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Sample records for concrete underground structures

  1. Failure of underground concrete structures subjected to blast loadings

    NASA Technical Reports Server (NTRS)

    Ross, C. A.; Nash, P. T.; Griner, G. R.

    1979-01-01

    The response and failure of two edges of free reinforced concrete slabs subjected to intermediate blast loadings are examined. The failure of the reinforced concrete structures is defined as a condition where actual separation or fracture of the reinforcing elements has occurred. Approximate theoretical methods using stationary and moving plastic hinge mechanisms with linearly varying and time dependent loadings are developed. Equations developed to predict deflection and failure of reinforced concrete beams are presented and compared with the experimental results.

  2. Failure mechanisms of concrete slab-soil double-layer structure subjected to underground explosion

    NASA Astrophysics Data System (ADS)

    Tan, Z.; Zhang, W.; Cho, C.; Han, X.

    2014-09-01

    The failure mechanism of a concrete slab-soil double-layer structure subjected to an underground explosion was investigated by experimental and numerical methods in this paper. Two underground explosion depths of 150 and 350 mm were tested. The typical failure modes such as the conoid spall of concrete, the bulge of the concrete slab and the cavity in the soil were obtained experimentally. Numerical simulations of the experiments were performed using a hydrodynamic code to analyze the effects of both the stress wave and the expansion of the blast products. Based on the experimental and numerical results, the effects of explosive depth, blast wave front and expansion of the blast products on the failure modes and failure mechanisms were discussed. The underground explosion process at different explosion depths was also analyzed. The results show that attenuation of the stress wave in the soil is significant. The blast wave front and the expansion of the blast products play different roles at different explosion depths. At the explosion depth of 150 mm, the failure mode is mainly caused by a point load induced by the blast wave front, whereas at the depth of 350 mm a sphere-shaped load resulting from the expansion of the blast products is a key factor for failure.

  3. Structural analysis of an underground reinforced concrete waste storage tank due to over-pressurization

    SciTech Connect

    Xu, J.; Bandyopadhyay, K.; Shteyngart, S. ); Eckert, H. )

    1993-01-01

    This paper presents the results of a structural analysis performed by use of the finite element method in determining the pressure-carrying capacity of an underground tank which contains nuclear wastes. The tank and surrounding soil were modeled and analyzed using the ABAQUS program. Special emphases were given on determining the effects of soil-containment interaction by employing Coulomb friction model. The effect of material properties was investigated by considering two sets of stress-strain data for the steel plates. In addition, a refined mesh was used to evaluate the strain concentration effects at steel liner thickness discontinuities.

  4. Structural analysis of an underground reinforced concrete waste storage tank due to over-pressurization

    SciTech Connect

    Xu, J.; Bandyopadhyay, K.; Shteyngart, S.; Eckert, H.

    1993-02-01

    This paper presents the results of a structural analysis performed by use of the finite element method in determining the pressure-carrying capacity of an underground tank which contains nuclear wastes. The tank and surrounding soil were modeled and analyzed using the ABAQUS program. Special emphases were given on determining the effects of soil-containment interaction by employing Coulomb friction model. The effect of material properties was investigated by considering two sets of stress-strain data for the steel plates. In addition, a refined mesh was used to evaluate the strain concentration effects at steel liner thickness discontinuities.

  5. Vitrified underground structures

    DOEpatents

    Murphy, Mark T.; Buelt, James L.; Stottlemyre, James A.; Tixier, Jr., John S.

    1992-01-01

    A method of making vitrified underground structures in which 1) the vitrification process is started underground, and 2) a thickness dimension is controlled to produce substantially planar vertical and horizontal vitrified underground structures. Structures may be placed around a contaminated waste site to isolate the site or may be used as aquifer dikes.

  6. Underground waste barrier structure

    DOEpatents

    Saha, Anuj J.; Grant, David C.

    1988-01-01

    Disclosed is an underground waste barrier structure that consists of waste material, a first container formed of activated carbonaceous material enclosing the waste material, a second container formed of zeolite enclosing the first container, and clay covering the second container. The underground waste barrier structure is constructed by forming a recessed area within the earth, lining the recessed area with a layer of clay, lining the clay with a layer of zeolite, lining the zeolite with a layer of activated carbonaceous material, placing the waste material within the lined recessed area, forming a ceiling over the waste material of a layer of activated carbonaceous material, a layer of zeolite, and a layer of clay, the layers in the ceiling cojoining with the respective layers forming the walls of the structure, and finally, covering the ceiling with earth.

  7. Nuclear Power Plant Concrete Structures

    SciTech Connect

    Basu, Prabir; Labbe, Pierre; Naus, Dan

    2013-01-01

    A nuclear power plant (NPP) involves complex engineering structures that are significant items of the structures, systems and components (SSC) important to the safe and reliable operation of the NPP. Concrete is the commonly used civil engineering construction material in the nuclear industry because of a number of advantageous properties. The NPP concrete structures underwent a great degree of evolution, since the commissioning of first NPP in early 1960. The increasing concern with time related to safety of the public and environment, and degradation of concrete structures due to ageing related phenomena are the driving forces for such evolution. The concrete technology underwent rapid development with the advent of chemical admixtures of plasticizer/super plasticizer category as well as viscosity modifiers and mineral admixtures like fly ash and silica fume. Application of high performance concrete (HPC) developed with chemical and mineral admixtures has been witnessed in the construction of NPP structures. Along with the beneficial effect, the use of admixtures in concrete has posed a number of challenges as well in design and construction. This along with the prospect of continuing operation beyond design life, especially after 60 years, the impact of extreme natural events ( as in the case of Fukushima NPP accident) and human induced events (e.g. commercial aircraft crash like the event of September 11th 2001) has led to further development in the area of NPP concrete structures. The present paper aims at providing an account of evolution of NPP concrete structures in last two decades by summarizing the development in the areas of concrete technology, design methodology and construction techniques, maintenance and ageing management of concrete structures.

  8. A computer program to facilitate performance assessment of underground low-level waste concrete vaults

    SciTech Connect

    Snyder, K.A.; Clifton, J.R.; Pommersheim, J.

    1996-08-01

    A computer program (4SIGHT) to facilitate performance assessment of underground concrete vaults for low level waste (LLW) disposal facilities is being developed at the National Institute of Standards and Technology (NIST). Specifically, the program predicts the hydraulic conductivity and the service life of an underground concrete vault. The hydraulic conductivity estimate is based upon empirical relations. The service life is estimated from consideration of three major degradation processes: steel reinforcement corrosion, sulfate attack, and leaching. The performance prediction is based upon ion transport equations for both diffusion and advection. Most importantly, the computer program incorporates the synergistic degradation effects of all three processes, and their effect upon the transport coefficients.

  9. Detection of underground structures and tunnels

    SciTech Connect

    Mack, J.M.; Moses, R.W.; Kelly, R.E.; Flynn, E.R.; Kraus, R.H.; Cogbill, A.H.; Stolarczyk, L.G.

    1996-09-01

    This is the final report of a one year, Laboratory Directed Research and Development project at Los Alamos National Laboratory. There is a continuing need in the United States defense and drug interdiction for effective over, convert, and standoff means of detecting underground tunnels, structures, and objects. This project sought to begin an assessment of electromagnetic and gravitational gradient detection approaches to the detection of underground structures and tunnels.

  10. Seismic design of circular-section concrete-lined underground openings: Preclosure performance considerations for the Yucca Mountain Site

    SciTech Connect

    Richardson, A.M.; Blejwas, T.E.

    1992-07-01

    Yucca Mountain, the potential site of a repository for high-level radioactive waste, is situated in a region of natural and man-made seismicity. Underground openings excavated at this site must be designed for worker safety in the seismic environment anticipated for the preclosure period. This includes accesses developed for site characterization regardless of the ultimate outcome of the repository siting process. Experience with both civil and mining structures has shown that underground openings are much more resistant to seismic effects than surface structures, and that even severe dynamic strains can usually be accommodated with proper design. This paper discusses the design and performance of lined openings in the seismic environment of the potential site. The types and ranges of possible ground motions (seismic loads) are briefly discussed. Relevant historical records of underground opening performance during seismic loading are reviewed. Simple analytical methods of predicting liner performance under combined in situ, thermal, and seismic loading are presented, and results of calculations are discussed in the context of realistic performance requirements for concrete-lined openings for the preclosure period. Design features that will enhance liner stability and mitigate the impact of the potential seismic load are reviewed. The paper is limited to preclosure performance concerns involving worker safety because present decommissioning plans specify maintaining the option for liner removal at seal locations, thus decoupling liner design from repository postclosure performance issues.

  11. 27. DIVERSION STRUCTURE WITH CONCRETE SIDEWALLS AND CONCRETE CHANNEL BEYOND, ...

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

    27. DIVERSION STRUCTURE WITH CONCRETE SIDEWALLS AND CONCRETE CHANNEL BEYOND, A SHORT DISTANCE WEST OF D STREET ABOUT ONE-QUARTER MILE SOUTH OF 9TH AVENUE (SECTION 26). - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

  12. Effect of underground urban structures on eutrophic coastal environment.

    PubMed

    Nakayama, Tadanobu; Watanabe, Masataka; Tanji, Kazunori; Morioka, Tohru

    2007-02-01

    The NIES Integrated Catchment-based Eco-hydrology (NICE) model was expanded to include the density current and solute-transport process of groundwater in the Kanto Plain and to incorporate the effects of water table and tidal fluctuations around the eutrophic Tokyo Bay, Japan (NICE-SEA). The simulation reproduced excellently the observed values of river discharge and groundwater level in the catchment. The simulated groundwater level shows a minus value (below the sea level) around the Tokyo metropolitan area because of excessive withdrawal around the urban area in the past. The model shows that the underground urban structures, sewage pipes, seashore concrete dikes, and embankments have changed the hydrologic cycle in the catchment and the nutrient supply to Tokyo Bay. In particular, the groundwater flow is interrupted and the phase is delayed, resulting in an increase in the groundwater level, and a decrease of groundwater seepage into Tokyo Bay. Furthermore, we propose four types of political scenario for provisioning human ecosystem service (ES) sites to promote infiltration. The simulated result forecasts that the groundwater level increases predominantly at a maximum value exceeding 40 cm in a scenario for farmland and productive green areas and that the level recovers in some parts of the urban area. This phenomenon is related to the cut-off of groundwater flow by underground urban structures and the sewer leakage into the aquifer, which also influences the decrease of submarine groundwater discharge around the western side of Tokyo Bay.

  13. Nondestructive evaluation of thick concrete structures

    NASA Astrophysics Data System (ADS)

    Clayton, Dwight A.

    2015-03-01

    Concrete has been used in the construction of nuclear power plants (NPPs) due to three primary properties: its low cost, structural strength, and ability to shield radiation. Examples of concrete structures important to the safety of Light Water Reactor (LWR) plants include the containment building, spent fuel pool, and cooling towers. Use in these structures has made concrete's long-term performance crucial for the safe operation of commercial NPPs. Extending LWR operating period to 60 years and beyond will likely increase susceptibility and severity of known forms of degradation. New mechanisms of materials degradation are also possible. This creates the need to be able to nondestructively evaluate the current subsurface concrete condition of aging concrete material in NPP structures. The size and complexity of NPP containment structures and heterogeneity of Portland cement concrete make characterization of the degradation extent a difficult task. Specially designed and fabricated test specimens can provide realistic flaws that are similar to actual flaws in terms of how they interact with a particular nondestructive evaluation (NDE) technique. Artificial test blocks allow the isolation of certain testing problems as well as the variation of certain parameters. Representative large heavily reinforced concrete specimens would allow for comparative testing to evaluate the state-of-the-art NDE in this area and to identify additional developments necessary to address the challenges potentially found in NPPs.

  14. Microbially influenced degradation of concrete structures

    NASA Astrophysics Data System (ADS)

    Rogers, Robert D.; Hamilton, Melinda A.; Nelson, Lee O.

    1998-03-01

    Steel reinforced concrete is the most widely used construction material in the world. The economic costs of repair or replacement of environmentally damaged concrete structures is astronomical. For example, half of the concrete bridges in the Federal Department of Transportation highway system are in need of major repairs. Microbially influenced degradation of concrete (MID) is one of the recognized degradative processes known to adversely affect concrete integrity. It is not possible to assign a specific percent of effect to any of these processes. However, MID has been shown to be as aggressive as any of the physical/chemical phenomena. In addition, the possibility exists that there is a synergism which results in cumulative effects from all the processes. Three groups of bacteria are known to promote MID. Of these, sulfur-oxidizing bacteria (SOB) are the most aggressive. Much is known about the nutritional needs of these bacteria. However, there has not been a biological linkage established between the presence of environmental, polluting sulfur sources and the degradation of concrete structures. It has been shown that the environmental pollutants sulfur dioxide and sulfite can be utilized by active SOB for the biological production of sulfuric acid. Therefore, it is not a reach of reality to assume that SOB exposed to these pollutants could have a major impact on the degradation of concrete structures. But, until the environment sulfur loop is closed it will not be possible to calculate how important SOB activity is in initiating and promoting damage.

  15. MODELING UNDERGROUND STRUCTURE VULNERABILITY IN JOINTED ROCK

    SciTech Connect

    R. SWIFT; D. STEEDMAN

    2001-02-01

    The vulnerability of underground structures and openings in deep jointed rock to ground shock attack is of chief concern to military planning and security. Damage and/or loss of stability to a structure in jointed rock, often manifested as brittle failure and accompanied with block movement, can depend significantly on jointed properties, such as spacing, orientation, strength, and block character. We apply a hybrid Discrete Element Method combined with the Smooth Particle Hydrodynamics approach to simulate the MIGHTY NORTH event, a definitive high-explosive test performed on an aluminum lined cylindrical opening in jointed Salem limestone. Representing limestone with discrete elements having elastic-equivalence and explicit brittle tensile behavior and the liner as an elastic-plastic continuum provides good agreement with the experiment and damage obtained with finite-element simulations. Extending the approach to parameter variations shows damage is substantially altered by differences in joint geometry and liner properties.

  16. Reusing recycled aggregates in structural concrete

    NASA Astrophysics Data System (ADS)

    Kou, Shicong

    The utilization of recycled aggregates in concrete can minimize environmental impact and reduce the consumption of natural resources in concrete applications. The aim of this thesis is to provide a scientific basis for the possible use of recycled aggregates in structure concrete by conducting a comprehensive programme of laboratory study to gain a better understanding of the mechanical, microstructure and durability properties of concrete produced with recycled aggregates. The study also explored possible techniques to of improve the properties of recycled aggregate concrete that is produced with high percentages (≧ 50%) of recycled aggregates. These techniques included: (a) using lower water-to-cement ratios in the concrete mix design; (b) using fly ash as a cement replacement or as an additional mineral admixture in the concrete mixes, and (c) precasting recycled aggregate concrete with steam curing regimes. The characteristics of the recycled aggregates produced both from laboratory and a commercially operated pilot construction and demolition (C&D) waste recycling plant were first studied. A mix proportioning procedure was then established to produce six series of concrete mixtures using different percentages of recycled coarse aggregates with and without the use of fly ash. The water-to-cement (binder) ratios of 0.55, 0.50, 0.45 and 0.40 were used. The fresh properties (including slump and bleeding) of recycled aggregate concrete (RAC) were then quantified. The effects of fly ash on the fresh and hardened properties of RAC were then studied and compared with those RAC prepared with no fly ash addition. Furthermore, the effects of steam curing on the hardened properties of RAC were investigated. For micro-structural properties, the interfacial transition zones of the aggregates and the mortar/cement paste were analyzed by SEM and EDX-mapping. Moreover, a detailed set of results on the fracture properties for RAC were obtained. Based on the experimental

  17. Monitoring of Concrete Structures Using Ofdr Technique

    NASA Astrophysics Data System (ADS)

    Henault, J. M.; Salin, J.; Moreau, G.; Delepine-Lesoille, S.; Bertand, J.; Taillade, F.; Quiertant, M.; Benzarti, K.

    2011-06-01

    Structural health monitoring is a key factor in life cycle management of infrastructures. Truly distributed fiber optic sensors are able to provide relevant information on large structures, such as bridges, dikes, nuclear power plants or nuclear waste disposal facilities. The sensing chain includes an optoelectronic unit and a sensing cable made of one or more optical fibers. A new instrument based on Optical Frequency Domain Reflectometry (OFDR), enables to perform temperature and strain measurements with a centimeter scale spatial resolution over hundred of meters and with a level of precision equal to 1 μstrain and 0.1 °C. Several sensing cables are designed with different materials targeting to last for decades in a concrete aggressive environment and to ensure an optimal transfer of temperature and strain from the concrete matrix to the optical fiber. Tests were carried out by embedding various sensing cables into plain concrete specimens and representative-scale reinforced concrete structural elements. Measurements were performed with an OFDR instrument; meanwhile, mechanical solicitations were imposed to the concrete element. Preliminary experiments are very promising since measurements performed with distributed sensing system are comparable to values obtained with conventional sensors used in civil engineering and with the Strength of Materials Modelling. Moreover, the distributed sensing system makes it possible to detect and localize cracks appearing in concrete during the mechanical loading.

  18. Concrete structure construction on the Moon

    NASA Technical Reports Server (NTRS)

    Matsumoto, Shinji; Namba, Haruyuki; Kai, Yoshiro; Yoshida, Tetsuji

    1992-01-01

    This paper describes a precast prestressed concrete structure system on the Moon and erection methods for this system. The horizontal section of the structural module is hexagonal so that various layouts of the modules are possible by connecting the adjacent modules to each other. For erection of the modules, specially designed mobile cranes are used.

  19. Service life prediction of reinforced concrete structures

    SciTech Connect

    Liang, M.T.; Wang, K.L.; Liang, C.H.

    1999-09-01

    This paper is focused on the estimation of durability and service life of reinforced concrete structures. Assuming that the chloride ion in concrete can be absorbed on tricalcium aluminate, calcium silicate hydrate, and by other constituents of hardened cement paste, hydrated or not, the exact analytical solution of the governing partial differential equation together with its boundary and initial conditions can be obtained through nondimensional parameters and Laplace's transform. When the results of an exact analytical solution using suitable parameters were compared with the results of previous experimental work, the differences were found to be very small. This suggests that the absorption model is of considerable value. The exact analytical solution with the saturation parameter and time and diffusion coefficients under different effective electrical potential could be used to predict both the experimental results and the service life of reinforced concrete structures.

