until the air temperature. Finally, the surface of the concrete specimen was detected clearly by the thermal images. As a result, this study shows that the corrosion thickness tends to get bigger, following the uprising temperature of the concrete specimen surfaces. The same kind of tendency can be observed by the thermal images, too.

  5. Development of early age shrinkage stresses in reinforced concrete bridge decks

    NASA Astrophysics Data System (ADS)

    William, Gergis W.; Shoukry, Samir N.; Riad, Mourad Y.

    2008-12-01

    This paper describes the instrumentation and data analysis of a reinforced concrete bridge deck constructed on 3-span continuous steel girders in Evansville, West Virginia. An instrumentation system consisting of 232 sensors is developed and implemented specifically to measure strains and temperature in concrete deck, strains in longitudinal and transverse rebars, the overall contraction and expansion of concrete deck, and crack openings. Data from all sensors are automatically collected every 30 minutes starting at the time of placing the concrete deck. Measured strain and temperature time-histories were used to calculate the stresses, which were processed to attenuate the thermal effects due to daily temperature changes and isolate the drying shrinkage component. The results indicated that most of concrete shrinkage occurs during the first three days. Under the constraining effects from stay-in-place forms and reinforcement, early age shrinkage leads to elevated longitudinal stress, which is the main factor responsible for crack initiation.

  6. Uniaxial Tension Test of Slender Reinforced Early Age Concrete Members

    PubMed Central

    Mimura, Yoichi; Yoshitake, Isamu; Zhang, Wenbo

    2011-01-01

    The present study aims to obtain the tensile properties of early age concrete based on a uniaxial tension test employing RC slender members. First, the paper shows that concrete strain is equal to the strain of rebar at the mid-span of the RC member. The tensile Young’s modulus and the strain capacity of early age concrete are estimated using strain measurements. The experiment indicated that the tensile Young’s modulus at an early age is higher than the compressive modulus. This observation was similar to one found in a previous investigation which used a direct tension test of early age concrete. Moreover, the paper describes how an empirical equation for mature concrete can be applied to the relation between uniaxial tensile strength and splitting tensile strength even in early age concrete. Based on a uniaxial tension test, the paper proposes an empirical equation for the relationship between standard bond stresses and relative slip. PMID:28824146

  7. Numerical analysis on seismic behavior of reinforced concrete beam to concrete filled steel tubular column connections with ring-beam

    NASA Astrophysics Data System (ADS)

    Zhao, Yi.; Xu, Li. Hua.

    2016-06-01

    This paper presents numerical study of the seismic behavior of reinforced concrete beam to concrete filled steel tube column connections with ring-beam. The material stress-strain relations, element type and boundary condition are selected, which are consistent with actual situation. Then the seismic behavior of this type of joint are researched by ABAQUS, and finite element analyses are conducted under cyclic loading. Its parameters are discussed including thickness of steel tubular column wall, sectional dimension of the ring-beam and strength of the core concrete. The results show that the ultimate capacity of the connections is improved with sectional dimension of the ring-beam increased. In the meanwhile, the influence on skeleton curve of the joints is slight of which included thickness of steel tubular column wall and strength of the core concrete.

  8. Numerical analysis on seismic behavior of reinforced concrete beam to concrete filled steel tubular column connections with ring-beam

    SciTech Connect

    Zhao, Yi.; Xu, Li. Hua.

    2016-06-08

    This paper presents numerical study of the seismic behavior of reinforced concrete beam to concrete filled steel tube column connections with ring-beam. The material stress-strain relations, element type and boundary condition are selected, which are consistent with actual situation. Then the seismic behavior of this type of joint are researched by ABAQUS, and finite element analyses are conducted under cyclic loading. Its parameters are discussed including thickness of steel tubular column wall, sectional dimension of the ring-beam and strength of the core concrete. The results show that the ultimate capacity of the connections is improved with sectional dimension of the ring-beam increased. In the meanwhile, the influence on skeleton curve of the joints is slight of which included thickness of steel tubular column wall and strength of the core concrete.

  9. Strength and deformability of concrete beams reinforced by non-metallic fiber and composite rebar

    NASA Astrophysics Data System (ADS)

    Kudyakov, K. L.; Plevkov, V. S.; Nevskii, A. V.

    2015-01-01

    Production of durable and high-strength concrete structures with unique properties has always been crucial. Therefore special attention has been paid to non-metallic composite and fiber reinforcement. This article describes the experimental research of strength and deformability of concrete beams with dispersed and core fiber-based reinforcement. As composite reinforcement fiberglass reinforced plastic rods with diameters 6 mm and 10 mm are used. Carbon and basalt fibers are used as dispersed reinforcement. The developed experimental program includes designing and production of flexural structures with different parameters of dispersed fiber and composite rebar reinforcement. The preliminary testing of mechanical properties of these materials has shown their effectiveness. Structures underwent bending testing on a special bench by applying flexural static load up to complete destruction. During the tests vertical displacements were recorded, as well as value of actual load, slippage of rebars in concrete, crack formation. As a result of research were obtained structural failure and crack formation graphs, value of fracture load and maximum displacements of the beams at midspan. Analysis of experimental data showed the effectiveness of using dispersed reinforcement of concrete and the need for prestressing of fiberglass composite rebar.

  10. Modeling of concrete cracking due to corrosion process of reinforcement bars

    SciTech Connect

    Bossio, Antonio; Monetta, Tullio; Bellucci, Francesco; Lignola, Gian Piero; Prota, Andrea

    2015-05-15

    The reinforcement corrosion in Reinforced Concrete (RC) is a major reason of degradation for structures and infrastructures throughout the world leading to their premature deterioration before design life was attained. The effects of corrosion of reinforcement are: (i) the reduction of the cross section of the bars, and (ii) the development of corrosion products leading to the appearance of cracks in the concrete cover and subsequent cover spalling. Due to their intrinsic complex nature, these issues require an interdisciplinary approach involving both material science and structural design knowledge also in terms on International and National codes that implemented the concept of durability and service life of structures. In this paper preliminary FEM analyses were performed in order to simulate pitting corrosion or general corrosion aimed to demonstrate the possibility to extend the results obtained for a cylindrical specimen, reinforced by a single bar, to more complex RC members in terms of geometry and reinforcement. Furthermore, a mechanical analytical model to evaluate the stresses in the concrete surrounding the reinforcement bars is proposed. In addition, a sophisticated model is presented to evaluate the non-linear development of stresses inside concrete and crack propagation when reinforcement bars start to corrode. The relationships between the cracking development (mechanical) and the reduction of the steel section (electrochemical) are provided. Finally, numerical findings reported in this paper were compared to experimental results available in the literature and satisfactory agreement was found.

  11. Behavior Of A Confined Tension Lap Splice In High-Strength Reinforced Concrete Beams

    NASA Astrophysics Data System (ADS)

    Abdel-Kareem, Ahmed H.; Abousafa, Hala; El-Hadidi, Omaia S.

    2015-09-01

    The results of an experimental program conducted on seventeen simply supported concrete beams to study the effect of transverse reinforcement on the behavior of the lap splice of a steel reinforcement in tension zones in high-strength concrete beams are presented. The parameters included in the experimental program were the concrete compressive strength, the lap splice length, the amount of transverse reinforcement provided within the splice region, and the shape of the transverse reinforcement around the spliced bars. The experimental results showed that the displacement ductility increased and the mode of failure changed from a splitting bond failure to a flexural failure when the amount of the transverse reinforcement in the splice region increased, and the compressive strength increased up to 100 MPa. The presence of the transverse reinforcement around the spliced bars had a pronounced effect on increasing the ultimate load, the ultimate deflection, and the displacement ductility. The prediction of maximum steel stresses for spliced bars using the ACI 318-05 building code was compared with the experimental results. The comparison showed that the effect of the transverse reinforcement around spliced bars has to be considered into the design equations for lap splice length in high-strength concrete beams.

  12. Survey of Experience Using Reinforced Concrete in Floating Marine Structures.

    DTIC Science & Technology

    1983-01-01

    Operations in the Concrete Ship Program," Journal of the American Concrete Institute, Vol. 16, No. 3, Jan . 1945. 3.3 Campbell, R. A., Chang, K. T., and...CONDEEP," Brochure from Norwegian Contractors. 3.11 Norge, Elf, "Frigg Field Treatment and Compression TCP2 Platform," Jan . 1976. 3.12 Graff, William J...34 Journal of Prestressed Concrete Institute, Vol. 22, No. 1, Jan .-Feb. 1977. 3.28 Anderson, A. R., "A 65,000 Ton Prestressed Concrete Floating Facility

  13. Bayesian decision and mixture models for AE monitoring of steel-concrete composite shear walls

    NASA Astrophysics Data System (ADS)

    Farhidzadeh, Alireza; Epackachi, Siamak; Salamone, Salvatore; Whittaker, Andrew S.

    2015-11-01

    This paper presents an approach based on an acoustic emission technique for the health monitoring of steel-concrete (SC) composite shear walls. SC composite walls consist of plain (unreinforced) concrete sandwiched between steel faceplates. Although the use of SC system construction has been studied extensively for nearly 20 years, little-to-no attention has been devoted to the development of structural health monitoring techniques for the inspection of damage of the concrete behind the steel plates. In this work an unsupervised pattern recognition algorithm based on probability theory is proposed to assess the soundness of the concrete infill, and eventually provide a diagnosis of the SC wall’s health. The approach is validated through an experimental study on a large-scale SC shear wall subjected to a displacement controlled reversed cyclic loading.

  14. Modeling and Measurement of Sustained Loading and Temperature-Dependent Deformation of Carbon Fiber-Reinforced Polymer Bonded to Concrete

    PubMed Central

    Jeong, Yoseok; Lee, Jaeha; Kim, WooSeok

    2015-01-01

    This paper aims at presenting the effects of short-term sustained load and temperature on time-dependent deformation of carbon fiber-reinforced polymer (CFRP) bonded to concrete and pull-off strength at room temperature after the sustained loading period. The approach involves experimental and numerical analysis. Single-lap shear specimens were used to evaluate temperature and short-term sustained loading effects on time-dependent behavior under sustained loading and debonding behavior under pull-off loading after a sustained loading period. The numerical model was parameterized with experiments on the concrete, FRP, and epoxy. Good correlation was seen between the numerical results and single-lap shear experiments. Sensitivity studies shed light on the influence of temperature, epoxy modulus, and epoxy thickness on the redistribution of interfacial shear stress during sustained loading. This investigation confirms the hypothesis that interfacial stress redistribution can occur due to sustained load and elevated temperature and its effect can be significant. PMID:28787948

  15. Behaviour and Analysis of Steel and Macro-Synthetic Fibre Reinforced Concrete Subjected to Reversed Cyclic Loading: A Pilot Investigation

    NASA Astrophysics Data System (ADS)

    Carnovale, David Joseph

    The benefits of fibre reinforced concrete (FRC) have been thoroughly investigated. Much of this work has focussed on steel FRC subjected to monotonic loads. Data on the structural behaviour of macro-synthetic FRC or FRC under cyclic loads is scarce. A pilot investigation on the shear behaviour of macro-synthetic FRC and on the behaviour of FRC under reversed cyclic in-plane shear loading was carried out. Five in-plane shear panel tests were performed. The parameters under study were the fibre material type (steel or macrosynthetic) and loading protocol. Additionally, a number of compression, direct tension, and flexural tests were performed to determine the material properties of the concretes for comparison. The material response of 2.0% by volume of macro-synthetic FRC matched closely with 1.0% steel FRC. Finally, building upon an existing steel FRC model, a model for macro-synthetic FRC in tension was proposed and a short verification study was undertaken.

  16. Nondestructive inspection of corrosion and delamination at the concrete-steel reinforcement interface

    NASA Astrophysics Data System (ADS)

    Miller, Tri Huu

    The proposed study explores the feasibility of detecting and quantifying corrosion and delamination (physical separation) at the interface between reinforcing steel bars and concrete using ultrasonic guided waves. The problem of corrosion of the reinforcing steel in structures has increased significantly in recent years. The emergence of this type of concrete deterioration, which was first observed in marine structures and chemical manufacturing plants, coincided with the increased applications of deicing salts (sodium and calcium chlorides) to roads and bridges during winter months in those states where ice and snow are of major concern. Concrete is strengthened by the inclusion of the reinforcement steel such as deformed or corrugated steel bars. Bonding between the two materials plays a vital role in maximizing performance capacity of the structural members. Durability of the structure is of concern when it is exposed to aggressive environments. Corrosion of reinforcing steel has led to premature deterioration of many concrete members before their design life is attained. It is therefore, important to be able to detect and measure the level of corrosion in reinforcing steel or delamination at the interface. The development and implementation of damage detection strategies, and the continuous health assessment of concrete structures then become a matter of utmost importance. The ultimate goal of this research is to develop a nondestructive testing technique to quantify the amount of corrosion in the reinforcing steel. The guided mechanical wave approach has been explored towards the development of such methodology. The use of an embedded ultrasonic network for monitoring corrosion in real structures is feasible due to its simplicity. The ultrasonic waves, specifically cylindrical guided waves can p ropagate a long distance along the reinforcing steel bars and are found to be sensitive to the interface conditions between steel bars and concrete. Ultrasonic

  17. Numerical Modelling of Reinforced Concrete Slabs under Blast Loads of Close-in Detonations Using the Lagrangian Approach

    NASA Astrophysics Data System (ADS)

    Shuaib, M.; Daoud, O.

    2015-07-01

    This paper includes an investigation for the deformations, including deflections and damage modes, which occur in reinforced concrete (RC) slabs when subjected to blast loads of explosions. The slab considered for the investigation is a one-way square RC slab with the dimensions of 1000 x 1000 x 40 mm, fixed supported at two opposite sides. It was subjected to close-in detonations of three different charge weights for a constant standoff distance. For the study, the slab was analysed using the numerical method by means of nonlinear finite element analysis. The slab was modelled as 3-D structural continuum using LS-DYNA software. For concrete modelling, two constitutive models were selected, namely the KCC and Winfrith concrete models. Blast loads were applied to the slab through the Lagrangian approach, and the blast command available in the software, namely LOAD_BLAST_ENHANCED, was selected for the application. The deflections and damage modes results obtained were compared to those from a previously published experiment. From the study, both the KCC and Winfrith concrete models effectively and satisfactorily estimated the actual slab maximum deflection. For damage modes, the KCC model appeared to be capable to capture satisfactorily the general damage mode including flexural cracks. However, the model could not capture the local shear mode at the middle of slab (spallation) because the Lagrangian approach does not simulate the interaction between the ambient air and the solid slab.

  18. Development of structural health monitoring and early warning system for reinforced concrete system

    SciTech Connect

    Iranata, Data E-mail: data@ce.its.ac.id; Wahyuni, Endah; Murtiadi, Suryawan; Widodo, Amien; Riksakomara, Edwin; Sani, Nisfu Asrul

    2015-04-24

    Many buildings have been damaged due to earthquakes that occurred recently in Indonesia. The main cause of the damage is the large deformation of the building structural component cannot accommodate properly. Therefore, it is necessary to develop the Structural Health Monitoring System (SHMS) to measure precisely the deformation of the building structural component in the real time conditions. This paper presents the development of SHMS for reinforced concrete structural system. This monitoring system is based on deformation component such as strain of reinforcement bar, concrete strain, and displacement of reinforced concrete component. Since the deformation component has exceeded the limit value, the warning message can be sent to the building occupies. This warning message has also can be performed as early warning system of the reinforced concrete structural system. The warning message can also be sent via Short Message Service (SMS) through the Global System for Mobile Communications (GSM) network. Hence, the SHMS should be integrated with internet modem to connect with GSM network. Additionally, the SHMS program is verified with experimental study of simply supported reinforced concrete beam. Verification results show that the SHMS has good agreement with experimental results.

  19. Development of structural health monitoring and early warning system for reinforced concrete system

    NASA Astrophysics Data System (ADS)

    Iranata, Data; Wahyuni, Endah; Murtiadi, Suryawan; Widodo, Amien; Riksakomara, Edwin; Sani, Nisfu Asrul

    2015-04-01

    Many buildings have been damaged due to earthquakes that occurred recently in Indonesia. The main cause of the damage is the large deformation of the building structural component cannot accommodate properly. Therefore, it is necessary to develop the Structural Health Monitoring System (SHMS) to measure precisely the deformation of the building structural component in the real time conditions. This paper presents the development of SHMS for reinforced concrete structural system. This monitoring system is based on deformation component such as strain of reinforcement bar, concrete strain, and displacement of reinforced concrete component. Since the deformation component has exceeded the limit value, the warning message can be sent to the building occupies. This warning message has also can be performed as early warning system of the reinforced concrete structural system. The warning message can also be sent via Short Message Service (SMS) through the Global System for Mobile Communications (GSM) network. Hence, the SHMS should be integrated with internet modem to connect with GSM network. Additionally, the SHMS program is verified with experimental study of simply supported reinforced concrete beam. Verification results show that the SHMS has good agreement with experimental results.

  20. Layer model for long-term deflection analysis of cracked reinforced concrete bending members

    NASA Astrophysics Data System (ADS)

    Bacinskas, Darius; Kaklauskas, Gintaris; Gribniak, Viktor; Sung, Wen-Pei; Shih, Ming-Hsiang

    2012-05-01

    A numerical technique has been proposed for the long-term deformation analysis of reinforced concrete members subjected to a bending moment. The technique based on the layer approach in a simple and rational way deals with such complex issues as concrete cracking and tension-stiffening as well as creep and shrinkage. The approach uses the material stress-strain relationships for compressive concrete, cracked tensile concrete and steel. Such effects as linear and nonlinear creep, cracking, tension-stiffening as well as the reduction in concrete tension strength due to sustained loading have been taken into account. The shrinkage effect has been modeled by means of adequate actions of axial force and bending moment. A statistical deflection calculation analysis has been carried out for 322 experimental reinforced concrete beams reported in the literature. The comparative analysis of the experimental and the modeling results has shown that the proposed technique has well captured the time-deflection behavior of reinforced concrete flexural members. The results of the predictions by ACI 318 and Eurocode 2 design codes have been also discussed.

  1. Incremental dynamic analysis of concrete moment resisting frames reinforced with shape memory composite bars

    NASA Astrophysics Data System (ADS)

    Zafar, Adeel; Andrawes, Bassem

    2012-02-01

    Fiber reinforced polymer (FRP) reinforcing bars have been used in concrete structures as an alternative to conventional steel reinforcement, in order to overcome corrosion problems. However, due to the linear behavior of the commonly used reinforcing fibers, they are not considered in structures which require ductility and damping characteristics. The use of superelastic shape memory alloy (SMA) fibers with their nonlinear elastic behavior as reinforcement in the composite could potentially provide a solution for this problem. Small diameter SMA wires are coupled with polymer matrix to produce SMA-FRP composite, which is sought in this research as reinforcing bars. SMA-FRP bars are sought in this study to enhance the seismic performance of reinforced concrete (RC) moment resisting frames (MRFs) in terms of reducing their residual inter-story drifts while still maintaining the elastic characteristics associated with conventional FRP. Three story one bay and six story two bay RC MRF prototype structures are designed with steel, SMA-FRP and glass-FRP reinforcement. The incremental dynamic analysis technique is used to investigate the behaviors of the two frames with the three different reinforcement types under a suite of ground motion records. It is found that the frames with SMA-FRP composite reinforcement exhibit higher performance levels including lower residual inter-story drifts, high energy dissipation and thus lower damage, which are important for structures in highly seismic zones.

  2. Mitigation of chloride and sulfate based corrosion in reinforced concrete via electrokinetic nanoparticle treatment

    NASA Astrophysics Data System (ADS)

    Kupwade-Patil, Kunal

    Concrete is a porous material which is susceptible to the migration of highly deleterious species such as chlorides and sulfates. Various external sources, including sea salt spray, direct seawater wetting, deicing salts and chlorides can contaminate reinforced concrete. Chlorides diffuse into the capillary pores of concrete and come into contact with the reinforcement. When chloride concentration at the reinforcement exceeds a threshold level it breaks down the passive oxide layer, leading to chloride induced corrosion. The application of electrokinetics using positively charged nanoparticles for corrosion protection in reinforced concrete structures is an emerging technology. This technique involves the principle of electrophoretic migration of nanoparticles to hinder chloride diffusion in the concrete. The return of chlorides is inhibited by the electrodeposited assembly of the nanoparticles at the reinforcement interface. This work examined the nanoparticle treatment impact on chloride and sulfate induced corrosion in concrete. Electrokinetic Nanoparticle (EN) treatments were conducted on reinforced cylindrical concrete, rectangular ASTM G109 specimens that simulate a bridge deck and full scale beam specimens. EN treatment to mitigate external sulfate attack in concrete was performed on cylindrical concrete specimens. Corrosion results indicated lower corrosion potentials and rates as compared to the untreated specimens. Scanning electron microscopy (SEM) showed a dense microstructure within the EN treated specimens. Chemical analysis (Raman spectroscopy, X ray-diffraction, and Fourier transform infrared spectroscopy FTIR) showed the presence of strength enhancing phases such as calcium aluminate hydrate (C-A-H) and increased amounts of calcium silicate hydrate (C-S-H) within the EN treated specimens. Strength and porosity results showed an increase in strength and a reduction in porosity among the EN treated specimens. EN treatment acted as a protective

  3. Improvement in performance of reinforced concrete structures using shape memory alloys

    NASA Astrophysics Data System (ADS)

    Bajoria, Kamal M.; Kaduskar, Shreya S.

    2015-04-01

    Shape memory alloys (SMA) are a unique class of materials which have ability to undergo large deformation and also regain its undeformed shape by removal of stress or by heating. This unique property could be effectively utilized to enhance the safety of a structure. This paper presents the pushover analysis performance of a Reinforced Concrete moment resistance frame with the traditional steel reinforcement replaced partially with Nickel-Titanium (Nitinol) SMA. The results are compared with the RC structure reinforced with conventional steel. Partial replacement of traditional steel reinforcement by SMA shows better performance.

  4. Seismic Performance Evaluation of Reinforced Concrete Frames Subjected to Seismic Loads

    NASA Astrophysics Data System (ADS)

    Zameeruddin, Mohd.; Sangle, Keshav K.

    2017-06-01

    Ten storied-3 bays reinforced concrete bare frame designed for gravity loads following the guidelines of IS 456 and IS 13920 for ductility is subjected to seismic loads. The seismic demands on this building were calculated by following IS 1893 for response spectra of 5% damping (for hard soil type). Plastic hinges were assigned to the beam and column at both ends to represent the failure mode, when member yields. Non-linear static (pushover) analysis was performed to evaluate the performance of the building in reference to first (ATC 40), second (FEMA 356) and next-generation (FEMA 440) performance based seismic design procedures. Base shear against top displacement curve of structure, known as pushover curve was obtained for two actions of plastic hinge behavior, force-controlled (brittle) and deformation-controlled (ductile) actions. Lateral deformation corresponding to performance point proves the building capability to sustain a certain level of seismic loads. The failure is represented by a sequence of formation of plastic hinges. Deformation-controlled action of hinges showed that building behaves like strong-column-weak-beam mechanism, whereas force-controlled action showed formation of hinges in the column. The study aims to understand the first, second and next generation performance based design procedure in prediction of actual building responses and their conservatism into the acceptance criteria.

  5. Axisymmetric analysis of a 1:6-scale reinforced concrete containment building using a distributed cracking model for the concrete

    SciTech Connect

    Weatherby, J.R.

    1987-09-01

    Results of axisymmetric structural analyses of a 1:6 scale model of a reinforced concrete nuclear containment building are presented. Both a finite element shell analysis and a simplified membrane analysis were made to predict the structural response and ultimate pressure capacity of the model. Analytical results indicate that the model will fail at an internal pressure of 187 psig when the stress level in the hoop reinforcement at the midsection of the cylinder exceeds the ultimate strength of the bar splices. 5 refs., 34 figs., 6 tabs.

  6. Bond slip model in cylindrical reinforced concrete elements confined with stirrups

    NASA Astrophysics Data System (ADS)

    Coccia, Simona; Di Maggio, Erica; Rinaldi, Zila

    2015-12-01

    An analytical model able to evaluate the bond-slip law of confined reinforced concrete elements is developed and presented in this paper. The model is based on the studies developed by Tepfers and by den Uijl and Bigaj on the thick-walled cylinder model and extended to the case of the presence of transverse reinforcement. The bond strength and the considered failure modes (splitting or pull-out failure) are expressed as a function of the geometrical (concrete cover and transverse reinforcement) and mechanical (concrete strength) parameters of the element. The application of the proposed methodology allows to forecast the failure mode, and equations for the bond-slip law are finally proposed for a range of steel strain lower than the yielding one.

  7. Reinforcement of asphalt concrete pavement by segments of exhausted fiber used for sorption of oil spill

    NASA Astrophysics Data System (ADS)

    Lukashevich, V. N.; Efanov, I. N.

    2015-01-01

    The paper is aimed at construction of the experimental road pavement made of dispersed reinforced asphalt concrete. Electronic paramagnetic resonance, infrared spectroscopy and fluorescent bitumen studies were used to prove that disperse reinforcement of asphalt concrete mixtures with fibers of exhausted sorbents reduce the selective filtration of low polymeric fractions of petroleum bitumen and improve its properties in the adsorption layer. Sesquioxides are neutralized as catalysts aging asphalt binder. This leads to improvement in the elasticity of bitumen films at low temperatures and provide better crack resistance of coatings to reduce the intensity of the aging of asphalt binder, and, therefore, to increase the durability of road pavements. The experimental road pavement made of dispersed reinforced asphalt concrete operated during 4 years and demonstrated better transport- performance properties in comparison with the analogue pavements.

  8. An expert system for the evaluation of reinforced concrete structure durability

    SciTech Connect

    Berra, M.; Bertolini, L.; Briglia, M.C.; Lazzari, L.; Pastore, T.

    1999-11-01

    A user-friendly expert system has been developed to evaluate primarily the durability of reinforced concrete structures, either in the design phase or during service life related to reinforcement corrosion. Besides the durability module, the ES has been provided with three other expert modules in order to support the user during the following activities: inspections, corrosion diagnosis and repair strategy (of concrete and reinforcement). Corrosion induced by carbonation and chlorides penetration and caused by concrete degradation such as sulfate attack, freeze/thaw cycles, alkali silica reaction are considered. The knowledge used for the expert system is based both on open literature and international standards as well as on specific experiences and proprietary databases. The paper describes main features of the system, including the modeling of the knowledge, input data, the algorithms, the rules and the outputs for each module.

  9. Behavior of Concrete Beams with Peel-Plied Aramid-Fiber-Reinforced Polymer Plates

    NASA Astrophysics Data System (ADS)

    Hong, Sungnam; Park, Sun-Kyu

    2016-03-01

    The effect of fiber-reinforced polymer (FRP) plates, to which a peel-ply was fastened to increase their bonding area, on the behavior of strengthened concrete beams was investigated. A total of six concrete beams were tested. For the FRP plates, aramid-fiber-reinforced polymer (AFRP) ones were used. The test variables included their surface treatment (smooth and deformed), the depth of removal of concrete cover (0 and 10 mm), and the number of the plates. Each beam was tested in four-point bending under displacement control up to failure. Based on the experimental results obtained, the effect of the peel-plied AFRP plates on the flexural behavior of the concrete beams was evaluated.