  20. Acoustic Emission Analysis of Prestressed Concrete Structures

    NASA Astrophysics Data System (ADS)

    Elfergani, H. A.; Pullin, R.; Holford, K. M.

    2011-07-01

    Corrosion is a substantial problem in numerous structures and in particular corrosion is very serious in reinforced and prestressed concrete and must, in certain applications, be given special consideration because failure may result in loss of life and high financial cost. Furthermore corrosion cannot only be considered a long term problem with many studies reporting failure of bridges and concrete pipes due to corrosion within a short period after they were constructed. The concrete pipes which transport water are examples of structures that have suffered from corrosion; for example, the pipes of The Great Man-Made River Project of Libya. Five pipe failures due to corrosion have occurred since their installation. The main reason for the damage is corrosion of prestressed wires in the pipes due to the attack of chloride ions from the surrounding soil. Detection of the corrosion in initial stages has been very important to avoid other failures and the interruption of water flow. Even though most non-destructive methods which are used in the project are able to detect wire breaks, they cannot detect the presence of corrosion. Hence in areas where no excavation has been completed, areas of serious damage can go undetected. Therefore, the major problem which faces engineers is to find the best way to detect the corrosion and prevent the pipes from deteriorating. This paper reports on the use of the Acoustic Emission (AE) technique to detect the early stages of corrosion prior to deterioration of concrete structures.

  1. 43. Launch Area, Underground Missile Storage Structure, detail of air ...

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

    43. Launch Area, Underground Missile Storage Structure, detail of air vent VIEW NORTHWEST - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  2. 42. Launch Area, Underground Missile Storage Structure, detail of escape ...

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

    42. Launch Area, Underground Missile Storage Structure, detail of escape hatch, elevator and air vent VIEW SOUTH - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  3. 36. Launch Area, Underground Missile Storage Structure, detail showing elevator, ...

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

    36. Launch Area, Underground Missile Storage Structure, detail showing elevator, air ventilators and personnel entrance VIEW SOUTHEAST - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  4. 37. Launch Area, Underground Missile Storage Structure, detail of personnel ...

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

    37. Launch Area, Underground Missile Storage Structure, detail of personnel entrance VIEW NORTH - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  5. 40. Launch Area, Underground Missile Storage Structure, detail of escape ...

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

    40. Launch Area, Underground Missile Storage Structure, detail of escape hatch and decontamination shower VIEW WEST - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  6. 38. Launch Area, Underground Missile Storage Structure, detail of conduit ...

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

    38. Launch Area, Underground Missile Storage Structure, detail of conduit service junction - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  7. 41. Launch Area, Underground Missile Storage Structure, detail of elevator ...

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

    41. Launch Area, Underground Missile Storage Structure, detail of elevator and air vents VIEW NORTHEAST - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  8. 75. SAC control center underground structure middle floor plan, drawing ...

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

    75. SAC control center underground structure middle floor plan, drawing number 32-02-03, dated 1 February, 1955 - Offutt Air Force Base, Strategic Air Command Headquarters & Command Center, Headquarters Building, 901 SAC Boulevard, Bellevue, Sarpy County, NE

  9. 72. SAC control center underground structure lower floor plan, drawing ...

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

    72. SAC control center underground structure lower floor plan, drawing number 32-02-03, dated 1 February 1955 - Offutt Air Force Base, Strategic Air Command Headquarters & Command Center, Headquarters Building, 901 SAC Boulevard, Bellevue, Sarpy County, NE

  10. 76. SAC control center underground structure upper floor plan, drawing ...

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

    76. SAC control center underground structure upper floor plan, drawing number 32-02-03, dated 1 February, 1955 - Offutt Air Force Base, Strategic Air Command Headquarters & Command Center, Headquarters Building, 901 SAC Boulevard, Bellevue, Sarpy County, NE

  11. 13. SAC command center, weather center, underground structure, building 501, ...

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

    13. SAC command center, weather center, underground structure, building 501, undated - Offutt Air Force Base, Strategic Air Command Headquarters & Command Center, Command Center, 901 SAC Boulevard, Bellevue, Sarpy County, NE

  12. Electrical resistance tomography for imaging concrete structures

    SciTech Connect

    Buettner, M.; Ramirez, A.; Daily, W.

    1995-11-08

    Electrical Resistance Tomography (ERT) has been used to non-destructively examine the interior of reinforced concrete pillars in the laboratory during a water infiltration experiment. ERT is a technique for determining the electrical resistivity distribution within a volume from measurement of injected currents and the resulting electrical potential distribution on the surface. The transfer resistance (ratio of potential to injected current) data are inverted using an algorithm based on a finite element forward solution which is iteratively adjusted in a least squares sense until the measured and calculated transfer resistances agree to within some predetermined value. Laboratory specimens of concrete pillars, 61.0 cm (24 in) in length and 20.3 cm (8 in) on a side, were prepared with various combinations of steel reinforcing bars and voids (1.27 cm diameter) which ran along the length of the pillars. An array of electrodes was placed around the pillar to allow for injecting current and measuring the resulting potentials. After the baseline resistivity distribution was determined, water was added to a void near one comer of the pillar. ERT was used to determine the resistivity distribution of the pillar at regular time intervals as water was added. The ERT images show very clearly that the water was gradually imbibed into the concrete pillar during the course of the experiment. The resistivity decreased by nearly an order of magnitude near the point of water addition in the first hour, and by nearly two orders of magnitude by the end of the experiment. Other applications for this technology include monitoring of curing in concrete structures, detecting cracks in concrete structures, detecting rebar location and corrosion state, monitoring slope stability and the stability of footings, detecting and monitoring leaks from storage tanks, monitoring thermal processes during environmental remediation, and for detecting and monitoring contaminants in soil and groundwater.

  13. Nondestructive Evaluation of Thick Concrete Structures

    SciTech Connect

    Clayton, Dwight A

    2015-01-01

    Materials issues are a key concern for the existing nuclear reactor fleet in the United States as material degradation can lead to increased maintenance, increased downtime, and increased risk. Extending reactor life to 60 years and beyond will likely increase susceptibility and severity of both known and new forms of degradation. A multitude of concrete-based structures are typically part of a light water reactor plant to provide foundation, support, shielding, and containment functions. The size and complexity of nuclear power plant containment structures and the heterogeneity of Portland cement concrete make characterization of the degradation extent a difficult task. This paper examines the benefits of using time-frequency analysis with Synthetic Aperture Focusing Technique (SAFT). By using wavelet packet decomposition, the original ultrasound signals are decomposed into various frequency bands that facilitates highly selective analysis of the signal’s frequency content and can be visualized using the familiar SAFT image reconstruction algorithm.

  14. Comparative testing of nondestructive examination techniques for concrete structures

    NASA Astrophysics Data System (ADS)

    Clayton, Dwight A.; Smith, Cyrus M.

    2014-03-01

    A multitude of concrete-based structures are typically part of a light water reactor (LWR) plant to provide foundation, support, shielding, and containment functions. Concrete has been used in the construction of nuclear power plants (NPPs) because of three primary properties, its inexpensiveness, its structural strength, and its ability to shield radiation. Examples of concrete structures important to the safety of LWR plants include containment building, spent fuel pool, and cooling towers. Comparative testing of the various NDE concrete measurement techniques requires concrete samples with known material properties, voids, internal microstructure flaws, and reinforcement locations. These samples can be artificially created under laboratory conditions where the various properties can be controlled. Other than NPPs, there are not many applications where critical concrete structures are as thick and reinforced. Therefore, there are not many industries other than the nuclear power plant or power plant industry that are interested in performing NDE on thick and reinforced concrete structures. This leads to the lack of readily available samples of thick and heavily reinforced concrete for performing NDE evaluations, research, and training. The industry that typically performs the most NDE on concrete structures is the bridge and roadway industry. While bridge and roadway structures are thinner and less reinforced, they have a good base of NDE research to support their field NDE programs to detect, identify, and repair concrete failures. This paper will summarize the initial comparative testing of two concrete samples with an emphasis on how these techniques could perform on NPP concrete structures.

  15. A Study on the Cover Failure in Concrete Structure Following Concrete Deterioration

    SciTech Connect

    Choo, Y.H.; Lee, Y.H.; Lee, C.M.; Lee, K.J.

    2008-07-01

    The RC (Reinforced Concrete) structures in the spent fuel dry storage is required structural integrity for a long period of the service life time. A study on the concrete cracking behavior by stress on concrete is necessary for life time estimation of structures because concrete cracking can reduce the radiation shielding performance and deteriorate the durability of spent fuel dry storage. The purpose of this study is to analyze the relationship between the range of the steel expansion and the crack creation and propagation using the ABAQUS tool. Parameters used in this study were concrete strength, concrete cover depth and the steel diameter. The value of steel radius to volume expansion was applied to suppose the expansion of reinforcing bar under the load condition. As a result of this case study, it is confirmed that the critical steel expansion which can initiate cracking is proportional to tensile strength. And primary factors which effect crack creation of concrete cover are in order of concrete strength, cover thickness and steel diameter. If concrete strength is lowered about its 30%, the rate of surface crack occurrence accelerates 15 times maximally. The critical expansion value of steel increased as the increment of concrete cover depth. The surface cracking of concrete cover was created at the value of steel expansion, ranging from 0.019 to 0.051 mm under the cover depth 50 mm. (authors)

  16. Electrical resistance tomography of concrete structures

    SciTech Connect

    Daily, W.; Ramirez, A.; Binley, A.; Henry-Poulter, S.

    1993-10-01

    The purpose of this work is to determine the feasibility of using Electrical resistance tomography (ERT) to nondestructively examine the interior of concrete structures such as bridge pillars and roadways. We report the results of experiments wherein ERT is used to image the two concrete specimens in the laboratory. Each specimen is 5 inches square and 12 inches long and contained steel reinforcing rods along its length. Twenty electrodes were placed on each sample and an-image of electrical resistivity distribution was generated from current and voltage measurements. We found that the images show the general location of the reinforcing steel and, what`s more important, delineate the absence of the steel. The method may therefore be useful for determining if such steel has been destroyed by corrosion, however to make it useful, the technique must have better resolution so that individual reinforcing steel units are resolved.

  17. 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.

  18. Strength of concrete structures under dynamic loading

    NASA Astrophysics Data System (ADS)

    Kumpyak, O. G.; Galyautdinov, Z. R.; Kokorin, D. N.

    2016-01-01

    The use of elastic supports is one the efficient methods of decreasing the dynamic loading. The paper describes the influence of elastic supports on the stress-strain state of steel concrete structures exposed to one-time dynamic loading resulting in failure. Oblique bending beams on elastic supports and their elastic, elastoplastic, and elastoplastic consolidation behavior are considered in this paper. For numerical calculations the developed computer program is used based on the finite element method. Research findings prove high efficiency of elastic supports under dynamic loading conditions. The most effective behavior of elastic supports is demonstrated at the elastoplastic stage. A good agreement is observed between the theoretical and experimental results.

  19. 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

  20. Research progress of microbial corrosion of reinforced concrete structure

    NASA Astrophysics Data System (ADS)

    Li, Shengli; Li, Dawang; Jiang, Nan; Wang, Dongwei

    2011-04-01

    Microbial corrosion of reinforce concrete structure is a new branch of learning. This branch deals with civil engineering , environment engineering, biology, chemistry, materials science and so on and is a interdisciplinary area. Research progress of the causes, research methods and contents of microbial corrosion of reinforced concrete structure is described. The research in the field is just beginning and concerted effort is needed to go further into the mechanism of reinforce concrete structure and assess the security and natural life of reinforce concrete structure under the special condition and put forward the protective methods.

  1. Application of Composite Mechanics to Composites Enhanced Concrete Structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Gotsis, Pascal K.

    2006-01-01

    A new and effective method is described to design composites to repair damage or enhance the overload strength of concrete infrastructures. The method is based on composite mechanics which is available in computer codes. It is used to simulate structural sections made from reinforced concrete which are typical in infrastructure as well as select reinforced concrete structures. The structural sections are represented by a number of layers through the thickness where different layers are used in concrete, and for the composite. The reinforced concrete structures are represented with finite elements where the element stiffness parameters are from the structural sections which are represented by composite mechanics. The load carrying capability of the structure is determined by progressive structural fracture. Results show up to 40 percent improvements for damage and for overload enhancement with relatively small laminate thickness for the structural sections and up to three times for the composite enhanced select structures (arches and domes).

  2. Maintenance and preservation of concrete structures. Report 3: Abrasion-erosion resistance of concrete

    NASA Astrophysics Data System (ADS)

    Liu, T. C.

    1980-07-01

    This report describes a laboratory test program on abrasion-erosion resistance of concrete, including the development of a new underwater abrasion-erosion test method. This program was designed to evaluate the relative abrasion-erosion resistance of various materials considered for use in the repair of erosion-damaged concrete structures. The test program encompassed three concrete types (conventional concrete, fiber-reinforced concrete, and polymer concrete); seven aggregate types (limestone, chert, trap rock, quartzite, granite, siliceous gravel, and slag); three principal water-cement rations (0.72, 0.54, and 0.40); and six types of surface treatment (vacuum, polyurethane coating, acrylic mortar coating, epoxy mortar coating, furan resin mortar coating, and iron aggregate topping). A total of 114 specimens made from 41 batches of concrete was tested. Based on the test data obtained, a comprehensive evaluation of the effects of various parameters on the abrasion-erosion resistance of concrete was presented. Materials suitable for use in the repair of erosion-damaged concrete structures were recommended. Additional work to correlate the reported findings with field performance was formulated.

  3. Evaluating the strength of concrete structure on terrace houses

    NASA Astrophysics Data System (ADS)

    Hasbullah, Mohd. Amran; Yusof, Rohana; Rahman, Mohd Nazaruddin Yusoff @ Abdul

    2016-08-01

    The concrete structure is the main component to support the structure of the building, but when concrete has been used for an extended period hence, it needs to be evaluated to determine the current strength, durability and how long it can last. The poor quality of concrete structures will cause discomfort to the user and, the safety will be affected due to lack of concrete strength. If these issues are not monitored or not precisely known performance, and no further action done then, the concrete structure will fail and eventually it will collapse. Five units of terrace houses that are built less than 10 years old with extension or renovations and have cracks at Taman Samar Indah, Samarahan, Sarawak have been selected for this study. The instrument used in this research is Ultrasonic Pulse Velocity (UPV), with the objective to determine the current strength and investigate the velocity of a pulse at the concrete cracks. The data showed that the average velocity of the pulse is less than 3.0 km/s and has shown that the quality of the concrete in the houses too weak scale / doubt in the strength of concrete. It also indicates that these houses need to have an immediate repair in order to remain secure other concrete structures.

  4. Thermal image study of detecting near-underground structures by means of infrared radiometer

    NASA Astrophysics Data System (ADS)

    Okamoto, Yoshizo; Fan, Zuofen; Liu, Chanliang; Inagaki, Terumi

    1995-03-01

    An infrared radiometer is used to detect several flaws of industrial structural elements, as one remote sensing device. The thermal image method (TIM) was carried out to analyze location and dimension of the internal flaws of mechanical components, like piping, vessel, slab and pile. Internal flaws were detected by visualizing abnormal behavior of radiation temperature distribution of the tested surface by solar and artificial heat injection. The induced nonuniform temperature shows the existence of the internal flaws imaged on the CRT display of the infrared radiometer. As one application subject, the TIM method was extensively applied to near-underground buried materials of ancient remains; such as corner stone, stone settlement, shell mound, and tomb. The paper represents basic experimental and analytical results of preliminary and demonstration model tests of the buried materials in the soil and rock by solar, direct, and indirect combustion heaters. After continuous irradiation heating, we measured and recorded transient radiation temperature distribution of the tested ground surface which inserts the model near-underground tests plates of stylene, concrete, stone and gravel, changing width and depth of the test plates. Nonuniform and discontinuous temperature distribution of the tested surface above the inserted plates shows the existence of near- underground buried materials. Furthermore, transient temperature and heat flow behavior was numerically analyzed by solving a transient two-dimensional heat-balance equation. Calculation results were quite useful to analyze the experimental heat flow behavior around the buried object.

  5. 206. Big Witch Road grade separation structure. This concrete box ...

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

    206. Big Witch Road grade separation structure. This concrete box culvert, built in 1950, is unusual in that the culvert's concrete bottom extends beyond the structure to the ends of its perpendicular wing walls. Facing northeast. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  6. 1. VARIABLEANGLE LAUNCHER (VAL) CONCRETE 'A' FRAME STRUCTURE SHOWING CAMERA ...

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

    1. VARIABLE-ANGLE LAUNCHER (VAL) CONCRETE 'A' FRAME STRUCTURE SHOWING CAMERA TOWER STRUCTURE LOOKING SOUTH AND ARCHED OPENING FOR ROADWAY. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  7. Interior view of coffee processing structure No. 1, showing concrete ...

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

    Interior view of coffee processing structure No. 1, showing concrete reservoirs on floor, view towards the west - Finca Silem, Coffee Processing Structure No. 1, Highway 139, Kilometer 9.3, Maraguez, Ponce Municipio, PR

  8. Geopolymer concrete for structural use: Recent findings and limitations

    NASA Astrophysics Data System (ADS)

    Nuruddin, M. F.; Malkawi, A. B.; Fauzi, A.; Mohammed, B. S.; Almattarneh, H. M.

    2016-06-01

    Geopolymer binders offer a possible solution for several problems that facing the current cement industry. These binders exhibit similar or better engineering properties compared to cement and can utilize several types of waste materials. This paper presents the recent research progress regarding the structural behaviour of reinforced geopolymer concrete members including beams, columns and slabs. The reported results showed that the structural behaviour of the reinforced geopolymer concrete members is similar to the known behaviour of the ordinary reinforced concrete members. In addition, the currently available standards have been conservatively used for analysis and designing of reinforced geopolymer concrete structures. On the other hand, the main hurdles facing the spread of geopolymer concrete was the absence of standards and the concerns about the long-term properties. Other issues included the safety, cost and liability.

  9. Evaluation of microbially-influenced degradation of massive concrete structures

    SciTech Connect

    Hamilton, M.A.; Rogers, R.D.; Zolynski, M.; Veeh, R.

    1996-08-01

    Many low level waste disposal vaults, both above and below ground, are constructed of concrete. One potential contributing agent to the destruction of concrete structures is microbially-influenced degradation (MID). Three groups of bacteria are known to create conditions that are conducive to destroying concrete integrity. They are sulfur oxidizing bacteria, nitrifying bacteria, and heterotrophic bacteria. Research is being conducted at the Idaho National Engineering Laboratory to assess the extent of naturally occurring microbially influenced degradation (MID) and its contribution to the deterioration of massive concrete structures. The preliminary steps to understanding the extent of MID, require assessing the microbial communities present on degrading concrete surfaces. Ultimately such information can be used to develop guidelines for preventive or corrective treatments for MID and aid in formulation of new materials to resist corrosion. An environmental study was conducted to determine the presence and activity of potential MID bacteria on degrading concrete surfaces of massive concrete structures. Scanning electron microscopy detected bacteria on the surfaces of concrete structures such as bridges and dams, where corrosion was evident. Enumeration of sulfur oxidizing thiobacilli and nitrogen oxidizing Nitrosomonas sp. and Nitrobacter sp. from surface samples was conducted. Bacterial community composition varied between sampling locations, and generally the presence of either sulfur oxidizers or nitrifiers dominated, although instances of both types of bacteria occurring together were encountered. No clear correlation between bacterial numbers and degree of degradation was exhibited.

  10. VIEW OF GUN EMPLACEMENT AND THE TABLELIKE CAST CONCRETE STRUCTURE ...

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

    VIEW OF GUN EMPLACEMENT AND THE TABLE-LIKE CAST CONCRETE STRUCTURE SHOWING THE SPALLED AREA ON ITS EAST SIDE (LEFT) WHERE THE SECOND PROJECTING ARM WAS BROKEN OFF. NOTE THE SLOPED CONCRETE PAD IN THE BACKGROUND. VIEW FACING SOUTHWEST - U.S. Naval Base, Pearl Harbor, Ford Island 5-Inch Antiaircraft Battery, East Gun Emplacement, Ford Island, Pearl City, Honolulu County, HI

  11. Analysis of concrete containment structures under severe accident loading conditions

    SciTech Connect

    Porter, V.L.

    1993-12-31

    One of the areas of current interest in the nuclear power industry is the response of containment buildings to internal pressures that may exceed design pressure levels. Evaluating the response of structures under these conditions requires computing beyond design load to the ultimate load of the containment. For concrete containments, this requirement means computing through severe concrete cracking and into the regime of wide-spread plastic rebar and/or tendon response. In this regime of material response, an implicit code can have trouble converging. This paper describes some of the author`s experiences with Version 5.2 of ABAQUS Standard and the ABAQUS concrete model in computing the axisymmetric response of a prestressed concrete containment to ultimate global structural failure under high internal pressures. The effects of varying the tension stiffening parameter in the concrete material model and variations of the parameters for the CONTROLS option are discussed.

  12. Simultaneous chloride removal and realkalinization of old concrete structures

    SciTech Connect

    Chatterji, S. )

    1994-01-01

    Many of the old concrete structures in Denmark and many other countries, especially those exposed to marine conditions, contain chloride. Many of these structures show extensive reinforcement corrosion. In this note an improved electrolytic technique has been suggested for simultaneous removal of chloride and realkalinization of old concrete structures. In the suggested technique auxiliary electrodes, Ca(OH)[sub 2] and Ca(NO[sub 3])[sub 2] solutions are used to avoid some of the risks associated with direct electrolysis.

  13. 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.

  14. 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.

  15. Design and application of a small size SAFT imaging system for concrete structure.

    PubMed

    Shao, Zhixue; Shi, Lihua; Shao, Zhe; Cai, Jian

    2011-07-01

    A method of ultrasonic imaging detection is presented for quick non-destructive testing (NDT) of concrete structures using synthesized aperture focusing technology (SAFT). A low cost ultrasonic sensor array consisting of 12 market available low frequency ultrasonic transducers is designed and manufactured. A channel compensation method is proposed to improve the consistency of different transducers. The controlling devices for array scan as well as the virtual instrument for SAFT imaging are designed. In the coarse scan mode with the scan step of 50 mm, the system can quickly give an image display of a cross section of 600 mm (L) × 300 mm (D) by one measurement. In the refined scan model, the system can reduce the scan step and give an image display of the same cross section by moving the sensor array several times. Experiments on staircase specimen, concrete slab with embedded target, and building floor with underground pipe line all verify the efficiency of the proposed method.

  16. Design and application of a small size SAFT imaging system for concrete structure

    NASA Astrophysics Data System (ADS)

    Shao, Zhixue; Shi, Lihua; Shao, Zhe; Cai, Jian

    2011-07-01

    A method of ultrasonic imaging detection is presented for quick non-destructive testing (NDT) of concrete structures using synthesized aperture focusing technology (SAFT). A low cost ultrasonic sensor array consisting of 12 market available low frequency ultrasonic transducers is designed and manufactured. A channel compensation method is proposed to improve the consistency of different transducers. The controlling devices for array scan as well as the virtual instrument for SAFT imaging are designed. In the coarse scan mode with the scan step of 50 mm, the system can quickly give an image display of a cross section of 600 mm (L) × 300 mm (D) by one measurement. In the refined scan model, the system can reduce the scan step and give an image display of the same cross section by moving the sensor array several times. Experiments on staircase specimen, concrete slab with embedded target, and building floor with underground pipe line all verify the efficiency of the proposed method.

  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. Effective Parameters on Seismic Design of Rectangular Underground Structures

    SciTech Connect

    Amiri, G. Ghodrati; Maddah, N.; Mohebi, B.

    2008-07-08

    Underground structures are a significant part of the transportation in the modern society and in the seismic zones should withstand against both seismic and static loadings. Embedded structures should conform to ground deformations during the earthquake but almost exact evaluation of structure to ground distortion is critical. Several two-dimensional finite difference models are used to find effective parameters on racking ratio (structure to ground distortion) including flexibility ratio, various cross sections, embedment depth, and Poisson's ratio of soil. Results show that influence of different cross sections, by themselves is negligible but embedment depth in addition to flexibility ratio and Poisson's ratio is known as a consequential parameter. A comparison with pseudo-static method (simplified frame analysis) is also performed. The results show that for a stiffer structure than soil, racking ratio decreases as the depth of burial decreases; on the other hand, shallow and flexible structures can suffer greater distortion than deeper ones up to 30 percents.

  19. Storage Area (1942 section), looking east, showing concrete structural elements ...

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

    Storage Area (1942 section), looking east, showing concrete structural elements and wall opening to vaults - Fort McNair, Film Store House, Fort Lesley J. McNair, P Street between Third & Fourth Streets, Southwest, Washington, District of Columbia, DC

  20. Credit BG. Southeast and northeast facades of concrete block structure ...

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

    Credit BG. Southeast and northeast facades of concrete block structure built in the late 1960s. It is now used to store miscellaneous equipment - Edwards Air Force Base, North Base, Liquid Oxygen Storage Facility, Second Street, Boron, Kern County, CA

  1. 52. CONCRETE FORMWORK FOR THE VAL CELLULAR 'A' FRAME STRUCTURE ...

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

    52. CONCRETE FORMWORK FOR THE VAL CELLULAR 'A' FRAME STRUCTURE LOOKING SOUTH, Date unknown, circa December 1946. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  2. 2. VAL CONCRETE 'A' FRAME STRUCTURE SHOWING CAMERA TOWER, PROJECTILE ...

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

    2. VAL CONCRETE 'A' FRAME STRUCTURE SHOWING CAMERA TOWER, PROJECTILE LOADING DECK AND BREECH END OF LAUNCHER BRIDGE LOOKING SOUTH. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  3. 53. VAL CONCRETE 'A' FRAME STRUCTURE AFTER FORMWORK REMOVED, Date ...

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

    53. VAL CONCRETE 'A' FRAME STRUCTURE AFTER FORMWORK REMOVED, Date unknown, circa December 1946. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  4. 51. CONCRETE FORMWORK FOR THE VAL CELLULAR 'A' FRAME STRUCTURE ...

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

    51. CONCRETE FORMWORK FOR THE VAL CELLULAR 'A' FRAME STRUCTURE LOOKING NORTHWEST, Date unknown, circa December 1946. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  5. 6. VAL LAUNCHER BRIDGE, CARRIAGE SUPPORT, CONCRETE 'A' FRAME STRUCTURE ...

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

    6. VAL LAUNCHER BRIDGE, CARRIAGE SUPPORT, CONCRETE 'A' FRAME STRUCTURE AND CAMERA TOWER LOOKING NORTHWEST. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  6. 7. VAL CONCRETE 'A' FRAME STRUCTURE SHOWING CAMERA TOWER ARCHED ...

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

    7. VAL CONCRETE 'A' FRAME STRUCTURE SHOWING CAMERA TOWER ARCHED OPENING FOR ROADWAY AND COUNTERWEIGHT SLOPE TAKEN FROM RESERVOIR LOOKING WEST. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  7. Underground structure characterization using motor vehicles as passive seismic sources

    NASA Astrophysics Data System (ADS)

    Kuzma, H. A.; Liu, Y.; Zhao, Y.; Rector, J.; Vaidya, S.

    2009-12-01

    The ability to detect and characterize underground voids will be critical to the success of On-Site Inspections (OSI) as mandated by the nuclear Comprehensive Test Ban Treaty (CTBT). OSIs may be conducted in order to successfully locate the Ground Zero of underground tests as well as infrastructure related to testing. Recently, our team has shown the potential of a new technique to detect underground objects using the amplitude of seismic surface waves generated by motor vehicles. In an experiment conducted in June, 2009 we were able to detect an abandoned railroad tunnel by recognizing a clear pattern in the surface waves scattered by the tunnel, using a signal generated by driving a car on a dirt road across the tunnel. Synthetic experiments conducted using physically realistic wave-equation models further suggest that the technique can be readily applied to detecting underground features: it may be possible to image structures of importance to OSI simply by laying out an array of geophones (or using an array already in place for passive listening for event aftershocks) and driving vehicles around the site. We present evidence from a set of field experiments and from synthetic modeling and inversion studies to illustrate adaptations of the technique for OSI. Signature of an abandoned underground railroad tunnel at Donner Summit, CA. To produce this image, a line of geophones was placed along a dirt road perpendicular to the tunnel (black box) and a single car was driven along the road. A normalized mean power-spectrum is displayed on a log scale as a function of meters from the center of the tunnel. The top of the tunnel was 18m below ground surface. The tunnel anomaly is made up of a shadow (light) directly above the tunnel and amplitude build-up (dark) on either side of the tunnel. The size of the anomaly (6 orders of magnitude) suggests that the method can be extended to find deep structures at greater distances from the source and receivers.

  8. Coating concrete secondary containment structures exposed to agrichemicals

    SciTech Connect

    Broder, M.F.; Nguyen, D.T.

    1995-06-01

    Concrete has traditionally been the material of choice for building secondary containment structures because it is relatively inexpensive and has structural properties which make it ideal for supporting the loads of vehicles and large tanks. However, concrete`s chemical properties make it susceptible to corrosion by some common fertilizers. Though fairly impervious to water movement, concrete is easily penetrated by vapors and solvents. It is also prone to cracking. For these reasons, the Environmental Protection Agency (EPA) believes that concrete alone may not provide an effective barrier to pesticide movement and has proposed that concrete in pesticide secondary containment structures be sealed or coated to reduce its permeability. Some state secondary containment regulations require that concrete exposed to fertilizers and pesticides be sealed or protected with a coating. Lacking guidelines, some retailers have used penetrating sealants to satisfy the law, even though these products provide little protection from chemical attack nor do they prevent pesticide egress. Other retailers who have applied thick film coatings which were properly selected have had disastrous results because the application was poorly done. Consequently, much skepticism exists regarding the performance and benefit of protective coatings.

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

    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 ismore » 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.« less

  10. 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

  11. Modeling of fracture of protective concrete structures under impact loads

    NASA Astrophysics Data System (ADS)

    Radchenko, P. A.; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S.

    2015-10-01

    This paper presents results of numerical simulation of interaction between a Boeing 747-400 aircraft and the protective shell of a nuclear power plant. The shell is presented as a complex multilayered cellular structure consisting of layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was performed three-dimensionally using the original algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. Dynamics of the stress-strain state and fracture of the structure were studied. Destruction is described using a two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of the cellular shell structure; cells start to destruct in an unloading wave originating after the compression wave arrival at free cell surfaces.

  12. 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.

  13. Modeling of fracture of protective concrete structures under impact loads

    SciTech Connect

    Radchenko, P. A. Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S.

    2015-10-27

    This paper presents results of numerical simulation of interaction between a Boeing 747-400 aircraft and the protective shell of a nuclear power plant. The shell is presented as a complex multilayered cellular structure consisting of layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was performed three-dimensionally using the original algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. Dynamics of the stress-strain state and fracture of the structure were studied. Destruction is described using a two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of the cellular shell structure; cells start to destruct in an unloading wave originating after the compression wave arrival at free cell surfaces.

  14. Monitoring of concrete structures using the ultrasonic pulse velocity method

    NASA Astrophysics Data System (ADS)

    Karaiskos, G.; Deraemaeker, A.; Aggelis, D. G.; Van Hemelrijck, D.

    2015-11-01

    Concrete is the material most produced by humanity. Its popularity is mainly based on its low production cost and great structural design flexibility. Its operational and ambient loadings including environmental effects have a great impact in the performance and overall cost of concrete structures. Thus, the quality control, the structural assessment, the maintenance and the reliable prolongation of the operational service life of the existing concrete structures have become a major issue. In the recent years, non-destructive testing (NDT) is becoming increasingly essential for reliable and affordable quality control and integrity assessment not only during the construction of new concrete structures, but also for the existing ones. Choosing the right inspection technique is always followed by a compromise between its performance and cost. In the present paper, the ultrasonic pulse velocity (UPV) method, which is the most well known and widely accepted ultrasonic concrete NDT method, is thoroughly reviewed and compared with other well-established NDT approaches. Their principles, inherent limitations and reliability are reviewed. In addition, while the majority of the current UPV techniques are based on the use of piezoelectric transducers held on the surface of the concrete, special attention is paid to a very promising technique using low-cost and aggregate-size piezoelectric transducers embedded in the material. That technique has been evaluated based on a series of parameters, such as the ease of use, cost, reliability and performance.

  15. Ceramic ware waste as coarse aggregate for structural concrete production.

    PubMed

    García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia M; Guerra-Romero, M Ignacio

    2015-01-01

    The manufacture of any kind of product inevitably entails the production of waste. The quantity of waste generated by the ceramic industry, a very important sector in Spain, is between 5% and 8% of the final output and it is therefore necessary to find an effective waste recovery method. The aim of the study reported in the present article was to seek a sustainable means of managing waste from the ceramic industry through the incorporation of this type of waste in the total replacement of conventional aggregate (gravel) used in structural concrete. Having verified that the recycled ceramic aggregates met all the technical requirements imposed by current Spanish legislation, established in the Code on Structural Concrete (EHE-08), then it is prepared a control concrete mix and the recycled concrete mix using 100% recycled ceramic aggregate instead of coarse natural aggregate. The concretes obtained were subjected to the appropriate tests in order to conduct a comparison of their mechanical properties. The results show that the concretes made using ceramic sanitary ware aggregate possessed the same mechanical properties as those made with conventional aggregate. It is therefore possible to conclude that the reuse of recycled ceramic aggregate to produce recycled concrete is a feasible alternative for the sustainable management of this waste. PMID:25188783

  16. Ceramic ware waste as coarse aggregate for structural concrete production.

    PubMed

    García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia M; Guerra-Romero, M Ignacio

    2015-01-01

    The manufacture of any kind of product inevitably entails the production of waste. The quantity of waste generated by the ceramic industry, a very important sector in Spain, is between 5% and 8% of the final output and it is therefore necessary to find an effective waste recovery method. The aim of the study reported in the present article was to seek a sustainable means of managing waste from the ceramic industry through the incorporation of this type of waste in the total replacement of conventional aggregate (gravel) used in structural concrete. Having verified that the recycled ceramic aggregates met all the technical requirements imposed by current Spanish legislation, established in the Code on Structural Concrete (EHE-08), then it is prepared a control concrete mix and the recycled concrete mix using 100% recycled ceramic aggregate instead of coarse natural aggregate. The concretes obtained were subjected to the appropriate tests in order to conduct a comparison of their mechanical properties. The results show that the concretes made using ceramic sanitary ware aggregate possessed the same mechanical properties as those made with conventional aggregate. It is therefore possible to conclude that the reuse of recycled ceramic aggregate to produce recycled concrete is a feasible alternative for the sustainable management of this waste.

  17. Remote sensing in investigation of engineered underground structures

    SciTech Connect

    Kane, W.F. |; Peters, D.C.; Speirer, R.A.

    1996-08-01

    Lineaments, linear features visible on remotely sensed imagery, can be used to predict ground control problems in underground structures. Lineaments were used to backpredict hazardous ground conditions in an underground constructed facility, a coal mine in Alabama. The mine property was mapped above and below the surface for fractures and other geologic structural features. Both parametric and nonparametric statistics were employed in correlating field data with information derived from lineament maps. Results showed that fractures observed on the surface dipped vertically and extended to the mine level. Direct correlation of fracture trends with lineament trends was not apparent. However, lineaments were correlated with a change in the local fracture trend from the regional geologic structural trend. This deviation between lineament trend and fracture trend was consistent and statistically significant. Forty-two percent of all roof failures could be directly correlated with lineaments. It was found that the number of roof failures decreased exponentially with distance from a lineament. However, no relationships were found between roof fall occurrences and lineament intersections or lengths.

  18. The Structure of Concrete Operational Thought.

    ERIC Educational Resources Information Center

    Tomlinson-Keasey, C.: And Others

    1979-01-01

    In a four-year longitudinal study of the development of concrete operational thought, children were administered tests assessing seriation; numeration; class inclusion; hierarchical classification; and conservation of mass, weight, and volume. Levels of seriation and numeration skills in kindergarten were powerful predictors of the acquisition of…

  19. 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.