  10. Chloride permeability and impact resistance of polypropylene-fiber-reinforced silica fume concrete

    SciTech Connect

    Toutanji, H.; McNeil, S.; Bayasi, Z.

    1998-07-01

    Permeability and impact resistance of polypropylene-fiber-reinforced concrete mixtures containing silica fume with variable design proportions were studied. Two fiber lengths were considered, 12.5 and 19 mm, and four fiber volume fractions, 0, 0.1%, 0.3%, and 0.5%. Silica fume was used as a replacement by weight of cement. Two silica fume contents were used, 5% and 10%. Results showed that the incorporation of polypropylene fibers increased the permeability of conventional concrete. The addition of silica fume improved fiber dispersion in the cementitious matrix, causing a significant reduction in the permeability of the polypropylene fiber reinforced concrete. Moreover, the addition of silica fume was noted to significantly enhance the polypropylene fiber effectiveness in improving the impact resistance of concrete.

  11. Nonlinear finite element analysis of PVA fiber reinforced high strength concrete columns under low cyclic loading

    NASA Astrophysics Data System (ADS)

    Su, Jun; Hu, Qiang; Liu, Jianping

    2017-04-01

    In this paper, four PVA fiber reinforced super-high-strength concrete columns under the low cyclic reciprocating load were studied by using the finite element analysis software OpenSEES and their hysteretic curves and skeleton curves were studied. The energy dissipation capacity of PVA fiber were analyzed to evaluate the effect of PVA fiber on the seismic performance of concrete columns. The results show that the restoring force curve of the finite element analysis software OpenSEES simulation agrees well with the experimental curve, which can fully reflect the hysteretic behavior of fiber reinforced concrete columns under low cyclic loading. The incorporation of PVA fiber can obviously improve the energy dissipation capacity of ordinary concrete columns.

  12. Evolution of the health of concrete structures by electrically conductive GFRP (glass fiber reinforced plastic) composites

    NASA Astrophysics Data System (ADS)

    Shin, Soon-Gi

    2002-02-01

    The function and performance of self-diagnostic composites embedded in concrete blocks and piles were investigated by bending tests and electrical resistance measurement. Carbon powder (CP) and carbon fiber (CF) were introduced into glass fiber reinforced plastic (GFRP) composites to provide electrical conductivity. The CPGFRP composite displays generally good performance in various bending tests of concrete block and piles compared to the CFGFRP composite. The electrical resistance of the CPGFRP composite increases remarkably at small strains in response to microcrack formation at about 200 μm strain, and can be used to detect smaller deformations before crack formation. The CPGFRP composite shows continuous change in resistance up to a large strain level just before the final fracture for concrete structures reinforced by steel bars. It is concluded that self-diagnostic composites can be used to predict damage and fracture in concrete blocks and piles.

  13. Evaluation of Sustainability of Multistory Reinforced Concrete Structure

    NASA Astrophysics Data System (ADS)

    Al-Tamimi, A. K.; Ibrahim, A.; Al-Sughaiyer, N.

    Three different types of concrete mixes of design strengths 100 MPa, 50 MPa, and 50 MPa lightweight were designed, produced, and analyzed in the effort to quantify their effects on sustainability and economics. An overall comparison taking into consideration the structural, environmental, and economical effectiveness was conducted to find the most beneficial and reliable material to be used in sustainable structures. Different concrete types were used in the design of typical multi story buildings of the same loadings and dimensions. The only input variables in this research are the different mixes of concrete. By fixing the applied loadings and the buildings' dimensions, the three different materials were studied in terms of their effects on the structural design of members, carbon footprint and sustainability, and economics. High strength concrete using microsilica was concluded to be the most effective material to be used in construction with the best effects on sustainability and economics.

  14. Determination of concrete cover thickness in a reinforced concrete pillar by observation of the scattered electromagnetic field

    NASA Astrophysics Data System (ADS)

    Di Gregorio, Pietro Paolo; Frezza, Fabrizio; Mangini, Fabio; Pajewski, Lara

    2017-04-01

    The electromagnetic scattered field by a reinforced concrete structure is calculated by means of frequency-domain numerical simulations and by making use of the scattered-field formulation. The concrete pillar, used as supporting architectural element, is modelled as a parallelepiped shell made of concrete material inside which are present steel bars. In order to make the model simpler, the steel bars are supposed running parallel to the air-pillar interface. To excite the model, a linearly-polarized plane wave impinging normally with respect to the pillars surface, is adopted. We consider two different polarizations in order to determine the most useful in terms of scattered-field sensitivity. Moreover, a preliminary frequency sweep allows us to choose the most suitable operating frequency depending on the dimensions of the pillar cross-section, the steel bars cross-section and the concrete cover. All the three components of the scattered field are monitored along a line just above the interface air-pillar. The electromagnetic properties of the materials employed in this study are present in the literature and, since a frequency-domain technique is adopted, no further approximation is needed. The results obtained for different values of the concrete cover are compared, with the goal of determining the scattered field dependence on the concrete cover thickness. Considering different concrete cover thicknesses, we want to provide an electromagnetic method to obtain this useful parameter by observation of the scattered electromagnetic field. One of the practical applications of this study in the field of Civil Engineering may be the use of ground penetrating radar (GPR) techniques to monitor the thickness of the concrete that separates the metal bars embedded in the pillar from the outer surface. A correct distance is useful because the concrete cover serves as a protection against external agents avoiding corrosion of the bars that might prejudice the reinforced

  15. Nonlinear micromechanics-based finite element analysis of the interfacial behaviour of FRP-strengthened reinforced concrete beams

    NASA Astrophysics Data System (ADS)

    Abd El Baky, Hussien

    --slip relation is developed considering the interaction between the interfacial normal and shear stress components along the bonded length. A new approach is proposed to describe the entire tau-s relationship based on three separate models. The first model captures the shear response of an orthotropic FRP laminate. The second model simulates the shear characteristics of an adhesive layer, while the third model represents the shear nonlinearity of a thin layer inside the concrete, referred to as the interfacial layer. The proposed bond--slip model reflects the geometrical and material characteristics of the FRP, concrete, and adhesive layers. Two-dimensional and three-dimensional nonlinear displacement-controlled finite element (FE) models are then developed to investigate the flexural and FRP/concrete interfacial responses of FRP-strengthened reinforced concrete beams. The three-dimensional finite element model is created to accommodate cases of beams having FRP anchorage systems. Discrete interface elements are proposed and used to simulate the FRP/concrete interfacial behaviour before and after cracking. The FE models are capable of simulating the various failure modes, including debonding of the FRP either at the plate end or at intermediate cracks. Particular attention is focused on the effect of crack initiation and propagation on the interfacial behaviour. This study leads to an accurate and refined interpretation of the plate-end and intermediate crack debonding failure mechanisms for FRP-strengthened beams with and without FRP anchorage systems. Finally, the FE models are used to conduct a parametric study to generalize the findings of the FE analysis. The variables under investigation include two material characteristics; namely, the concrete compressive strength and axial stiffness of the FRP laminates as well as three geometric properties; namely, the steel reinforcement ratio, the beam span length and the beam depth. The parametric study is followed by a statistical

  16. Crack identification for reinforced concrete using PZT based smart rebar active sensing diagnostic network

    NASA Astrophysics Data System (ADS)

    Song, N. N.; Wu, F.

    2016-04-01

    An active sensing diagnostic system using PZT based smart rebar for SHM of RC structure has been currently under investigation. Previous test results showed that the system could detect the de-bond of concrete from reinforcement, and the diagnostic signals were increased exponentially with the de-bonding size. Previous study also showed that the smart rebar could function well like regular reinforcement to undertake tension stresses. In this study, a smart rebar network has been used to detect the crack damage of concrete based on guided waves. Experimental test has been carried out for the study. In the test, concrete beams with 2 reinforcements have been built. 8 sets of PZT elements were mounted onto the reinforcement bars in an optimized way to form an active sensing diagnostic system. A 90 kHz 5-cycle Hanning-windowed tone burst was used as input. Multiple cracks have been generated on the concrete structures. Through the guided bulk waves propagating in the structures from actuators and sensors mounted from different bars, crack damage could be detected clearly. Cases for both single and multiple cracks were tested. Different crack depths from the surface and different crack numbers have been studied. Test result shows that the amplitude of sensor output signals is deceased linearly with a propagating crack, and is decreased exponentially with increased crack numbers. From the study, the active sensing diagnostic system using PZT based smart rebar network shows a promising way to provide concrete crack damage information through the "talk" among sensors.

  17. Influence of cyclic freeze-thaw on the parameters of the electric response to the pulse mechanical excitation of concrete reinforced by glass fibre reinforced polymer bars

    NASA Astrophysics Data System (ADS)

    Fursa, T. V.; Petrov, M. V.; Korzenok, I. N.

    2016-02-01

    Studies of the influence of cyclic freeze-thaw on the parameters of electric response from samples of concrete reinforced by glass fibre reinforced polymer (GFRP) bars were conducted. It is found that an increase in the number of freeze-thaw cycles increases the attenuation coefficient of energy of electric responses and moves the centre of gravity of spectrum to the low-frequency area. The results can be used to develop a method of nondestructive testing of reinforced concrete.

  18. Selected Bibliography on Fiber-Reinforced Cement and Concrete. Supplement Number 4.

    DTIC Science & Technology

    1982-08-01

    Building Industry," L’Industria Italiana del Cemento , Vol 50, No. 12, Dec 1980, pp 1135-1144. 19. Bartos, P., "Pullout Failure of Fibres Embedded in Cement...Vol 43, No. 11, Nov 1977, pp 561-564. 21. Bassan, M., "Model of Behavior of Fiber-Reinforced Concretes Under Impact Stresses," il Cemento , Vol 74, No...Pastes," il Cemento , Vol 75, No. 3, Jul-Sep 1978, pp 277-284. 210. Mills, R. H., "Age-Embrittlement of Glass-Reinforced Concrete Containing Blastfurance

  19. Performance Evaluation for Enhancement of Some of the Engineering Properties of Bamboo as Reinforcement in Concrete

    NASA Astrophysics Data System (ADS)

    Kute, S. Y.; Wakchaure, M. R.

    2013-11-01

    Bamboo is one of the alternative materials with strong potential for reinforcing the cement matrices. Unlike steel, during casting and curing of concrete, reinforced bamboo absorbs water and expands, which results in radial cracking of surrounding concrete. When curing is stopped, bamboo starts shrinking slowly loosing the contact with concrete. The dimensional changes of bamboo resulting from moisture and temperature variations, causes de-bonding which affects the bond strength severely. This paper presents the results of experimental investigations made to evaluate potential of bamboo to be used as concrete reinforcement. Specimens with and without node were extracted from well seasoned Dendrocalamus strictus variety of bamboo. They were tested for water absorption, dimensional changes, tensile and bond strength in M20 concrete with twenty different treatments. The paper also presents the comparison of bond strength of mild steel, TMT steel and untreated bamboo with that of bamboo having different low cost treatments for reducing the water absorption thereby enhancing bond strength of bamboo in concrete.

  20. Effectiveness of Fiber Reinforcement on the Mechanical Properties and Shrinkage Cracking of Recycled Fine Aggregate Concrete

    PubMed Central

    Nam, Jeongsoo; Kim, Gyuyong; Yoo, Jaechul; Choe, Gyeongcheol; Kim, Hongseop; Choi, Hyeonggil; Kim, Youngduck

    2016-01-01

    This paper presents an experimental study conducted to investigate the effect of fiber reinforcement on the mechanical properties and shrinkage cracking of recycled fine aggregate concrete (RFAC) with two types of fiber—polyvinyl alcohol (PVA) and nylon. A small fiber volume fraction, such as 0.05% or 0.1%, in RFAC with polyvinyl alcohol or nylon fibers was used for optimum efficiency in minimum quantity. Additionally, to make a comparative evaluation of the mechanical properties and shrinkage cracking, we examined natural fine aggregate concrete as well. The test results revealed that the addition of fibers and fine aggregates plays an important role in improving the mechanical performance of the investigated concrete specimens as well as controlling their cracking behavior. The mechanical properties such as compressive strength, splitting tensile strength, and flexural strength of fiber-reinforced RFAC were slightly better than those of non-fiber-reinforced RFAC. The shrinkage cracking behavior was examined using plat-ring-type and slab-type tests. The fiber-reinforced RFAC showed a greater reduction in the surface cracks than non-fiber-reinforced concrete. The addition of fibers at a small volume fraction in RFAC is more effective for drying shrinkage cracks than for improving mechanical performance. PMID:28773256

  1. Effectiveness of Fiber Reinforcement on the Mechanical Properties and Shrinkage Cracking of Recycled Fine Aggregate Concrete.

    PubMed

    Nam, Jeongsoo; Kim, Gyuyong; Yoo, Jaechul; Choe, Gyeongcheol; Kim, Hongseop; Choi, Hyeonggil; Kim, Youngduck

    2016-02-26

    This paper presents an experimental study conducted to investigate the effect of fiber reinforcement on the mechanical properties and shrinkage cracking of recycled fine aggregate concrete (RFAC) with two types of fiber-polyvinyl alcohol (PVA) and nylon. A small fiber volume fraction, such as 0.05% or 0.1%, in RFAC with polyvinyl alcohol or nylon fibers was used for optimum efficiency in minimum quantity. Additionally, to make a comparative evaluation of the mechanical properties and shrinkage cracking, we examined natural fine aggregate concrete as well. The test results revealed that the addition of fibers and fine aggregates plays an important role in improving the mechanical performance of the investigated concrete specimens as well as controlling their cracking behavior. The mechanical properties such as compressive strength, splitting tensile strength, and flexural strength of fiber-reinforced RFAC were slightly better than those of non-fiber-reinforced RFAC. The shrinkage cracking behavior was examined using plat-ring-type and slab-type tests. The fiber-reinforced RFAC showed a greater reduction in the surface cracks than non-fiber-reinforced concrete. The addition of fibers at a small volume fraction in RFAC is more effective for drying shrinkage cracks than for improving mechanical performance.

  2. Effects of Particle Size on the Shear Behavior of Coarse Grained Soils Reinforced with Geogrid.

    PubMed

    Kim, Daehyeon; Ha, Sungwoo

    2014-02-07

    In order to design civil structures that are supported by soils, the shear strength parameters of soils are required. Due to the large particle size of coarse-grained soils, large direct shear tests should be performed. In this study, large direct shear tests on three types of coarse grained soils (4.5 mm, 7.9 mm, and 15.9 mm) were performed to evaluate the effects of particle size on the shear behavior of coarse grained soils with/without geogrid reinforcements. Based on the direct shear test results, it was found that, in the case of no-reinforcement, the larger the maximum particle size became, the larger the friction angle was. Compared with the no-reinforcement case, the cases reinforced with either soft geogrid or stiff geogrid have smaller friction angles. The cohesion of the soil reinforced with stiff geogrid was larger than that of the soil reinforced with soft geogrid. The difference in the shear strength occurs because the case with a stiff geogrid has more soil to geogrid contact area, leading to the reduction in interlocking between soil particles.

  3. Comparison of rates of general corrosion and maximum pitting penetration on concrete embedded steel reinforcement

    SciTech Connect

    Gonzalez, J.A.; Feliu, S. ); Andrade, C.; Alonso, C. )

    1995-02-01

    Local attack of reinforcement is observed usually in chloride-contaminated concrete. When mechanical weakening of the concrete structure is affected by the bar section loss in the places where corrosion is intensified, the maximum penetration of the deepest pits happens to be a very relevant datum. In this work average corrosion values are compared with maximum pit depth values. Using natural corrosion tests and accelerated tests, it has been found that the maximum penetration of localized attack on steel embedded in concrete containing chlorides is equivalent to about four to eight times the average general penetration.

  4. Wrinkling of reinforced plates subjected to shear stresses

    NASA Technical Reports Server (NTRS)

    Seydel, Edgar

    1931-01-01

    An analysis is made here of the problem of long plates with transverse stiffeners subject to shear. A typical example would be a long Wagner beam. The shear stress is calculated at which the web wrinkles and shear stress becomes a maximum. The equation is solved for both a condition of free support and rigidity of support on the edges.

  5. Flexural Behaviour Of Reinforced Concrete Beams Containing Expanded Glass As Lightweight Aggregates

    NASA Astrophysics Data System (ADS)

    Khatib, Jamal; Jefimiuk, Adrian; Khatib, Sammy

    2015-12-01

    The flexural properties of reinforced concrete beams containing expanded glass as a partial fine aggregate (sand) replacement are investigated. Four concrete mixes were employed to conduct this study. The fine aggregate was replaced with 0%, 25%, 50% and 100% (by volume) expanded glass. The results suggest that the incorporation of 50% expanded glass increased the workability of the concrete. The compressive strength was decreasing linearly with the increasing amount of expanded glass. The ductility of the concrete beam significantly improved with the incorporation of the expanded glass. However, the load-carrying capacity of the beam and load at which the first crack occurs was reduced. It was concluded that the inclusion of expanded glass in structural concrete applications is feasible.

  6. Stress-based topology optimization of concrete structures with prestressing reinforcements

    NASA Astrophysics Data System (ADS)

    Luo, Yangjun; Wang, Michael Yu; Deng, Zichen

    2013-11-01

    Following the extended two-material density penalization scheme, a stress-based topology optimization method for the layout design of prestressed concrete structures is proposed. The Drucker-Prager yield criterion is used to predict the asymmetrical strength failure of concrete. The prestress is considered by making a reasonable assumption on the prestressing orientation in each element and adding an additional load vector to the structural equilibrium function. The proposed optimization model is thus formulated as to minimize the reinforcement material volume under Drucker-Prager yield constraints on elemental concrete local stresses. In order to give a reasonable definition of concrete local stress and prevent the stress singularity phenomenon, the local stress interpolation function and the ɛ -relaxation technique are adopted. The topology optimization problem is solved using the method of moving asymptotes combined with an active set strategy. Numerical examples are given to show the efficiency of the proposed optimization method in the layout design of prestressed concrete structures.

  7. Damage evaluation of reinforced concrete frame based on a combined fiber beam model

    NASA Astrophysics Data System (ADS)

    Shang, Bing; Liu, ZhanLi; Zhuang, Zhuo

    2014-04-01

    In order to analyze and simulate the impact collapse or seismic response of the reinforced concrete (RC) structures, a combined fiber beam model is proposed by dividing the cross section of RC beam into concrete fiber and steel fiber. The stress-strain relationship of concrete fiber is based on a model proposed by concrete codes for concrete structures. The stress-strain behavior of steel fiber is based on a model suggested by others. These constitutive models are implemented into a general finite element program ABAQUS through the user defined subroutines to provide effective computational tools for the inelastic analysis of RC frame structures. The fiber model proposed in this paper is validated by comparing with experiment data of the RC column under cyclical lateral loading. The damage evolution of a three-dimension frame subjected to impact loading is also investigated.

  8. Flexural Behaviour Of Reinforced Concrete Beams Containing Expanded Glass As Lightweight Aggregates

    NASA Astrophysics Data System (ADS)

    Khatib, Jamal; Jefimiuk, Adrian; Khatib, Sammy

    2015-12-01

    The flexural properties of reinforced concrete beams containing expanded glass as a partial fine aggregate (sand) replacement are investigated. Four concrete mixes were employed to conduct this study. The fine aggregate was replaced with 0%, 25%, 50% and 100% (by volume) expanded glass. The results suggest that the incorporation of 50% expanded glass increased the workability of the concrete. The compressive strength was decreasing linearly with the increasing amount of expanded glass. The ductility of the concrete beam significantly improved with the incorporation of the expanded glass. However, the load-carrying capacity of the beam and load at which the first crack occurs was reduced. It was concluded that the inclusion of expanded glass in structural concrete applications is feasible.

  9. Corrosion Behavior of Steel Reinforcement in Concrete with Recycled Aggregates, Fly Ash and Spent Cracking Catalyst

    PubMed Central

    Gurdián, Hebé; García-Alcocel, Eva; Baeza-Brotons, Francisco; Garcés, Pedro; Zornoza, Emilio

    2014-01-01

    The main strategy to reduce the environmental impact of the concrete industry is to reuse the waste materials. This research has considered the combination of cement replacement by industrial by-products, and natural coarse aggregate substitution by recycled aggregate. The aim is to evaluate the behavior of concretes with a reduced impact on the environment by replacing a 50% of cement by industrial by-products (15% of spent fluid catalytic cracking catalyst and 35% of fly ash) and a 100% of natural coarse aggregate by recycled aggregate. The concretes prepared according to these considerations have been tested in terms of mechanical strengths and the protection offered against steel reinforcement corrosion under carbonation attack and chloride-contaminated environments. The proposed concrete combinations reduced the mechanical performance of concretes in terms of elastic modulus, compressive strength, and flexural strength. In addition, an increase in open porosity due to the presence of recycled aggregate was observed, which is coherent with the changes observed in mechanical tests. Regarding corrosion tests, no significant differences were observed in the case of the resistance of these types of concretes under a natural chloride attack. In the case of carbonation attack, although all concretes did not stand the highly aggressive conditions, those concretes with cement replacement behaved worse than Portland cement concretes. PMID:28788613

  10. On impedance measurement of reinforced concrete on the surface for estimate of corroded rebar

    NASA Astrophysics Data System (ADS)

    Sasamoto, Akira; Yu, Jun; Harada, Yoshihisa; Iwata, Masahiro; Noguchi, Kazuhiro

    2017-04-01

    In an estimate of health monitoring for reinforced concrete, corrosion degree of rebar is important parameter but is not easy to be estimated by non destructive testing. A few test method such as half cell method or polarization resistance method could be a 'perfect' nondestructive method if luckily having had wired connection to rebar without destructing target concrete. In this presentation it is reported the experimental result that an impedance measurement on surface of reinforced concretes is able to distinguish corroded rebar from healthy rebar. The contact electrode on concrete surface are simple structure made of urethane sponge and needle. Impedance measurement are carried out with frequency response analyzer with frequency range from 0.01Hz to 1MHz, typical amplitude of imposed voltage are 10 volt. We made concrete specimens under two different corrosion process. One process(pre corrosion) has rebars corroded by electrolysis in salty water before concrete casting and another process (post corrosion) has concrete specimens being corroded during the curing. The results of application of developed method to these corroded specimens show the method is useful to estimate corrosion level of rebars.

  11. Assessment of the Mechanical Properties of Sisal Fiber-Reinforced Silty Clay Using Triaxial Shear Tests

    PubMed Central

    Wu, Yankai; Li, Yanbin; Niu, Bin

    2014-01-01

    Fiber reinforcement is widely used in construction engineering to improve the mechanical properties of soil because it increases the soil's strength and improves the soil's mechanical properties. However, the mechanical properties of fiber-reinforced soils remain controversial. The present study investigated the mechanical properties of silty clay reinforced with discrete, randomly distributed sisal fibers using triaxial shear tests. The sisal fibers were cut to different lengths, randomly mixed with silty clay in varying percentages, and compacted to the maximum dry density at the optimum moisture content. The results indicate that with a fiber length of 10 mm and content of 1.0%, sisal fiber-reinforced silty clay is 20% stronger than nonreinforced silty clay. The fiber-reinforced silty clay exhibited crack fracture and surface shear fracture failure modes, implying that sisal fiber is a good earth reinforcement material with potential applications in civil engineering, dam foundation, roadbed engineering, and ground treatment. PMID:24982951

  12. Assessment of the mechanical properties of sisal fiber-reinforced silty clay using triaxial shear tests.

    PubMed

    Wu, Yankai; Li, Yanbin; Niu, Bin

    2014-01-01

    Fiber reinforcement is widely used in construction engineering to improve the mechanical properties of soil because it increases the soil's strength and improves the soil's mechanical properties. However, the mechanical properties of fiber-reinforced soils remain controversial. The present study investigated the mechanical properties of silty clay reinforced with discrete, randomly distributed sisal fibers using triaxial shear tests. The sisal fibers were cut to different lengths, randomly mixed with silty clay in varying percentages, and compacted to the maximum dry density at the optimum moisture content. The results indicate that with a fiber length of 10 mm and content of 1.0%, sisal fiber-reinforced silty clay is 20% stronger than nonreinforced silty clay. The fiber-reinforced silty clay exhibited crack fracture and surface shear fracture failure modes, implying that sisal fiber is a good earth reinforcement material with potential applications in civil engineering, dam foundation, roadbed engineering, and ground treatment.

  13. Behavior of Concrete Panels Reinforced with Synthetic Fibers, Mild Steel, and GFRP Composites Subjected to Blasts

    SciTech Connect

    C. P. Pantelides; T. T. Garfield; W. D. Richins; T. K. Larson; J. E. Blakeley

    2012-03-01

    The paper presents experimental data generated for calibrating finite element models to predict the performance of reinforced concrete panels with a wide range of construction details under blast loading. The specimens were 1.2 m square panels constructed using Normal Weight Concrete (NWC) or Fiber Reinforced Concrete (FRC). FRC consisted of macro-synthetic fibers dispersed in NWC. Five types of panels were tested: NWC panels with steel bars; FRC panels without additional reinforcement; FRC panels with steel bars; NWC panels with glass fiber reinforced polymer (GFRP) bars; and NWC panels reinforced with steel bars and external GFRP laminates on both faces. Each panel type was constructed with three thicknesses: 152 mm, 254 mm, and 356 mm. FRC panels with steel bars had the best performance for new construction. NWC panels reinforced with steel bars and external GFRP laminates on both faces had the best performance for strengthening or rehabilitation of existing structures. The performance of NWC panels with GFRP bars was strongly influenced by the bar spacing. The behavior of the panels is classified in terms of damage using immediate occupancy, life safety, and near collapse performance levels. Preliminary dynamic simulations are compared to the experimental results.

  14. Behavior of Concrete Panels Reinforced with Synthetic Fibers, Mild Steel, and GFRP Composites Subjected to Blasts

    SciTech Connect

    C. P. Pantelides; T. T. Garfield; W. D. Richins; T. K. Larson; J. E. Blakeley

    2012-03-01

    The paper presents experimental data generated for calibrating finite element models to predict the performance of reinforced concrete panels with a wide range of construction details under blast loading. The specimens were 1.2 m square panels constructed using Normal Weight Concrete (NWC) or Fiber Reinforced Concrete (FRC). FRC consisted of macro-synthetic fibers dispersed in NWC. Five types of panels were tested: NWC panels with steel bars; FRC panels without additional reinforcement; FRC panels with steel bars; NWC panels with glass fiber reinforced polymer (GFRP) bars; and NWC panels reinforced with steel bars and external GFRP laminates on both faces. Each panel type was constructed with three thicknesses: 152 mm, 254 mm, and 356 mm. FRC panels with steel bars had the best performance for new construction. NWC panels reinforced with steel bars and external GFRP laminates on both faces had the best performance for strengthening or rehabilitation of existing structures. The performance of NWC panels with GFRP bars was strongly influenced by the bar spacing. The behavior of the panels is classified in terms of damage using immediate occupancy, life safety, and near collapse performance levels. Preliminary dynamic simulations are compared to the experimental results.