  20. Cracking assessment in concrete structures by distributed optical fiber

    NASA Astrophysics Data System (ADS)

    Rodríguez, Gerardo; Casas, Joan R.; Villaba, Sergi

    2015-03-01

    In this paper, a method to obtain crack initiation, location and width in concrete structures subjected to bending and instrumented with an optical backscattered reflectometer (OBR) system is proposed. Continuous strain data with high spatial resolution and accuracy are the main advantages of the OBR system. These characteristics make this structural health monitoring technique a useful tool in early damage detection in important structural problems. In the specific case of reinforced concrete structures, which exhibit cracks even in-service loading, the possibility to obtain strain data with high spatial resolution is a main issue. In this way, this information is of paramount importance concerning the durability and long performance and management of concrete structures. The proposed method is based on the results of a test up to failure carried out on a reinforced concrete slab. Using test data and different crack modeling criteria in concrete structures, simple nonlinear finite element models were elaborated to validate its use in the localization and appraisal of the crack width in the testing slab.

  1. Estimation of underground structure at Prambanan area, Yogyakarta, Indonesia

    SciTech Connect

    Thein, Pyi Soe; Pramumijoyo, Subagyo; Wilopo, Wahyu; Husein, Salahuddin; Setianto, Agung; Brotopuspito, Kirbani Sri; Kiyono, Junji

    2015-04-24

    In this study, we investigated the underground structure at Prambanan area, Yogyakarta. We performed single observations of microtremor at 124 sites in Prambanan area. The results enabled us to estimate the site-dependent shaking characteristics of earthquake ground motion. We also conducted 2-site bore holes investigation to gain a representative determination of the soil condition of subsurface structures in Prambanan. From the SPT of borehole observations, the prambanan area corresponds to relatively soil condition with Vs ≤ 298 m/s, the predominant periods due to horizontal vertical ratios (HVSRs) are in the range of 0.48 to 1.19 s and the frequency are in the range of 0.95 to 1.92 Hz. By making these observations, we can obtain a relationship between the predominant periods, frequency and distribution of the first layer thickness of the sediment.

  2. Basic Study and Application for Ultrasound Dispersion in Concrete Structures

    NASA Astrophysics Data System (ADS)

    Mihara, T.; Maruta, M.; Hamajima, T.; Udagawa, Y.; Tashiro, H.

    2011-06-01

    In this research, after the simulation of FEM analysis using the three dimensional concrete model, we focused on the large dispersion of the transmitted echo in concrete due to the velocity difference between aggregate and mortar. Then to support the efficient measurement for this large dispersion the super-broad band ultrasonic measurement system using step function pulsar combined with the broad band transducer of 500 kHz in frequency was applied for the transmission and reflection measurement of the concrete specimen with a thickness of 200 mm. Furthermore, the spatial averaging measurement procedure for a virtual larger transducer was applied as a basic research of the ultrasonic evaluation for industrial concrete structure.

  3. Reliability evaluation of prestressed concrete containment structures

    SciTech Connect

    Pires, J.; Hwang, H.; Reich, M.

    1985-01-01

    The probabilistic safety evaluation of a realistic unbonded prestressed concrete containment building subjected to combinations of static and dynamic loads is presented. Loads considered include dead load, prestressing, accidental internal pressure, tornado and earthquake loads. Pertinent load parameters are the occurrence rate, duration and intensity. These parameters are treated as random variables for most of the loads. Limit state probabilities conditional on a specific load combination are calculated using the analytical procedure developed at BNL, which makes use of the finite element method and random vibration theory. Lifetime limit state probabilities are calculated using a load coincidence formulation. 3 refs., 2 figs., 2 tabs.

  4. Method and apparatus for constructing an underground barrier wall structure

    DOEpatents

    Dwyer, Brian P.; Stewart, Willis E.; Dwyer, Stephen F.

    2002-01-01

    A method and apparatus for constructing a underground barrier wall structure using a jet grout injector subassembly comprising a pair of primary nozzles and a plurality of secondary nozzles, the secondary nozzles having a smaller diameter than the primary nozzles, for injecting grout in directions other than the primary direction, which creates a barrier wall panel having a substantially uniform wall thickess. This invention addresses the problem of the weak "bow-tie" shape that is formed during conventional jet injection when using only a pair of primary nozzles. The improvement is accomplished by using at least four secondary nozzles, of smaller diameter, located on both sides of the primary nozzles. These additional secondary nozzles spray grout or permeable reactive materials in other directions optimized to fill in the thin regions of the bow-tie shape. The result is a panel with increased strength and substantially uniform wall thickness.

  5. STUDY ON THE EFFECTIVENESS OF EARTHQUAKE-RESISTANT JOINT AGAINST SEISMIC DISPLACEMENT IN UNDERGROUND STRUCTURE

    NASA Astrophysics Data System (ADS)

    Otsuka, Hisanori; Aibe, Takeaki; Soejima, Sumireko

    In the current seismic design of underground structure, only earthquake shaking is considered and the influence of fault displacement is not considered. However, since linear underground structure such as tunnels have a possibility to be constructed across faults, they have a probability to get severe damage due to the fault displacement. In this study, Soil-underground structure-seismic fault model is analyzed by 3D finite element analysis considering slip and exfoliation between structure and the effect of fault displacement on the underground structure are evaluated. Further more the applicability of the earthquake resistant joints used for underground structure as countermeasure of ground excitations to fault displacements are studied by the numerical analysis, and it is clarified that the more increasing the number of joints and the decreasing of the space of joints introduce the more reducing of cross sectional forces.

  6. A Simple Demonstration of Concrete Structural Health Monitoring Framework

    SciTech Connect

    Mahadevan, Sankaran; Agarwal, Vivek; Cai, Guowei; Nath, Paromita; Bao, Yanqing; Bru Brea, Jose Maria; Koester, David; Adams, Douglas; Kosson, David

    2015-03-01

    Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high confidence actionable information regarding structural integrity that supports operational and maintenance decisions. This ongoing research project is seeking to develop a probabilistic framework for health diagnosis and prognosis of aging concrete structures in a nuclear power plant subjected to physical, chemical, environment, and mechanical degradation. The proposed framework consists of four elements—damage modeling, monitoring, data analytics, and uncertainty quantification. This report describes a proof-of-concept example on a small concrete slab subjected to a freeze-thaw experiment that explores techniques in each of the four elements of the framework and their integration. An experimental set-up at Vanderbilt University’s Laboratory for Systems Integrity and Reliability is used to research effective combination of full-field techniques that include infrared thermography, digital image correlation, and ultrasonic measurement. The measured data are linked to the probabilistic framework: the thermography, digital image correlation data, and ultrasonic measurement data are used for Bayesian calibration of model parameters, for diagnosis of damage, and for prognosis of future damage. The proof-of-concept demonstration presented in this report highlights the significance of each element of the framework and their integration.

  7. Superelastic SMA-FRP composite reinforcement for concrete structures

    NASA Astrophysics Data System (ADS)

    Wierschem, Nicholas; Andrawes, Bassem

    2010-02-01

    For many years there has been interest in using fiber-reinforced polymers (FRPs) as reinforcement in concrete structures. Unfortunately, due to their linear elastic behavior, FRP reinforcing bars are never considered for structural damping or dynamic applications. With the aim of improving the ductility and damping capability of concrete structures reinforced with FRP reinforcement, this paper studies the application of SMA-FRP, a relatively novel type of composite reinforced with superelastic shape memory alloy (SMA) wires. The cyclic tensile behavior of SMA-FRP composites are studied experimentally and analytically. Tests of SMA-FRP composite coupons are conducted to determine their constitutive behavior. The experimental results are used to develop and calibrate a uniaxial SMA-FRP analytical model. Parametric and case studies are performed to determine the efficacy of the SMA-FRP reinforcement in concrete structures and the key factors governing its behavior. The results show significant potential for SMA-FRP reinforcement to improve the ductility and damping of concrete structures while still maintaining its elastic characteristic, typical of FRP reinforcement.

  8. PRESENT STATE AND PROBLEMS OF ASSET MANAGEMENT IN THE UNDERGROUND STRUCTURE

    NASA Astrophysics Data System (ADS)

    Kamemura, Katsumi; Ikejiri, Takeshi; Kushido, Hitoshi; Sasao, Haruo; Takahashi, Akira; Yamada, Hiroyuki

    Improvement of infrastructures in Japan is now shifting its pivoting foot from the age of construction and increasing to the age of maintenance. After the importance of maintenance was pointed out, a lot of studies about engineering techniques concerning to the maintenance has been carried out at various organizations and authorities.However, their effort is not enough till now for the establishment of rational maintenance techniques, especially in the underground structures. On the other hand, against the background of the realization for safer and more secured society, the use of an underground space is more and more expected. So the development of the maintenance and management technique in the underground structure becomes more and more important, indispensable problem. Here, the technique to evaluate the performance and the deterioration characteristic of the underground structure were examined from the viewpoint of the asset management, aiming at contributing to the establishment of the maintenance and management technique of the underground structure.

  9. Effect of exposure delay of concrete into aggressive environment

    NASA Astrophysics Data System (ADS)

    Abimouloud, Youcef; Kriker, Abdelouahed

    2016-07-01

    Some regions in the world suffered since several years from environmental problems such as underground level water rising. Water table effects durability of concrete implantation in the underground by the ease of luckless chemical elements ingress mainly through concrete the foundations of structures such as sulfate, chloride, and acids. For that reason a lot of foundations structures were made with SRPC (sulfate resisting Portland cement). This study is a contribution to assess the effect of exposure delay of concrete into aggressive fields, as a kind of cure which protects concrete from aggressive factors and allows it to acquire the needed strength. The study has shown that concrete exposure delay into aggressive environment is not a kind of cure mainly for concrete made with SRPC. Concrete with SRPC immediately exposed to aggressive environment shows a better mechanical resistance than concrete that has known exposure delay.

  10. OBLIQUE VIEW SHOWING THE ADDED TABLELIKE CAST CONCRETE STRUCTURE WITH ...

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

    OBLIQUE VIEW SHOWING THE ADDED TABLE-LIKE CAST CONCRETE STRUCTURE WITH ARM PROJECTING TO THE WEST (RIGHT). VIEW FACING SOUTHEAST - U.S. Naval Base, Pearl Harbor, Ford Island 5-Inch Antiaircraft Battery, East Gun Emplacement, Ford Island, Pearl City, Honolulu County, HI

  11. 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.

  12. 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

  13. 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

  14. Credit BG. Southwest and southeast facades of concrete block structure ...

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

    Credit BG. Southwest and southeast facades of concrete block structure built in the late 1960s. Fire House No. 4 (Building 4456) appears in background at right - Edwards Air Force Base, North Base, Liquid Oxygen Repair Facility, Second Street, Boron, Kern County, CA

  15. Treatment Prevents Corrosion in Steel and Concrete Structures

    NASA Technical Reports Server (NTRS)

    2007-01-01

    In the mid-1990s, to protect rebar from corrosion, NASA developed an electromigration technique that sends corrosion-inhibiting ions into rebar to prevent rust, corrosion, and separation from the surrounding concrete. Kennedy Space Center worked with Surtreat Holding LLC, of Pittsburgh, Pennsylvania, a company that had developed a chemical option to fight structural corrosion, combining Surtreat's TPS-II anti-corrosive solution and electromigration. Kennedy's materials scientists reviewed the applicability of the chemical treatment to the electromigration process and determined that it was an effective and environmentally friendly match. Ten years later, NASA is still using this approach to fight concrete corrosion, and it has also developed a new technology that will further advance these efforts-a liquid galvanic coating applied to the outer surface of reinforced concrete to protect the embedded rebar from corrosion. Surtreat licensed this new coating technology and put it to use at the U.S. Army Naha Port, in Okinawa, Japan. The new coating prevents corrosion of steel in concrete in several applications, including highway and bridge infrastructures, piers and docks, concrete balconies and ceilings, parking garages, cooling towers, and pipelines. A natural compliment to the new coating, Surtreat's Total Performance System provides diagnostic testing and site analysis to identify the scope of problems for each project, manufactures and prescribes site-specific solutions, controls material application, and verifies performance through follow-up testing and analysis.

  16. Effect of calcifying bacteria on permeation properties of concrete structures.

    PubMed

    Achal, V; Mukherjee, A; Reddy, M S

    2011-09-01

    Microbially enhanced calcite precipitation on concrete or mortar has become an important area of research regarding construction materials. This study examined the effect of calcite precipitation induced by Sporosarcina pasteurii (Bp M-3) on parameters affecting the durability of concrete or mortar. An inexpensive industrial waste, corn steep liquor (CSL), from starch industry was used as nutrient source for the growth of bacteria and calcite production, and the results obtained with CSL were compared with those of the standard commercial medium. Bacterial deposition of a layer of calcite on the surface of the specimens resulted in substantial decrease of water uptake, permeability, and chloride penetration compared with control specimens without bacteria. The results obtained with CSL medium were comparable to those obtained with standard medium, indicating the economization of the biocalcification process. The results suggest that calcifying bacteria play an important role in enhancing the durability of concrete structures. PMID:21104104

  17. 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.

  18. 49 CFR 195.250 - Clearance between pipe and underground structures.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... underground structures. Any pipe installed underground must have at least 12 inches (305 millimeters) of... for drainage tile the minimum clearance may be less than 12 inches (305 millimeters) but not less than 2 inches (51 millimeters). However, where 12 inches (305 millimeters) of clearance is...

  19. 49 CFR 195.250 - Clearance between pipe and underground structures.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... underground structures. Any pipe installed underground must have at least 12 inches (305 millimeters) of... for drainage tile the minimum clearance may be less than 12 inches (305 millimeters) but not less than 2 inches (51 millimeters). However, where 12 inches (305 millimeters) of clearance is...

  20. 49 CFR 195.250 - Clearance between pipe and underground structures.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... underground structures. Any pipe installed underground must have at least 12 inches (305 millimeters) of... for drainage tile the minimum clearance may be less than 12 inches (305 millimeters) but not less than 2 inches (51 millimeters). However, where 12 inches (305 millimeters) of clearance is...

  1. 49 CFR 195.250 - Clearance between pipe and underground structures.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... underground structures. Any pipe installed underground must have at least 12 inches (305 millimeters) of... for drainage tile the minimum clearance may be less than 12 inches (305 millimeters) but not less than 2 inches (51 millimeters). However, where 12 inches (305 millimeters) of clearance is...

  2. 49 CFR 195.250 - Clearance between pipe and underground structures.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... underground structures. Any pipe installed underground must have at least 12 inches (305 millimeters) of... for drainage tile the minimum clearance may be less than 12 inches (305 millimeters) but not less than 2 inches (51 millimeters). However, where 12 inches (305 millimeters) of clearance is...

  3. 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.

  4. Nondestructive evaluation of concrete structures by nonstationary thermal wave imaging

    NASA Astrophysics Data System (ADS)

    Mulaveesala, Ravibabu; Panda, Soma Sekhara Balaji; Mude, Rupla Naik; Amarnath, Muniyappa

    2012-06-01

    Reinforced concrete structures (RCS) have potential application in civil engineering and with the advent of nuclear engineering RCS to be capable enough to withstanding a variety of adverse environmental conditions. However, failures/loss of durability of designed structures due to premature reinforcement corrosion of rebar is a major constrain. Growing concern of safety of structure due to pre-mature deterioration has led to a great demand for development of non-destructive and non-contact testing techniques for monitoring and assessing health of RCS. This paper presents an experimental investigation of rebar corrosion by non-stationary thermal wave imaging. Experimental results have been proven, proposed approach is an effective technique for identification of corrosion in rebar in the concrete samples.

  5. Static Nonlinear Analysis In Concrete Structures

    SciTech Connect

    Hemmati, Ali

    2008-07-08

    Push-over analysis is a simple and applied approach which can be used for estimation of demand responses influenced by earthquake stimulations. The analysis is non-linear static analysis of the structure affected under increasing lateral loads and specifying the displacement--load diagram or structure capacity curve, draw the curve the base shear values and lateral deflection on the roof level of the building will be used. However, for estimation of the real behavior of the structure against earthquake, the non-linear dynamic analysis approaches and various accelerographs should be applied. Of course it should be noted that this approach especially in relation with tall buildings is complex and time consuming. In the article, the different patterns of lateral loading in push-over analysis have been compared with non-linear dynamic analysis approach so that the results represented accordingly. The researches indicated the uniformly--distributed loading is closer to real status.

  6. Research in nondestructive evaluation techniques for nuclear reactor concrete structures

    NASA Astrophysics Data System (ADS)

    Clayton, Dwight; Smith, Cyrus

    2014-02-01

    The purpose of the Materials Aging and Degradation (MAaD) Pathway of the Department of Energy's Light Water Reactor Sustainability (LWRS) Program is to develop the scientific basis for understanding and predicting longterm environmental degradation behavior of material in nuclear power plants and to provide data and methods to assess the performance of systems, structures, and components (SSCs) essential to safe and sustained nuclear power plant operations. The understanding of aging-related phenomena and their impacts on SSCs is expected to be a significant issue for any nuclear power plant planning for long-term operations (i.e. service beyond the initial license renewal period). Management of those phenomena and their impacts during long-term operations can be better enable by improved methods and techniques for detection, monitoring, and prediction of SSC degradation. The MAaD Pathway R&D Roadmap for Concrete, "Light Water Reactor Sustainability Nondestructive Evaluation for Concrete Research and Development Roadmap", focused initial research efforts on understanding the recent concrete issues at nuclear power plants and identifying the availability of concrete samples for NDE techniques evaluation and testing. [1] An overview of the research performed by ORNL in these two areas is presented here.

  7. Application of the self-diagnosis composite into concrete structure

    NASA Astrophysics Data System (ADS)

    Matsubara, Hideaki; Shin, Soon-Gi; Okuhara, Yoshiki; Nomura, Hiroshi; Yanagida, Hiroaki

    2001-04-01

    The function and performance of the self-diagnosis composites embedded in mortar/concrete blocks and concrete piles were investigated by bending tests and electrical resistance measurements. Carbon powder (CP) and carbon fiber (CF) were introduced in glass fiber reinforced plastics composites to obtain electrical conductivity. The CP composite has commonly good performances in various bending tests of block and pile specimens, comparing to the CF composite. The electrical resistance of the CP composite increases in a small strain to response remarkably micro-crack formation at about 200 (mu) strain and to detect well to smaller deformations before the crack formation. The CP composite possesses a continuous resistance change up to a large strain level near the final fracture of concrete structures reinforced by steel bars. The cyclic bending tests showed that the micro crack closed at unloading state was able to be evaluated from the measurement of residual resistance. It has been concluded that the self- diagnosis composite is fairly useful for the measurement of damage and fracture in concrete blocks and piles.