  15. Fracture detection in concrete by glass fiber cloth reinforced plastics

    NASA Astrophysics Data System (ADS)

    Shin, Soon-Gi; Lee, Sung-Riong

    2006-04-01

    Two types of carbon (carbon fiber and carbon powder) and a glass cloth were used as conductive phases and a reinforcing fiber, respectively, in polymer rods. The carbon powder was used for fabricating electrically conductive carbon powder-glass fiber reinforced plastic (CP-GFRP) rods. The carbon fiber tows and the CP-GFRP rods were adhered to mortar specimens using epoxy resin and glass fiber cloth. On bending, the electrical resistance of the carbon fiber tow attached to the mortar specimen increased greatly after crack generation, and that of the CP-GFRP rod increased after the early stages of deflection in the mortar. Therefore, the CP-GFRP rod is superior to the carbon fiber tow in detecting fractures. Also, by reinforcing with a glass fiber cloth reinforced plastic, the strength of the mortar specimens became more than twice as strong as that of the unreinforced mortar.

  16. Upscaling Cement Paste Microstructure to Obtain the Fracture, Shear, and Elastic Concrete Mechanical LDPM Parameters.

    PubMed

    Sherzer, Gili; Gao, Peng; Schlangen, Erik; Ye, Guang; Gal, Erez

    2017-02-28

    Modeling the complex behavior of concrete for a specific mixture is a challenging task, as it requires bridging the cement scale and the concrete scale. We describe a multiscale analysis procedure for the modeling of concrete structures, in which material properties at the macro scale are evaluated based on lower scales. Concrete may be viewed over a range of scale sizes, from the atomic scale (10(-10) m), which is characterized by the behavior of crystalline particles of hydrated Portland cement, to the macroscopic scale (10 m). The proposed multiscale framework is based on several models, including chemical analysis at the cement paste scale, a mechanical lattice model at the cement and mortar scales, geometrical aggregate distribution models at the mortar scale, and the Lattice Discrete Particle Model (LDPM) at the concrete scale. The analysis procedure starts from a known chemical and mechanical set of parameters of the cement paste, which are then used to evaluate the mechanical properties of the LDPM concrete parameters for the fracture, shear, and elastic responses of the concrete. Although a macroscopic validation study of this procedure is presented, future research should include a comparison to additional experiments in each scale.

  17. Design synthesis of a boron/epoxy reinforced metal shear web.

    NASA Technical Reports Server (NTRS)

    Laakso, J. H.

    1972-01-01

    An advanced composite shear web design concept has been developed for the Space Shuttle Orbiter main engine thrust beam structure. Various web concepts were synthesized by a computer-aided adaptive random search procedure. A practical concept is identified having a titanium-clad, boron/epoxy plate with vertical boron/epoxy reinforced stiffeners. Baseline composite and titanium shear resistant designs are compared; the composite concept is 28% lighter than the titanium web. Element test results show the metal cladding effectively reinforces critical composite load transfer and fastener hole areas making the composite web concept practical for other shear structure applications.-

  18. Energy Dissipation Capacity of Reinforced Concrete Beams Strengthened with CFRP Strips

    NASA Astrophysics Data System (ADS)

    Hong, Sungnam; Park, Sun-Kyu

    2016-05-01

    Cyclic loading tests were performed to investigate the energy dissipation capacities of reinforced concrete (RC) beams strengthened with carbon-fiber-reinforced polymer (CFRP) strips. Four RC beams were manufactured and three-point loaded. Responses of the strengthened beams to the cyclic loadings were measured, including deflections at the center of their span and strains of the CFRP strips and reinforcing steel rebars. Based on test results, the energy dissipation capacity of the strengthened beams were evaluated in comparison with that of an unstrengthened control beam.

  19. Damage evaluation for concrete structures using fiber-reinforced composites as self-diagnosis materials

    NASA Astrophysics Data System (ADS)

    Yoshitake, Kenji; Shiba, Keiji; Suzuki, Makoto; Sugita, Minoru; Okuhara, Yoshiki

    2004-07-01

    Health monitoring techniques that utilize structural materials with the ability to diagnose their own condition, so-called self-diagnosis materials, have been under development. The authors have developed two types of electrically conductive fiber reinforced composite to diagnose cracks in concrete structures: a high sensitivity detection sensor and maximum strain memory sensor. Three points bending tests on pre-notched reinforced concrete beam under the cyclic loading is presented using these two self-diagnosis materials, with attention towards the relationship between crack width of the concrete beam and electric resistance. Moreover, effects of volume fraction of carbon particle on memorizing maximum strain are investigated. It has been proved that both self-diagnosis materials are highly effective to detect the cracks in the concrete. And present strain can be obtained by the proposed fiber reinforced plastic composites. Although volume fraction of carbon particle has significant influence on the characteristics of memorizing maximum strain, maximum strain of the concrete structures can be memorized using the appropriate self-diagnosis materials.

  20. Degradation and mechanism of the mechanics and durability of reinforced concrete slab in a marine environment

    NASA Astrophysics Data System (ADS)

    Wu, Sheng-xing; Liu, Guan-guo; Bian, Han-bing; Lv, Wei-bo; Jiang, Jian-hua

    2016-04-01

    An experimental research was conducted to determine the corrosion and bearing capacity of a reinforced concrete (RC) slab at different ages in a marine environment. Results show that the development of corrosion-induced cracks on a slab in a marine environment can be divided into three stages according to crack morphology at the bottom of the slab. In the first stage, cracks appear. In the second stage, cracks develop from the edges to the middle of the slab. In the third stage, longitudinal and transverse corrosion-induced cracks coexist. The corrosion ratio of reinforcements nonlinearly increases with the age, and the relationship between the corrosion ratio of the reinforcements and the corrosion-induced crack width of the concrete is established. The flexural capacity of the corroded RC slab nonlinearly decreases with the age, and the model for the bearing capacity factor of the corroded RC slab is established. The mid-span deflection of the corroded RC slab that corresponds to the yield of the reinforcements linearly increases with the increase in corrosion ratio. Finally, the mechanisms of corrosion morphology and the degradation of the mechanical properties of an RC slab in a marine environment are discussed on the basis of the basic theories of steel corrosion in concrete and concrete structure design.

  1. Unidirectional Core-Shell Hybrids for Concrete Reinforcement - A preliminary Study

    DTIC Science & Technology

    1994-02-01

    18, no. 1, Jan 1987, pp 13-23. 38. Z. Hashin and B.W. Rosen. "The elastic moduli of fiber-reinforced materials," Journal of Applied Mechanics, vol 31...MAT DIV. MATHEY, GAITHERSBURG. MD NEPTCO / RACZELOWSKI. PAWTUCKET. RI NEW ZEALAND CONCRETE RSCH ASSN / LIB, PORIRUA, NORTHWESTERN UNIVERSITY / BAZANT

  2. RETENTION BASIN, ASSOCIATED WITH PUMP HOUSE, TRA636. TWO REINFORCED CONCRETE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    RETENTION BASIN, ASSOCIATED WITH PUMP HOUSE, TRA-636. TWO REINFORCED CONCRETE BASINS ARE ADJACENT TO ONE ANOTHER. CAMERA FACING SOUTH. INL NEGATIVE NO. 2397A. Unknown Photographer, 5/13/1951 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  3. Mathematical modeling of vibration processes in reinforced concrete structures for setting up crack initiation monitoring

    NASA Astrophysics Data System (ADS)

    Bykov, A. A.; Matveenko, B. P.; Serovaev, G. S.; Shardakov, I. N.; Shestakov, A. P.

    2015-03-01

    The contemporary construction industry is based on the use of reinforced concrete structures, but emergency situations resulting in fracture can arise in their exploitation. In a majority of cases, reinforced concrete fracture is realized as the process of crack formation and development. As a rule, the appearance of the first cracks does not lead to the complete loss of the carrying capacity but is a fracture precursor. One method for ensuring the safe operation of building structures is based on crack initiation monitoring. A vibration method for the monitoring of reinforced concrete structures is justified in this paper. An example of a reinforced concrete beam is used to consider all stages related to the analysis of the behavior of natural frequencies in the development of a crack-shaped defect and the use of the obtained numerical results for the vibration test method. The efficiency of the method is illustrated by the results of modeling of the physical part of the method related to the analysis of the natural frequency evolution as a response to the impact action in the crack development process.

  4. Applications of fiber reinforced concrete containers in France and in Slovakia

    SciTech Connect

    Verdier, A.; Delgrande, J.; Remias, V.

    1995-12-31

    Radioactive waste immobilization is an integral part of operations in nuclear facilities. The goal of immobilization is to contain radioactive materials in a waste form which can maintain its integrity over very long periods of time, thus effectively isolating the materials from the environment and hence from the public. This is true regardless of the activity of the waste, including low-, and medium-level waste (LLW, MLW). A multiple-year research effort by COGEMA culminated in the development of a new process to immobilize nuclear waste in concrete containers reinforced with metal fibers. The fiber reinforced concrete containers satisfy all French safety requirements relating to waste immobilization and disposal, and have been certified by ANDRA, the national radioactive waste management agency. The fiber reinforced concrete containers have been fabricated on a production scale since July 1990 by Sogefibre, a jointly-owned subsidiary of SGN and Campaign Generale des Eaux. This technology is being transferred to Slovenske Elektrarne (Slovak Power Plant) to intern the waste produced by Bohunice and Mochovce power plants in cubical fiber reinforced concrete containers.

  5. Detection of active corrosion in reinforced and prestressed concrete: overview of NIST TIP project

    NASA Astrophysics Data System (ADS)

    Gonzalez-Nunez, M. A.; Nanni, A.; Matta, F.; Ziehl, P.

    2011-04-01

    The US transportation infrastructure has been receiving intensive public and private attention in recent years. The Federal Highway Administration estimates that 42 percent of the nearly 600,000 bridges in the Unites States are in need of structural or functional rehabilitation1. Corrosion of reinforcement steel is the main durability issue for reinforced and prestressed concrete structures, especially in coastal areas and in regions where de-icing salts are regularly used. Acoustic Emission (AE) has proved to be a promising method for detecting corrosion in steel reinforced and prestressed concrete members. This type of non-destructive test method primarily measures the magnitude of energy released within a material when physically strained. The expansive ferrous byproducts resulting from corrosion induce pressure at the steel-concrete interface, producing longitudinal and radial microcracks that can be detected by AE sensors. In the experimental study presented herein, concrete block specimens with embedded steel reinforcing bars and strands were tested under accelerated corrosion to relate the AE activity with the onset and propagation stages of corrosion. AE data along with half cell potential measurements and galvanic current were recorded to examine the deterioration process. Finally, the steel strands and bars were removed from the specimens, cleaned and weighed. The results were compared vis-à-vis Faraday's law to correlate AE measurements with degree of corrosion in each block.

  6. Mechanical properties of fiber reinforced lightweight concrete composites

    SciTech Connect

    Perez-Pena, M. ); Mobasher, B. )

    1994-01-01

    Hybrid composites with variable strength/toughness properties can be manufactured using combinations of brittle or ductile mesh in addition to brittle and ductile matrix reinforcements. The bending and tensile properties of thin sheet fiber cement composites made from these mixtures were investigated. Composites consisted of a woven mesh of either polyvinyl chloride (PVC) coated E-glass or polypropylene (PP) fibers for the surface reinforcement. In addition, chopped polypropylene, acrylic, nylon, and alkali-resistant (AR) glass fibers were used for the core reinforcement. It is shown that by controlling fiber contents, types, and combinations, design objectives such as strength, stiffness and toughness, can be achieved. Superior post-cracking behavior was measured for composites reinforced both with glass mesh and PP mesh. Load carrying capacity of PP mesh composites can be increased with the use of 1% or higher chopped PP fibers. Glass mesh composites with short AR glass fibers as matrix reinforcement indicate an increased matrix cracking strength and modulus of rupture. Combinations of PP mesh/short AR glass did not show a substantial improvement in the matrix ultimate strength. An increased nylon fiber surface area resulted in improved post peak response.

  7. Concrete material characterization reinforced concrete tank structure Multi-Function Waste Tank Facility

    NASA Astrophysics Data System (ADS)

    Winkel, B. V.

    1995-03-01

    The purpose of this report is to document the Multi-Function Waste Tank Facility (MWTF) Project position on the concrete mechanical properties needed to perform design/analysis calculations for the MWTF secondary concrete structure. This report provides a position on MWTF concrete properties for the Title 1 and Title 2 calculations. The scope of the report is limited to mechanical properties and does not include the thermophysical properties of concrete needed to perform heat transfer calculations. In the 1970's, a comprehensive series of tests were performed at Construction Technology Laboratories (CTL) on two different Hanford concrete mix designs. Statistical correlations of the CTL data were later generated by Pacific Northwest Laboratories (PNL). These test results and property correlations have been utilized in various design/analysis efforts of Hanford waste tanks. However, due to changes in the concrete design mix and the lower range of MWTF operating temperatures, plus uncertainties in the CTL data and PNL correlations, it was prudent to evaluate the CTL data base and PNL correlations, relative to the MWTF application, and develop a defendable position. The CTL test program for Hanford concrete involved two different mix designs: a 3 kip/sq in mix and a 4.5 kip/sq in mix. The proposed 28-day design strength for the MWTF tanks is 5 kip/sq in. In addition to this design strength difference, there are also differences between the CTL and MWTF mix design details. Also of interest, are the appropriate application of the MWTF concrete properties in performing calculations demonstrating ACI Code compliance. Mix design details and ACI Code issues are addressed in Sections 3.0 and 5.0, respectively. The CTL test program and PNL data correlations focused on a temperature range of 250 to 450 F. The temperature range of interest for the MWTF tank concrete application is 70 to 200 F.

  8. Concrete material characterization reinforced concrete tank structure Multi-Function Waste Tank Facility

    SciTech Connect

    Winkel, B.V.

    1995-03-03

    The purpose of this report is to document the Multi-Function Waste Tank Facility (MWTF) Project position on the concrete mechanical properties needed to perform design/analysis calculations for the MWTF secondary concrete structure. This report provides a position on MWTF concrete properties for the Title 1 and Title 2 calculations. The scope of the report is limited to mechanical properties and does not include the thermophysical properties of concrete needed to perform heat transfer calculations. In the 1970`s, a comprehensive series of tests were performed at Construction Technology Laboratories (CTL) on two different Hanford concrete mix designs. Statistical correlations of the CTL data were later generated by Pacific Northwest Laboratories (PNL). These test results and property correlations have been utilized in various design/analysis efforts of Hanford waste tanks. However, due to changes in the concrete design mix and the lower range of MWTF operating temperatures, plus uncertainties in the CTL data and PNL correlations, it was prudent to evaluate the CTL data base and PNL correlations, relative to the MWTF application, and develop a defendable position. The CTL test program for Hanford concrete involved two different mix designs: a 3 kip/in{sup 2} mix and a 4.5 kip/in{sup 2} mix. The proposed 28-day design strength for the MWTF tanks is 5 kip/in{sup 2}. In addition to this design strength difference, there are also differences between the CTL and MWTF mix design details. Also of interest, are the appropriate application of the MWTF concrete properties in performing calculations demonstrating ACI Code compliance. Mix design details and ACI Code issues are addressed in Sections 3.0 and 5.0, respectively. The CTL test program and PNL data correlations focused on a temperature range of 250 to 450 F. The temperature range of interest for the MWTF tank concrete application is 70 to 200 F.

  9. Primer on Durability of Nuclear Power Plant Reinforced Concrete Structures - A Review of Pertinent Factors

    SciTech Connect

    Naus, Dan J

    2007-02-01

    The objective of this study was to provide a primer on the environmental effects that can affect the durability of nuclear power plant concrete structures. As concrete ages, changes in its properties will occur as a result of continuing microstructural changes (i.e., slow hydration, crystallization of amorphous constituents, and reactions between cement paste and aggregates), as well as environmental influences. These changes do not have to be detrimental to the point that concrete will not be able to meet its performance requirements. Concrete, however, can suffer undesirable changes with time because of improper specifications, a violation of specifications, or adverse performance of its cement paste matrix or aggregate constituents under either physical or chemical attack. Contained in this report is a discussion on concrete durability and the relationship between durability and performance, a review of the historical perspective related to concrete and longevity, a description of the basic materials that comprise reinforced concrete, and information on the environmental factors that can affect the performance of nuclear power plant concrete structures. Commentary is provided on the importance of an aging management program.

  10. Image enhancement for on-site X-ray nondestructive inspection of reinforced concrete structures.

    PubMed

    Pei, Cuixiang; Wu, Wenjing; Ueaska, Mitsuru

    2016-11-22

    The use of portable and high-energy X-ray system can provide a very promising approach for on-site nondestructive inspection of inner steel reinforcement of concrete structures. However, the noise properties and contrast of the radiographic images for thick concrete structures do often not meet the demands. To enhance the images, we present a simple and effective method for noise reduction based on a combined curvelet-wavelet transform and local contrast enhancement based on neighborhood operation. To investigate the performance of this method for our X-ray system, we have performed several experiments with using simulated and experimental data. With comparing to other traditional methods, it shows that the proposed image enhancement method has a better performance and can significantly improve the inspection performance for reinforced concrete structures.

  11. Effect of Mesh Distribution on Impact Resistance Performance of Kenaf Fibre Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Che Muda, Zakaria; Thiruchelvam, Sivadass; Syamsir, Agusril; Sheng, Chiam Yung; Beddu, Salmia; Nasharuddin Mustapha, Kamal; Usman, Fathoni; Liyana Mohd Kamal, Nur; Ashraful Alam, Md; Birima, Ahmed H.; Zaroog, O. S.

    2016-03-01

    This paper investigate the effect of the mesh distribution on the impact performance of kenaf fibre mesh reinforced concrete (KFMRC) for the concrete slab of 300mm × 300mm size reinforced with varied thickness and mesh diameter subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.236 kg drop at 0.40 m height has been used in this research work. The objective of this research is to study the effect of the mesh distribution on the impact resistance kenaf fibre mesh concrete for various slab thickness and mesh diameter. 2-layers one Top and one Bottom mesh distribution kenaf mesh is the most efficient in the ability to control crack formation and propagation against impact energy followed by 1-layer Middle mesh distribution and lastly the 1-layer Top mesh distribution is the least effective.

  12. Adaptive Crack Modeling with Interface Solid Elements for Plain and Fiber Reinforced Concrete Structures

    PubMed Central

    Zhan, Yijian

    2017-01-01

    The effective analysis of the nonlinear behavior of cement-based engineering structures not only demands physically-reliable models, but also computationally-efficient algorithms. Based on a continuum interface element formulation that is suitable to capture complex cracking phenomena in concrete materials and structures, an adaptive mesh processing technique is proposed for computational simulations of plain and fiber-reinforced concrete structures to progressively disintegrate the initial finite element mesh and to add degenerated solid elements into the interfacial gaps. In comparison with the implementation where the entire mesh is processed prior to the computation, the proposed adaptive cracking model allows simulating the failure behavior of plain and fiber-reinforced concrete structures with remarkably reduced computational expense. PMID:28773130

  13. Adaptive Crack Modeling with Interface Solid Elements for Plain and Fiber Reinforced Concrete Structures.

    PubMed

    Zhan, Yijian; Meschke, Günther

    2017-07-08

    The effective analysis of the nonlinear behavior of cement-based engineering structures not only demands physically-reliable models, but also computationally-efficient algorithms. Based on a continuum interface element formulation that is suitable to capture complex cracking phenomena in concrete materials and structures, an adaptive mesh processing technique is proposed for computational simulations of plain and fiber-reinforced concrete structures to progressively disintegrate the initial finite element mesh and to add degenerated solid elements into the interfacial gaps. In comparison with the implementation where the entire mesh is processed prior to the computation, the proposed adaptive cracking model allows simulating the failure behavior of plain and fiber-reinforced concrete structures with remarkably reduced computational expense.

  14. Experimental and modeling study of chloride ingress into concrete and reinforcement corrosion initiation

    NASA Astrophysics Data System (ADS)

    Yu, Hui

    Effects of reinforcement and coarse aggregate on chloride ingression into concrete and reinforcement corrosion initiation have been studied with experimental and modeling (finite element method) analyses. Once specimens were fabricated and exposed to a chloride solution, various experimental techniques were employed to determine the effect of reinforcement and coarse aggregate on time-to-corrosion and chloride ingress and concentration at corrosion locations. Model analyses were performed to verify and explain the experimental results. Based upon the results, it was determined that unexpectedly higher chloride concentrations were present on the top of the rebar trace than that to the side at the same depth and an inverse concentration gradient (increasing [ Cl-] with increasing depth) occurred near the top of rebars. Also, coarse aggregate volume profile in close proximity to the rebar and spatial distribution of these aggregates, in conjunction with the physical obstruction afforded by reinforcement to chloride flow, complicates concrete sampling for Cl- intended to define the critical concentration of this species to initiate corrosion. Modeling analyses that considered cover thickness, chloride threshold concentration, reinforcement size and shape, and coarse aggregate type and percolation confirmed the experimental findings. The results, at least in part, account for the relatively wide spread in chloride corrosion threshold values reported in the literature and illustrate that more consistent chloride threshold concentrations can be acquired from mortar or paste specimens than from concrete ones.

  15. Corrosion monitoring of reinforcing steel in concrete by electrochemical sensors

    NASA Astrophysics Data System (ADS)

    Qiao, Guofu; Hong, Yi; Ou, Jinping

    2010-04-01

    Health degradation by corrosion of steel in civil engineering, especially in rough environment, is a persistent problem. Structural health monitoring (SHM) techniques can lead to improved estimates of structural safety and serviceability. A novel all solid state-current confined corrosion sensor has been developed to provide the platform for corrosion monitoring of the steel bar in concrete beam by electrochemical method. Finite element method has been used to certify the current confined effect of the sensor. The sensors have been used in concrete beams to monitor the corrosion of the steel bar. Also, half-cell potential of the beam has obtained. The results shows that the corrosion sensor can effectively confine the current in the fixed area which is 45mm×π×Dsteel bar and the monitoring results of the corrosion sensor are accurate.

  16. Development of hybrid polypropylene-steel fiber-reinforced concrete

    SciTech Connect

    Qian, C.X.; Stroeven, P.

    2000-01-01

    This research first investigates the optimization of fiber size, fiber content, and fly ash content in hybrid polypropylene-steel fiber concrete with low fiber content based on general mechanical properties. The research results show that a certain content of fine particles such as fly ash is necessary to evenly disperse fibers. The different sizes of steel fibers contributed to different mechanical properties, at least to a different degree. Additions of a small fiber type had a significant influence on the compressive strength, but the splitting tensile strength was only slightly affected. A large fiber type gave rise to opposite mechanical effects, which were further fortified by optimization of the aspect ratio. There is a synergy effect in the hybrid fibers system. The fracture properties and the dynamic properties will be further investigated for the hybrid fibers concrete with good general mechanical properties.

  17. Advanced Constitutive Modeling of Plain and Reinforced Concretes

    DTIC Science & Technology

    1988-12-31

    plastic models. Plain concrete, on the other hand. is one of the most complex structural materials in current use and, despite numerous efforts in...influence of basic material and geometric properties on damage accumulation and failure conditions. Under Tasks 1 and 2. a new, advanced model of...purpose of this study was to ascertain the influence of fundamental material , interface, and 4 0Ill l lll l * geometric properties on the nonlinear

  18. Development of Advanced Constitutive Models for Plain and Reinforced Concrete.

    DTIC Science & Technology

    1985-04-08

    1473, 83 APR EOITION OP T JAN 73 IS OBSOLETE. U.nclassified SECURITY CLASSIFICATION OF 7THIS PAGE TABLE OF CONTENTS SECTI ON PAGE FOREWORD...the older theory used to develop the concrete models described by Bazant and Bhat (24 ) and Bazant and Shieh. (25 ) Proper closure of hysteresis loops...is guaranteed in the present theory, so that artifices, such as the jump-kinematic hardening introduced by Bazant and Shieh, (25 ) are not required

  19. Improved Strength Design of Reinforced Concrete Hydraulic Structures - Research Support

    DTIC Science & Technology

    1992-04-01

    DC 20503. 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE I. REPORT TYPE AND DATES COVERED I April 1992 Final report 4. TITLE AND SUBTITLE S. FUNDING...for tension -control fail- ures and for pure compression failures. These are the failure zones that are of primary interest for the design of RCHS...concrete Tension control failures 16. PRICE CODE hydraulic structures 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY

  20. Response Simulation of a Micro Reinforced Concrete Target Under Ballistic Impact

    NASA Astrophysics Data System (ADS)

    Mohan, V.; Rajasankar, J.; Iyer, N. R.

    2014-05-01

    The response of concrete structures subjected to impact loading has received extensive attention in both civil and military applications. Research on improving the shock resistance of concrete has led to the development of cementitious composites. Micro Reinforced Concrete (MRC), a type of cementitious composite, is a concrete matrix embedded with multilayered steel wire meshes. This paper presents 3D hydrocode simulations of MRC panels subjected to impact under a ballistic range. A finite element model based on Lagrange formulation is used to represent both a 300 mm × 300 mm × 100 mm target with 30 layers of wire mesh and a 5.56 × 45 mm projectile in simulations. Penetration depth and damage patterns of the MRC mesh cement composite panel are numerically compared with those of the field experiment. The results show a relatively good agreement.