  8. Research in nondestructive evaluation techniques for nuclear reactor concrete structures

    SciTech Connect

    Clayton, Dwight; Smith, Cyrus

    2014-02-18

    The purpose of the Materials Aging and Degradation (MAaD) Pathway of the Department of Energy's Light Water Reactor Sustainability (LWRS) Program is to develop the scientific basis for understanding and predicting longterm environmental degradation behavior of material in nuclear power plants and to provide data and methods to assess the performance of systems, structures, and components (SSCs) essential to safe and sustained nuclear power plant operations. The understanding of aging-related phenomena and their impacts on SSCs is expected to be a significant issue for any nuclear power plant planning for long-term operations (i.e. service beyond the initial license renewal period). Management of those phenomena and their impacts during long-term operations can be better enable by improved methods and techniques for detection, monitoring, and prediction of SSC degradation. The MAaD Pathway R and D Roadmap for Concrete, 'Light Water Reactor Sustainability Nondestructive Evaluation for Concrete Research and Development Roadmap', focused initial research efforts on understanding the recent concrete issues at nuclear power plants and identifying the availability of concrete samples for NDE techniques evaluation and testing. [1] An overview of the research performed by ORNL in these two areas is presented here.

  9. 47. Quincy, MA, BO37, Launch Area, Underground Missile Storage Structure, ...

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

    47. Quincy, MA, BO-37, Launch Area, Underground Missile Storage Structure, detail of elevator VIEW EAST - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  10. 44. Quincy, MA, BO37, Launch Area, Underground Missile Storage Structure, ...

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

    44. Quincy, MA, BO-37, Launch Area, Underground Missile Storage Structure, general interior view VIEW SOUTHWEST - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  11. 48. Quincy, MA, BO37, Launch Area, Underground Missile Storage Structure, ...

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

    48. Quincy, MA, BO-37, Launch Area, Underground Missile Storage Structure, interior detail of water and hydraulic pumps VIEW WEST - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  12. 10. Site D57 & 58L, Underground Missile Storage Structure, Type ...

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

    10. Site D-57 & 58-L, Underground Missile Storage Structure, Type B, Plans, U.S. Army Corps of Engineers, 13 December 1953 - Newport NIKE Missile Battery D-57/58, Launch Area, Newport Road, Carleton, Monroe County, MI

  13. 49. Quincy, MA, BO37, Launch Area, Underground Missile Storage Structure, ...

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

    49. Quincy, MA, BO-37, Launch Area, Underground Missile Storage Structure, interior detail of air vent system VIEW WEST - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  14. Structural analysis of underground gunite storage tanks. Environmental Restoration Program

    SciTech Connect

    1995-08-01

    This report documents the structural analysis of the 50-ft diameter underground gunite storage tanks constructed in 1943 and located in the Oak Ridge National Laboratory (ORNL) South Tank Farm, known as Facility 3507 in the 3500-3999 area. The six gunite tanks (W-5 through W-10) are spaced in a 2 {times} 3 matrix at 60 ft on centers with 6 ft of soil cover. Each tank (Figures 1, 2, and 3) has an inside diameter of 50 ft, a 12-ft vertical sidewall having a thickness of 6 in. (there is an additional 1.5-in. inner liner for much of the height), and a spherical domed roof (nominal thickness is 10 in.) rising another 6 ft, 3 in. at the center of the tank. The thickness of both the sidewall and the domed roof increases to 30 in. near their juncture. The tank floor is nominally 3-in. thick, except at the juncture with the wall where the thickness increases to 9 in. The tanks are constructed of gunite (a mixture of Portland cement, sand, and water in the form of a mortar) sprayed from the nozzle of a cement gun against a form or a solid surface. The floor and the dome are reinforced with one layer of welded wire mesh and reinforcing rods placed in the radial direction. The sidewall is reinforced with three layers of welded wire mesh, vertical {1/2}-in. rods, and 21 horizontal rebar hoops (attached to the vertical rods) post-tensioned to 35,000 psi stress. The haunch at the sidewall/roof junction is reinforced with 17 horizontal rebar hoops post-tensioned with 35,000 to 40,000 psi stress. The yield strength of the post-tensioning steel rods is specified to be 60,000 psi, and all other steel is 40,000 psi steel. The specified 28-day design strength of the gunite is 5,000 psi.

  15. Activities in support of continuing the service of nuclear power plant concrete structures

    SciTech Connect

    Naus, Dan J

    2012-01-01

    In general, nuclear power plant concrete structure s performance has been very good; however, aging of concrete structures occurs with the passage of time that can potentially result in degradation if is effects are not controlled. Safety-related nuclear power plant concrete structures are described. In-service inspection and testing requirements in the U.S. are summarized. The interaction of the license renewal process and concrete structures is noted. A summary of operating experience related to aging of nuclear power plant concrete structures is provided. Several candidate areas are identified where additional research would be beneficial for aging management of nuclear power plant concrete structures. Finally, an update on recent activities at Oak Ridge National Laboratory related to aging management of nuclear power plant concrete structures is provided.

  16. The Effect of Elevated Temperature on Concrete Materials and Structures - a Literature Review.

    SciTech Connect

    Naus, Dan J

    2006-03-01

    The objective of this limited study was to provide an overview of the effects of elevated temperature on the behavior of concrete materials and structures. In meeting this objective the effects of elevated temperatures on the properties of ordinary Portland cement concrete constituent materials and concretes are summarized. The effects of elevated temperature on high-strength concrete materials are noted and their performance compared to normal strength concretes. A review of concrete materials for elevated-temperature service is presented. Nuclear power plant and general civil engineering design codes are described. Design considerations and analytical techniques for evaluating the response of reinforced concrete structures to elevated-temperature conditions are presented. Pertinent studies in which reinforced concrete structural elements were subjected to elevated temperatures are described.

  17. The Study on the Durability of Submerged Structure Displacement due to Concrete Failure

    NASA Astrophysics Data System (ADS)

    Mohd, M.; Zainon, O.; Rasib, A. W.; Majid, Z.

    2016-09-01

    Concrete structures that exposed to marine environments are subjected to multiple deterioration mechanisms. An overview of the existing technology for submerged concrete, pressure resistant, concrete structures which related such as cracks, debonds, and delamination are discussed. Basic knowledge related to drowning durability such as submerged concrete structures in the maritime environment are the durability of a concrete and the ability to resist to weathering, chemical attack, abrasion or other deterioration processes. The measuring techniques and instrumentation for geometrical monitoring of submerged structural displacements have traditionally been categorized into two groups according to the two main groups, namely as geodetic surveying and geotechnical structural measurements of local displacements. This paper aims to study the durability of submerged concrete displacement and harmful effects of submerged concrete structures.

  18. Strain evaluation of strengthened concrete structures using FBG sensors

    NASA Astrophysics Data System (ADS)

    Lau, Kin-tak; Zhou, Li-min; Ye, Lin

    1999-12-01

    Fibre-optic Bragg Grating (FBG) sensor presents a great deal of potential in monitoring the internal status of the concrete structures after repairing or strengthening by an external adhered reinforcement. It can be used in a variety of configurations ranging from pointwise to multi-point strain measurement in order to investigate the strain distribution of the structures. In this paper, an experimental investigation on the rectangular notched-concrete beam, which was strengthened by glass fibre composites with the embedment of multiplexing FBG sensors is presented. Three point bending test was performed to investigate the strain profile of the specimen. Frequency modulated continuous wave (FMCW) technique was used to measure the strain variation of the fibre-grating regions. The results give a good agreement with the electrical resistance strain gauge in early loading condition. The difference of the strain-measuring results between the strain-gauge and FBG sensor was increased when further increasing the applied load. It was suspected that the micro/marco cracks occurred on the concrete surface and that the externally bonded strain-measuring device cannot be detected.

  19. Strain evaluation of strengthened concrete structures using FBG sensors

    SciTech Connect

    Lau Kintak; Zhou Limin; Ye Lin

    1999-12-02

    Fibre-optic Bragg Grating (FBG) sensor presents a great deal of potential in monitoring the internal status of the concrete structures after repairing or strengthening by an external adhered reinforcement. It can be used in a variety of configurations ranging from pointwise to multi-point strain measurement in order to investigate the strain distribution of the structures. In this paper, an experimental investigation on the rectangular notched-concrete beam, which was strengthened by glass fibre composites with the embedment of multiplexing FBG sensors is presented. Three point bending test was performed to investigate the strain profile of the specimen. Frequency modulated continuous wave (FMCW) technique was used to measure the strain variation of the fibre-grating regions. The results give a good agreement with the electrical resistance strain gauge in early loading condition. The difference of the strain-measuring results between the strain-gauge and FBG sensor was increased when further increasing the applied load. It was suspected that the micro/marco cracks occurred on the concrete surface and that the externally bonded strain-measuring device cannot be detected.

  20. Temperature effects in concrete structures measured with fibre Bragg grating

    NASA Astrophysics Data System (ADS)

    Silva, Jean C.; Martelli, Cicero; Penner, Elisabeth; Kalinowski, Hypolito J.

    2004-06-01

    We analyze the action of fire, causing degradation in a concrete cantilever beam using dynamic testing. The structure is instrumented with two fiber Bragg gratings (FBG) sensors. One of them is used to measure vibration and another one is used to measure temperature inside of the cantilever beam, while the beam is exposed to fire. The temperature in the cantilever beam increased until 150°C and a reduction in the strength of concrete can be observed through the modal analysis. A fiber Bragg grating interrogation system, based on tunable filter method, is used for the static and dynamic measurements during the experiments. That system has low cost and it is easy to assemble and maintain when compared to other available instruments.

  1. Image-based monitoring of structural damage: concrete surface cracks

    NASA Astrophysics Data System (ADS)

    Chen, ZhiQiang; Chang, Barbara; Hutchinson, Tara C.

    2008-03-01

    Nondestructive imaging has been a widely used approach for detection of local structural damage in the engineering community. By combining image analysis methods, quantities describing the type, severity and extent of damage can be extracted within the spatial domain of images. However, the current practice of structural health monitoring requires a temporal characterization of structural damage, or some correlation of structural damage with response data. To accomplish this, one needs to consider the time scale in using any of the nondestructive imaging techniques, which in turn demands the use of spatial-temporal image analysis. In this paper, we address the temporal occurrence of cracks on the surface of concrete structural members, and attempt to monitor cracks, including their inception and propagation, using temporal image data. We assume under some conditions for objects in a pair of temporal images that only planar rigid-body motion takes place in the image domain, while cracks are treated as a type of local anomaly. The unknown motion parameters are estimated by means of a manifold-based optimization procedure, and the obtained manifold distance (MD) measure is used as a motion-invariant feature to describe the temporal occurrence of concrete cracks. Numerical analyses are conducted with the use of video clips from two laboratory experiments. It is concluded in this paper that the MD-based spatial-temporal image analysis can be an effective means for monitoring local damage of structural components that occurs and is accompanied by structural motion induced by loading.

  2. Review: Impact of underground structures on the flow of urban groundwater

    NASA Astrophysics Data System (ADS)

    Attard, Guillaume; Winiarski, Thierry; Rossier, Yvan; Eisenlohr, Laurent

    2016-02-01

    Property economics favours the vertical development of cities but flow of groundwater can be affected by the use of underground space in them. This review article presents the state of the art regarding the impact of disturbances caused by underground structures (tunnels, basements of buildings, deep foundations, etc.) on the groundwater flow in urban aquifers. The structures built in the underground levels of urban areas are presented and organised in terms of their impact on flow: obstacle to the flow or disturbance of the groundwater budget of the flow system. These two types of disturbance are described in relation to the structure area and the urban area. The work reviewed shows, on one hand, the individual impacts of different urban underground structures, and on the other, their cumulative impacts on flow, using real case studies. Lastly, the works are placed in perspective regarding the integration of underground structures with the aim of operational management of an urban aquifer. The literature presents deterministic numerical modelling as a tool capable of contributing to this aim, in that it helps to quantify the effect of an underground infrastructure project on groundwater flow, which is crucial for decision-making processes. It can also be an operational decision-aid tool for choosing construction techniques or for formulating strategies to manage the water resource.

  3. 28. CONCRETE DIVERSION STRUCTURE ON THE WEST SIDE OF D ...

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

    28. CONCRETE DIVERSION STRUCTURE ON THE WEST SIDE OF D STREET ABOUT ONE-QUARTER MILE SOUTH OF 9TH AVNEUE (SECTION 26); THE LATERAL CONTINUES NORTHEAST WHILE A SIDE DITCH PROCEEDS NORTHWARD. THE DIVERSION STRUCTURE SHOWN IN CO-43-A-27 IS VISIBLE IN THE DISTANCE. - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

  4. Numerical simulation of deformation and fracture of space protective shell structures from concrete and fiber concrete under pulse loading

    NASA Astrophysics Data System (ADS)

    Radchenko, P. A.; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S.

    2015-11-01

    This paper presents results of numerical simulation of interaction between aircraft Boeing 747-400 and protective shell of nuclear power plant. The shell is presented as complex multilayered cellular structure comprising layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was held three-dimensionally using the author's algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. The dynamics of stress-strain state and fracture of structure were studied. Destruction is described using two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of shell cellular structure—cells start to destruct in unloading wave, originating after output of compression wave to the free surfaces of cells.

  5. Structural health monitoring method for curved concrete bridge box girders

    NASA Astrophysics Data System (ADS)

    Glišić, Branko; Posenato, Daniele; Inaudi, Daniele; Figini, Angelo

    2008-03-01

    Curved concrete bridge girders have very complex internal forces, stress and strain distribution. As a consequence of their shape, not only the usual bending moments and shear forces are generated, but also important torsion moments are created. These moments "rotate" the axes of principal tensional stresses increasing the risk of cracking. Post-tensioning can prevent the cracks, but the added compression forces introduced in different directions increase the complexity of stress and strain fields. Therefore, the curved post-tensioned concrete girders must be particularly designed and carefully constructed. However, the real structural behavior should be verified, and risks and uncertainties related to structural design and quality of construction minimized. Structural health monitoring is a natural solution for these issues. Structural health monitoring method, based on the use of fiber optic interferometric technology including long-gage sensors and inclinometers, is presented in this paper. A 36 meters long curved post-tensioned bridge box girder is equipped with so-called parallel and so-called crossed sensor topologies, and inclinometers, in order to monitor axial strain, both horizontal and vertical curvature changes, torsion, average shear strain and rotations in both vertical plans. Important parts of structure life such as construction, post-tensioning and first years of service are registered, analyzed and presented.

  6. 12. "TEST STANDS NOS. 11, 13, & 15; CONCRETE STRUCTURAL ...

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

    12. "TEST STANDS NOS. 1-1, 1-3, & 1-5; CONCRETE STRUCTURAL SECTIONS AND DETAILS." Specifications No. OC12-50-10; Drawing No. 60-09-06; no sheet number within title block. D.O. SERIES 1109/16, Rev. E. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04353 Eng. 177, Rev. E; Date: 26 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  7. 13. "TEST STANDS NOS. 11, 13, & 15; CONCRETE STRUCTURAL ...

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

    13. "TEST STANDS NOS. 1-1, 1-3, & 1-5; CONCRETE STRUCTURAL SECTIONS AND DETAILS." Specifications No. OC12-50-10; Drawing No. 60-09-04; no sheet number within title block. D.O. SERIES 1109/18, Rev. D. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04353 Eng. 177, Rev. D, no change; Date: 18 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  8. 10. "TEST STANDS NOS. 11, 13, & 15; CONCRETE STRUCTURAL ...

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

    10. "TEST STANDS NOS. 1-1, 1-3, & 1-5; CONCRETE STRUCTURAL SECTIONS AND DETAILS." Specifications No. OC12-50-10; Drawing No. 60-09-04; no sheet number within title block. D.O. SERIES 1109/14, Rev. B. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04353 Eng. 177, Rev. B; Date: 21 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  9. 11. "TEST STANDS NOS. 11, 13, & 15; CONCRETE STRUCTURAL ...

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

    11. "TEST STANDS NOS. 1-1, 1-3, & 1-5; CONCRETE STRUCTURAL SECTIONS AND DETAILS." Specifications No. OC12-50-10; Drawing No. 60-09-04; no sheet number within title block. D.O. SERIES 1109/15, Rev. E. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04353 Eng. 177, Rev. E; Date: 21 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  10. 9. "TEST STANDS NOS. 11, 13, & 15; CONCRETE STRUCTURAL ...

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

    9. "TEST STANDS NOS. 1-1, 1-3, & 1-5; CONCRETE STRUCTURAL SECTIONS AND DETAILS." Specifications No. ENG 04-35350-10; Drawing No. 60-09-04; no sheet number within title block. D.O. SERIES 1109/13. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04353 Eng. 177, no change; Date: 17 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  11. 4. "TEST STAND NO. 13, CONCRETE STRUCTURAL PLAN AND ELEVATION." ...

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

    4. "TEST STAND NO. 1-3, CONCRETE STRUCTURAL PLAN AND ELEVATION." Specifications No. OC11-50-10; Drawing No. 60-09-06; no sheet number within title block. D.O. SERIES 1109/12 REV. E. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04-353 Eng. 177, Rev. E; Date: 17 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-3, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  12. Wireless system for explosion detection in underground structures

    NASA Astrophysics Data System (ADS)

    Chikhradze, M.; Bochorishvili, N.; Akhvlediani, I.; Kukhalashvili, D.; Kalichava, I.; Mataradze, E.

    2009-06-01

    Considering the growing threat of terrorist or accidental explosions in underground stations, underground highway and railway sections improvement of system for protecting people from explosions appears urgent. Current automatic protective devices with blast identification module and blast damping absorbers of various designs as their basic elements cannot be considered effective. Analysis revealed that low reliability of blast detection and delayed generation of start signal for the activation of an absorber are the major disadvantages of protective devices. Besides the transmission of trigger signal to an energy absorber through cable communication reduces the reliability of the operation of protective device due to a possible damage of electric wiring under blast or mechanical attack. This paper presents the outcomes of the studies conducted to select accurate criteria for blast identification and to design wireless system of activation of defensive device. The results of testing of blast detection methods (seismic, EMP, optical, on overpressure) showed that the proposed method, which implies constant monitoring of overpressure in terms of its reliability and response speed, best meets the requirements. Proposed wireless system for explosions identification and activation of protective device consists of transmitter and receiver modules. Transmitter module contains sensor and microprocessor equipped with blast identification software. Receiver module produces activation signal for operation of absorber. Tests were performed in the underground experimental base of Mining Institute. The time between the moment of receiving signal by the sensor and activation of absorber - 640 microsecond; distance between transmitter and receiver in direct tunnel - at least 150m; in tunnel with 900 bending - 50m. This research is sponsored by NATO's Public Diplomacy Division in the framework of "Science for Peace".

  13. Structural behavior of concrete box bridge using embedded FBG sensors

    NASA Astrophysics Data System (ADS)

    Chung, Wonseok; Kang, Donghoon

    2012-04-01

    For the structural monitoring of railway bridges, electromagnetic interference (EMI) is a significant problem as modern railway lines are powered by high-voltage electric power feeding systems. Fiber optic sensing systems are free from EMI and have been successfully applied in civil engineering fields. This study presents the application of fiber Bragg grating (FBG)-based sensing systems to precast concrete box railway bridges. A 20 m long full-scale precast concrete box railway girder was fabricated and tested in order to identify its static performance. The experimental program involved the measurement of the nonlinear static behavior until failure. Multiplexed FBG strain sensors were embedded along the length of steel rebar and a strain-induced wavelength shift was measured in order to monitor internal strains. The measured values from the FBG-based sensors are compared with the results using electric signal-based sensors. The results show that the FBG sensing system is promising and can improve the efficiency of structural monitoring for modern railway bridges.

  14. Thermal nondestructive testing (TNDT) of adhesively bonded composite reinforcements applied to concrete civil structures

    NASA Astrophysics Data System (ADS)

    Burleigh, Douglas D.; Bohner, Richard

    1999-02-01

    Thermographic nondestructive testing was performed on composite reinforcements applied to two concrete civil structures. Information on the types of defects which occur in these structures and their locations has led to process improvements in the application of adhesively bonded laminated composites to steel reinforce concrete structures.

  15. 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.

  16. 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.

  17. Overview of Activities in the U.S. Related to Continued Service of NPP Concrete Structures

    SciTech Connect

    Naus, Dan J

    2011-01-01

    Safety-related nuclear power plant concrete structures are described and commentary on continued service assessments of these structures is provided. In-service inspection and testing requirements in the U.S. are summarized. The license renewal process in the U.S. is outlined and its current status noted. A summary of operating experience related to U.S. nuclear power plant concrete structures is presented. Several candidate areas are identified where additional research would be of benefit to aging management of NPP concrete structures. Finally current ORNL activities related to aging-management of concrete structures are outlined: development of operating experience database, application of structural reliability theory, and compilation of elevated temperature concrete material property data and information.

  18. 77 FR 69508 - Inservice Inspection of Prestressed Concrete Containment Structures With Grouted Tendons

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-19

    ... Register on April 28, 2011 (76 FR 23845) for a 60-day public comment period. The public comment period... COMMISSION Inservice Inspection of Prestressed Concrete Containment Structures With Grouted Tendons AGENCY... Concrete Containment Structures with Grouted Tendons.'' This guide describes a method that the NRC...

  19. 46. Quincy, MA, BO37, Launch Area, Underground Missile Storage Structure, ...

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

    46. Quincy, MA, BO-37, Launch Area, Underground Missile Storage Structure, interior view of elevator system with overhead doors in open position and hydraulic shaft in left foreground VIEW WEST - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  20. 45. Quincy, MA, BO37, Launch Area, Underground Missile Storage Structure, ...

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

    45. Quincy, MA, BO-37, Launch Area, Underground Missile Storage Structure, general interior view of elevator system and wall-mounted control pad VIEW EAST - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  1. 50. Quincy, MA, BO37, Launch Area, Underground Missile Storage Structure, ...

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

    50. Quincy, MA, BO-37, Launch Area, Underground Missile Storage Structure, view of staircase, access to personnel quarters with circular air shaft in ceiling VIEW EAST - NIKE Missile Battery PR-79, Launch Area, East Windsor Road south of State Route 101, Foster, Providence County, RI

  2. Underground nuclear waste containments

    SciTech Connect

    Bandyopadhyay, K.K.

    1995-11-01

    In the United States, about a hundred million gallons of high-level nuclear waste are stored in underground containments. Basically, these containments are of two different designs: single-shell and double-shell structures. The single-shell structures consist of reinforced concrete cylindrical walls seated on circular mats and enclosed on top with torispherical domes or circular flat roofs. The walls and the basemats are lined with carbon steel. The double-shell structures provide another layer of protection and constitute a completely enclosed steel containment within the single-shell structure leaving an annular space between the two walls. Single-shell containments are of earlier vintage and were built in the period 1945-1965. Double-shell structures were built through the 1960s and 1970s. Experience gained in building and operating the single-shell containments was used in enhancing the design and construction of the double-shell structures. Currently, there are about 250 underground single-shell and double-shell structures containing the high-level waste with an inventory of about 800 million curies. During their service lives, especially in early stages, these structures were subjected to thermal excursions of varying extents; also, they have aged in the chemical environment. Furthermore, in their remaining service lives, the structures may be subjected to loads for which they were not designed, such as larger earthquakes or chemical explosions. As a result, the demonstration of safety of these underground nuclear containments poses a challenge to structural engineers, which increases with time. Regardless of current plans for gradual retrieval of the waste and subsequent solidification for disposal, many of these structures are expected to continue to contain the waste through the next 20-40 years. In order to verify their structural capabilities in fulfilling this mission, several studies were recently performed at Brookhaven National Laboratory.

  3. Simulations of Underground Structures Subjected to Synamic Loading Using the Distinct Element Method

    SciTech Connect

    Morris, J.P.; Glenn, L.A.; Heuze, F.E.; Blair, S.C.

    2002-04-17

    The authors present results from a parameter study investigating the stability of underground structures in response to ground shock. Direct simulation requires detailed knowledge of both the facility itself and the surrounding geology. In practice, however, key details (joint spacing, joint stiffness, reinforcement) may not be available. Thus, in order to place bounds upon the predicted behavior of a given facility, an extensive series of simulations representing different realizations may be required. They will discuss the distinct element method (DEM) with particular emphasis on techniques for achieving improved computational efficiency, including the handling of contact detection and approaches to parallelization. Some continuum approaches to the simulation of underground facilities are discussed along with results from underground explosions. Finally, their DEM code is used to simulate dynamic loading of several generic subterranean facilities in hard rock for a range of joint properties and sources, demonstrating the suitability of the DEM for this application.

  4. Bond-slip detection of concrete-encased composite structure using electro-mechanical impedance technique

    NASA Astrophysics Data System (ADS)

    Liang, Yabin; Li, Dongsheng; Parvasi, Seyed Mohammad; Kong, Qingzhao; Lim, Ing; Song, Gangbing

    2016-09-01

    Concrete-encased composite structure is a type of structure that takes the advantages of both steel and concrete materials, showing improved strength, ductility, and fire resistance compared to traditional reinforced concrete structures. The interface between concrete and steel profiles governs the interaction between these two materials under loading, however, debonding damage between these two materials may lead to severe degradation of the load transferring capacity which will affect the structural performance significantly. In this paper, the electro-mechanical impedance (EMI) technique using piezoceramic transducers was experimentally investigated to detect the bond-slip occurrence of the concrete-encased composite structure. The root-mean-square deviation is used to quantify the variations of the impedance signatures due to the presence of the bond-slip damage. In order to verify the validity of the proposed method, finite element model analysis was performed to simulate the behavior of concrete-steel debonding based on a 3D finite element concrete-steel bond model. The computed impedance signatures from the numerical results are compared with the results obtained from the experimental study, and both the numerical and experimental studies verify the proposed EMI method to detect bond slip of a concrete-encased composite structure.

  5. An attempt to validate the ultra-accelerated microbar and the concrete performance test with the degree of AAR-induced damage observed in concrete structures

    SciTech Connect

    Leemann, Andreas; Merz, Christine

    2013-07-15

    There is little knowledge about the relation between AAR-induced damage observed in structures and the expansion potential obtained with accelerated tests. In this study, aggregates used in structures damaged by AAR were tested with the microbar test (MBT/AFNOR XP 18-594) and the concrete performance test (CPT/AFNOR P18-454). After the tests, the samples were examined using optical and scanning electron microscopy. Based on the results, the significance of the microbar test has to be examined very critically. The agreement of measured expansion, reacted rock types and the composition of the reaction products between the on-site concrete and the reproduced concrete subjected to the CPT clearly indicates that the reaction mechanisms in the structure and in the concrete performance test are comparable. As such, the concrete performance test seems to be an appropriate tool to test the potential reactivity of specific concrete mixtures.

  6. Concrete structural analysis tools and properties for Hanford site waste tank evaluation

    SciTech Connect

    Moore, C.J.; Peterson, W.S.; Winkel, B.V.; Weiner, E.O.

    1995-09-01

    As Hanford Site Contractors address maintenance and future structural demands on nuclear waste tanks built as early as 1943, it is necessary to address their current safety margins and ensure safe margins are maintained. Although the current civil engineering practice has building codes for reinforced concrete design guidelines, the tanks were not constructed to today`s building codes and future demands potentially result in loads and modifications to the tanks that are outside the original design basis and current practice. The Hanford Site engineering staff has embraced nonlinear finite-element modeling of concrete in an effort to obtain a more accurate understanding of the actual tank margins. This document brings together and integrates past Hanford Site nonlinear reinforced concrete analysis methods, past Hanford Site concrete testing, public domain research testing, and current concrete research directions. This document, including future revisions, provides the structural engineering overview (or survey) for a consistent, accurate approach to nonlinear finite-element modeling of reinforced concrete for Hanford Site waste storage tanks. This report addresses concrete strength and modulus degradation with temperature, creep, shrinkage, long-term sustained loads, and temperature degradation of rebar and concrete bonds. Recommendations are given for parameter studies and evaluation techniques for review of nonlinear finite-element analysis of concrete.

  7. 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.

  8. Numerical and Experimental Studies on Impact Loaded Concrete Structures

    SciTech Connect

    Saarenheimo, Arja; Hakola, Ilkka; Karna, Tuomo; Hyvarinen, Juhani

    2006-07-01

    An experimental set-up has been constructed for medium scale impact tests. The main objective of this effort is to provide data for the calibration and verification of numerical models of a loading scenario where an aircraft impacts against a nuclear power plant. One goal is to develop and take in use numerical methods for predicting response of reinforced concrete structures to impacts of deformable projectiles that may contain combustible liquid ('fuel'). Loading, structural behaviour, like collapsing mechanism and the damage grade, will be predicted by simple analytical methods and using non-linear FE-method. In the so-called Riera method the behavior of the missile material is assumed to be rigid plastic or rigid visco-plastic. Using elastic plastic and elastic visco-plastic material models calculations are carried out by ABAQUS/Explicit finite element code, assuming axisymmetric deformation mode for the missile. With both methods, typically, the impact force time history, the velocity of the missile rear end and the missile shortening during the impact were recorded for comparisons. (authors)

  9. Structure soil structure interaction effects: Seismic analysis of safety related collocated concrete structures

    SciTech Connect

    Joshi, J.R.

    2000-06-20

    The Process, Purification and Stack Buildings are collocated safety related concrete shear wall structures with plan dimensions in excess of 100 feet. An important aspect of their seismic analysis was the determination of structure soil structure interaction (SSSI) effects, if any. The SSSI analysis of the Process Building, with one other building at a time, was performed with the SASSI computer code for up to 50 frequencies. Each combined model had about 1500 interaction nodes. Results of the SSSI analysis were compared with those from soil structure interaction (SSI) analysis of the individual buildings, done with ABAQUS and SASSI codes, for three parameters: peak accelerations, seismic forces and the in-structure floor response spectra (FRS). The results may be of wider interest due to the model size and the potential applicability to other deep soil layered sites. Results obtained from the ABAQUS analysis were consistently higher, as expected, than those from the SSI and SSSI analyses using the SASSI. The SSSI effect between the Process and Purification Buildings was not significant. The Process and Stack Building results demonstrated that under certain conditions a massive structure can have an observable effect on the seismic response of a smaller and less stiff structure.

  10. Crack monitoring capability of plastic optical fibers for concrete structures

    NASA Astrophysics Data System (ADS)

    Zhao, Jinlei; Bao, Tengfei; Chen, Rui

    2015-08-01

    Optical fibers have been widely used in structural health monitoring. Traditional silica fibers are easy to break in field applications due to their brittleness. Thus, silica fibers are proposed to be replaced by plastic optical fibers (POFs) in crack monitoring in this study. Moreover, considering the uncertainty of crack propagation direction in composite materials, the influence of the angles between fibers and cracks on the monitoring capability of plastic optical fibers is studied. A POF sensing device was designed and the relationship between light intensity loss and crack width under different fiber/crack angles was first measured through the device. Then, three-point bend tests were conducted on concrete beams. POFs were glued to the bottom surfaces of the beams and light intensity loss with crack width was measured. Experimental results showed that light intensity loss in plastic optical fibers increased with crack width increase. Therefore, application of plastic optical fibers in crack monitoring is feasible. Moreover, the results also showed that the sensitivity of the POF crack sensor decreased with the increase of angles between fibers and cracks.

  11. 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.

  12. Superplasticizer effect on cement paste structure and concrete freeze-thaw resistance

    NASA Astrophysics Data System (ADS)

    Shuldyakov, Kirill; Kramar, Lyudmila; Trofimov, Boris; Ivanov, Ilya

    2016-01-01

    Article presents the results of studies of various types of superplasticizer additives and their influence on concrete structure and resistance under cyclic freezing-thawing. Glenium ACE 430 was taken as a polycarboxylate superplasticizer, and SP-1 - as a naphthalene-formaldehyde superplasticizer. It is revealed that at identical structure, W/C and fluidity of concrete mix, application of the polycarboxylate superplasticizer, Glenium AC 430, in comparison to the naphthalene-formaldehyde one SP-1, facilitates the increase of the concrete grade in freeze and thaw resistance from F2300 to F2400, concrete freeze and thaw resistance can be possible even higher if the gravel with higher freeze and thaw resistance is applied. To assess the superplasticizers influence on cement paste structure tests of the phase composition of the cement paste of the studied concrete were conducted. It is established that the use of polycarboxylate superplasticizer together with silica fume facilitates formation of cement plaster structure from tobermorite gel. This gel has increased basicity and is resistant to crystallization due to cyclic freezing. It is shown that in the presence of SP-1+SF in the cement paste of concrete during hydration the structure of hydrosilicate phases preferably comprises of C-S-H(I) and C-S-H(II) phases which actively crystallize while cyclic freezing and thawing and reduce freeze-thaw resistance of concrete.

  13. A Reusable PZT Transducer for Monitoring Initial Hydration and Structural Health of Concrete

    PubMed Central

    Yang, Yaowen; Divsholi, Bahador Sabet; Soh, Chee Kiong

    2010-01-01

    During the construction of a concrete structure, strength monitoring is important to ensure the safety of both personnel and the structure. Furthermore, to increase the efficiency of in situ casting or precast of concrete, determining the optimal time of demolding is important for concrete suppliers. Surface bonded lead zirconate titanate (PZT) transducers have been used for damage detection and parameter identification for various engineering structures over the last two decades. In this work, a reusable PZT transducer setup for monitoring initial hydration of concrete and structural health is developed, where a piece of PZT is bonded to an enclosure with two bolts tightened inside the holes drilled in the enclosure. An impedance analyzer is used to acquire the admittance signatures of the PZT. Root mean square deviation (RMSD) is employed to associate the change in concrete strength with changes in the PZT admittance signatures. The results show that the reusable setup is able to effectively monitor the initial hydration of concrete and the structural health. It can also be detached from the concrete for future re-use. PMID:22399929

  14. Activities in Support of Continuing the Service of Nuclear Power Plant Safety-Related Concrete Structures

    SciTech Connect

    Naus, Dan J

    2010-01-01

    Nuclear power plant concrete structures are described. In-service inspection and testing requirements in the U.S. are summarized. The license renewal process in the U.S. is outlined and its current status provided. Operating experience related to performance of the concrete structures is presented. Basic components of a program to manage aging of the concrete structures are identified and described: degradation mechanisms, damage models, and material performance; assessment and remediation (i.e., component selection, in-service inspection, non-destructive examinations, and remedial actions); and estimation of performance at present or some future point in time (i.e., application of structural reliability theory to the design and optimization of in-service inspection/maintenance strategies, and determination of the effects of degradation on plant risk). Finally, areas are noted where additional research would be of benefit to aging management of nuclear power plant concrete structures.

  15. Activities in Support of Continuing the Service of Nuclear Power Plant Safety-Related Concrete Structures

    SciTech Connect

    Naus, Dan J

    2014-01-01

    Nuclear power plant (NPP) concrete structures are described. In-service inspection and testing requirements in the U.S. are summarized. The license renewal process in the U.S. is outlined and its current status provided. Operating experience related to performance of the concrete structures is presented. Basic components of a program to manage aging of the concrete structures are identified and described: (1) Degradation mechanisms, damage models, and material performance; (2) Assessment and remediation: i.e., component selection, in- service inspection, non-destructive examinations, and remedial actions; and (3) Estimation of performance at present or some future point in time: i.e., application of structural reliability theory to the design and optimization of in-service inspection/maintenance strategies, and determination of the effects of degradation on plant risk. Finally, areas are noted where additional research would be of benefit to aging management of nuclear power plant concrete structures.

  16. A STRUCTURAL INTEGRITY ASSESSMENT OF UNDERGROUND PIPING ASSOCIATED WITH THE TRANSFER OF RADIOACTIVE WASTE

    SciTech Connect

    Wiersma, B

    2006-04-25

    Radioactive wastes are confined in 49 underground storage tanks at the Savannah River Site. The waste is transported between tanks via underground transfer piping. An assessment of the structural integrity of the transfer piping was performed to ensure that the present condition of the piping was sound and to provide life expectancy estimates for the piping based on anticipated service. The assessment reviewed the original design of the piping, the potential and observed degradation mechanisms, the results from past inspections of the piping, and a Fitness-For-Service evaluation for a section of piping that experienced pitting in a locally thinned area. The assessment concluded that the piping was structurally sound. Assuming that service conditions remain the same, the piping will remain functional for its intended service life.

  17. 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.

  18. 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.

  19. Lightweight concrete materials and structural systems for water tanks for thermal storage. Final report

    SciTech Connect

    Buckman, R.W. Jr.; Elia, G.G.; Ichikawa, Y.