  1. Development of Advanced Constitutive Models for Plain and Reinforced Concrete.

    DTIC Science & Technology

    1986-04-01

    Concrete,"’ Mechanics of MateriaLs, 3 (1984), 271. 2. Read, H. E., Discussion of "Hysteretic Endochronic Theory for Sand," by Z. P. Bazant , R. J. Krizek and...C.-L. Shieh, Journa L of Engineering Mechanics, Vol. III(1), Jan . 1985, 103. 3. Hegemier, G. A., H. Murakami, and L. J. Hageman, "On Tension...T ’ TM ’’ -x ’ ’"- REFERENCES Bazant , Z. P., and L. Cedolin (1979), "Blunt Crack Propagation in Finite Element Analysis," J. Engr. Mechs. Div., ASCE

  2. Foamed, Fiber-Reinforced Concrete as a Fragment Collecting Medium

    DTIC Science & Technology

    1998-08-01

    single projectile penetrations. Thick blocks of SACON when attacked with a weapon, such as the M16A2 rifle, firing multiple rounds into the same point...friction-type trap where the incoming projectile loses energy by crushing the cellular structure of the concrete. Bullets traveling the same path into the...the M16A2 rifle firing the 5.56- mm NATO Ball M855 round. The M16A2 has a muzzle velocity of 990 to 1,000 m/s and a cyclic rate of fire in the $burst

  3. Brittleness of Reinforced Concrete Structures under Arctic Conditions,

    DTIC Science & Technology

    1986-05-01

    reinforced beams and of unreinforced ____________________________ beams T7 and T8. -IOMM 30 mmRange of peak Drop Masshc~gf Enrgy values of the A Drp Nass...eigt Enrgy load impulse k 00m1 100/30 29 t0O.. .16 2 ’ 00/180 1 77 ’ 8..29 - 750mm - 3 200/90 177 28...41 4 200/120 235 34...46 500mm 5 200/240 471 47

  4. Mechanical Behavior of Steel Fiber-Reinforced Concrete Beams Bonded with External Carbon Fiber Sheets.

    PubMed

    Gribniak, Viktor; Tamulenas, Vytautas; Ng, Pui-Lam; Arnautov, Aleksandr K; Gudonis, Eugenijus; Misiunaite, Ieva

    2017-06-17

    This study investigates the mechanical behavior of steel fiber-reinforced concrete (SFRC) beams internally reinforced with steel bars and externally bonded with carbon fiber-reinforced polymer (CFRP) sheets fixed by adhesive and hybrid jointing techniques. In particular, attention is paid to the load resistance and failure modes of composite beams. The steel fibers were used to avoiding the rip-off failure of the concrete cover. The CFRP sheets were fixed to the concrete surface by epoxy adhesive as well as combined with various configurations of small-diameter steel pins for mechanical fastening to form a hybrid connection. Such hybrid jointing techniques were found to be particularly advantageous in avoiding brittle debonding failure, by promoting progressive failure within the hybrid joints. The use of CFRP sheets was also effective in suppressing the localization of the discrete cracks. The development of the crack pattern was monitored using the digital image correlation method. As revealed from the image analyses, with an appropriate layout of the steel pins, brittle failure of the concrete-carbon fiber interface could be effectively prevented. Inverse analysis of the moment-curvature diagrams was conducted, and it was found that a simplified tension-stiffening model with a constant residual stress level at 90% of the strength of the SFRC is adequate for numerically simulating the deformation behavior of beams up to the debonding of the CFRP sheets.

  5. Mechanical Behavior of Steel Fiber-Reinforced Concrete Beams Bonded with External Carbon Fiber Sheets

    PubMed Central

    Gribniak, Viktor; Tamulenas, Vytautas; Ng, Pui-Lam; Arnautov, Aleksandr K.; Gudonis, Eugenijus; Misiunaite, Ieva

    2017-01-01

    This study investigates the mechanical behavior of steel fiber-reinforced concrete (SFRC) beams internally reinforced with steel bars and externally bonded with carbon fiber-reinforced polymer (CFRP) sheets fixed by adhesive and hybrid jointing techniques. In particular, attention is paid to the load resistance and failure modes of composite beams. The steel fibers were used to avoiding the rip-off failure of the concrete cover. The CFRP sheets were fixed to the concrete surface by epoxy adhesive as well as combined with various configurations of small-diameter steel pins for mechanical fastening to form a hybrid connection. Such hybrid jointing techniques were found to be particularly advantageous in avoiding brittle debonding failure, by promoting progressive failure within the hybrid joints. The use of CFRP sheets was also effective in suppressing the localization of the discrete cracks. The development of the crack pattern was monitored using the digital image correlation method. As revealed from the image analyses, with an appropriate layout of the steel pins, brittle failure of the concrete-carbon fiber interface could be effectively prevented. Inverse analysis of the moment-curvature diagrams was conducted, and it was found that a simplified tension-stiffening model with a constant residual stress level at 90% of the strength of the SFRC is adequate for numerically simulating the deformation behavior of beams up to the debonding of the CFRP sheets. PMID:28773024

  6. Effects of manufacturing techniques on the flexural behavior of steel fiber-reinforced concrete

    SciTech Connect

    Toutanji, H.; Bayasi, Z.

    1998-01-01

    This paper presents experimental research investigating the effects of manufacturing techniques on the mechanical properties of steel fiber-reinforced concrete. Both the effects of curing environments and that of testing direction relative to casting direction on the mechanical properties of fiber-reinforced concrete are reported. Specimens were cured in three different environmental conditions: steam, moisture, and air. Results show that steam curing, as compared to moisture curing, does not enhance the flexural strength of steel fibrous concrete but does reduce flexural toughness. As expected, air curing shows detrimental effects on all aspects of the test results, as compared to steam and moisture curing. The flexural behavior of steel fiber-reinforced concrete is strongly affected by testing direction. When testing direction is perpendicular to casting direction, specimens exhibit reductions in both flexural strength and toughness compared to the case when testing and casting directions are parallel. The effect of testing direction relative to casting direction on flexural strength and toughness increases with increasing the flowability (workability) of the fibrous mixture, which encourages fiber settlement during placement.

  7. Seismic fragility analysis of lap-spliced reinforced concrete columns retrofitted by SMA wire jackets

    NASA Astrophysics Data System (ADS)

    Choi, Eunsoo; Park, Sun-Hee; Chung, Young-Soo; Kim, Hee Sun

    2013-08-01

    The aim of this study is to provide seismic fragility curves of reinforced concrete columns retrofitted by shape memory alloy wire jackets and thus assess the seismic performance of the columns against earthquakes, comparing them with reinforced concrete columns with lap-spliced and continuous reinforcement. For that purpose, this study first developed analytical models of the experimental results of the three types of columns, (1) lap-spliced reinforcement, (2) continuous reinforcement and (3) lap-spliced reinforcement and retrofitted by SMA wire jackets, using the OpenSEES program, which is oriented to nonlinear dynamic analysis. Then, a suite of ten recorded ground motions was used to conduct dynamic analyses of the analytical models with scaling of the peak ground acceleration from 0.1g to 1.0g in steps of 0.1g. From the static experimental tests, the column retrofitted with SMA wire jackets had a larger displacement ductility by a factor of 2.3 times that of the lap-spliced column, which was 6% larger compared with the ductility of the continuous reinforcement column. From the fragility analyses, the SMA wire jacketed column had median values of 0.162g and 0.567g for yield and collapse, respectively. For the yield damage state, the SMA wire jacketed column had a median value similar to the continuous reinforcement column. However, for the complete damage state, the SMA wire jacketed column showed a 1.33 times larger median value than the continuously reinforcement column.

  8. The corrosion pattern of reinforcement and its influence on serviceability of reinforced concrete members in chloride environment

    SciTech Connect

    Zhang Ruijin; Castel, Arnaud; Francois, Raoul

    2009-11-15

    This paper deals with two corroded reinforcement concrete beams, which have been stored under sustained load in a chloride environment for 14 and 23 years respectively. The evolution of corrosion pattern of reinforcement and its influence on serviceability are studied. In chloride-induced corrosion process, corrosion cracking affects significantly the corrosion pattern. During the corrosion cracking initiation period, only local pitting corrosion occurs. At early stage of cracking propagation, localized pitting corrosion is still predominant as cracks widths are very small and cracks are not interconnected, but a general corrosion slowly develops as the cracks widen. At late cracking stage, interconnected cracking with wide width develops along large parts of the beam leading to a general corrosion pattern. Macrocells and microcells concepts are used for the interpretation of the results. Mechanical experiments and corrosion simulation tests are performed to clarify the influence of this corrosion pattern evolution on the serviceability of the beams (deflection increase). Experimental results show that, when the corrosion is localized (early cracking stage), the steel-concrete bond loss is the main factor affecting the beams serviceability. The local cross-section loss resulting from pitting attack does not significantly influence the deflection of the beam. When corrosion is generalized (late cracking stage), as the steel-concrete bond is already lost, the generalized steel cross-section reduction becomes the main factor affecting the beams serviceability. But, at this stage, the deflection increase is slower due to the low general corrosion rate.

  9. Carbon paint anode for reinforced concrete bridges in coastal environments

    SciTech Connect

    Cramer, Stephen D.; Bullard, Sophie J.; Covino, Bernard S., Jr.; Holcomb, Gordon R.; Russell, James H.; Cryer, C.B.; Laylor, H.M.

    2002-01-01

    Solvent-based acrylic carbon paint anodes were installed on the north approach spans of the Yaquina Bay Bridge (Newport OR) in 1985. The anodes continue to perform satisfactorily after more than 15 years service. The anodes were inexpensive to apply and field repairs are easily made. Depolarization potentials are consistently above 100 mV with long-term current densities around 2 mA/m 2. Bond strength remains adequate, averaging 0.50 MPa (73 psi). Some deterioration of the anode-concrete interface has occurred in the form of cracks and about 4% of the bond strength measurements indicated low or no bond. Carbon anode consumption appears low. The dominant long-term anode reaction appears to be chlorine evolution, which results in limited further acidification of the anode-concrete interface. Chloride profiles were depressed compared to some other coastal bridges suggesting chloride extraction by the CP system. Further evidence of outward chloride migration was a flat chloride profile between the anode and the outer rebar.

  10. Reliability and flexural behavior of triangular and T-reinforced concrete beams

    NASA Astrophysics Data System (ADS)

    Al-Ansari, Mohammed S.

    2015-12-01

    The paper studied the behavior of reinforced concrete triangular and T-beams. Three reinforced concrete beams were tested experimentally and analyzed analytically using the finite element method. Their reliability was also assessed using the reliability index approach. The results showed that the finite element vertical displacements compared well with those obtained experimentally. They also showed that the vertical displacements obtained using the finite element method were larger than those obtained experimentally. This is a strong indication that the finite element results were conservative and reliable. The results showed that the triangular beams exhibited higher ductility at failure than did the T-beam. The plastic deformations at failure of the triangular beams were higher than that of the T-beam. This is a strong indication of the higher ductility of the triangular beams compared to the T-beam. Triangular beams exhibited smaller cracks than did T-beams for equal areas of steel and concrete. The design moment strengths M c computed using the American Concrete Institute (ACI) design formulation were safe and close to those computed using experimental results. The experimental results validated the reliability analysis results, which stated that the triangular beams are more reliable than T-beams for equal areas of steel and concrete.

  11. Experimental and numerical investigation of concrete structures with metal and non-metal reinforcement at impulse loadings

    NASA Astrophysics Data System (ADS)

    Radchenko, P. A.; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S.; Kudyakov, K. L.

    2016-11-01

    Manufacturing durable and high-strength concrete structures has always been a relevant objective. Therefore special attention has been paid to non-metallic composite reinforcement. This paper considers experimental and numerical studies of nature of fracture and crack formation in concrete beams with rod composite reinforcement. Fiber glass rods, 6 mm in diameter, have been used as composite reinforcement. Concrete elements have been tested under dynamic load using special pile driver. The obtained results include patterns of fracture and crack formation, maximum load value and maximum element deflection. Comparative analysis of numerical and experimental studies has been held.

  12. Research about tensile sensitive characteristics of carbon fibre reinforced concrete and security self-diagnosis system of beam

    NASA Astrophysics Data System (ADS)

    Huang, Longnan; Wang, Xinbo; Zhang, Dongxing

    2009-07-01

    Based on real-time diagnosis of health status of reinforced concrete beam, intellectual supervisory layer of carbon fiber reinforced concrete (CFRC) was set up at the bottom of girder structure. The intrinsic law of tensile sensitive characteristic of CFRC was studied and the electrical property collection and the stress transformation system of structure intellectual layer were established. It depends on the premise that carbon fibers are conductive, and that a stable relationship between electric resistivity and stress field exists. The security self-diagnosis of girder structure was fulfilled through online real-time monitoring and evaluation on electrical signal of intelligence layer of reinforced concrete beam.

  13. Monitoring Concrete Deterioration Due to Reinforcement Corrosion by Integrating Acoustic Emission and FBG Strain Measurements.

    PubMed

    Li, Weijie; Xu, Changhang; Ho, Siu Chun Michael; Wang, Bo; Song, Gangbing

    2017-03-22

    Corrosion of concrete reinforcement members has been recognized as a predominant structural deterioration mechanism for steel reinforced concrete structures. Many corrosion detection techniques have been developed for reinforced concrete structures, but a dependable one is more than desired. Acoustic emission technique and fiber optic sensing have emerged as new tools in the field of structural health monitoring. In this paper, we present the results of an experimental investigation on corrosion monitoring of a steel reinforced mortar block through combined acoustic emission and fiber Bragg grating strain measurement. Constant current was applied to the mortar block in order to induce accelerated corrosion. The monitoring process has two aspects: corrosion initiation and crack propagation. Propagation of cracks can be captured through corresponding acoustic emission whereas the mortar expansion due to the generation of corrosion products will be monitored by fiber Bragg grating strain sensors. The results demonstrate that the acoustic emission sources comes from three different types, namely, evolution of hydrogen bubbles, generation of corrosion products and crack propagation. Their corresponding properties are also discussed. The results also show a good correlation between acoustic emission activity and expansive strain measured on the specimen surface.

  14. Monitoring Concrete Deterioration Due to Reinforcement Corrosion by Integrating Acoustic Emission and FBG Strain Measurements

    PubMed Central

    Li, Weijie; Xu, Changhang; Ho, Siu Chun Michael; Wang, Bo; Song, Gangbing

    2017-01-01

    Corrosion of concrete reinforcement members has been recognized as a predominant structural deterioration mechanism for steel reinforced concrete structures. Many corrosion detection techniques have been developed for reinforced concrete structures, but a dependable one is more than desired. Acoustic emission technique and fiber optic sensing have emerged as new tools in the field of structural health monitoring. In this paper, we present the results of an experimental investigation on corrosion monitoring of a steel reinforced mortar block through combined acoustic emission and fiber Bragg grating strain measurement. Constant current was applied to the mortar block in order to induce accelerated corrosion. The monitoring process has two aspects: corrosion initiation and crack propagation. Propagation of cracks can be captured through corresponding acoustic emission whereas the mortar expansion due to the generation of corrosion products will be monitored by fiber Bragg grating strain sensors. The results demonstrate that the acoustic emission sources comes from three different types, namely, evolution of hydrogen bubbles, generation of corrosion products and crack propagation. Their corresponding properties are also discussed. The results also show a good correlation between acoustic emission activity and expansive strain measured on the specimen surface. PMID:28327510

  15. Probabilistic failure modelling of reinforced concrete structures subjected to chloride penetration

    NASA Astrophysics Data System (ADS)

    Nogueira, Caio Gorla; Leonel, Edson Denner; Coda, Humberto Breves

    2012-12-01

    Structural durability is an important criterion that must be evaluated for every type of structure. Concerning reinforced concrete members, chloride diffusion process is widely used to evaluate durability, especially when these structures are constructed in aggressive atmospheres. The chloride ingress triggers the corrosion of reinforcements; therefore, by modelling this phenomenon, the corrosion process can be better evaluated as well as the structural durability. The corrosion begins when a threshold level of chloride concentration is reached at the steel bars of reinforcements. Despite the robustness of several models proposed in literature, deterministic approaches fail to predict accurately the corrosion time initiation due the inherent randomness observed in this process. In this regard, structural durability can be more realistically represented using probabilistic approaches. This paper addresses the analyses of probabilistic corrosion time initiation in reinforced concrete structures exposed to chloride penetration. The chloride penetration is modelled using the Fick's diffusion law. This law simulates the chloride diffusion process considering time-dependent effects. The probability of failure is calculated using Monte Carlo simulation and the first order reliability method, with a direct coupling approach. Some examples are considered in order to study these phenomena. Moreover, a simplified method is proposed to determine optimal values for concrete cover.

  16. Estimation of in-situ stresses in concrete members using polarized ultrasonic shear waves

    NASA Astrophysics Data System (ADS)

    Chen, Andrew; Schumacher, Thomas

    2014-02-01

    Ultrasonic testing is commonly used to detect flaws, estimate geometries, and characterize properties of materials and structures. Acoustoelasticity refers to the dependency of stress wave velocity with applied stresses and is a phenomenon that has been known by geophysicists since the 1960s. A way to capitalize on this effect for concrete applications is by using ultrasonic shear waves which are particularly sensitive to applied stresses when polarized in the direction of the applied stress. The authors conducted an experiment on a 150 mm (6 in.) diameter concrete cylinder specimen with a length of 305 mm (12 in.) that was loaded in discrete load steps to failure. At each load step two ultrasonic shear waves were transmitted through the specimen, one with the polarization perpendicular and the other transverse to the applied stress. The velocity difference between the two sets of polarized shear waves was found to correlate with the applied stress in the specimen. Two potential applications for this methodology include estimation of stresses in pre-stressed concrete bridge girders and investigation of load redistribution in structural support elements after extreme events. This paper introduces the background of the methodology, presents an analysis of the collected data, and discusses the relationship between the recorded signals and the applied stress.

  17. Stainless and Galvanized Steel, Hydrophobic Admixture and Flexible Polymer-Cement Coating Compared in Increasing Durability of Reinforced Concrete Structures

    NASA Astrophysics Data System (ADS)

    Tittarelli, Francesca; Giosuè, Chiara; Mobili, Alessandra

    2017-08-01

    The use of stainless or galvanized steel reinforcements, a hydrophobic admixture or a flexible polymer-cement coating were compared as methods to improve the corrosion resistance of sound or cracked reinforced concrete specimens exposed to chloride rich solutions. The results show that in full immersion condition, negligible corrosion rates were detected in all cracked specimens, except those treated with the flexible polymer-cement mortar as preventive method against corrosion and the hydrophobic concrete specimens. High corrosion rates were measured in all cracked specimens exposed to wet-dry cycles, except for those reinforced with stainless steel, those treated with the flexible polymer-cement coating as restorative method against reinforcement corrosion and for hydrophobic concrete specimens reinforced with galvanized steel reinforcements.

  18. Computational aspects of crack growth in sandwich plates from reinforced concrete and foam

    NASA Astrophysics Data System (ADS)

    Papakaliatakis, G.; Panoskaltsis, V. P.; Liontas, A.

    2012-12-01

    In this work we study the initiation and propagation of cracks in sandwich plates made from reinforced concrete in the boundaries and from a foam polymeric material in the core. A nonlinear finite element approach is followed. Concrete is modeled as an elastoplastic material with its tensile behavior and damage taken into account. Foam is modeled as a crushable, isotropic compressible material. We analyze slabs with a pre-existing macro crack at the position of the maximum bending moment and we study the macrocrack propagation, as well as the condition under which we have crack arrest.

  19. The determination of the constitutive parameters of a medium with application to a reinforced concrete pad

    NASA Technical Reports Server (NTRS)

    Poggio, A. J.; Burke, G. L.; Pennock, S. T.

    1995-01-01

    This report describes the experimental and analytical efforts performed to determine the constitutive parameters of a reinforced concrete pad on which an aircraft (the NASA Boeing 757) was parked while its internal electromagnetic environment was measured. This concrete pad is part of the Large Electromagnetic System-Level Illuminator (LESLI) test facility at the Phillips Laboratory, Kirtland Air Force Base, New Mexico. The relative dielectric constant, conductivity, index of refraction, and reflection coefficient have been determined over the frequency range of 0 to 300 MHz and are presented.

  20. Experimental and theoretical analysis of CFRP reinforced concrete beam anchored by CF anchors

    NASA Astrophysics Data System (ADS)

    Zhuang, Ning; Ma, Ye-ming; Dong, Hong-han; Chen, Da

    2017-04-01

    Carbon fiber-reinforced polymer (CFRP) sheets is used to strengthen RC members widely. However, in the actual projects, premature separation of the CFRP sheet from the concrete surface is observed frequently, key issue in CFRP application is the performance of the connection between the CFRP sheet and the peripheral RC members. This paper presented the results of an experimental study to investigate mechanical properties of carbon fiber (CF) anchor dowels, a new CFRP anchoring method, and based on the experimental results, obtained the bearing capacity calculation formula of concrete beam strengthened with CFRP anchoring by carbon fiber anchor dowels .

  1. Field applications of a carbon fiber sheet material for strengthening reinforced concrete structure

    SciTech Connect

    Thomas, J.; Kliger, H.S.; Yoshizawa, Hiroyuki

    1996-12-31

    Forca Tow Sheet is now being introduced into the USA as a viable alternative to conventional concrete strengthen techniques. This carbon fiber shoot material is externally bonded to reinforced concrete and masonry structures and serves to strengthen existing conditions. Based on the growing use of Tow Sheet in the Japanese market die US infrastructure market is beginning to apply this technology on a number of diverse repair projects. This paper describes actual field applications on industrial and public structures in the US and Japan. Also included are the results of one yen of monitoring of die Japanese structure.

  2. Recycled and virgin plastics in fiber reinforced concrete. Final report, October 1994--August 1997

    SciTech Connect

    Tawfiq, K.S.

    1998-08-30

    The primary objectives of this study is to conduct a laboratory investigation to evaluate the intrinsic stress that can cause cracking of concrete mixed recommended by the Florida Department of Transportation with the addition of monofilament and fibrillated polypropylene and monofilament polyolefin fibers, subjected to highly cyclic loading. In addition, the flexural behavior of concrete reinforced with recycled post-consumer in-house made fibers will be study and Finite Element Methods (FEM) following laboratory work would be used to establish comparable numerical models for the flexural test and pavement overlays.

  3. Simulation of pre-breakdown phase of electrical discharge in reinforced concrete

    NASA Astrophysics Data System (ADS)

    Kuznetsova, N. S.; Yudin, A. S.; Voitenko, N. V.

    2017-05-01

    The application of an electrical discharge technology for destructive recycling of the reinforced concrete is considered. Its main advantages, in comparison with the mechanical methods, are that the electrical discharge channel acting as a rock-breaking tool has an unlimited service life, and a lifetime of the electrode systems is much higher. The physical and mathematical model of the discharge development is described. The simulation results have shown that the discharge channel propagation velocity and the trajectory depend on the reinforcement locality and the voltage amplitude. The voltage affects the average speed of the discharge structure development which can reach the value of up to υ=5·103 m/s. It is also shown that the reinforcing elements located between the electrodes attract the growing discharge structure. The lower the distance between the vertical axis of the high voltage electrode and the metal reinforcement position, the more probability of the discharge channel orientation towards this element.

  4. Fiber-Reinforced Polymer Composite Materials Systems to Enhance Reinforced Concrete Structures

    DTIC Science & Technology

    1998-02-01

    and low temperature evaluation of FRP performance. Field demonstrations included evaluation of carbon fiber reinforced polymer tendons for post...glass fiber reinforced polymer cables as tie back tension members, and a test fixture was designed and fabricated to evaluate post stressing tendon

  5. Static Tests of Shallow-Buried Reinforced Concrete Arches

    DTIC Science & Technology

    1988-09-01

    0 O 6 . 7 . 0 0 PSSR - PSI a 0 0 0 ’ u- ( f9 u.J ° __ oj -t , 0 1 , 2 . 0 0 O 0, 7."] 0 .. .. tOl.i Ii i 0 10 I 20 30i . 40 b 60 i 0. l 0 585 RRCH TEST...FPC EC XINT, IFLAGSIGC, BPP ,SH,RHOS) IMPLICIT INTEGER 82(1-N) C CALCULATE INITIAL TANGENT MODULUS AND UNLOAD SLOPE OF CONCRETE MODEL SLOPE = 1000.0FPC...O02SFPC)/(FPC-I000.0) IF (RHOS .EQ. 0) THEN EGH - 0.0 ELSE E50H - 0. 755RHOS$SQRT ( BPP /S*I) END IF Z - 0.5/(E5OU+E5OH-0.002) SISC - FPCS(1-Z*(EC-0.002

  6. A micromorphic model for steel fiber reinforced concrete.

    PubMed

    Oliver, J; Mora, D F; Huespe, A E; Weyler, R

    2012-10-15

    A new formulation to model the mechanical behavior of high performance fiber reinforced cement composites with arbitrarily oriented short fibers is presented. The formulation can be considered as a two scale approach, in which the macroscopic model, at the structural level, takes into account the mesostructural phenomenon associated with the fiber-matrix interface bond/slip process. This phenomenon is contemplated by including, in the macroscopic description, a micromorphic field representing the relative fiber-cement displacement. Then, the theoretical framework, from which the governing equations of the problem are derived, can be assimilated to a specific case of the material multifield theory. The balance equation derived for this model, connecting the micro stresses with the micromorphic forces, has a physical meaning related with the fiber-matrix bond slip mechanism. Differently to previous procedures in the literature, addressed to model fiber reinforced composites, where this equation has been added as an additional independent ingredient of the methodology, in the present approach it arises as a natural result derived from the multifield theory. Every component of the composite is defined with a specific free energy and constitutive relation. The mixture theory is adopted to define the overall free energy of the composite, which is assumed to be homogeneously constituted, in the sense that every infinitesimal volume is occupied by all the components in a proportion given by the corresponding volume fraction. The numerical model is assessed by means of a selected set of experiments that prove the viability of the present approach.

  7. Dynamic response of concrete beams externally reinforced with carbon fiber reinforced plastic (CFRP) subjected to impulsive loads

    SciTech Connect

    Jerome, D.M.; Ross, C.A.

    1996-12-31

    A series of 54 laboratory scale concrete beams 3 x 3 x 30 in. in size were impulsively loaded to failure in a drop weight impact machine. The beams had no internal reinforcement, but instead were externally reinforced on the bottom or tension side of the beams with 1, 2, and 3 ply AS4C/1919 graphite epoxy panels. In addition, several of the beams were also reinforced on the sides with 3 ply CFRP. The beams were simply supported in a drop weight machine and subjected to impact loads with amplitudes up to 10 kips, and durations less than 1 ms, at beam midspan. Measurements made during the loading event included beam total load, midspan displacement, as well as midspan strain at 3 locations in the beam`s cross-section. A high speed framing camera was also used to record the beam`s displacement-time behavior as well as to gain insight into the failure mechanisms. Beam midspan accelerations were determined by double differentiation of the displacement versus time data, and in turn, the beam`s inertial loads were calculated using the beam`s equivalent mass. Beam dynamic bending loads versus time were determined from the difference between the total load versus time and the inertial load versus time data. Bending loads versus displacements were also determined along with fracture energies. Failure to correct the loads for inertia will result in incorrect conclusions being drawn from the data, especially for bending resistance of brittle concrete test specimens. A comparison with quasistatic bending (fracture) energy data showed that the dynamic failure energy absorbed by the beams was always less than the static fracture energy, due to the brittle nature of concrete when impulsively loaded.

  8. Behaviour of fibre-reinforced high-performance concrete in exterior beam-column joint

    NASA Astrophysics Data System (ADS)

    Muthupriya, P.; Boobalan, S. C.; Vishnuram, B. G.

    2014-09-01

    This paper presents the effect of reinforced high performance concrete (HPC) in exterior beam-column joint with and without fibre under monotonic loading. In this experimental investigation, cross-diagonal bars have been provided at the joint for reducing the congestion of reinforcement in joints, and also M75 grade of concrete with optimum mix proportion of 10 % silica fume and 0.3 % glass fibre was used. Four exterior beam-column joint sub-assemblages were tested. The specimens were divided into two types based on the reinforcement detailing. Type A comprises two joint sub-assemblages with joint detailing as per construction code of practice in India (IS 456-2000), and Type B comprises two joint sub-assemblages with joint detailing as per ductile detailing code of practice in India (IS 13920-1993). In each group there was one specimen of control mix and the remaining one specimen of fibre-reinforced mix. All the test specimens were designed to satisfy the strong column-weak beam concept. The performances of specimens were compared with the control mix and the fibre-reinforced mix. The results show that exterior beam-column joint specimens with silica fume and glass fibre in the HPC mix showed better performance.