    1980-12-01

    Thermally efficient hot water storage tanks were designed, fabricated and evaluated. The tanks were made using cellular concrete at a nominal density of 100 lb/ft/sup 3/ for the structural elements and at a 30 lb/ft/sup 3/ density for the insulating elements. Thermal performance testing of the tanks was done using a static decay test since the test procedure specified in ASHRAE 94-77 was not experimentally practical. A series of composition modifications to the cellular concrete mix were investigated and the addition of alkaline resistant glass fibers was found to enhance the mechanical properties at no sacrifice in thermal behavior. Economic analysis indicated that cellular concrete provides a cost-effective insulating material. The total portability of the plant for producing cellular concrete makes cellular concrete amenable to on-site fabrication and uniquely adaptable to retrofit applications.

  20. 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.

  1. Detection of sulfur in the reinforced concrete structures using a dual pulsed LIBS system

    NASA Astrophysics Data System (ADS)

    Gondal, M. A.; Dastageer, A.; Maslehuddin, M.; Alnehmi, A. J.; Al-Amoudi, O. S. B.

    2012-04-01

    In concrete structures, an excessive amount of sulfate ions can cause severe damage to the strength and the stability of the building structures and hence a sensitive and reliable technique for sulfate ion detection in concrete is highly desirable. Laser-induced breakdown spectroscopy (LIBS) is one of the most reliable and sensitive techniques to identify the presence of potentially dangerous sulfur in the concrete structure. The atomic emission lines of sulfur lying in the 200-900 nm region are mostly singly ionized states and hence inherently very weak. In order to enhance the sensitivity of the conventional LIBS system, we employed a dual pulsed LIBS system for detection of weak spectral line of sulfur in concrete using the S II peak at 545.38 nm as a marker for quantifying sulfur content in the concrete. The 1064 nm fundamental and 266 nm fourth harmonic of the Nd:YAG laser in conjunction with Spectrograph/gated ICCD camera are the core factors in improvement of sensitivity. Furthermore, the dual pulsed LIBS system and the fine maneuvering of the gate parameters and interpulse delay yielded improvement in the sensitivity, and resulted in a systematic correlation of the LIBS signal with the concentration of sulfur in the concrete sample. In order to quantify the sulfur content in concrete, a calibration curve was also drawn by recording the LIBS spectra of sample having sulfur in various concentrations. The limit of detection achieved with our dual pulsed LIBS system is approximately 38 μg/g.

  2. Using emissivity-corrected thermal maps to locate deep structural defects in concrete bridge decks

    SciTech Connect

    Del Grande, N.K.; Durbin, P.F.

    1995-04-05

    Dual-band infrared (DBIR) thermal imaging is a promising, non-contact, nondestructive evaluation tool to evaluate the amount of deteriorated concrete on asphalt-covered bridge decks. We conducted proof-of-principle demonstrations to characterize defects in concrete structures which could be detected with DBIR thermal imaging. We constructed two identical concrete slabs with synthetic delaminations, e.g., 1/8-in. thick styrofoam squares, implanted just above the 2-in.-deep steel reinforcement bars. We covered one of the slabs with a 2-in. layer of asphalt. We mounted the DBIR cameras on a tower platform, to simulate the optics needed to conduct bridge-deck inspections from a moving vehicle. We detected 4-in. implants embedded in concrete and 9-in. implants embedded in asphalt-covered concrete. The midday (above-ambient) and predawn (below-ambient) delamination-site temperatures correlated with the implant sizes. Using DBIR image ratios, we enhanced thermal-contrast and removed emissivity-noise, e.g., from concrete compositional variations and clutter. Using the LLNL/VIEW code, we removed the asphalt thermal-gradient mask, to depict the 4-in. deep, 9-in. square, concrete implant size. We plan to image bridge deck defects, from a moving vehicle, for accurate estimations of the amount of deteriorated concrete impairing the deck integrity. Potential longterm benefits are affordable and reliable rehabilitation for asphalt-covered decks.

  3. Using emissivity-corrected thermal maps to locate deep structural defects in concrete bridge decks

    NASA Astrophysics Data System (ADS)

    DelGrande, Nancy; Durbin, Philip F.

    1995-05-01

    Dual-band infrared (DBIR) thermal imaging is a promising, noncontact, nondestructive evaluation tool to evaluate the amount of deteriorated concrete on asphalt-covered bridge decks. We conducted proof-of-principle demonstrations to characterize defects in concrete structures which could be detected with DBIR thermal imaging. We constructed two identical concrete slabs with synthetic delaminations, e.g., 1.8-in. thick styrofoam squares, implanted just above the 2-in. deep steel reinforcement bars. We covered one of the slabs with a 2-in. layer of asphalt. We mounted the DBIR cameras on a tower platform, to simulate the optics needed to conduct bridge-deck inspections from a moving vehicle. We detected 4-in. implants embedded in concrete and 9-in. implants embedded in asphalt-cevered concrete. The midday (above ambient) and predawn (below ambient) delamination-site temperatures correlated with the implant sizes. Using DBIR image ratios, we enhanced thermal-constrast and removed emissivity-noise, e.g., from concrete compositional variations and clutter. Using the LLNL/VIEW code, we removed the asphalt thermal-gradient mask to depict the 4-in. deep, 9- in. square, concrete implant site. We plan to image bridge deck defects from a moving vehicle for accurate estimations of the amount of deteriorated concrete impairing the deck integrity. Potential longterm benefits are affordable and reliable rehabilitation for asphalt-covered decks.

  4. Underground structure of terrestrial mud volcanoes and abnormal water pressure formation in Niigata, Central JAPAN

    NASA Astrophysics Data System (ADS)

    Tanaka, K.; Shinya, T.; Miyata, Y.; Tokuyasu, S.

    2005-12-01

    Activity of mud volcano is thought to be caused by an abnormal water pressure generated in deep underground and make a serious problem for underground constructions such as railway tunnel, underground facility for radwaste and so on. It is important to investigate the underground structure of a mud volcano and the mechanism of abnormal water formation for site selection and safety assessment of such facilities. Serious trouble such as tunnel wall collapse due to the rock swelling has happened 180m deep under mud volcanoes. It took more than 10 years to excavate the section of 150 m long. 4 terrestrial mud volcanoes were found in the Tertiary sedimentary basin in Niigata, central Japan All the mud volcanoes are distributed along the rim of the topographic basin that is located at the NE-SW trending crest of mountainous area and distributed along the wing of anticline. Geological structure inside basin is heavily disturbed. The extinct mud volcano is exposed in the side-slope of newly constructed road and the internal vent structure of mud volcano can be observed. The vent is 30 m in diameter and is consisted of mud breccia and scaly network clay that is thought to be generated by hydro-fracturing and the following water-rock interaction between mudstone and groundwater. Groundwater erupted from mud volcano is highly saline with electric conductivity of 15 mS/cm and high 18 O/16 O isotope ratio of 1.2 parmillage. Also, the vitrinite reflectance is 1.5 to 1.9 % that is not expected in the sedimentary rocks exposed near ground surface. As a result, it is assumed that these erupted materials were introduced from the deep underground about 4000 m deep. CSA-MT geophysical exploration was carried out to survey the underground structure and obtained the profile of electrical resistivity from the surface to 800 m in depth. It is found that the disk-shaped low resistivity zone less than 1 m due to the high salinity content is identified in underground 600 m deep, 200 m thick

  5. Finite element analysis of various methods for protection of concrete structures against spalling during fire

    NASA Astrophysics Data System (ADS)

    Witek, A.; Gawin, D.; Pesavento, F.; Schrefler, B. A.

    2007-02-01

    A mathematical model of hygro-thermo-mechanical phenomena in heated concrete, treated as multiphase porous material is briefly presented. Some modifications necessary to analyse high-temperature performance of a concrete containing the PP-fibres have been introduced, experimentally validated and applied for analysis of performance of a concrete tunnel lining during a 10-MW fire and the ISO standard fire. Three methods for protecting concrete structures against excessive degradation in fire conditions have been numerically analysed by means of the computer model. The analysed protection methods are based either upon application on a structure surface of a reflective layer, or covering it with a protective layer made of a very porous concrete or an addition of the PP fibres to the concrete mix. Efficiency of these methods has been numerically analysed in thermal conditions corresponding to the ISO-834 standard fire. The results obtained show that even relatively simple methods, like application a protective layer or increasing the surface reflectance, can retard to some extent concrete degradation during a fire.

  6. NDE application of ultrasonic tomography to a full-scale concrete structure.

    PubMed

    Choi, Hajin; Popovics, John S

    2015-06-01

    Newly developed ultrasonic imaging technology for large concrete elements, based on tomographic reconstruction, is presented. The developed 3-D internal images (velocity tomograms) are used to detect internal defects (polystyrene foam and pre-cracked concrete prisms) that represent structural damage within a large steel reinforced concrete element. A hybrid air-coupled/contact transducer system is deployed. Electrostatic air-coupled transducers are used to generate ultrasonic energy and contact accelerometers are attached on the opposing side of the concrete element to detect the ultrasonic pulses. The developed hybrid testing setup enables collection of a large amount of high-quality, through-thickness ultrasonic data without surface preparation to the concrete. The algebraic reconstruction technique is used to reconstruct p-wave velocity tomograms from the obtained time signal data. A comparison with a one-sided ultrasonic imaging method is presented for the same specimen. Through-thickness tomography shows some benefit over one-sided imaging for highly reinforced concrete elements. The results demonstrate that the proposed through-thickness ultrasonic technique shows great potential for evaluation of full-scale concrete structures in the field.

  7. Evaluation of ternary blended cements for use in transportation concrete structures

    NASA Astrophysics Data System (ADS)

    Gilliland, Amanda Louise

    This thesis investigates the use of ternary blended cement concrete mixtures for transportation structures. The study documents technical properties of three concrete mixtures used in federally funded transportation projects in Utah, Kansas, and Michigan that used ternary blended cement concrete mixtures. Data were also collected from laboratory trial batches of ternary blended cement concrete mixtures with mixture designs similar to those of the field projects. The study presents the technical, economic, and environmental advantages of ternary blended cement mixtures. Different barriers of implementation for using ternary blended cement concrete mixtures in transportation projects are addressed. It was concluded that there are no technical, economic, or environmental barriers that exist when using most ternary blended cement concrete mixtures. The technical performance of the ternary blended concrete mixtures that were studied was always better than ordinary portland cement concrete mixtures. The ternary blended cements showed increased durability against chloride ion penetration, alkali silica reaction, and reaction to sulfates. These blends also had less linear shrinkage than ordinary portland cement concrete and met all strength requirements. The increased durability would likely reduce life cycle costs associated with concrete pavement and concrete bridge decks. The initial cost of ternary mixtures can be higher or lower than ordinary portland cement, depending on the supplementary cementitious materials used. Ternary blended cement concrete mixtures produce less carbon dioxide emissions than ordinary portland cement mixtures. This reduces the carbon footprint of construction projects. The barriers associated with implementing ternary blended cement concrete for transportation projects are not significant. Supplying fly ash returns any investment costs for the ready mix plant, including silos and other associated equipment. State specifications can make

  8. 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.

  9. Vibration measurement and mode analysis on concrete structures with embedded fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Tjin, Chuan S.; Moyo, Pilate; Zheng, Xiahua; Brownjohn, James M. W.

    2001-08-01

    This paper reports our work on the applications of fiber Bragg grating-based strain sensors for the vibration tests and mode analysis on concrete structures. The arrayed fiber grating strain sensors, which were wavelength-division-multiplexed along the fibers, were attached onto the reinforced bars (rebars) before concrete was poured in to form a 5.5m long, 0.3m wide, 0.15m deep reinforced concrete beam. The embedded sensors will provide quasi-distributed real-time dynamic strain information along the length of the beam. For verification with the FBG strain sensors, some electrical accelerometers were also placed on the top surface of the concrete beam. All the data from FBG sensors and electrical accelerometers were recorded and analyzed by a computer. In the experiments, a hammer and an electrical shaker were used to excite the structure. The experimental results obtained with the FBG sensors show good consistency with the theoretical analysis.

  10. 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.

  11. Urban groundwater age modeling under unconfined condition - Impact of underground structures on groundwater age: Evidence of a piston effect

    NASA Astrophysics Data System (ADS)

    Attard, Guillaume; Rossier, Yvan; Eisenlohr, Laurent

    2016-04-01

    In this paper, underground structures are shown to have a major influence on the groundwater mean age distribution described as a dispersive piston effect. Urban underground development does not occur without impacts on subsoil resources. In particular, groundwater resources can be vulnerable and generate disturbances when this space is exploited. Groundwater age spatial distribution data are fundamental for resource management as it can provide operational sustainability indicators. However, the application of groundwater age modeling is neglected regarding the potential effect of underground structures in urban areas. A three dimensional modeling approach was conducted to quantify the impact of two underground structures: (1) an impervious structure and (2) a draining structure. Both structures are shown to cause significant mixing processes occurring between shallow and deeper aquifers. The design technique used for draining structures is shown to have the greatest impact, generating a decrease in mean age of more than 80% under the structure. Groundwater age modeling is shown to be relevant for highlighting the role played by underground structures in advective-dispersive flows in urban areas.

  12. Embedded micro-sensor for monitoring pH in concrete structures

    NASA Astrophysics Data System (ADS)

    Srinivasan, Rengaswamy; Phillips, Terry E.; Bargeron, C. Brent; Carlson, Micah A.; Schemm, Elizabeth R.; Saffarian, Hassan M.

    2000-04-01

    Three major causes of corrosion of steel in concrete are chloride ions (Cl-), temperature (T) and acidity (pH). Under normal operating temperatures and with pH above 13, steel does not undergo pitting corrosion. In presence of Cl-, if the pH decreases below 12, the probability of pitting increases. Acid rain and atmospheric carbon dioxide cause the pH to drop in concrete, often leading to corrosion of the structure with the concomitant cost of repair or replacement. Currently, the pH level in concrete is estimated through destructive testing of the structures. Glass ISFET, and other pH sensors that need maintenance and calibration cannot be embedded in concrete. In this paper, we describe an inexpensive solid state pH sensor that can be embedded in concrete, to detect pH changes at the early stages. It employs a chemical reagent, trinitrobenzenesulfonic acid (TNBS) that exhibits changes in optical properties in the 12 - 14 pH range, and is held in a film of a sol-gel/TNBS composite on an optically transparent surface. A simple LED/filter/photodiode transducer monitors pH-induced changes in TNBS. Such a device needs no periodic calibration or maintenance. The optical window, the light-source and sensor can be easily housed and encapsulated in a chemically inert structure, and embedded in concrete.

  13. Methodology for Assessing the Probability of Corrosion in Concrete Structures on the Basis of Half-Cell Potential and Concrete Resistivity Measurements

    PubMed Central

    2013-01-01

    In recent years, the corrosion of steel reinforcement has become a major problem in the construction industry. Therefore, much attention has been given to developing methods of predicting the service life of reinforced concrete structures. The progress of corrosion cannot be visually assessed until a crack or a delamination appears. The corrosion process can be tracked using several electrochemical techniques. Most commonly the half-cell potential measurement technique is used for this purpose. However, it is generally accepted that it should be supplemented with other techniques. Hence, a methodology for assessing the probability of corrosion in concrete slabs by means of a combination of two methods, that is, the half-cell potential method and the concrete resistivity method, is proposed. An assessment of the probability of corrosion in reinforced concrete structures carried out using the proposed methodology is presented. 200 mm thick 750 mm  ×  750 mm reinforced concrete slab specimens were investigated. Potential Ecorr and concrete resistivity ρ in each point of the applied grid were measured. The experimental results indicate that the proposed methodology can be successfully used to assess the probability of corrosion in concrete structures. PMID:23766706

  14. Methodology for assessing the probability of corrosion in concrete structures on the basis of half-cell potential and concrete resistivity measurements.

    PubMed

    Sadowski, Lukasz

    2013-01-01

    In recent years, the corrosion of steel reinforcement has become a major problem in the construction industry. Therefore, much attention has been given to developing methods of predicting the service life of reinforced concrete structures. The progress of corrosion cannot be visually assessed until a crack or a delamination appears. The corrosion process can be tracked using several electrochemical techniques. Most commonly the half-cell potential measurement technique is used for this purpose. However, it is generally accepted that it should be supplemented with other techniques. Hence, a methodology for assessing the probability of corrosion in concrete slabs by means of a combination of two methods, that is, the half-cell potential method and the concrete resistivity method, is proposed. An assessment of the probability of corrosion in reinforced concrete structures carried out using the proposed methodology is presented. 200 mm thick 750 mm  ×  750 mm reinforced concrete slab specimens were investigated. Potential E corr and concrete resistivity ρ in each point of the applied grid were measured. The experimental results indicate that the proposed methodology can be successfully used to assess the probability of corrosion in concrete structures.

  15. Analytical solutions for the seismic response of underground structures under SH wave propagation

    SciTech Connect

    Smerzini, C.; Aviles, J.; Sanchez-Sesma, F. J.

    2008-07-08

    A theoretical approach is presented to study the antiplane seismic response of underground structures subjected to the incidence of plane waves. The structure is assumed to be a circular inclusion embedded in a homogenous, isotropic and linear visco-elastic halfspace and its mathematical formulation is approached through the theory of multiple scattering and diffraction. The inclusion may consist either of a cavity, with or without a ring-shaped boundary, or it may be filled in with a linear-elastic material, without loss of generality. The seismic response of the inclusion and its influence on surface ground motions are analyzed in both frequency and time domains. The dependence of the transfer function amplitudes on several parameters, such as the angle of incident SH waves, the frequency content of the excitation, the impedance contrast between the inclusion and the surrounding medium and the position along the ground surface, is underlined. Considering the lack of analytical solutions for quantifying the modification of ground motions induced by subterranean inhomogeneities, the results of this study can be used, on one side, as benchmark for both geophysical investigations and numerical dynamic soil-structure interaction studies, and, on the other side, to support the formulation of simplified approaches and/or formulas for the seismic design and assessment of underground structures.