  9. TEMP-STRESS analysis of a reinforced concrete vessel under internal pressure

    SciTech Connect

    Marchertas, A.H.; Kennedy, J.M.; Pfeiffer, P.A.

    1987-01-01

    Prediction of the response of the Sandia National laboratory 1/6-scale reinforced concrete containment model test was obtained by Argonne National Laboratory (ANL) employing a computer program developed by ANL. The test model was internally pressurized to failure. The two-dimensional code TEMP-STRESS (1-5) has been developed at ANL for stress analysis of plane and axisymmetric 2-D reinforced structures under various thermal conditions. The program is applicable to a wide variety of nonlinear problems, and is utilized in the present study. The comparison of these pretest computations with test data on the containment model should be a good indication of the state of the code.

  10. Finite element simulation of ultrasonic waves in corroded reinforced concrete for early-stage corrosion detection

    NASA Astrophysics Data System (ADS)

    Tang, Qixiang; Yu, Tzuyang

    2017-04-01

    In reinforced concrete (RC) structures, corrosion of steel rebar introduces internal stress at the interface between rebar and concrete, ultimately leading to debonding and separation between rebar and concrete. Effective early-stage detection of steel rebar corrosion can significantly reduce maintenance costs and enable early-stage repair. In this paper, ultrasonic detection of early-stage steel rebar corrosion inside concrete is numerically investigated using the finite element method (FEM). Commercial FEM software (ABAQUS) was used in all simulation cases. Steel rebar was simplified and modeled by a cylindrical structure. 1MHz ultrasonic elastic waves were generated at the interface between rebar and concrete. Two-dimensional plain strain element was adopted in all FE models. Formation of surface rust in rebar was modeled by changing material properties and expanding element size in order to simulate the rust interface between rebar and concrete and the presence of interfacial stress. Two types of surface rust (corroded regions) were considered. Time domain and frequency domain responses of displacement were studied. From our simulation result, two corrosion indicators, baseline (b) and center frequency (fc) were proposed for detecting and quantifying corrosion.

  11. Flexural behavior of reinforced concrete beams strengthened with advanced composite materials

    SciTech Connect

    Shahawy, M.A.; Beitelman, T.

    1996-12-31

    This paper presents the results of a feasibility study to investigate the flexural behavior of structurally damaged reinforced and prestressed concrete members retrofitted with bonded carbon fiber materials. The effect of CFRP laminates, bonded to the soffit of precracked reinforced concrete rectangular and tee beams, is investigated in terms of flexural strength, deflections, cracking behavior and failure modes. The results indicate that strengthening of significantly cracked structural members by bonding Carbon laminates is structurally efficient and that the retrofitted members are restored to stiffness and strength values nearly equal to or greater than those of the original. The results indicate that the retrofitted members maintained adequate structural integrity and composite action at all stages of testing up to failure.

  12. Effect of Thickness and Fibre Volume Fraction on Impact Resistance of Steel Fibre Reinforced Concrete (SFRC)

    NASA Astrophysics Data System (ADS)

    Che Muda, Zakaria; Usman, Fathoni; Syamsir, Agusril; Shao Yang, Chen; Nasharuddin Mustapha, Kamal; Beddu, Salmia; Thiruchelvam, Sivadass; Liyana Mohd Kamal, Nur; Ashraful Alam, Md; Birima, Ahmed H.; Itam, Zarina; Zaroog, O. S.

    2016-03-01

    This paper investigate the effect of the thickness and fibre volume fraction (VF) on the impact performance of steel fibre reinforced concrete (SFRC) for the concrete slab of 300mm × 300mm size reinforced subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.236 kg drop at 0.57 m height has been used in this research work. The objective of this research is to study the relationship of impact resistance SFRC against slab thickness and volume fraction. There is a good linear correlation between impact resistances of SFRC against slab thickness. However the impact resistance of SFRC against percentage of volume fraction exhibit a non-linear relationship.

  13. Effect of Steel Fibres Distribution on Impact Resistance Performance of Steel Fibre Reinforced Concrete (SFRC)

    NASA Astrophysics Data System (ADS)

    Che Muda, Zakaria; Liyana Mohd Kamal, Nur; Syamsir, Agusril; Shao Yang, Chen; Beddu, Salmia; Nasharuddin Mustapha, Kamal; Thiruchelvam, Sivadass; Usman, Fathoni; Itam, Zarina; Ashraful Alam, Md; Birima, Ahmed H.; Zaroog, O. S.

    2016-03-01

    This paper investigate the effect of the mesh distribution on the impact performance of steel fibre reinforced concrete (SFRC) for the concrete slab of 300mm × 300mm size reinforced with varied thickness and fraction volume subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.236 kg drop at 0.57 m height has been used in this research work. The objective of this research is to study the effect of the mesh distribution on the impact resistance SFRC for various slab thickness and fraction volume. Random fibre distribution is the more effective than the top and bottom fibre distribution in terms of absorption of impact energy, crack resistance, the ability to control crack formation and propagation against impact energy.

  14. Influence of Tension Stiffening on the Flexural Stiffness of Reinforced Concrete Circular Sections.

    PubMed

    Morelli, Francesco; Amico, Cosimo; Salvatore, Walter; Squeglia, Nunziante; Stacul, Stefano

    2017-06-18

    Within this paper, the assessment of tension stiffening effects on a reinforced concrete element with the circular sections subjected to axial and bending loads is presented. To this purpose, an enhancement of an analytical model already present within the actual technical literature is proposed. The accuracy of the enhanced method is assessed by comparing the experimental results carried out in past research and the numerical ones obtained by the model. Finally, a parametric study is executed in order to study the influence of axial compressive force on the flexural stiffness of reinforced concrete elements that are characterized by a circular section, comparing the secant stiffness evaluated at yielding and at maximum resistance, considering and not considering the effects of tension stiffness.

  15. Influence of Tension Stiffening on the Flexural Stiffness of Reinforced Concrete Circular Sections

    PubMed Central

    Morelli, Francesco; Amico, Cosimo; Salvatore, Walter; Squeglia, Nunziante; Stacul, Stefano

    2017-01-01

    Within this paper, the assessment of tension stiffening effects on a reinforced concrete element with circular section subjected to axial and bending loads is presented. To this purpose, an enhancement of an analytical model already present within the actual technical literature is proposed. The accuracy of the enhanced method is assessed by comparing the experimental results carried out in past research and the numerical ones obtained by the model. Finally, a parametric study is executed in order to study the influence of axial compressive force on the flexural stiffness of reinforced concrete elements that are characterized by a circular section, comparing the secant stiffness evaluated at yielding and at maximum resistance, considering and not considering the effects of tension stiffness. PMID:28773028

  16. Damage detection of simply supported reinforced concrete beam by S transform

    NASA Astrophysics Data System (ADS)

    Liu, Ning; Xi, Jiaxin; Zhang, Xuebing; Liu, Zhenzhou

    2017-08-01

    Signal processing is the key component of vibration-based structural damage detection. The S transform is variable window of short time Fourier transform (STFT) or an extension of wavelet transform (WT). The goal of using S transform is to extract subtle changes in the vibration signals in order to detect and quantify the damage in the structure. This paper presents the concentrated load is applied to the simply supported reinforced concrete beam and adopting the stepwise loading method, the vibration signals of each loading and unloading state is obtained by using the hammer impact. Then the vibration data of the reinforced concrete beam pre-damage and post-damage is analysed by S transform. Experimental result shows the potential ability of S transform in identifying peak energy changes and multiple reflections with different loading force state.

  17. LONG-TERM EFFECTS OF WASTE SOLUTIONS ON CONCRETE AND REINFORCING STEEL

    SciTech Connect

    DANIEL JI; START DC; KAAR PH

    1983-05-28

    This report has been prepared for the In Situ Waste Disposal Program Tank Assessment Task (WG-11) as part of an investigation to evaluate the long-term performance of waste storage tanks at the Hanford Site. This report, prepared by the Portland Cement Association, presents the results of four years of concrete degradation studies which exposed concrete and reinforcing steel, under load and at 180 F, to simulated double-shell slurry, simulated salt cake solution, and a control solution. Exposure length varied from 3 months to 36 months. In all cases, examination of the concrete and reinforcing steel at the end of the exposure indicated there was no attack, i.e., no evidence of rusting, cracking, disruption of mill scale or loss of strength. Radioactive waste resulting from the chemical processing of reactor fuel for recovery of special nuclear materials (primarily plutonium), has been accumulating at the Hanford Site since 1944. The defense waste is currently being stored in underground waste tanks and in capsules stored in water basins. Current U.S. Department of Energy (DOE) strategy is to emphasize development and implementation of technology for removal, solidification, and final disposition of defense waste at the Savannah River Site first, then at the Hanford Site. Final disposal of waste in tanks at Hanford is expected to consist of in-place stabilization of most tanks. Selected tank wastes may be retrieved. Disposal operations will be carried out during the next several decades. Consequently, defense waste will remain in the existing underground tanks at Hanford for at least several decades. To ensure the safe storage of the waste, the waste storage tanks are being evaluated for continued service as part of the DOE Waste Tank Evaluation Program (AR-005-10-02-G). Technical studies and laboratory tests have been conducted to determine the effect of the stored waste's chemicals and temperature on the reinforced concrete. Waste solutions, which can be

  18. Analysis and design of on-grade reinforced concrete track support structures

    NASA Technical Reports Server (NTRS)

    Mclean, F. G.; Williams, R. D.; Greening, L. R.

    1972-01-01

    For the improvement of rail service, the Department of Transportation, Federal Rail Administration, is sponsoring a test track on the Atchison, Topeka, and Santa Fe Railway. The test track will contain nine separate rail support structures, including one conventional section for control and three reinforced concrete structures on grade, one slab and two beam sections. The analysis and design of these latter structures was accomplished by means of the finite element method, NASTRAN, and is presented.

  19. Field Testing of High Current Electrokinetic Nanoparticle Treatment for Corrosion Mitigation in Reinforced Concrete

    NASA Technical Reports Server (NTRS)

    Cardenas, Henry; Alexander, Joshua; Kupwade-Patil, Kunal; Calle, Luz marina

    2010-01-01

    Electrokinetic Nanoparticle (EN) treatment was used as a rapid repair measure to mitigate chloride induced corrosion of reinforced concrete in the field. EN treatment uses an electric field to transport positively charged nanoparticles to the reinforcement through the concrete capillary pores. Cylindrical reinforced concrete specimens were batched with 4.5 wt % salt content (based on cement mass). Three distinct electrokinetic treatments were conducted using high current density (up to 5 A/m2) to form a chloride penetration barrier that was established in 5 days, as opposed to the traditional 6-8 weeks, generally required for electrochemical chloride extraction (ECE). These treatments included basic EN treatment, EN with additional calcium treatment, and basic ECE treatment. Field exposures were conducted at the NASA Beachside Corrosion Test Site, Kennedy Space Center, Florida, USA. The specimens were subjected to sea water immersion at the test site as a posttreatment exposure. Following a 30-day post-treatment exposure period, the specimens were subjected to indirect tensile testing to evaluate treatment impact. The EN treated specimens exhibited 60% and 30% increases in tensile strength as compared to the untreated controls and ECE treated specimens respectively. The surfaces of the reinforcement bars of the control specimens were 67% covered by corrosion products. In contrast, the EN treated specimens exhibited corrosion coverage of only 4%. Scanning electron microscopy (SEM) revealed a dense concrete microstructure adjacent to the bars of the treated specimens as compared to the control and ECE specimens. Energy dispersive spectroscopic (EDS) analysis of the polished EN treated specimens showed a reduction in chloride content by a factor of 20 adjacent to the bars. This study demonstrated that EN treatment was successful in forming a chloride penetration barrier rapidly. This work also showed that the chloride barrier was effective when samples were exposed to

  20. Performance Assessment of Discontinuous Fibers in Fiber Reinforced Concrete: Current State-of-the-Art

    DTIC Science & Technology

    2017-07-01

    Modeling for Force Protection” ERDC/GSL TR-17-19 ii Abstract Fiber-reinforced concretes have been developed and tested for years. During this...understanding of fiber performance has been based on a single fiber pullout test . Through the years these tests have provided critical insight into...multiple fiber pullout tests (Cusatis et al. 2015). ................... 11 Figure 5. Load vs. slip curves for initial fiber spacing tests (Burchfield

  1. Integrity assessment of grouted posttensioning cables and reinforced concrete of a nuclear containment building

    NASA Astrophysics Data System (ADS)

    Philipose, K.; Shenton, B.

    2011-04-01

    The Containment Buildings of CANDU Nuclear Generating Stations were designed to house nuclear reactors and process equipment and also to provide confinement of releases from a potential nuclear accident such as a Loss Of Coolant Accident (LOCA). To meet this design requirement, a post-tensioning system was designed to induce compressive stresses in the structure to counteract the internal design pressure. The CANDU reactor building at Gentilly-1 (G-1), Quebec, Canada (250 MWe) was built in the early 1970s and is currently in a decommissioned state. The structure at present is under surveillance and monitoring. In the year 2000, a field investigation was conducted as part of a condition assessment and corrosion was detected in some of the grouted post-tension cable strands. However, no further work was done at that time to determine the cause, nature, impact and extent of the corrosion. An investigation of the Gentilly-1 containment building is currently underway to assess the condition of grouted post-tensioning cables and reinforced concrete. At two selected locations, concrete and steel reinforcements were removed from the containment building wall to expose horizontal cables. Individual cable strands and reinforcement bars were instrumented and measurements were taken in-situ before removing them for forensic examination and destructive testing to determine the impact of ageing and corrosion. Concrete samples were also removed and tested in a laboratory. The purpose of the field investigation and laboratory testing, using this structure as a test bed, was also to collect material ageing data and to develop potential Nondestructive Examination (NDE) methods to monitor Containment Building Integrity. The paper describes the field work conducted and the test results obtained for concrete, reinforcement and post-tensioning cables.

  2. Utilization of power plant bottom ash as aggregates in fiber-reinforced cellular concrete.

    PubMed

    Lee, H K; Kim, H K; Hwang, E A

    2010-02-01

    Recently, millions tons of bottom ash wastes from thermoelectric power plants have been disposed of in landfills and coastal areas, regardless of its recycling possibility in construction fields. Fiber-reinforced cellular concrete (FRCC) of low density and of high strength may be attainable through the addition of bottom ash due to its relatively high strength. This paper focuses on evaluating the feasibility of utilizing bottom ash of thermoelectric power plant wastes as aggregates in FRCC. The flow characteristics of cement mortar with bottom ash aggregates and the effect of aggregate type and size on concrete density and compressive strength were investigated. In addition, the effects of adding steel and polypropylene fibers for improving the strength of concrete were also investigated. The results from this study suggest that bottom ash can be applied as a construction material which may not only improve the compressive strength of FRCC significantly but also reduce problems related to bottom ash waste.

  3. Research on construction technology of shaped steel reinforced concrete beam and column

    NASA Astrophysics Data System (ADS)

    Zhu, Shan; Zhang, Zimeng; Liu, Lengjing; Bu, Fangming

    2017-04-01

    The Shaped Steel Reinforced Concrete structures are increasingly used in large-span or irregularly shaped public buildings. In the actual construction, cross-operation of steel structures and concrete is more frequent. Traditional construction method causes a lot of quality problems easily like installation deviation of beam and column, improper treatment of steel at the joints of beams and columns, and unevenness of concrete surface. If you can not take timely measures to deal with or prevent, it will inevitably have a great impact on the reliability of the structure, and also delay the construction schedule. This paper makes related research about the quality issues, proposes corresponding solutions and provides a complete set of construction technology processes. At last, through engineering case, we analyze the economic and social benefits.

  4. Improved Bond Equations for Fiber-Reinforced Polymer Bars in Concrete.

    PubMed

    Pour, Sadaf Moallemi; Alam, M Shahria; Milani, Abbas S

    2016-08-30

    This paper explores a set of new equations to predict the bond strength between fiber reinforced polymer (FRP) rebar and concrete. The proposed equations are based on a comprehensive statistical analysis and existing experimental results in the literature. Namely, the most effective parameters on bond behavior of FRP concrete were first identified by applying a factorial analysis on a part of the available database. Then the database that contains 250 pullout tests were divided into four groups based on the concrete compressive strength and the rebar surface. Afterward, nonlinear regression analysis was performed for each study group in order to determine the bond equations. The results show that the proposed equations can predict bond strengths more accurately compared to the other previously reported models.

  5. Improved Bond Equations for Fiber-Reinforced Polymer Bars in Concrete

    PubMed Central

    Pour, Sadaf Moallemi; Alam, M. Shahria; Milani, Abbas S.

    2016-01-01

    This paper explores a set of new equations to predict the bond strength between fiber reinforced polymer (FRP) rebar and concrete. The proposed equations are based on a comprehensive statistical analysis and existing experimental results in the literature. Namely, the most effective parameters on bond behavior of FRP concrete were first identified by applying a factorial analysis on a part of the available database. Then the database that contains 250 pullout tests were divided into four groups based on the concrete compressive strength and the rebar surface. Afterward, nonlinear regression analysis was performed for each study group in order to determine the bond equations. The results show that the proposed equations can predict bond strengths more accurately compared to the other previously reported models. PMID:28773859

  6. Evaluation of non-metallic fiber reinforced concrete in new full depth pcc pavements. Final report

    SciTech Connect

    Ramakrishnan, V.; Tolmare, N.S.

    1998-12-30

    This final report presents the construction and performance evaluation of a new full depth pavement, constructed with a new type non-metallic fiber reinforced concrete (NMFRC). The mixture proportions used, the quality control tests conducted for the evaluation of the fresh and hardened concrete properties, the procedure used for mixing, transporting, placing, consolidating, finishing, and curing of the concrete are described. Periodic inspection of the full depth pavement was done and this report includes the results of these inspections. The feasibility of using this NMFRC in the construction of highway structures has been discussed. The new NMFRC with enhanced fatigue, impact resistance, modulus of rupture, ductility and toughness properties is suitable for the construction of full depth pavements. However, a life-cycle cost analysis shows that NMFRC is not a favorable choice, because of it`s high initial cost.

  7. Computer-Aided Construction at Designing Reinforced Concrete Columns as Per Ec

    NASA Astrophysics Data System (ADS)

    Zielińska, M.; Grębowski, K.

    2015-02-01

    The article presents the authors' computer program for designing and dimensioning columns in reinforced concrete structures taking into account phenomena affecting their behaviour and information referring to design as per EC. The computer program was developed with the use of C++ programming language. The program guides the user through particular dimensioning stages: from introducing basic data such as dimensions, concrete class, reinforcing steel class and forces affecting the column, through calculating the creep coefficient taking into account the impact of imperfection depending on the support scheme and also the number of mating members at load shit, buckling length, to generating the interaction curve graph. The final result of calculations provides two dependence points calculated as per methods of nominal stiffness and nominal curvature. The location of those points relative to the limit curve determines whether the column load capacity is assured or has been exceeded. The content of the study describes in detail the operation of the computer program and the methodology and phenomena which are indispensable at designing axially and eccentrically the compressed members of reinforced concrete structures as per the European standards.

  8. Application of fiber-reinforced plastic rods as prestressing tendons in concrete structures. Final report

    SciTech Connect

    Mattock, A.H.; Babaei, K.

    1989-08-01

    The study is concerned with the possibility of utilizing fiber-reinforced plastic rods as prestressing tendons, in place of traditional steel tendons, in elements of prestressed-concrete bridges exposed to corrosive environments. A survey was made of available information on the behavior characteristics of fiber-reinforced plastic tension elements and, in particular, those of glass-fiber-reinforced (GFR) tension elements. Also, an analytical study was made of the flexural behavior of concrete elements prestressed by GFR tendons. Based on the analytical study and on the survey of available information, an assessment is made of the impact on the design of prestressed-concrete members if GFR tendons are used. Some preliminary design recommendations are made, together with proposals for research needed before GFR prestressing tendons should be used in practice. Four GFR tendons with Con-Tech Systems anchorages were tested, the primary variable being the embedded length of the GFR rods in the anchorages. All the tendons failed by the rods pulling out of the anchorages. For embedded lengths of 15.2 in or greater, the failure loads were 90% of the advertised tendon strength of 220 ksi, or about 100% of the guaranteed tensile strength of 197 ksi (60 kN/rod).

  9. Sensitivity Analysis of Corrosion Rate Prediction Models Utilized for Reinforced Concrete Affected by Chloride

    NASA Astrophysics Data System (ADS)

    Siamphukdee, Kanjana; Collins, Frank; Zou, Roger

    2013-06-01

    Chloride-induced reinforcement corrosion is one of the major causes of premature deterioration in reinforced concrete (RC) structures. Given the high maintenance and replacement costs, accurate modeling of RC deterioration is indispensable for ensuring the optimal allocation of limited economic resources. Since corrosion rate is one of the major factors influencing the rate of deterioration, many predictive models exist. However, because the existing models use very different sets of input parameters, the choice of model for RC deterioration is made difficult. Although the factors affecting corrosion rate are frequently reported in the literature, there is no published quantitative study on the sensitivity of predicted corrosion rate to the various input parameters. This paper presents the results of the sensitivity analysis of the input parameters for nine selected corrosion rate prediction models. Three different methods of analysis are used to determine and compare the sensitivity of corrosion rate to various input parameters: (i) univariate regression analysis, (ii) multivariate regression analysis, and (iii) sensitivity index. The results from the analysis have quantitatively verified that the corrosion rate of steel reinforcement bars in RC structures is highly sensitive to corrosion duration time, concrete resistivity, and concrete chloride content. These important findings establish that future empirical models for predicting corrosion rate of RC should carefully consider and incorporate these input parameters.

  10. Field Testing of High Current Electrokinetic Nanoparticle Treatment for Corrosion Mitigation in Reinforced Concrete

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina; Alexander, Joshua B.; Cardenas, Henry E.; Kupwade-Patil, Kunal

    2008-01-01

    This work examines field performance of nanoscale pozzolan treatments delivered el ctrokinetically to suppress chloride induced corrosion of concrete reinforcement. The particles are 20 nm silica spheres coated with 2 nm alumina particles that carry a net positive charge. Earlier work demonstrated that the alumina particles were stripped from the silica carriers and formed a dense phase with an interparticle spacing that is small enough to inhibit the transport of solvated chlorides. A D.C. field was used to inject the particles into the pores of concrete specimens, directly toward the mild steel bars that were embedded within each 3 inch diameter by 6 inch length concrete specimen. The voltage was held constant at 25 v per inch of concrete cover for a period of 7 days. These voltages permitted current densities as high as 3 A/sq m. During the final 3 days, a 1 molar solution of calcium nitrate tetrahydrate was used to provide a source of calcium to facilitate stronger and more densified phase formation within the pores. In a departure from prior work the particle treatments were started concurrent with chloride extraction in order to determine if particle delivery would inhibit chloride transport. Following treatment the specimens were immersed in seawater for 4 weeks. After this posttreatment exposure, the specimens were tested for tensile strength and the steel reinforcement was examined for evidence of corrosion. Scanning electron microscopy was conducted to assess impact on microstructure.

  11. Reinforcement of Shear Thinning Protein Hydrogels by Responsive Block Copolymer Self-Assembly

    PubMed Central

    Glassman, Matthew J.; Chan, Jacqueline

    2014-01-01

    Shear thinning hydrogels are promising materials that exhibit rapid self-healing following the cessation of shear, making them attractive for a variety of applications including injectable biomaterials. In this work, self-assembly is demonstrated as a strategy to introduce a reinforcing network within shear thinning artificially engineered protein gels, enabling a responsive transition from an injectable state at low temperatures with a low yield stress to a stiffened state at physiological temperatures with resistance to shear thinning, higher toughness, and reduced erosion rates and creep compliance. Protein-polymer triblock copolymers capable of the responsive self-assembly of two orthogonal networks have been synthesized by conjugating poly(N-isopropylacrylamide) to the N- and C- termini of a protein midblock decorated with coiled-coil self-associating domains. Midblock association forms a shear-thinning network, while endblock aggregation at elevated temperatures introduces a second, independent physical network into the protein hydrogel. These new, reversible crosslinks introduce extremely long relaxation times and lead to a five-fold increase in the elastic modulus, significantly larger than is expected from transient network theory. Thermoresponsive reinforcement reduces the high temperature creep compliance by over four orders of magnitude, decreases the erosion rate by at least a factor of five, and increases the yield stress by up to a factor of seven. The reinforced hydrogels also exhibit enhanced resistance to plastic deformation and failure in uniaxial compression. Combined with the demonstrated potential of shear thinning artificial protein hydrogels for various uses, including the minimally-invasive implantation of bioactive scaffolds, this reinforcement mechanism broadens the range of applications that can be addressed with shear-thinning physical gels. PMID:25568642

  12. Corrosion process and structural performance of a 17 year old reinforced concrete beam stored in chloride environment

    SciTech Connect

    Vidal, T. Castel, A. Francois, R.

    2007-11-15

    The long-term corrosion process of reinforced concrete beams is studied in this paper. The reinforced concrete elements were stored in a chloride environment for 17years under service loading in order to be representative of real structural conditions. At different stages, cracking maps were drawn, total chloride contents were measured and mechanical tests were performed. Results show that the bending cracks and their width do not influence significantly the service life of the structure. The chloride threshold at the reinforcement depth, used by standards as a single parameter to predict the end of the initiation period, is a necessary but not a sufficient parameter to define service life. The steel-concrete interface condition is also a determinant parameter. The bleeding of concrete is an important cause of interface de-bonding which leads to an early corrosion propagation of the reinforcements. The structural performance under service load (i.e.: stiffness in flexure) is mostly affected by the corrosion of the tension reinforcement (steel cross-section and the steel-concrete bond reduction). Limit-state service life design based on structural performance reduction in terms of serviceability shows that the propagation period of the corrosion process is an important part of the reinforced concrete service life.

  13. Evaluation of a metal shear web selectively reinforced with filamentary composites for space shuttle application

    NASA Technical Reports Server (NTRS)

    Laakso, J. H.; Straayer, J. W.

    1974-01-01

    A final program summary is reported for test and evaluation activities that were conducted for space shuttle web selection. Large scale advanced composite shear web components were tested and analyzed to evaluate application of advanced composite shear web construction to a space shuttle orbiter thrust structure. The shear web design concept consisted of a titanium-clad + or - 45 deg boron/epoxy web laminate stiffened with vertical boron-epoxy reinforced aluminum stiffeners and logitudinal aluminum stiffening. The design concept was evaluated to be efficient and practical for the application that was studied. Because of the effects of buckling deflections, a requirement is identified for shear buckling resistant design to maximize the efficiency of highly-loaded advanced composite shear webs.

  14. Ultra-high performance fibre-reinforced concrete under impact: experimental analysis of the mechanical response in extreme conditions and modelling using the Pontiroli, Rouquand and Mazars model.

    PubMed

    Erzar, Benjamin; Pontiroli, Christophe; Buzaud, Eric

    2017-01-28

    To evaluate the vulnerability of ultra-high performance fibre-reinforced concrete (UHPFRC) infrastructure to rigid projectile penetration, over the last few years CEA-Gramat has led an experimental and numerical research programme in collaboration with French universities. During the penetration process, concrete is subjected to extreme conditions of pressure and strain rate. Plasticity mechanisms as well as dynamic tensile and/or shear damage are activated during the tunnelling phase and the cratering of the concrete target. Each mechanism has been investigated independently at the laboratory scale and the role of steel fibres especially has been analysed to understand their influence on the macroscopic behaviour. To extend the experimental results to the structural scale, penetration tests on UHPFRC slabs have been conducted by CEA-Gramat. The analysis of this dataset combined with material characterization experiments allows the role of steel fibres to be identified in the different plasticity and damage mechanisms occurring during penetration. In parallel, some improvements have been introduced into the concrete model developed by Pontiroli, Rouquand and Mazars (PRM model), especially to take into account the contribution made by the fibres in the tensile fracture process. After a primary phase of validation, the capabilities of the PRM model are illustrated by performing numerical simulations of projectile penetration into UHPFRC concrete structures.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  15. Ultra-high performance fibre-reinforced concrete under impact: experimental analysis of the mechanical response in extreme conditions and modelling using the Pontiroli, Rouquand and Mazars model

    NASA Astrophysics Data System (ADS)

    Erzar, Benjamin; Pontiroli, Christophe; Buzaud, Eric

    2017-01-01

    To evaluate the vulnerability of ultra-high performance fibre-reinforced concrete (UHPFRC) infrastructure to rigid projectile penetration, over the last few years CEA-Gramat has led an experimental and numerical research programme in collaboration with French universities. During the penetration process, concrete is subjected to extreme conditions of pressure and strain rate. Plasticity mechanisms as well as dynamic tensile and/or shear damage are activated during the tunnelling phase and the cratering of the concrete target. Each mechanism has been investigated independently at the laboratory scale and the role of steel fibres especially has been analysed to understand their influence on the macroscopic behaviour. To extend the experimental results to the structural scale, penetration tests on UHPFRC slabs have been conducted by CEA-Gramat. The analysis of this dataset combined with material characterization experiments allows the role of steel fibres to be identified in the different plasticity and damage mechanisms occurring during penetration. In parallel, some improvements have been introduced into the concrete model developed by Pontiroli, Rouquand and Mazars (PRM model), especially to take into account the contribution made by the fibres in the tensile fracture process. After a primary phase of validation, the capabilities of the PRM model are illustrated by performing numerical simulations of projectile penetration into UHPFRC concrete structures. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  16. Quantifying reinforced concrete bridge deck deterioration using ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Martino, Nicole Marie

    Bridge decks are deteriorating at an alarming rate due to corrosion of the reinforcing steel, requiring billions of dollars to repair and replace them. Furthermore, the techniques used to assess the decks don't provide enough quantitative information. In recent years, ground penetrating radar (GPR) has been used to quantify deterioration by comparing the rebar reflection amplitudes to technologies serving as ground truth, because there is not an available amplitude threshold to distinguish healthy from corroded areas using only GPR. The goal of this research is to understand the relationship between GPR and deck deterioration, and develop a model to determine deterioration quantities with GPR alone. The beginning of this research determines that not only is the relationship between GPR and rebar corrosion stronger than the relationship between GPR and delaminations, but that the two are exceptionally correlated (90.2% and 86.6%). Next, multiple bridge decks were assessed with GPR and half-cell potential (HCP). Statistical parameters like the mean and skewness were computed for the GPR amplitudes of each deck, and coupled with actual corrosion quantities based on the HCP measurements to form a future bridge deck model that can be used to assess any deck with GPR alone. Finally, in order to understand exactly which component of rebar corrosion (rust, cracking or chloride) attenuates the GPR data, computational modeling was carried out to isolate each variable. The results indicate that chloride is the major contributor to the rebar reflection attenuation, and that computational modeling can be used to accurately simulate GPR attenuation due to chloride.

  17. Effect of shearing on the reinforcement properties of vital wheat gluten

    USDA-ARS?s Scientific Manuscript database

    An aqueous dispersion of vital wheat gluten and styrene-butadiene rubber was subjected to high-shear mixing in an attempt to reduce the aggregate size and enhance filler-matrix interactions with the goal of improving the reinforcement properties of the overall composite. Composites were formulated u...

  18. Application of the wave finite element method to reinforced concrete structures with damage

    NASA Astrophysics Data System (ADS)

    El Masri, Evelyne; Ferguson, Neil; Waters, Timothy

    2016-09-01

    Vibration based methods are commonly deployed to detect structural damage using sensors placed remotely from potential damage sites. Whilst many such techniques are modal based there are advantages to adopting a wave approach, in which case it is essential to characterise wave propagation in the structure. The Wave Finite Element method (WFE) is an efficient approach to predicting the response of a composite waveguide using a conventional FE model of a just a short segment. The method has previously been applied to different structures such as laminated plates, thinwalled structures and fluid-filled pipes. In this paper, the WFE method is applied to a steel reinforced concrete beam. Dispersion curves and wave mode shapes are first presented from free wave solutions, and these are found to be insensitive to loss of thickness in a single reinforcing bar. A reinforced beam with localised damage is then considered by coupling an FE model of a short damaged segment into the WFE model of the undamaged beam. The fundamental bending, torsion and axial waves are unaffected by the damage but some higher order waves of the cross section are significantly reflected close to their cut-on frequencies. The potential of this approach for detecting corrosion and delamination in reinforced concrete beams will be investigated in future work.

  19. Impact Resistance Behaviour of Light Weight Rice Husk Concrete with Bamboo Reinforcement

    NASA Astrophysics Data System (ADS)

    Che Muda, Zakaria; Beddu, Salmia; Syamsir, Agusril; Sigar Ating, Joshua; Liyana Mohd Kamal, Nur; Nasharuddin Mustapha, Kamal; Thiruchelvam, Sivadass; Usman, Fathoni; Ashraful Alam, Md; Birima, Ahmed H.; Zaroog, O. S.

    2016-03-01

    This paper investigate the performance of lightweight rice husk concrete (LWRHC) with varied bamboo reinforcement content for the concrete slab of 300mm × 300mm size reinforced with varied slab thickness subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.236 kg drop at 0.65 m height has been used in this research work. The main variables for the study is to find the relationship of the impact resistance against the amount of bamboo reinforcement and slab thickness. A linear relationship has been established between first and ultimate crack resistance against bamboo diameters and slab thickness by the experiment. The linear relationship has also been established between the service (first) crack and ultimate crack resistance against the bamboo reinforcement diameter and slab thickness. 5% RH content exhibit better first and ultimate crack resistance up to 1.80 times and up to 1.72 times respectively against 10% RH content.

  20. Impact resistance of sustainable construction material using light weight oil palm shells reinforced geogrid concrete slab

    NASA Astrophysics Data System (ADS)

    Muda, Z. C.; Malik, G.; Usman, F.; Beddu, S.; Alam, M. A.; Mustapha, K. N.; Birima, A. H.; Zarroq, O. S.; Sidek, L. M.; Rashid, M. A.

    2013-06-01

    This paper investigate the performance of lightweight oil palm shells (OPS) concrete slab with geogrid reinforcement of 300mm × 300mm size with 20mm, 30mm and 40 mm thick casted with different geogrid orientation and boundary conditions subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.2 kg drop at 1 m height has been used in this research work. The main variables for the study is to find the relationship of the impact resistance the slab thickness, boundary conditions and geogrid reinforcement orientation. Test results indicate that the used of the geogrid reinforcement increased the impact resistance under service (first) limit crack up to 5.9 times and at ultimate limit crack up to 20.1 times against the control sample (without geogrid). A good linear relationship has been established between first and ultimate crack resistance against the slab thickness. The orientation of the geogrid has minor significant to the crack resistance of the OPS concrete slab. OPS geogrid reinforced slab has a good crack resistance properties that can be utilized as a sustainable impact resistance construction materials.

  1. Analytical and Experimental Assessment of Seismic Vulnerability of Beam-Column Joints without Transverse Reinforcement in Concrete Buildings

    NASA Astrophysics Data System (ADS)

    Hassan, Wael Mohammed

    Beam-column joints in concrete buildings are key components to ensure structural integrity of building performance under seismic loading. Earthquake reconnaissance has reported the substantial damage that can result from inadequate beam-column joints. In some cases, failure of older-type corner joints appears to have led to building collapse. Since the 1960s, many advances have been made to improve seismic performance of building components, including beam-column joints. New design and detailing approaches are expected to produce new construction that will perform satisfactorily during strong earthquake shaking. Much less attention has been focused on beam-column joints of older construction that may be seismically vulnerable. Concrete buildings constructed prior to developing details for ductility in the 1970s normally lack joint transverse reinforcement. The available literature concerning the performance of such joints is relatively limited, but concerns about performance exist. The current study aimed to improve understanding and assessment of seismic performance of unconfined exterior and corner beam-column joints in existing buildings. An extensive literature survey was performed, leading to development of a database of about a hundred tests. Study of the data enabled identification of the most important parameters and the effect of each parameter on the seismic performance. The available analytical models and guidelines for strength and deformability assessment of unconfined joints were surveyed and evaluated. In particular, The ASCE 41 existing building document proved to be substantially conservative in joint shear strength estimation. Upon identifying deficiencies in these models, two new joint shear strength models, a bond capacity model, and two axial capacity models designed and tailored specifically for unconfined beam-column joints were developed. The proposed models strongly correlated with previous test results. In the laboratory testing phase of

  2. Effect of Waste Plastic Shreds on Bond Resistance between Concrete and Steel Reinforcement

    NASA Astrophysics Data System (ADS)

    Osifala, K. B.; Salau, M. A.; Adeniyi, A. A.

    2015-11-01

    This paper investigates the effect of waste plastic shreds on steel-concrete bond. Forty RILEM test specimens with 16mm and 20mm diameter high-yield reinforcing bars were cast and tested. Fifteen specimens with 16mm and 20mm each were cast with the addition of waste plastic shreds at varying percentages of 1%, 1.5% and 2%; another ten RILEM specimens with 16mm and 20mm diameter bars at 0% of waste plastic shreds were cast as reference. Nine 150mm cubes, with three taken from each batch of various percentages of waste plastic shreds, were used to monitor the concrete strength. From the test results and analysis, the compressive strength of concrete was found to reduce with increased percentages of waste plastic shreds, while the waste plastic shreds material was found not to improve the bond resistance between concrete and steel. However, though lower than normal concrete, there was an increase in the bond resistance with increase in the percent of plastic shreds. The bond resistance of 16mm was also found to be higher than that of 20mm in all the specimens tested.

  3. Seismic load tests on reinforced concrete beam-column sandwich joints with strengthening measures

    NASA Astrophysics Data System (ADS)

    Yang, Zhi-hong; Li, Ying-min; Liu, Jian-wei

    2010-03-01

    Reinforced concrete high-rise buildings with high strength concrete (HSC) column and normal strength concrete (NSC) floor are popular nowadays. For these structures, it is ineffective to construct beam-column joint with high strength concrete. So beam-column joints with normal strength concrete attract abundant attention and are strongly recommended in china recent years. In this paper, we refer to this type of joints as sandwich joints. In order to improve seismic behavior of sandwich joints with high stress, strengthening measures including addition of vertical dowels, addition of diagonal bars, and enhancement of joint constraint were proposed to apply to engineering practice recent years. In this paper, 6 full scale sandwich joint specimens were test under cyclic load to investigate the validity of strengthening measures. Tested specimens were consist of 1 specimen with additional vertical dowels, 2 specimens with additional diagonal bars, and 1 specimen with additional lateral beams, compared with 2 specimens without strengthening measures. Integrated seismic performances of these specimens were studied, such as load resistance behavior, deflection performance, ductility, energy dissipation behavior, beam bars anchorage capacity and so on. Based on the experimental results, the effect and mechanical behavior of strengthening measures were analyzed.

  4. Seismic load tests on reinforced concrete beam-column sandwich joints with strengthening measures

    NASA Astrophysics Data System (ADS)

    Yang, Zhi-Hong; Li, Ying-Min; Liu, Jian-Wei

    2009-12-01

    Reinforced concrete high-rise buildings with high strength concrete (HSC) column and normal strength concrete (NSC) floor are popular nowadays. For these structures, it is ineffective to construct beam-column joint with high strength concrete. So beam-column joints with normal strength concrete attract abundant attention and are strongly recommended in china recent years. In this paper, we refer to this type of joints as sandwich joints. In order to improve seismic behavior of sandwich joints with high stress, strengthening measures including addition of vertical dowels, addition of diagonal bars, and enhancement of joint constraint were proposed to apply to engineering practice recent years. In this paper, 6 full scale sandwich joint specimens were test under cyclic load to investigate the validity of strengthening measures. Tested specimens were consist of 1 specimen with additional vertical dowels, 2 specimens with additional diagonal bars, and 1 specimen with additional lateral beams, compared with 2 specimens without strengthening measures. Integrated seismic performances of these specimens were studied, such as load resistance behavior, deflection performance, ductility, energy dissipation behavior, beam bars anchorage capacity and so on. Based on the experimental results, the effect and mechanical behavior of strengthening measures were analyzed.

  5. Experimental Study on Mechanical Property of Steel Reinforced Concrete L-Shaped Short Columns

    NASA Astrophysics Data System (ADS)

    Li, Zhe; Qin, Hao; Dang, Hui; Li, Hui; Zhang, Jian-Shan

    The horizontal press performance of column is deteriorated because of its special-shaped section. Moreover, because the antiseismic performance of column is worse, special-shaped column is only used in regions where seismic intensity is lower. So the main problem is to enhance the ductility and shear capacity. This test study on mechanical performance has been carried out through 14 SRCLSSC and 2 RCLSSC. The study focuses on the impacts of test axial load ratio (nt), hooped reinforcement ratio (ρv), shear span ratio (λ) and steel ratio (ρss) on the shear strength and the antiseismic performance of SRCLSSC. It can be concluded that the shear strength of SRCLSSC is increasing with the increasing of nt and ρss, but the degree of increasing is small when nt is a certainty value, and that the shear strength of SRCLSSC is decreasing with increasing of λ The shear resistance formula of L-shaped column is derived through tests, the calculated results are in correspondence with those of the tests. It also can be concluded that the hysteretic loops of the SRCLSSC are full and the hysteretic behaviors are improved; the displacement ductility is increasing with increasing of ρv and ρss, but decreasing with the increasing of nt; the degree of variety in high axial load ratio is larger than that in low axial load ratio. If steel bars are added, the shear strength and displacement ductility of SRCLSSC are increased in a large degree.

  6. Analytical and Experimental Studies of the Seismic Performance of Reinforced Concrete Structural Wall Boundary Elements

    NASA Astrophysics Data System (ADS)

    Hilson, Christopher William

    Following the February 27, 2010 Mw 8.8 Maule earthquake, an international effort was undertaken to better understand reasons for observed damage to concrete structural walls in buildings located in the affected region of Chile and to address potential design implications. The Chilean building code for concrete structures is based on the U.S. ACI 318 building code; however, based on the observed performance of over 400 buildings in the March 1985 earthquake-impacted Vina del Mar, Chilean Code NCh433.Of96 included an exception that special boundary elements (SBEs)---which are commonly required for walls in U.S. buildings---need not be provided. By taking exception to the special boundary element detailing provisions, the Chilean code allowed thin wall boundary zones with relatively large (typically 20 cm) spacing of transverse reinforcement (essentially unconfined) to be constructed. Given these differences, the 2010 earthquake is an excellent opportunity to assess the performance of reinforced concrete buildings designed using modern codes similar to those used in the United States. Data from damaged and undamaged buildings, as well as from parametric and experimental studies, are used to provide recommendations to improve the efficacy of U.S. provisions designed to inhibit structural damage at wall boundaries. Seven Chilean buildings were selected to investigate the performance of boundary elements during the 2010 earthquake. Several walls from each of the seven buildings were chosen to evaluate the ACI 318-11 Section 21.9.6.2 displacement-based trigger equation for determining if SBEs would have been required and if observed damage was consistent with the evaluation result (i.e., SBE required, no damage; SBE required, damage observed). The propensity of boundary longitudinal reinforcement to buckle was also investigated, taking into consideration the influence of boundary transverse reinforcement configuration and longitudinal reinforcement strain history. In

  7. Retrofit of hollow concrete masonry infilled steel frames using glass fiber reinforced plastic laminates

    NASA Astrophysics Data System (ADS)

    Hakam, Zeyad Hamed-Ramzy

    2000-11-01

    This study focuses on the retrofit of hollow concrete masonry infilled steel frames subjected to in-plane lateral loads using glass fiber reinforced plastic (GFRP) laminates that are epoxy-bonded to the exterior faces of the infill walls. An extensive experimental investigation using one-third scale modeling was conducted and consisted of two phases. In the first phase, 64 assemblages, half of which were retrofitted, were tested under various combined in-plane loading conditions similar to those which different regions of a typical infill wall are subjected to. In the second phase, one bare and four masonry-infilled steel frames representative of a typical single-story, single-bay panel were tested under diagonal loading to study the overall behavior and the infill-frame interaction. The relative infill-to-frame stiffness was varied as a test parameter by using two different steel frame sections. The laminates altered the failure modes of the masonry assemblages and reduced the variability and anisotropic nature of the masonry. For the prisms which failed due to shear and/or mortar joint slip, significant strength increases were observed. For those exhibiting compression failure modes, a marginal increase in strength resulted. Retrofitting the infilled frames resulted in an average increase in initial stiffness of two-fold compared to the unretrofitted infilled frames, and seemed independent of the relative infill-to-frame stiffness. However, the increase in the load-carrying capacity of the retrofitted frames compared to the unretrofitted counterparts was higher for those with the larger relative infill-to-frame stiffness parameter. Unlike the unretrofitted infill walls, the retrofitted panels demonstrated almost identical failure modes that were characterized as "strictly comer crushing" in the vicinity of the loaded comers whereas no signs of distress were evident throughout the remainder of the infill. The laminates also maintained the structural integrity of

  8. The long term effects of cathodic protection on corroding, pre-stressed concrete structures: Hydrogen embrittlement of the reinforcing steel

    NASA Astrophysics Data System (ADS)

    Enos, David George

    Assessment of the effect of cathodic protection on a chloride contaminated bridge pile involves the definition of the hydrogen embrittlement behavior of the pearlitic reinforcement combined with quantification of the local (i.e., at the steel/concrete interface) chemical and electrochemical conditions, both prior to and throughout the application of cathodic protection. The hydrogen embrittlement behavior of the reinforcement was assessed through a combination of Devanathan/Stachurski permeation experiments to quantify subsurface hydrogen concentrations, CsbH, as a function of the applied hydrogen overpotential, eta, and crack initiation tests for bluntly notched and fatigue pre-cracked tensile specimens employing elastic-plastic finite element analysis and linear elastic fracture mechanics, respectively. A threshold mobile lattice hydrogen concentration for embrittlement of 2×10sp{-7} mol/cmsp3 was established for bluntly notched and fatigue pre-cracked specimens. Crack initiation occurred by the formation of shear cracks oriented at an angle approaching 45sp° from the tensile axis, as proposed by Miller and Smith (Miller, 1970), in regions where both the longitudinal and shear stresses were maximized (i.e., near the notch root). These Miller cracks then triggered longitudinal splitting which continued until fast fracture of the remaining ligament occurred. Instrumented laboratory scale piles were constructed and partially immersed in ASTM artificial ocean water. With time, localized corrosion (crevicing) was initiated along the reinforcement, and was accompanied by an acidic shift in the pH of the occluded environment due to ferrous ion hydrolysis. Cathodic protection current densities from -0.1 muA/cmsp2 to -3.0 muA/cmsp2 were applied via a skirt anode located at the waterline. Current densities as low as 0.66 muA/cmsp2 were sufficient to deplete the dissolved oxygen concentration at the steel/concrete interface and result in the observance of hydrogen

  9. Investigation of the Suitability of the Bazant Endochronic Material Model for Modelling the Concrete in a SAMSON Analysis of a Reinforced Concrete Beam.

    DTIC Science & Technology

    1979-07-01

    I I ‘ S I I I ( ~~NVESTIGATION OF THE I SUITABILITY OF THE BAZANT ENDOCHRONIC I MATERIAL MODEL FOR MODELLING THE CONCRETE IN A SAMSON ~NALYSIS OF I A...4. T ITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED INVESTIGATION OF THE SUITABILITY OF THE BAZANT FINAL ENDOCHRONIC...MATERIAL MO-DEL FOR MODELLING THE JAN — May 1979 CONC RETE IN A SAMSON ANALYSIS OF A REINFORCED 6. PERFORMING ORG. REPORT NUMBER CONCRETE BEAM

  10. Monitoring of transverse displacement of reinforced concrete beams under flexural loading with embedded arrays of optical fibers

    NASA Astrophysics Data System (ADS)

    Gonzalez-Tinoco, Juan E.; Gomez-Rosas, Enrique R.; Guzmán-Olguín, Héctor; Khotiaintsev, Sergei; Zuñiga-Bravo, Miguel A.

    2015-04-01

    We present results of an ongoing study of structural health monitoring of concrete elements by means of arrays of telecommunications-grade optical fibers embedded in such elements. In this work, we show a possibility of using this technique for monitoring the transverse displacement of the reinforced concrete beams under flexural loading. We embedded a number of multimode silica-core/polymer-clad/polymer-coated optical fibers in a mold with preinstalled reinforcing steel bars and fresh concrete mix. Then the concrete was compacted and cured. Some optical fibers were broken during the fabrication process. The fiber survival rate varied with concrete grade, compacting technique and optical fiber type. The fibers that survived the fabrication process were employed for the monitoring. They were connected to the optical transmitter and receiver that formed a part of a larger measurement system. The system continuously measured the optical transmission of all optical fibers while the reinforced concrete beams were subjected to incremental transverse loading. We observed a quasi-linear decrease in optical transmission in all optical fibers of the array vs. the applied load and respective flexural displacement. Although the underlying phenomena that lead to such a variation in optical transmission are not clear yet, the observed behavior might be of interest for assessing the transverse displacement of the reinforced concrete beams under flexural loading.

  11. Development and mechanical characterization of carbon-fiber-reinforced cement composites and mechanical properties and structural applications of steel-fiber-reinforced concrete. (Volumes I and II)

    SciTech Connect

    Bayasi, M.Z.

    1989-01-01

    Based on a comprehensive experimental study on carbon fiber reinforced cement composites incorporating the Ashland's industrial grade carbon fiber reinforced cement composites incorporating the Ashland's inductrial grade carbon fibers (Carboflex), the optimum mix variables and processing techniques were decided. The types and proportions of different mix constituents, the fiber lengths and volume fractions, and the mixing and curing procedures which produce desirable fresh mix properties and superior hardened material performance were decided. A comprehensive experimental data set on the performance characteristics of carbon fiber reinforced cement was also generated. The research was performed in three phases: (1) Establishment of the mixing procedure and mix proportions for achieving desirable fresh mix characteristics; (2) Assessment of the trends in the effects of different mix variables on the strength of air cured specimens and further optimization of the mix proportions for achieving superior strength characteristics in addition to the desirable fresh mix workability; and (3) Optimization of the curing condition and full mechanical characterization for carbon fiber reinforced cement composites with some optimum values of fiber length and volume fraction. A comprehensive investigation was performed on the material properties and structural applications of steel fiber reinforced concrete. In studies on the application of steel fiber reinforced concrete a load bearing structural elements, the effects of steel fibers on improving the strength and ductility of concrete footings under bearing pressure, and enhancing bond between deformed bars and concrete were investigated.

  12. The use of a Phosphate-Based Migrating Corrosion Inhibitor to Repair Reinforced Concrete Elements Contaminated by Chlorides

    NASA Astrophysics Data System (ADS)

    Tittarelli, Francesca; Mobili, Alessandra; Bellezze, Tiziano

    2017-08-01

    The use of sodium monofluorophosphate (MFP) was experimented as migrator inhibiting treatment against corrosion of reinforced concrete elements induced by chlorides. The results show that sodium monofluorophosphate, applied by surface impregnation, is able to slow down reinforcement corrosion only for reinforcing steel bars with concrete cover not thicker than 1 cm. This limitation is most probably due to the difficulty, with the type of application adopted, in making MFP to reach concentrations high enough to inhibit the corrosive process at greater depths from the impregnation surface.

  13. Investigation of factors influencing chloride extraction efficiency during electrochemical chloride extraction from reinforcing concrete

    NASA Astrophysics Data System (ADS)

    Sharp, Stephen R.

    2005-11-01

    Electrochemical chloride extraction (ECE) is an accelerated bridge restoration method similar to cathodic protection, but operates at higher current densities and utilizes a temporary installation. Both techniques prolong the life of a bridge by reducing the corrosion rate of the reinforcing bar when properly applied. ECE achieves this by moving chlorides away from the reinforcement and out of the concrete while simultaneously increasing the alkalinity of the electrolyte near the reinforcing steel. Despite the proven success, significant use of ECE has not resulted in part due to an incomplete understanding in the following areas: (1) An estimation of the additional service life that can be expected following treatment when the treated member is again subjected to chlorides; (2) The cause of the decrease in current flow and, therefore, chloride removal rate during treatment; (3) Influence of water-to-cement (w/c) ratio and cover depth on the time required for treatment. This dissertation covers the research that is connected to the last two areas listed above. To begin examining these issues, plain carbon steel reinforcing bars (rebar) were embedded in portland cement concrete slabs of varying water-to-cement (w/c) ratios and cover depths, and then exposed to chlorides. A fraction of these slabs had sodium chloride added as an admixture, with all of the slabs subjected to cyclical ponding with a saturated solution of sodium chloride. ECE was then used to remove the chlorides from these slabs while making electrical measurements in the different layers between the rebar (cathode) and the titanium mat (anode) to follow the progress of the ECE process. During this study, it was revealed that the resistance of the outer concrete surface layer increases during ECE, inevitably restricting current flow, while the resistance of the underlying concrete decreases or remains constant. During ECE treatment, a white residue formed on the surface of the concrete. Analyses of the

  14. Experimental Study on the Strength Characteristics and Water Permeability of Hybrid Steel Fibre Reinforced Concrete.

    PubMed

    Singh, M P; Singh, S P; Singh, A P

    2014-01-01

    Results of an investigation conducted to study the effect of fibre hybridization on the strength characteristics such as compressive strength, split tensile strength, and water permeability of steel fibre reinforced concrete (SFRC) are presented. Steel fibres of different lengths, that is, 12.5 mm, 25 mm, and 50 mm, having constant diameter of 0.6 mm, were systematically combined in different mix proportions to obtain mono, binary, and ternary combinations at each of 0.5%, 1.0%, and 1.5% fibre volume fraction. A concrete mix containing no fibres was also cast for reference purpose. A total number of 1440 cube specimens of size 100∗100∗100 mm were tested, 480 each for compressive strength, split tensile strength, and water permeability at 7, 28, 90, and 120 days of curing. It has been observed from the results of this investigation that a fibre combination of 33% 12.5 mm + 33% 25 mm + 33% 50 mm long fibres can be adjudged as the most appropriate combination to be employed in hybrid steel fibre reinforced concrete (HySFRC) for optimum performance in terms of compressive strength, split tensile strength and water permeability requirements taken together.

  15. A micromechanical approach to elastic and viscoelastic properties of fiber reinforced concrete

    SciTech Connect

    Pasa Dutra, V.F.; Maghous, S. Campos Filho, A.; Pacheco, A.R.

    2010-03-15

    Some aspects of the constitutive behavior of fiber reinforced concrete (FRC) are investigated within a micromechanical framework. Special emphasis is put on the prediction of creep of such materials. The linear elastic behavior is first examined by implementation of a Mori-Tanaka homogenization scheme. The micromechanical predictions for the overall stiffness prove to be very close to finite element solutions obtained from the numerical analysis of a representative elementary volume of FRC modeled as a randomly heterogeneous medium. The validation of the micromechanical concepts based on comparison with a set of experiments, shows remarkable predictive capabilities of the micromechanical representation. The second part of the paper is devoted to non-ageing viscoelasticity of FRC. Adopting a Zener model for the behavior of the concrete matrix and making use of the correspondence principle, the homogenized relaxation moduli are derived analytically. The validity of the model is established by mean of comparison with available experiment measurements of creep strain of steel fiber reinforced concrete under compressive load. Finally, the model predictions are compared to those derived from analytical models formulated within a one-dimensional setting.

  16. Experimental Study on the Strength Characteristics and Water Permeability of Hybrid Steel Fibre Reinforced Concrete

    PubMed Central

    Singh, M. P.; Singh, S. P.; Singh, A. P.

    2014-01-01

    Results of an investigation conducted to study the effect of fibre hybridization on the strength characteristics such as compressive strength, split tensile strength, and water permeability of steel fibre reinforced concrete (SFRC) are presented. Steel fibres of different lengths, that is, 12.5 mm, 25 mm, and 50 mm, having constant diameter of 0.6 mm, were systematically combined in different mix proportions to obtain mono, binary, and ternary combinations at each of 0.5%, 1.0%, and 1.5% fibre volume fraction. A concrete mix containing no fibres was also cast for reference purpose. A total number of 1440 cube specimens of size 100∗100∗100 mm were tested, 480 each for compressive strength, split tensile strength, and water permeability at 7, 28, 90, and 120 days of curing. It has been observed from the results of this investigation that a fibre combination of 33% 12.5 mm + 33% 25 mm + 33% 50 mm long fibres can be adjudged as the most appropriate combination to be employed in hybrid steel fibre reinforced concrete (HySFRC) for optimum performance in terms of compressive strength, split tensile strength and water permeability requirements taken together. PMID:27379298

  17. Heat transfer mechanisms in fiber-reinforced polymer composites bonded to concrete

    NASA Astrophysics Data System (ADS)

    Brown, Jeff; Baker, Rebecca; Kallemeyn, Lisa

    2007-04-01

    This research project investigated heat transfer mechanisms that occur during radiant heating of glass/epoxy composites bonded to concrete. The ultimate goal is to develop a field procedure for estimating the thickness of fiber-reinforced polymer (FRP) composites used to strengthen existing reinforced concrete structures. Thickness is an important parameter in the design and implementation of nondestructive testing procedures that evaluate bond in FRP systems. Four concrete samples (15 cm x 30 cm x 5 cm) were constructed with glass/epoxy composite bonded to the surface. The thickness of the composite varied from 1mm to 4mm and thermocouples were placed at 1mm intervals through the depth of the composite. Experimental data was compared with a simple theoretical model that predicts the surface temperature response of a layered system subjected to a uniform heat flux. Two factors were shown to significantly influence the heat transfer mechanism: surface absorptivity of the FRP composite and convective cooling. Additional analytical modeling using the finite element method was performed to account for these affects in an effort to obtain a better estimate of FRP thickness based on experimental data.

  18. Development and evaluation of the epoxy repair method for reinforced concrete flexural members

    NASA Astrophysics Data System (ADS)

    Kongsuwan, S.

    1980-03-01

    Repair procedures were developed based on both the evaluation of the past epoxy repair methods and the pilot study in this research. Fifteen reinforced concrete beams were failed in flexure to produce failures ranging from light to heavily damaged. The damaged beams were repaired using the methods developed and tested. It was concluded that it is possible to repair failed reinforced concrete beams (particularly in flexure) by using the developed repair method. The loading capacity of a repaired beam was verified both experimentally and theoretically as being restorable to approximately the same level as of the original beam regardless of the type and degree of failure. The durability of repaired beams, subjected to cycle loading, is somewhat less than the durability of the original beams. The decrease of durability of the repaired beams is attributed by the softening of steel, the amount of epoxy present in the concrete, and the presence of microcracks. Repaired beams which were failed by one cycle loading were found to behave identically to the original undamaged beams.

  19. Compressive Behavior of Fiber-Reinforced Concrete with End-Hooked Steel Fibers

    PubMed Central

    Lee, Seong-Cheol; Oh, Joung-Hwan; Cho, Jae-Yeol

    2015-01-01

    In this paper, the compressive behavior of fiber-reinforced concrete with end-hooked steel fibers has been investigated through a uniaxial compression test in which the variables were concrete compressive strength, fiber volumetric ratio, and fiber aspect ratio (length to diameter). In order to minimize the effect of specimen size on fiber distribution, 48 cylinder specimens 150 mm in diameter and 300 mm in height were prepared and then subjected to uniaxial compression. From the test results, it was shown that steel fiber-reinforced concrete (SFRC) specimens exhibited ductile behavior after reaching their compressive strength. It was also shown that the strain at the compressive strength generally increased along with an increase in the fiber volumetric ratio and fiber aspect ratio, while the elastic modulus decreased. With consideration for the effect of steel fibers, a model for the stress–strain relationship of SFRC under compression is proposed here. Simple formulae to predict the strain at the compressive strength and the elastic modulus of SFRC were developed as well. The proposed model and formulae will be useful for realistic predictions of the structural behavior of SFRC members or structures. PMID:28788011

  20. Thermal analysis of GFRP-reinforced continuous concrete decks subjected to top fire

    NASA Astrophysics Data System (ADS)

    Hawileh, Rami A.; Rasheed, Hayder A.

    2017-09-01

    This paper presents a numerical study that investigates the behavior of continuous concrete decks doubly reinforced with top and bottom glass fiber reinforced polymer (GFRP) bars subjected to top surface fire. A finite element (FE) model is developed and a detailed transient thermal analysis is performed on a continuous concrete bridge deck under the effect of various fire curves. A parametric study is performed to examine the top cover thickness and the critical fire exposure curve needed to fully degrade the top GFRP bars while achieving certain fire ratings for the deck considered. Accordingly, design tables are prepared for each fire curve to guide the engineer to properly size the top concrete cover and maintain the temperature in the GFRP bars below critical design values in order to control the full top GFRP degradation. It is notable to indicate that degradation of top GFRP bars do not pose a collapse hazard but rather a serviceability concern since cracks in the negative moment region widen resulting in simply supported spans.

  1. Compressive Behavior of Fiber-Reinforced Concrete with End-Hooked Steel Fibers.

    PubMed

    Lee, Seong-Cheol; Oh, Joung-Hwan; Cho, Jae-Yeol

    2015-03-27

    In this paper, the compressive behavior of fiber-reinforced concrete with end-hooked steel fibers has been investigated through a uniaxial compression test in which the variables were concrete compressive strength, fiber volumetric ratio, and fiber aspect ratio (length to diameter). In order to minimize the effect of specimen size on fiber distribution, 48 cylinder specimens 150 mm in diameter and 300 mm in height were prepared and then subjected to uniaxial compression. From the test results, it was shown that steel fiber-reinforced concrete (SFRC) specimens exhibited ductile behavior after reaching their compressive strength. It was also shown that the strain at the compressive strength generally increased along with an increase in the fiber volumetric ratio and fiber aspect ratio, while the elastic modulus decreased. With consideration for the effect of steel fibers, a model for the stress-strain relationship of SFRC under compression is proposed here. Simple formulae to predict the strain at the compressive strength and the elastic modulus of SFRC were developed as well. The proposed model and formulae will be useful for realistic predictions of the structural behavior of SFRC members or structures.

  2. Shear wall experiments and design in Japan

    SciTech Connect

    Park, Y.J.; Hofmayer, C.

    1994-12-01

    This paper summarizes the results of recent survey studies on the available experimental data bases and design codes/standards for reinforced concrete (RC) shear wall structures in Japan. Information related to the seismic design of RC reactor buildings and containment structures was emphasized in the survey. The seismic requirements for concrete structures, particularly those related to shear strength design, are outlined. Detailed descriptions are presented on the development of Japanese shear wall equations, design requirements for containment structures, and ductility requirements.

  3. A Wireless Passive Sensing System for Displacement/Strain Measurement in Reinforced Concrete Members.

    PubMed

    Ozbey, Burak; Erturk, Vakur B; Demir, Hilmi Volkan; Altintas, Ayhan; Kurc, Ozgur

    2016-04-08

    In this study, we show a wireless passive sensing system embedded in a reinforced concrete member successfully being employed for the measurement of relative displacement and strain in a simply supported beam experiment. The system utilizes electromagnetic coupling between the transceiver antenna located outside the beam, and the sensing probes placed on the reinforcing bar (rebar) surface inside the beam. The probes were designed in the form of a nested split-ring resonator, a metamaterial-based structure chosen for its compact size and high sensitivity/resolution, which is at µm/microstrains level. Experiments were performed in both the elastic and plastic deformation cases of steel rebars, and the sensing system was demonstrated to acquire telemetric data in both cases. The wireless measurement results from multiple probes are compared with the data obtained from the strain gages, and an excellent agreement is observed. A discrete time measurement where the system records data at different force levels is also shown. Practical issues regarding the placement of the sensors and accurate recording of data are discussed. The proposed sensing technology is demonstrated to be a good candidate for wireless structural health monitoring (SHM) of reinforced concrete members by its high sensitivity and wide dynamic range.

  4. A Wireless Passive Sensing System for Displacement/Strain Measurement in Reinforced Concrete Members

    PubMed Central

    Ozbey, Burak; Erturk, Vakur B.; Demir, Hilmi Volkan; Altintas, Ayhan; Kurc, Ozgur

    2016-01-01

    In this study, we show a wireless passive sensing system embedded in a reinforced concrete member successfully being employed for the measurement of relative displacement and strain in a simply supported beam experiment. The system utilizes electromagnetic coupling between the transceiver antenna located outside the beam, and the sensing probes placed on the reinforcing bar (rebar) surface inside the beam. The probes were designed in the form of a nested split-ring resonator, a metamaterial-based structure chosen for its compact size and high sensitivity/resolution, which is at µm/microstrains level. Experiments were performed in both the elastic and plastic deformation cases of steel rebars, and the sensing system was demonstrated to acquire telemetric data in both cases. The wireless measurement results from multiple probes are compared with the data obtained from the strain gages, and an excellent agreement is observed. A discrete time measurement where the system records data at different force levels is also shown. Practical issues regarding the placement of the sensors and accurate recording of data are discussed. The proposed sensing technology is demonstrated to be a good candidate for wireless structural health monitoring (SHM) of reinforced concrete members by its high sensitivity and wide dynamic range. PMID:27070615

  5. Quantification of ergonomic hazards for ironworkers performing concrete reinforcement tasks during heavy highway construction.

    PubMed

    Buchholz, Bryan; Paquet, Victor; Wellman, Helen; Forde, Martin

    2003-01-01

    A study was conducted to assess the ergonomic hazards of ironwork job tasks associated with concrete reinforcement work at a large highway construction site. PATH (posture, activity, tools, and handling) analysis, a work-sampling method, was used to provide task-based estimates of the percentage of time ironworkers spent in specified postures of the trunk, arms, and legs; performed activities; used tools; and handled loads. A total of 2128 PATH observations were made of 17 ironworkers performing 5 job tasks: (1) ground-level reinforcement bar (rebar) construction, (2) wall rebar construction, (3) ventilation rebar construction, (4) preparation work, and (5) supervising. Nonneutral trunk postures were observed frequently (exceeding 30%) and manual material handling (MMH) was the most commonly observed activity (exceeding 20%) for all job tasks except supervising. The percentage of time workers spent in specific postures, activities performed, tool use, and MMH activities differed significantly between the five main job tasks, even when supervising was excluded from the analysis. It was concluded that ironworkers are exposed to significant ergonomic hazards when performing concrete reinforcing tasks, and that opportunities exist for the implementation of ergonomic interventions. Further, the results of this study can be used to target specific hazardous tasks for ergonomic interventions and confirms the need to use a task-based exposure assessment strategy to properly assess ergonomic risk profiles for nonstructured jobs such as construction.

  6. Thermal-sprayed zinc anodes for cathodic protection of steel-reinforced concrete bridges

    SciTech Connect

    Bullard, Sophie J.; Covino, Bernard S., Jr.; Cramer, Stephen D.; McGill, Galen E.

    1996-01-01

    Thermal-sprayed zinc anodes are being used in Oregon in impressed current cathodic protection (ICCP) systems for reinforced concrete bridges. The U.S. Department of Energy, Albany Research Center, is collaborating with the Oregon Department of Transportation (ODOT) to evaluate the long-term performance and service life of these anodes. Laboratory studies were conducted on concrete slabs coated with 0.5 mm (20 mil) thick, thermal-sprayed zinc anodes. The slabs were electrochemically aged at an accelerated rate using an anode current density of 0.032 A/m2 (3mA/ft2). Half the slabs were preheated before thermal-spraying with zinc; the other half were unheated. Electrochemical aging resulted in the formation at the zinc-concrete interface of a thin, low pH zone (relative to cement paste) consisting primarily of ZnO and Zn(OH)2, and in a second zone of calcium and zinc aluminates and silicates formed by secondary mineralization. Both zones contained elevated concentrations of sulfate and chloride ions. The original bond strength of the zinc coating decreased due to the loss of mechanical bond to the concrete with the initial passage of electrical charge (aging). Additional charge led to an increase in bond strength to a maximum as the result of secondary mineralization of zinc dissolution products with the cement paste. Further charge led to a decrease in bond strength and ultimately coating disbondment as the interfacial reaction zones continued to thicken. This occurred at an effective service life of 27 years at the 0.0022 A/m2 (0.2 mA/ft2) current density typically used by ODOT in ICCP systems for coastal bridges. Zinc coating failure under tensile stress was primarily cohesive within the thickening reaction zones at the zinc-concrete interface. There was no difference between the bond strength of zinc coatings on preheated and unheated concrete surfaces after long service times.

  7. Degradation processes of reinforced concretes by combined sulfate–phosphate attack

    SciTech Connect

    Secco, Michele; Lampronti, Giulio Isacco; Schlegel, Moritz-Caspar; Maritan, Lara; Zorzi, Federico

    2015-02-15

    A novel form of alteration due to the interaction between hydrated cement phases and sulfate and phosphate-based pollutants is described, through the characterization of concrete samples from an industrial reinforced concrete building. Decalcification of the cement matrices was observed, with secondary sulfate and phosphate-based mineral formation, according to a marked mineralogical and textural zoning. Five alteration layers may be detected: the two outermost layers are characterized by the presence of gypsum–brushite solid solution phases associated with anhydrous calcium sulfates and phosphates, respectively, while a progressive increase in apatite and ammonium magnesium phosphates is observable in the three innermost layers, associated with specific apatite precursors (brushite, octacalcium phosphate and amorphous calcium phosphate, respectively). The heterogeneous microstructural development of secondary phases is related to the chemical, pH and thermal gradients in the attacked cementitious systems, caused by different sources of pollutants and the exposure to the sun's radiation.

  8. Assessment of Reinforced Concrete Surface Breaking Crack Using Rayleigh Wave Measurement

    PubMed Central

    Lee, Foo Wei; Chai, Hwa Kian; Lim, Kok Sing

    2016-01-01

    An improved single sided Rayleigh wave (R-wave) measurement was suggested to characterize surface breaking crack in steel reinforced concrete structures. Numerical simulations were performed to clarify the behavior of R-waves interacting with surface breaking crack with different depths and degrees of inclinations. Through analysis of simulation results, correlations between R-wave parameters of interest and crack characteristics (depth and degree of inclination) were obtained, which were then validated by experimental measurement of concrete specimens instigated with vertical and inclined artificial cracks of different depths. Wave parameters including velocity and amplitude attenuation for each case were studied. The correlations allowed us to estimate the depth and inclination of cracks measured experimentally with acceptable discrepancies, particularly for cracks which are relatively shallow and when the crack depth is smaller than the wavelength. PMID:26959028

  9. Modelling of steel fiber-reinforced concrete under multi-axial loads

    SciTech Connect

    Swaddiwudhipong, Somsak . E-mail: cvesomsa@nus.edu.sg; Seow, Puay Eng Constance

    2006-07-15

    Fifty-four plain concrete and steel fiber-reinforced concrete (SFRC) plate specimens containing 0.5%, 1.0% and 1.5% of hooked fibers were tested under biaxial compression. The experimental results obtained were used to verify a failure surface developed earlier by the authors for SFRC under multi-axial loads. An equation has also been proposed in this study to predict the strain at failure for SFRC under multi-axial loads, {epsilon} {sub ci}. The proposed failure criterion and equation to predict {epsilon} {sub ci} were incorporated into a constitutive model in a well-established finite-element software, ABAQUS. Experiments of SFRC plate specimens under multi-axial loads and beams under two-point load were modeled to illustrate the application of the failure surface to SFRC under varying load conditions. Good agreement between analytical and experimental results is observed.

  10. Time reverse modeling of acoustic emissions in a reinforced concrete beam.

    PubMed

    Kocur, Georg Karl; Saenger, Erik H; Grosse, Christian U; Vogel, Thomas

    2016-02-01

    The time reverse modeling (TRM) is applied for signal-based acoustic emission (AE) analysis of reinforced concrete (RC) specimens. TRM uses signals obtained from physical experiments as input. The signals are re-emitted numerically into a structure in a time-reversed manner, where the wavefronts interfere and appear as dominant concentrations of energy at the origin of the AE. The experimental and numerical results presented for selected AE signals confirm that TRM is capable of localizing AE activity in RC caused by concrete cracking. The accuracy of the TRM results is corroborated by three-dimensional crack distributions obtained from X-ray computed tomography images. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Assessment of Reinforced Concrete Surface Breaking Crack Using Rayleigh Wave Measurement.

    PubMed

    Lee, Foo Wei; Chai, Hwa Kian; Lim, Kok Sing

    2016-03-05

    An improved single sided Rayleigh wave (R-wave) measurement was suggested to characterize surface breaking crack in steel reinforced concrete structures. Numerical simulations were performed to clarify the behavior of R-waves interacting with surface breaking crack with different depths and degrees of inclinations. Through analysis of simulation results, correlations between R-wave parameters of interest and crack characteristics (depth and degree of inclination) were obtained, which were then validated by experimental measurement of concrete specimens instigated with vertical and inclined artificial cracks of different depths. Wave parameters including velocity and amplitude attenuation for each case were studied. The correlations allowed us to estimate the depth and inclination of cracks measured experimentally with acceptable discrepancies, particularly for cracks which are relatively shallow and when the crack depth is smaller than the wavelength.

  12. Highly Conductive Carbon Fiber Reinforced Concrete for Icing Prevention and Curing.

    PubMed

    Galao, Oscar; Bañón, Luis; Baeza, Francisco Javier; Carmona, Jesús; Garcés, Pedro

    2016-04-12

    This paper aims to study the feasibility of highly conductive carbon fiber reinforced concrete (CFRC) as a self-heating material for ice formation prevention and curing in pavements. Tests were carried out in lab ambient conditions at different fixed voltages and then introduced in a freezer at -15 °C. The specimens inside the freezer were exposed to different fixed voltages when reaching +5 °C for prevention of icing and when reaching the temperature inside the freezer, i.e., -15 °C, for curing of icing. Results show that this concrete could act as a heating element in pavements with risk of ice formation, consuming a reasonable amount of energy for both anti-icing (prevention) and deicing (curing), which could turn into an environmentally friendly and cost-effective deicing method.

  13. Highly Conductive Carbon Fiber Reinforced Concrete for Icing Prevention and Curing

    PubMed Central

    Galao, Oscar; Bañón, Luis; Baeza, Francisco Javier; Carmona, Jesús; Garcés, Pedro

    2016-01-01

    This paper aims to study the feasibility of highly conductive carbon fiber reinforced concrete (CFRC) as a self-heating material for ice formation prevention and curing in pavements. Tests were carried out in lab ambient conditions at different fixed voltages and then introduced in a freezer at −15 °C. The specimens inside the freezer were exposed to different fixed voltages when reaching +5 °C for prevention of icing and when reaching the temperature inside the freezer, i.e., −15 °C, for curing of icing. Results show that this concrete could act as a heating element in pavements with risk of ice formation, consuming a reasonable amount of energy for both anti-icing (prevention) and deicing (curing), which could turn into an environmentally friendly and cost-effective deicing method. PMID:28773406

  14. Study of chloride ion migration in reinforced concrete under cathodic protection. Final report

    SciTech Connect

    Orlova, N.V.; Westall, J.C.; Rehani, M.; Koretsky, M.D.

    1999-09-01

    The migration of chloride ions in concrete with steel reinforcement was investigated. Mortar blocks (15 cm x 15 cm x 17 cm) of various composition (water to cement ratio, chloride ion content) were cast with an iron mesh cathode imbedded along one face and a thermally sprayed zinc anode applied to the opposite face. Current densities of 0.033 and 0.066 A (sq m) were applied to the blocks over a period of one year at constant temperature and humidity. The zinc face was covered with a pond of saturated calcium hydroxide to prevent polarization of the zinc-concrete interface. Over the course of polarization, potential vs. time curves were recorded and samples of mortar were extracted for determination of chloride concentration.

  15. Preliminary investigation on the suitablity of using fiber reinforced concrete in the construction of a hazardous waste disposal vessel

    SciTech Connect

    Ramey, M.R.; Daie-e, G.

    1988-07-01

    There are certain hazardous wastes that must be contained in an extremely secure vessel for transportation and disposal. The vessel, among other things, must be able to withstand relatively large impacts without rupturing. Such containment vessels therefore must be able to absorb substantial amounts of energy during an impact and still perform their function. One of the impacts that the vessel must withstand is a 30-foot fall onto an unyielding surface. For some disposal scenarios it is proposed to encase the waste in a steel enclosure which is to be surrounded by a thick layer of concrete which, in turn, is encased by a relatively thin steel shell. Tests on concrete in compression and flexure, including static, dynamic and impact tests, have shown that low modulus concretes tend to behave in a less brittle manner than higher modulus concretes. Tests also show that fiber reinforced concretes have significantly greater ductility, crack propagation resistance and toughness than conventional concretes. Since it is known that concrete is a reasonably brittle material, it is necessary to do impact tests on sample containment structures consisting of thin-walled metal containers having closed ends which are filled with concrete, grout, or fiber reinforced concrete. This report presents the results of simple tests aimed at observing the behavior of sample containment structures subjected to impacts due to a fall from 30 feet. 8 figs., 4 tabs.

  16. Effect of Geotextile Reinforcement on Shear Strength of Sandy Soil: Laboratory Study

    NASA Astrophysics Data System (ADS)

    Denine, Sidali; Della, Noureddine; Dlawar, Muhammed Rawaz; Sadok, Feia; Canou, Jean; Dupla, Jean-Claude

    2016-12-01

    This paper presents results of a series of undrained monotonic compression tests on loose sand reinforced with geotextile mainly to study the effect of confining stress on the mechanical behaviour of geotextile reinforced sand. The triaxial tests were performed on reconstituted specimens of dry natural sand prepared at loose relative density (Dr = 30%) with and without geotextile layers and consolidated to three levels of confining pressures 50, 100 and 200 kPa, where different numbers and different arrangements of reinforcement layers were placed at different heights of the specimens (0, 1 and 2 layers). The behaviour of test specimens was presented and discussed. Test results showed that geotextile inclusion improves the mechanical behaviour of sand, a significant increase in the shear strength and cohesion value is obtained by adding up layers of reinforcement. Also, the results indicate that the strength ratio is more pronounced for samples which were subjected to low value of confining pressure. The obtained results reveal that high value of confining pressure can restrict the sand shear dilatancy and the more effect of reinforcement efficiently.

  17. Uncertainties Concerning the Free Vibration of Inhomogeneous Orthotropic Reinforced Concrete Plates

    NASA Astrophysics Data System (ADS)

    Shahsavar, Vahid Lal; Tofighi, Samira

    2014-09-01

    Analyzing nearly collapsed and broken structures gives good insights into possible architectural and engineering design mistakes and faults in the detailing and mismanagement of a construction by building contractors. Harmful vibration effects of construction operations occur frequently. The background reviews have demonstrated that the problem of the vibration serviceability of long-span concrete floors in buildings is complex and interdisciplinary in nature. In public buildings, floor vibration control is required in order to meet Serviceability Limit States that ensure the comfort of the users of a building. In industrial buildings, machines are often placed on floors. Machines generate vibrations of various frequencies, which are transferred to supporting constructions. Precision machines require a stable floor with defined and known dynamic characteristics. In recent years there has been increasing interest in the motion of elastic bodies whose material properties (density, elastic moduli, etc.) are not constant, but vary with their position, perhaps in a random manner. Concrete is a non-homogeneous and anisotropic material. Modeling the mechanical behavior of reinforced concrete (RC) is still one of the most difficult challenges in the field of structural engineering. One of several methods for determining the dynamic modulus of the elasticity of engineering materials is the vibration frequency procedure. In this method, the required variables except for the modulus of elasticity are accurately and certainly determined. In this research, the uncertainly analysis of the free vibration of inhomogeneous orthotropic reinforced concrete plates has been investigated. Due to the numerous outputs obtained, the software package has been written in Matlab, and an analysis of the data and drawing related charts has been done.

  18. Experience-based training of students on concretes reinforced by recycled carbon fibers

    NASA Astrophysics Data System (ADS)

    Cosgun, Cumhur; Patlolla, Vamsidhar R.; Alzahrani, Naif; Zeineddine, Hatim F.; Asmatulu, Eylem

    2017-04-01

    Fiber reinforcement increases many properties of the concretes, such as toughness, strength, abrasion, and resistance to corrosion. Use of recycled carbon fibers from industrial waste offers many advantages because it will reduce the waste, contribute the economy, protect natural resources and improve the property of structural units. The City of Wichita, KS is known to be "Air Capital of the World" where many aircraft companies have been producing aircraft, parts and components. Due to the superior properties of composites (e.g., light weight, low density, high impact resistance), they have been highly used by aircraft industry. Prepreg is the most preferred combination of the fiber and resin due to the easy application, but it has a limited shelf life (e.g., three months to one year at most) and scrap has no use after all in the same industry. Every year tons of un-used prepreg or after use scrap are being collected in Wichita, KS. Recycling prepreg from the post-consumer waste offers great advantages of waste reduction and resource conservation in the city. Reusing the carbon fibers obtained from outdated prepreg composites for concrete reinforcement will offer double advantages for our environment and concrete structures. In this study, recycled carbon fibers of the outdated prepreg composites were collected, and then incorporated with concretes at different ratios prior to the molding and mechanical testing. An undergraduate student was involved in the project and observed all the process during the laboratory studies, as well as data collection, analysis and presentation. We believe that experience based learning will enhance the students' skills and interest into the scientific and engineering studies.

  19. Experimental and analytical behavior of strengthened reinforced concrete columns with steel angles and strips

    NASA Astrophysics Data System (ADS)

    Khalifa, Essam S.; Al-Tersawy, Sherif H.

    2014-06-01

    The need of strengthening reinforced concrete columns, due to loss of strength and/or stiffness, is an essential requirement due to variation of the loads and environmental conditions applied on these columns. Steel jackets around the reinforced concrete (RC) columns are usually made by means of steel plates covering all over the column surface area. For the value of engineering purposes, another technique was developed using steel angles at the corners of the RC columns connected with discrete steel strips. In this paper, an experimental program is designed to evaluate the improvement in load-carrying capacity, stiffness and ductility of strengthened RC columns, concomitant with steel angles and strips. Despite of prevailing a substantially increased loading capacity and strength a pronounced enhancement in ductility and stiffness has been reported. A need for experimental test results with low value of concrete strength to mimic the local old-age structures condition that required strengthening in local countries. Seven columns specimens are tested to evaluate the strength improvement provided by steel strengthening of columns. The method of strengthened steel angles with strips is compared with another strengthening technique. This technique includes connected and unconnected steel-casing specimens. The observed experimental results describe load-shortening curves, horizontal strains in stirrups and steel strips, as well as description of failure mode. The extra-confinement pressure, due to existence of steel cage, of the strengthened RC column can be also observed from experimental results. The code provisions that predict the load-carrying capacity of the strengthened RC composite column has a discrepancy in the results. For this reason, an analytical model is developed in this paper to compare the code limit with experimental observed results. The proposed model accounts for the composite action for concrete confinement and enhancement of the local buckling

  20. Earthquake Resilient Tall Reinforced Concrete Buildings at Near-Fault Sites Using Base Isolation and Rocking Core Walls

    NASA Astrophysics Data System (ADS)

    Calugaru, Vladimir

    : two isolation systems (both implemented below a three-story basement), isolation periods equal to 4, 5, and 6 s, and two levels of flexural strength of the wall. The first isolation system combines tension-resistant friction pendulum bearings and nonlinear fluid viscous dampers (NFVDs); the second combines low-friction tension-resistant cross-linear bearings, lead-rubber bearings, and NFVDs. Finally, this dissertation investigates the seismic response of four 20-story buildings hypothetically located in the San Francisco Bay Area, 0.5 km from the San Andreas fault. One of the four studied buildings is fixed-base (FB), two are base-isolated (BI), and one uses a combination of base isolation and a rocking core wall (BIRW). Above the ground level, a reinforced concrete core wall provides the majority of the lateral force resistance in all four buildings. The FB and BI buildings satisfy requirements of ASCE 7-10. The BI and BIRW buildings use the same isolation system, which combines tension-resistant friction pendulum bearings and nonlinear fluid viscous dampers. The rocking core-wall includes post-tensioning steel, buckling-restrained devices, and at its base is encased in a steel shell to maximize confinement of the concrete core. The total amount of longitudinal steel in the wall of the BIRW building is 0.71 to 0.87 times that used in the BI buildings. Response history two-dimensional analysis is performed, including the vertical components of excitation, for a set of ground motions scaled to the design earthquake and to the maximum considered earthquake (MCE). While the FB building at MCE level of shaking develops inelastic deformations and shear stresses in the wall that may correspond to irreparable damage, the BI and the BIRW buildings experience nominally elastic response of the wall, with floor accelerations and shear forces which are 0.36 to 0.55 times those experienced by the FB building. The response of the four buildings to two historical and two simulated

  1. 1. U.S. Route 250 grade separation structure. This reinforced concrete, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. U.S. Route 250 grade separation structure. This reinforced concrete, rigid frame structure was built in 1941. Its relatively flat arch provided maximum useful clearance in a short span and the physics of the design eliminated the need for extensive abutments to contain the thrust of traditional arches, making it ideally suited as a grade separation structure. BLRI designers made extensive use of theses bridges for crossing small streams and creeks, and grade separation structures, ornamenting them with a rustic stone facade. View is of the south-southeast elevation. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  2. Experimental investigation and numerical modeling of carbonation process in reinforced concrete structures Part II. Practical applications

    SciTech Connect

    Saetta, Anna V.; Vitaliani, Renato V

    2005-05-01

    The mathematical-numerical method developed by the authors to predict the corrosion initiation time of reinforced concrete structures due to carbonation process, recalled in Part I of this work, is here applied to some real cases. The final aim is to develop and test a practical method for determining the durability characteristics of existing buildings liable to carbonation, as well as estimating the corrosion initiation time of a building at the design stage. Two industrial sheds with different ages and located in different areas have been analyzed performing both experimental tests and numerical analyses. Finally, a case of carbonation-induced failure in a prestressed r.c. beam is presented.

  3. Strength, and Behavior of Steel Fiber-Reinforced Concrete and Soil Structures Interaction Studies.

    DTIC Science & Technology

    1987-06-29

    AUTHOR(S) Hon-Yim Ko 13&. TYPE OF REPORT 1 3b, IFIMI COVk:RE%. 14. DATE OF REPORT (k’r.. Mo.. Day) j 5. PAGE COUNT Final F RO 1/15/I81 TO 8/31/84j 6/29/87...GR. Fiber-Reinforced Concrete; Biaxial Tension -Compression; ___________________________ SolStucture Interaction, Numerical Modeling, Centrifuge...compression- tension loadings. A new piece of direct tension loading apparatus was designed and assembled for this study. Load history effects on the

  4. Static and dynamic pile testing of reinforced concrete piles with structure integrated fibre optic strain sensors

    NASA Astrophysics Data System (ADS)

    Schilder, Constanze; Kohlhoff, Harald; Hofmann, Detlef; Basedau, Frank; Habel, Wolfgang R.; Baeßler, Matthias; Niederleithinger, Ernst; Georgi, Steven; Herten, Markus

    2013-05-01

    Static and dynamic pile tests are carried out to determine the load bearing capacity and the quality of reinforced concrete piles. As part of a round robin test to evaluate dynamic load tests, structure integrated fibre optic strain sensors were used to receive more detailed information about the strains along the pile length compared to conventional measurements at the pile head. This paper shows the instrumentation of the pile with extrinsic Fabry-Perot interferometers sensors and fibre Bragg gratings sensors together with the results of the conducted static load test as well as the dynamic load tests and pile integrity tests.

  5. Hybrid Effect Evaluation of Steel Fiber and Carbon Fiber on the Performance of the Fiber Reinforced Concrete

    PubMed Central

    Song, Weimin; Yin, Jian

    2016-01-01

    Fiber reinforcement is an important method to enhance the performance of concrete. In this study, the compressive test and impact test were conducted, and then the hybrid effect between steel fiber (SF) and carbon fiber (CF) was evaluated by employing the hybrid effect index. Compressive toughness and impact toughness of steel fiber reinforced concrete (SFRC), carbon fiber reinforced concrete (CFRC) and hybrid fiber reinforced concrete (HFRC) were explored at steel fiber volume fraction 0.5%, 1%, 1.5% and carbon fiber 0.1%, 0.2%, 0.3%. Results showed that the addition of steel fiber and carbon fiber can increase the compressive strength. SF, CF and the hybridization between them could increase the compressive toughness significantly. The impact test results showed that as the volume of fiber increased, the impact number of the first visible crack and the ultimate failure also increased. The improvement of toughness mainly lay in improving the crack resistance after the first crack. Based on the test results, the positive hybrid effect of steel fiber and carbon fiber existed in hybrid fiber reinforced concrete. The relationship between the compressive toughness and impact toughness was also explored. PMID:28773824

  6. Hybrid Effect Evaluation of Steel Fiber and Carbon Fiber on the Performance of the Fiber Reinforced Concrete.

    PubMed

    Song, Weimin; Yin, Jian

    2016-08-18

    Fiber reinforcement is an important method to enhance the performance of concrete. In this study, the compressive test and impact test were conducted, and then the hybrid effect between steel fiber (SF) and carbon fiber (CF) was evaluated by employing the hybrid effect index. Compressive toughness and impact toughness of steel fiber reinforced concrete (SFRC), carbon fiber reinforced concrete (CFRC) and hybrid fiber reinforced concrete (HFRC) were explored at steel fiber volume fraction 0.5%, 1%, 1.5% and carbon fiber 0.1%, 0.2%, 0.3%. Results showed that the addition of steel fiber and carbon fiber can increase the compressive strength. SF, CF and the hybridization between them could increase the compressive toughness significantly. The impact test results showed that as the volume of fiber increased, the impact number of the first visible crack and the ultimate failure also increased. The improvement of toughness mainly lay in improving the crack resistance after the first crack. Based on the test results, the positive hybrid effect of steel fiber and carbon fiber existed in hybrid fiber reinforced concrete. The relationship between the compressive toughness and impact toughness was also explored.

  7. Fiber reinforced concrete: Characterization of flexural toughness and some studies on fiber-matrix bond-slip interaction

    NASA Astrophysics Data System (ADS)

    Dubey, Ashish

    One major problem associated with the testing of fiber reinforced concrete specimens under flexural loading is that the measured post-cracking response is severely affected by the stiffness of the testing machine. As a consequence, misleading results are obtained when such a flexural response is used for the characterization of composite toughness. An assessment of a new toughness characterization technique termed the Residual Strength Test Method (RSTM) has been made. In this technique, a stable narrow crack is first created in the specimen by applying a flexural load in parallel with a steel plate under controlled conditions. The plate is then removed, and the specimen is tested in a routine manner in flexure to obtain the post-crack load versus displacement response. Flexural response for a variety of fiber reinforced cementitious composites obtained using the Residual Strength Test Method has been found to correlate very well with those obtained with relatively stiffer test configurations such as closed-loop test machines. The Residual Strength Test Method is found to be effective in differentiating between different fiber types, fiber lengths, fiber configurations, fiber volume fractions, fiber geometries and fiber moduli. In particular, the technique has been found to be extremely useful for testing cement-based composites containing fibers at very low dosages (<0.5% by volume). An analytical model based on shear lag theory is introduced to study the problem of fiber pullout in fiber reinforced composites. The proposed model eliminates limitations of many earlier models and captures essential features of pullout process, including progressive interfacial debonding, Poisson's effect, and variation in interfacial properties during the fiber pullout process. Interfacial debonding is modeled using an interfacial shear strength criterion. Influence of normal contact stress at the fiber-matrix interface is considered using shrink-fit theory, and the interfacial

  8. Governing equations of multi-component rigid body-spring discrete element models of reinforced concrete columns

    NASA Astrophysics Data System (ADS)

    Guan, P. B.; Tingatinga, E. A.; Longalong, R. E.; Saguid, J.

    2016-09-01

    During the past decades, the complexity of conventional methods to perform seismic performance assessment of buildings led to the development of more effective approaches. The rigid body spring-discrete element method (RBS-DEM) is one of these approaches and has recently been applied to the study of the behavior of reinforced concrete (RC) buildings subjected to strong earthquakes. In this paper, the governing equations of RBS-DEM planar elements subjected to lateral loads and horizontal ground motion are presented and used to replicate the hysteretic behavior of experimental RC columns. The RBS-DEM models of columns are made up of rigid components connected by systems of springs that simulate axial, shear, and bending behavior of an RC section. The parameters of springs were obtained using Response-2000 software and the hysteretic response of the models of select columns from the Pacific Earthquake Engineering Research (PEER) Structural Performance Database were computed numerically. Numerical examples show that one-component models were able to simulate the initial stiffness reasonably, while the displacement capacity of actual columns undergoing large displacements were underestimated.

  9. Improved Seismic Risk Assessment of Non-ductile Reinforced Concrete Buildings

    NASA Astrophysics Data System (ADS)

    Fuselier, Blaine Jacob

    Existing reinforced concrete (RC) buildings built to non-ductile specifications are highly susceptible to damage given lateral loads induced from earthquake ground motions. To explore the effects of these ground motions, non-linear finite element analyses are being used in research and practice to model representations of non-ductile RC buildings as well as conduct probabilistic analyses of their seismic fragility in as-built and retrofitted conditions. This study examines the influence of modeling fidelity on the response and fragility of non-ductile RC buildings, testing the role of explicitly capturing local failure in the finite element model as well as providing new insight into the probability of component damage levels given system level failure. Also, a survey is presented to assess the tagging decisions made during post-earthquake rapid evaluations of reinforced concrete buildings and compare these results to empirical data from past earthquake reconnaissance reports. The results of this study will provide insight into several key issues in seismic performance assessment for RC buildings.

  10. Nonstructural damages of reinforced concrete buildings due to 2015 Ranau earthquake

    NASA Astrophysics Data System (ADS)

    Adiyanto, Mohd Irwan; Majid, Taksiah A.; Nazri, Fadzli Mohamed

    2017-07-01

    On 15th June 2016 a moderate earthquake with magnitude Mw5.9 was occurred in Sabah, Malaysia. Specifically, the epicentre was located at 16 km northwest of Ranau. Less than two days after the first event, a reconnaissance mission took action to investigate the damages on buildings. Since the reinforced concrete buildings in Ranau were designed based on gravity and wind load only, a lot of minor to severe damages was occurred. This paper presents the damages on the nonstructural elements of reinforced concrete buildings due to Ranau earthquake. The assessment was conducted via in-situ field investigation covering the visual observation, taking photo, and interview with local resident. Based on in-situ field investigation, there was a lot of damages occurred on the nonstructural elements like the brick walls. Such damages cannot be neglected since it can cause injury and fatality to the victims. Therefore, it can be concluded that the installation of nonstructural elements should be reviewed for the sake of safety.

  11. The behaviour of reinforced concrete structure due to earthquake load using Time History analysis Method

    NASA Astrophysics Data System (ADS)

    Afifuddin, M.; Panjaitan, M. A. R.; Ayuna, D.

    2017-02-01

    Earthquakes are one of the most dangerous, destructive and unpredictable natural hazards, which can leave everything up to a few hundred kilometres in complete destruction in seconds. Indonesia has a unique position as an earthquake prone country. It is the place of the interaction for three tectonic plates, namely the Indo-Australian, Eurasian and Pacific plates. Banda Aceh is one of the cities that located in earthquake-prone areas. Due to the vulnerable conditions of Banda Aceh some efforts have been exerted to reduce these unfavourable conditions. Many aspects have been addressed, starting from community awareness up to engineering solutions. One of them is all buildings that build in the city should be designed as an earthquake resistant building. The objectives of this research are to observe the response of a reinforced concrete structure due to several types of earthquake load, and to see the performance of the structure after earthquake loads applied. After Tsunami in 2004 many building has been build, one of them is a hotel building located at simpang lima. The hotel is made of reinforced concrete with a height of 34.95 meters with a total area of 8872.5 m2 building. So far this building was the tallest building in Banda Aceh.

  12. Structural health monitoring of a reinforced concrete building during the severe typhoon Vicente in 2012.

    PubMed

    Kuok, Sin-Chi; Yuen, Ka-Veng

    2013-01-01

    The goal of this study is to investigate the structural performance of reinforced concrete building under the influence of severe typhoon. For this purpose, full-scale monitoring of a 22-story reinforced concrete building was conducted during the entire passage process of a severe typhoon "Vicente." Vicente was the eighth tropical storm developed in the Western North Pacific Ocean and the South China Sea in 2012. Moreover, it was the strongest and most devastating typhoon that struck Macao since 1999. The overall duration of the typhoon affected period that lasted more than 70 hours and the typhoon eye region covered Macao for around one hour. The wind and structural response measurements were acquired throughout the entire typhoon affected period. The wind characteristics were analyzed using the measured wind data including the wind speed and wind direction time histories. Besides, the structural response measurements of the monitored building were utilized for modal identification using the Bayesian spectral density approach. Detailed analysis of the field data and the typhoon generated effects on the structural performance are discussed.

  13. Smart CFRP systems for the controlled retrofitting of reinforced concrete members

    NASA Astrophysics Data System (ADS)

    Schaller, M.-B.; Käseberg, S.; Kuhne, M.

    2010-09-01

    During the last ten years an increasing amount of Carbon Fiber Reinforced Polymer (CFRP) applications to rehabilitate damaged concrete elements was observed. Thereby some important disadvantages of the brittle materials must be considered, for example the low ductility of the bond between CFRP and concrete and brittle failure of FRP. With embedded sensor systems it is possible to measure crack propagation and strains. In this paper a sensor based CFRP system will be presented, that can be used for strengthening and measuring. The used optical fibers with Fiber Bragg Gratings (FBG) have a large number of advantages in opposite to electrical measuring methods. Examples are small dimensions, low weight as well as high static and dynamic resolution of measured values. The main problem during the investigations was the fixing of the glass fiber and the small FBG at the designated position. In this paper the possibility of setting the glass fiber with embroidery at the reinforcing fiber material will be presented. On the basis of four point bending tests on beams (dimensions of 700 x 150 x 150 mm) and tests on wrapped columns the potential of the Smart CFRP system is introduced.

  14. Study on Flexural Behaviour of Ternary Blended Reinforced Self Compacting Concrete Beam with Conventional RCC Beam

    NASA Astrophysics Data System (ADS)

    Marshaline Seles, M.; Suryanarayanan, R.; Vivek, S. S.; Dhinakaran, G.

    2017-07-01

    The conventional concrete when used for structures having dense congested reinforcement, the problems such as external compaction and vibration needs special attention. In such case, the self compacting concrete (SCC) which has the properties like flow ability, passing and filling ability would be an obvious answer. All those SCC flow behavior was governed by EFNARC specifications. In present study, the combination type of SCC was prepared by replacing cement with silica fume (SF) and metakaolin (MK) along with optimum dosages of chemical admixtures. From the fresh property test, cube compressive strength and cylinder split tensile strength, optimum ternary mix was obtained. In order to study the flexural behavior, the optimum ternary mix was taken in which beam specimens of size 1200 mm x 100 mm x 200 mm was designed as singly reinforced section according to IS: 456-2000, Limit state method. Finally the comparative experimental analysis was made between conventional RCC and SCC beams of same grade in terms of flexural strength namely yield load & ultimate load, load- deflection curve, crack size and pattern respectively.

  15. Structural Health Monitoring of a Reinforced Concrete Building during the Severe Typhoon Vicente in 2012

    PubMed Central

    2013-01-01

    The goal of this study is to investigate the structural performance of reinforced concrete building under the influence of severe typhoon. For this purpose, full-scale monitoring of a 22-story reinforced concrete building was conducted during the entire passage process of a severe typhoon “Vicente.” Vicente was the eighth tropical storm developed in the Western North Pacific Ocean and the South China Sea in 2012. Moreover, it was the strongest and most devastating typhoon that struck Macao since 1999. The overall duration of the typhoon affected period that lasted more than 70 hours and the typhoon eye region covered Macao for around one hour. The wind and structural response measurements were acquired throughout the entire typhoon affected period. The wind characteristics were analyzed using the measured wind data including the wind speed and wind direction time histories. Besides, the structural response measurements of the monitored building were utilized for modal identification using the Bayesian spectral density approach. Detailed analysis of the field data and the typhoon generated effects on the structural performance are discussed. PMID:24282385

  16. Performance of Zinc Anodes for Cathodic Protection of Reinforced Concrete Bridges

    SciTech Connect

    Covino, Bernard S. Jr.; Cramer, Stephen D.; Bullard, Sophie J.; Holcomb, Gordon R.; Russell, James H.; Collins, W. Keith; Laylor, Martin H.; Cryer, Curtis B.

    2002-03-01

    Operation of thermal spray zinc (Zn) anodes for cathodic protection (CP) of reinforced concrete structures was investigated in laboratory and field studies conducted by the Albany Research Center (ARC) in collaboration with the Oregon Department of Transportation. The purposes of the research presented in this report were: evaluate the need for preheating concrete to improve the adhesion of the anode; estimate the service life of thermal spray Zn CP anodes; determine the optimum thickness for Zn CP anodes; characterize the anode-concrete interfacial chemistry; and correlate field and laboratory results. Laboratory studies involved accelerated electrochemical aging of thermal sprayed Zn anodes on concrete slabs, some of which were periodically wetted while others were unwetted. Concrete used in the slabs contained either 1.2 or 3 kg NaCl /m3 (2 or 5 lbs NaCl /yd3) as part of the concrete mix design. The Zn anodes were applied to the slabs using the twin wire arc-spray technique. Half of the slabs were preheated to 120-160 C (250-320 F) to improve the initial Zn anode bond strength and the other half were not. Accelerated aging was done at a current density of 0.032 A/m2 (3 mA/ft2), 15 times that used on Oregon DOT Coastal bridges, i.e, . 0.0022 A/m2 (0.2 mA/ft2) Cores from the Cape Creek Bridge (OR), the Richmond San Rafael Bridge (CA), and the East Camino Underpass (CA) were used to study the anode-concrete interfacial chemistry, to relate the chemistry to electrochemical age at the time of sampling, and to compare the chemistry of the field anodes to the chemistry of anodes from the laboratory studies. Cores from a CALTRANS study of a silane sealant used prior to the application of the Zn anodes and cores with galvanized rebar from the Longbird Bridge (Bermuda) were also studied. Aged laboratory and field anodes were characterized by measuring some or all of the following parameters: thickness, bond strength, anode-concrete interfacial chemistry, bulk chemistry

  17. Design Criteria for Deflection Capacity of conventionally Reinforced Concrete Slabs. Phase I. State-of-the-Art Report.

    DTIC Science & Technology

    1980-10-01

    Arching Action in Restrained Reinforced Concrete Slabs (from Ref. 13) -5- is split into two parts. Part of the load is assumed carried by strips in the X...of the tensile strength of the concrete. Nor could catenary action due to tensile membrane stresses account for the observed behavior. It was...concluded that the large increase in slab capacity was due to the development of in-plane com- pressive forces, termed " arching " or "dome action". For

  18. Distributed fiber optic sensors for monitoring reinforced concrete piles using Brillouin scattering

    NASA Astrophysics Data System (ADS)

    de Battista, N.; Kechavarzi, C.; Soga, K.

    2016-05-01

    In this paper we report on advances made in the installation and use of distributed fiber optic sensors to monitor reinforced concrete piles subjected to static load tests. Eight concrete test piles, at three construction sites in London, have recently been instrumented with embedded DFOS. The Brillouin optical time domain reflectometry (BOTDR) technique was used to measure the changes in internal strain and temperature of the piles, during concrete curing and during load testing. These data were used to assess the quality of the pile and derive the load capacity parameters to be used in the foundation design of tall buildings which are to be erected on these sites. The measurements obtained from the DFOS system agreed well with the measurements taken simultaneously using conventional point sensors embedded in the piles. Whereas the conventional sensors only provided measurements at a small number of locations within the piles, the DFOS system made it possible to record the complete strain / temperature profiles along the length of the piles.

  19. Comparison of UPE and GPR systems for the survey of reinforced concrete structures

    NASA Astrophysics Data System (ADS)

    Derobert, Xavier; Villain, Géraldine; Joubert, Anaelle

    2014-05-01

    The objective of this study is to compare two non-destructive techniques using sonic and radar pulses for the survey of reinforced concre structures. The first studied testing method is a Ultrasonic (US) Pulse-Echo (model M2502, from Acoustic Control Systems manufacturer) composed of an array of 12 S-wave transmitters and 12 receivers in one bloc. Their central frequency is equal to 55 kHz. As the averaged USvelocities in concrete tend to 1800-3000 m/s, the corresponding wavelengths tend to 3-5 cm. The Ground-penetrating radar (GPR) system has been performed with high frequency antennas above 1 GHz (1.5 and 2.6 GHz antennas), which lead to the same range of EM wavelengths than the US ones. Measurements have been performed on some thick reinforced concrete elements of structures, and then are compared in term of resolution, depth penetration and ease to use. One of the studied elements is a concrete beam (dimensions : 16 m long, 0.5 m width and 1 m high) designed in an European Projet (FP7_ISTIMES) and damaged by controled impacts of blocks of several tons dropped from few meters [1]. Therefore, the objective of this studyis to compare the two techniques, and for the last studied element to detect the major cracks and the spallings of the cover concrete which are visible from the opposite side. References: Malhotra V.M., Carino, N.J., CRC Handbook on Nondestructive Testing of Concrete, CRC Press LLC, , 1991, 343p. Taffe A., Wiggenhauser H., Validation for Thickness Measurement in Civil Engineering with Ultrasonic Echo, International Symposium NDT-CE, Saint-Louis, USA, 2006, pp506-512. Géraldine Villain, Anaëlle Luczak, Olivier Durand, Xavier Dérobert, Deepening of the measurement technique by Ultrasonic Pulse Echo UPE, Report, IFSTTAR, January 2011, 22p. Catapano I., Di Napoli R., Soldovieri F., Bavusi M., Loperte A., Dumoulin J. (2012), « Structural monitoring via microwave tomography-enhanced GPR : the Montagnole test site », J. Geophys. Eng., Vol. 9, pp. 100-107.

  20. History of the Development of Liquid-Applied Coatings for Protection of Reinforced Concrete

    NASA Technical Reports Server (NTRS)

    Curran, Joseph J.; Hansen, marlin H.

    2005-01-01

    Corrosion of reinforcing steel in concrete is an insidious problem for structures at Kennedy Space Center (KSC). KSC is located on the coast of Florida in a highly corrosive atmosphere. Launch pads, highway bridge infrastructure, and buildings are strongly affected. To mitigate these problems, NASA initiated a development program for a Galvanic Liquid-Applied Coating System (GLACS). A breakthrough in this area would have great commercial value in transportation, marine and construction industry infrastructures. The patented NASA GLACS system has undergone considerable testing to meet the needs of commercialization. A moisture-cure coating gives excellent adhesion with ease of application compared to existing galvanic products on the market. The latest development, GalvaCori; can be sprayed or hand applied to almost any structure shape. A self-adhesive conductive tape system has been devised to simplify current collection within the coating areas. In testing programs, millivolt potential and milliamp output per square foot of anode have been closely studied at actual test sites. These two parameters are probably the most challenging items of a resin-based, room-temperature-applied, galvanic coating. Extensive re-formulation has resulted in a system that provides the needed polarization for catholic protection of reinforcing steel in concrete in a variety of structure environments. The rate of corrosion of rebar in concrete is greatly affected by the environment of the structure. In addition to this, for any given concrete structure; moisture level, carbonization, and chloride contamination influences the rate of rebar corrosion. Similarly, the cathodic protection level of galvanic systems is also dependent on the moisture level of the concrete. GalvaCorr is formulated to maintain galvanic activity as the moisture level of the structure declines. GalvaCorr is available as a three-part kit. The mixing step requires about ten minutes. The viscosity can be easily