  16. Photogrammetric analysis of concrete specimens and structures for condition assessment

    NASA Astrophysics Data System (ADS)

    D'Amico, Nicolas; Yu, Tzuyang

    2016-04-01

    Deterioration of civil infrastructure in America demands routine inspection and maintenance to avoid catastrophic failures from occurring. Among many other non-destructive evaluations (NDE), photogrammetry is an accessible and realistic approach used for non-destructive evaluation (NDE) of a civil infrastructure systems. The objective of this paper is to explore the capabilities of photogrammetry for locating, sizing, and analyzing the remaining capacity of a specimen or system using point cloud data. Geometric interpretations, composed from up to 70 photographs are analyzed as a mesh or point cloud models. In this case study, concrete, which exhibits a large amount of surface texture features, was thoroughly examined. These evaluative techniques discussed were applied to concrete cylinder models as well as portions of civil infrastructure including buildings, retaining walls, and bridge abutments. In this paper, the aim is to demonstrate the basic analytical functionality of photogrammetry, as well as its applicability to in-situ civil infrastructure systems. In concrete specimens defect length and location can be evaluated in a fully defined model (one with the maximum amount of correctly acquired photographs) with less than 2% error. Error was found to be inversely proportional to the number of acceptable photographs acquired, remaining significantly under 10% error for any model with enough data to render. Furthermore, volumetric stress evaluations were applied using a cross sectional evaluation technique to locate the critical area, and determine the severity of damages. Finally, findings and the accuracy of the results are discussed.

  17. Online Monitoring of Concrete Structures in Nuclear Power Plants: Interim Report

    SciTech Connect

    Mahadevan, Sankaran; Cai, Guowei; Agarwal, Vivek

    2015-03-01

    The existing fleet of nuclear power plants in the United States have initial operating licenses of 40 years, and many of these plants have applied for and received license extensions. As plant structures, systems, and components age, their useful life—considering both structural integrity and performance—is reduced as a result of deterioration of the materials. Assessment and management of aging concrete structures in nuclear plants require a more systematic approach than simple reliance on existing code-based design margins of safety. Structural health monitoring is required to produce actionable information regarding structural integrity that supports operational and maintenance decisions. The online monitoring of concrete structures project conducted under the Advanced Instrumentation, Information, and Control Technologies Pathway of the Light Water Reactor Sustainability program at Idaho National Laboratory is seeking to develop and demonstrate capabilities for concrete structures health monitoring. Through this research project, several national laboratories and Vanderbilt University propose to develop a framework of research activities for the health monitoring of nuclear power plant concrete structures that includes the integration of four elements—damage modeling, monitoring, data analytics, and uncertainty quantification. This report briefly discusses activities in this project during October-December, 2014. The most significant activity during this period was the organizing of a two-day workshop on research needs in online monitoring of concrete structures, hosted by Vanderbilt University in November 2014. Thirty invitees from academia, industry and government participated in the workshop. The presentations and discussions at the workshop surveyed current activities related to concrete structures deterioration modeling and monitoring, and identified the challenges, knowledge gaps, and opportunities for advancing the state of the art; these

  18. 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.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    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.

  1. DYNAPCON: a computer code for dynamic analysis of prestressed concrete structures. [LMFBR

    SciTech Connect

    Marchertas, A.H.

    1982-09-01

    A finite element computer code for the transient analysis of prestressed concrete reactor vessels (PCRVs) for LMFBR containment is described. The method assumes rotational symmetry of the structure. Time integration is by an explicit method. The quasistatic prestressing operation of the PCRV model is performed by a dynamic relaxation technique. The material model accounts for the crushing and tensile cracking in arbitrary direction in concrete and the elastic-plastic behavior of reinforcing steel. The variation of the concrete tensile cracking and compressive crushing limits with strain rate is taken into account. Relative slip is permitted between the concrete and tendons. Several example solutions are presented and compared with experimental results. These sample problems range from simply supported beams to small scale models of PCRV's. It is shown that the analytical methods correlate quite well with experimental results, although in the vicinity of the failure load the response of the models tend to be quite sensitive to input parameters.

  2. 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.

  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. Structural effects of radiation-induced volumetric expansion on unreinforced concrete biological shields

    DOE PAGES

    Le Pape, Y.

    2015-11-22

    Limited literature (Pomaro et al., 2011, Mirhosseini et al., 2014, Salomoni et al., 2014 and Andreev and Kapliy, 2014) is available on the structural analysis of irradiated concrete biological shield (CBS), although extended operations of nuclear powers plants may lead to critical neutron exposure above 1.0 × 10+19 n cm₋2. To the notable exception of Andreev and Kapliy, available structural models do not account for radiation-induced volumetric expansion, although it was found to develop important linear dimensional change of the order of 1%, and, can lead to significant concrete damage (Le Pape et al., 2015). A 1D-cylindrical model of anmore » unreinforced CBS accounting for temperature and irradiation effects is developed. Irradiated concrete properties are characterized probabilistically using the updated database collected by Oak Ridge National Laboratory (Field et al., 2015). The overstressed concrete ratio (OCR) of the CBS, i.e., the proportion of the wall thickness being subject to stresses beyond the resistance of concrete, is derived by deterministic and probabilistic analysis assuming that irradiated concrete behaves as an elastic materials. In the bi-axial compressive zone near the reactor cavity, the OCR is limited to 5.7%, i.e., 8.6 cm (3$_2^1$ in.), whereas, in the tension zone, the OCR extends to 72%, i.e., 1.08 m (42$_2^1$ in.). Finally, we find that these results, valid for a maximum neutron fluence on the concrete surface of 3.1 × 10+19 n cm₋2 (E > 0.1 MeV) and, obtained after 80 years of operation, give an indication of the potential detrimental effects of prolonged irradiation of concrete in nuclear power plants.« less

  5. Characterization of basin concrete in support of structural integrity demonstration for extended storage

    SciTech Connect

    Duncan, A.

    2014-09-30

    Concrete core samples from C basin were characterized through material testing and analysis to verify the design inputs for structural analysis of the L Basin and to evaluate the type and extent of changes in the material condition of the concrete under extended service for fuel storage. To avoid the impact on operations, core samples were not collected from L area, but rather, several concrete core samples were taken from the C Basin prior to its closure. C basin was selected due to its similar environmental exposure and service history compared to L Basin. The microstructure and chemical composition of the concrete exposed to the water was profiled from the water surface into the wall to evaluate the impact and extent of exposure. No significant leaching of concrete components was observed. Ingress of carbonation or deleterious species was determined to be insignificant. No evidence of alkali-silica reactions (ASR) was observed. Ettringite was observed to form throughout the structure (in air voids or pores); however, the sulfur content was measured to be consistent with the initial concrete that was used to construct the facility. Similar ettringite trends were observed in the interior segments of the core samples. The compressive strength of the concrete at the mid-wall of the basin was measured, and similar microstructural analysis was conducted on these materials post compression testing. The microstructure was determined to be similar to near-surface segments of the core samples. The average strength was 4148 psi, which is well-above the design strength of 2500 psi. The analyses showed that phase alterations and minor cracking in a microstructure did not affect the design specification for the concrete.

  6. Structural effects of radiation-induced volumetric expansion on unreinforced concrete biological shields

    SciTech Connect

    Le Pape, Y.

    2015-11-22

    Limited literature (Pomaro et al., 2011, Mirhosseini et al., 2014, Salomoni et al., 2014 and Andreev and Kapliy, 2014) is available on the structural analysis of irradiated concrete biological shield (CBS), although extended operations of nuclear powers plants may lead to critical neutron exposure above 1.0 × 10+19 n cm₋2. To the notable exception of Andreev and Kapliy, available structural models do not account for radiation-induced volumetric expansion, although it was found to develop important linear dimensional change of the order of 1%, and, can lead to significant concrete damage (Le Pape et al., 2015). A 1D-cylindrical model of an unreinforced CBS accounting for temperature and irradiation effects is developed. Irradiated concrete properties are characterized probabilistically using the updated database collected by Oak Ridge National Laboratory (Field et al., 2015). The overstressed concrete ratio (OCR) of the CBS, i.e., the proportion of the wall thickness being subject to stresses beyond the resistance of concrete, is derived by deterministic and probabilistic analysis assuming that irradiated concrete behaves as an elastic materials. In the bi-axial compressive zone near the reactor cavity, the OCR is limited to 5.7%, i.e., 8.6 cm (3$_2^1$ in.), whereas, in the tension zone, the OCR extends to 72%, i.e., 1.08 m (42$_2^1$ in.). Finally, we find that these results, valid for a maximum neutron fluence on the concrete surface of 3.1 × 10+19 n cm₋2 (E > 0.1 MeV) and, obtained after 80 years of operation, give an indication of the potential detrimental effects of prolonged irradiation of concrete in nuclear power plants.

  7. 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.

  8. Damage Source Identification of Reinforced Concrete Structure Using Acoustic Emission Technique

    PubMed Central

    Panjsetooni, Alireza; Bunnori, Norazura Muhamad; Vakili, Amir Hossein

    2013-01-01

    Acoustic emission (AE) technique is one of the nondestructive evaluation (NDE) techniques that have been considered as the prime candidate for structural health and damage monitoring in loaded structures. This technique was employed for investigation process of damage in reinforced concrete (RC) frame specimens. A number of reinforced concrete RC frames were tested under loading cycle and were simultaneously monitored using AE. The AE test data were analyzed using the AE source location analysis method. The results showed that AE technique is suitable to identify the sources location of damage in RC structures. PMID:23997681

  9. Corrosion of Carbon Steel and Corrosion-Resistant Rebars in Concrete Structures Under Chloride Ion Attack

    NASA Astrophysics Data System (ADS)

    Mohamed, Nedal; Boulfiza, Mohamed; Evitts, Richard

    2013-03-01

    Corrosion of reinforced concrete is the most challenging durability problem that threatens reinforced concrete structures, especially structures that are subject to severe environmental conditions (i.e., highway bridges, marine structures, etc.). Corrosion of reinforcing steel leads to cracking and spalling of the concrete cover and billions of dollars are spent every year on repairing such damaged structures. New types of reinforcements have been developed to avoid these high-cost repairs. Thus, it is important to study the corrosion behavior of these new types of reinforcements and compare them to the traditional carbon steel reinforcements. This study aimed at characterizing the corrosion behavior of three competing reinforcing steels; conventional carbon steel, micro-composite steel (MMFX-2) and 316LN stainless steel, through experiments in carbonated and non-carbonated concrete exposed to chloride-laden environments. Synthetic pore water solutions have been used to simulate both cases of sound and carbonated concrete under chloride ions attack. A three-electrode corrosion cell is used for determining the corrosion characteristics and rates. Multiple electrochemical techniques were applied using a Gamry PC4™ potentiostat manufactured by Gamry Instruments (Warminster, PA). DC corrosion measurements were applied on samples subjected to fixed chloride concentration in the solution.

  10. Rebar corrosion monitoring in concrete structure under salt water enviroment using fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Pan, Yuheng; Liu, Tiegen; Jiang, Junfeng; Liu, Kun; Wang, Shuang; He, Pan; Yan, Jinlin

    2015-08-01

    Monitoring corrosion of steel reinforcing bars is critical for the durability and safety of reinforced concrete structures. Corrosion sensors based on fiber optic have proved to exhibit meaningful benefits compared with the conventional electric ones. In recent years, Fiber Bragg Grating (FBG) has been used as a new kind of sensing element in an attempt to directly monitor the corrosion in concrete structure due to its remarkable advantages. In this paper, we present a novel kind of FBG based rebar corrosion monitoring sensor. The rebar corrosion is detected by volume expansion of the corroded rebar by transferring it to the axial strain of FBG when concrete structure is soaked in salt water. An accelerated salt water corrosion test was performed. The experiment results showed the corrosion can be monitored effectively and the corrosion rate is obtained by volume loss rate of rebar.

  11. Wireless surface acoustic wave sensors for displacement and crack monitoring in concrete structures

    NASA Astrophysics Data System (ADS)

    Perry, M.; McKeeman, I.; Saafi, M.; Niewczas, P.

    2016-03-01

    In this work, we demonstrate that wireless surface acoustic wave devices can be used to monitor millimetre displacements in crack opening during the cyclic and static loading of reinforced concrete structures. Sensors were packaged to extend their gauge length and to protect them against brittle fracture, before being surface-mounted onto the tensioned surface of a concrete beam. The accuracy of measurements was verified using computational methods and optical-fibre strain sensors. After packaging, the displacement and temperature resolutions of the surface acoustic wave sensors were 10 μ {{m}} and 2 °C respectively. With some further work, these devices could be retrofitted to existing concrete structures to facilitate wireless structural health monitoring.

  12. Alkali-silica reaction products: Comparison between samples from concrete structures and laboratory test specimens

    SciTech Connect

    Sachlova, Sarka Prikryl, Richard; Pertold, Zdenek

    2010-12-15

    Alkali-silica gels (ASG) were investigated in concrete from bridge structures (constructed from the 1920s to 2000), as well as in experimental specimens; employing optical microscopy, petrographic image analysis, and scanning electron microscopy combined with energy dispersive spectroscopy (SEM/EDS). The main differences were found in the chemical composition and morphology of the ASGs. ASGs which had formed in older concrete samples (50-80 years old) show a partly crystalline structure and higher Ca{sup 2+} content, indicating their aging and maturation. Younger concrete samples and experimental test specimens exhibit the presence of amorphous ASG. The chemistry of ASG from experimental specimens reflects the chemical composition of accelerating solutions. - Research Highlights: {yields} Quantitative analysis of alkali-silica gels {yields} Comparison of ASR in experimental conditions with ASR in bridge structures {yields} Investigation of factors affecting alkali-silica reaction {yields} Investigation of ASR of different types of aggregates.

  13. Compressive strength evaluation of structural lightweight concrete by non-destructive ultrasonic pulse velocity method.

    PubMed

    Bogas, J Alexandre; Gomes, M Glória; Gomes, Augusto

    2013-07-01

    In this paper the compressive strength of a wide range of structural lightweight aggregate concrete mixes is evaluated by the non-destructive ultrasonic pulse velocity method. This study involves about 84 different compositions tested between 3 and 180 days for compressive strengths ranging from about 30 to 80 MPa. The influence of several factors on the relation between the ultrasonic pulse velocity and compressive strength is examined. These factors include the cement type and content, amount of water, type of admixture, initial wetting conditions, type and volume of aggregate and the partial replacement of normal weight coarse and fine aggregates by lightweight aggregates. It is found that lightweight and normal weight concretes are affected differently by mix design parameters. In addition, the prediction of the concrete's compressive strength by means of the non-destructive ultrasonic pulse velocity test is studied. Based on the dependence of the ultrasonic pulse velocity on the density and elasticity of concrete, a simplified expression is proposed to estimate the compressive strength, regardless the type of concrete and its composition. More than 200 results for different types of aggregates and concrete compositions were analyzed and high correlation coefficients were obtained. PMID:23351273

  14. Numerical simulation of hydro-thermo-mechanical behavior of concrete structures exposed to elevated temperatures

    NASA Astrophysics Data System (ADS)

    Chung, Jae Hyeon

    In this study, thermal spalling of high-strength concrete structural elements has been investigated by developing numerical models capable of analyzing the combined effects of mass and heat transfer phenomena on thermally induced stresses. Through the use of finite difference simulations, this study investigates moisture effects on thermodynamic states of concrete at elevated temperatures and the influence of pore pressure on development of thermal stress induced by temperature gradients. A finite element stress analysis model is combined with finite difference simulations to predict stress states capable of inducing spalling of the type that has been observed both in the field and in laboratory fire testing of concrete structural elements. The combined hydro-thermo-mechanical analysis procedure presented here may eventually serve as a critical component of stress analysis used for evaluating the fire resistance of high-strength concrete structural systems. The model of concrete exposed to fire that is developed herein involves mass and heat transport phenomena in a multi-phase continuum. Simultaneous flow of multiple fluid phases (i.e., liquid and gaseous) is modeled using newly proposed constitutive relationships that are considered more accurate than those previously available in terms of assessment of thermodynamic state variables of concrete system. In addition, numerical simulations are used to explore the effects that steel reinforcing bars have on internal temperature and pressure within concrete members. Pore pressure and temperature time histories from hydro-thermal finite difference simulations are presented and discussed. Results from the simulations yield an improved understanding of the thermodynamic state variables such as pore pressure, temperature, and degree of liquid water saturation. Selection of constitutive models to describe the flow characteristics of concrete and the procedures implemented for the creation of the concrete models are also

  15. Parameterization of Damage in Reinforced Concrete Structures Using Model Updating

    NASA Astrophysics Data System (ADS)

    ABDEL WAHAB, M. M.; DE ROECK, G.; PEETERS, B.

    1999-12-01

    This paper describes the application of finite element model updating to reinforced concrete beams in order to detect and quantify damage. Three simply supported beams are considered in this study: two of them are subjected to a single concentrated load while the third one to two concentrated loads. The static loading system is applied in different steps up to failure so that dynamic measurements can be carried out after each load step. The measured modal parameters are used afterwards to update a finite element model in order to localize and to quantify the damage. The updating algorithm is based on the sensitivity approach in which the discrepancies between the analytical and experimental modal data are minimized in an iterative manner. A new concept for damage parametrization is introduced. A damage function characterized by three parameters is proposed. In such a function, only three parameters are used to describe the damage pattern of the reinforced concrete beams. These parameters are related to the bending stiffness of the beams and updated so that the measured natural frequencies are reproduced. The results demonstrate the efficiency of the proposed technique to quantify the damage pattern.

  16. Ultrasonic assessment of service life of concrete structures subject to reinforcing steel corrosion

    NASA Astrophysics Data System (ADS)

    Udegbunam, Ogechukwu Christian

    Over half of the bridges in the United States were built before 1970. Such bridges and the network of roads that they carry include the Inter State system, which was built as part of the great public works program, following the end of the Second World War. During that era, the emphasis was on strength design and economical construction of new structures, and not much premium was placed on durability and maintainability concerns. Since the end of this construction boom in the early 1970s, the concern for the durability of transportation infrastructure has steadily gained prominence among those agencies that must secure, program and administer funds for maintaining highway networks. The objective of this research was to develop a nondestructive method of assessing the durability of concrete bridge decks susceptible to damage from corrosion of embedded reinforcing steel. This was accomplished by formulating a holistic approach that accounts for the major factors that influence corrosion based deterioration of reinforced concrete. In this approach, the assessment of the durability of concrete bridge decks is based on a model that estimates the time it takes for the cover concrete to fail a result of stresses caused by expansion of reinforcing steel bars, due to corrosion activities. This time to failure is comprised of two distinct periods that must be evaluated before the problem can be solved. The research consisted of an experimental program and an analytical study. In the experimental program concrete specimens were cast and tested to determine their diffusivity and mechanical properties. The diffusivity was used to evaluate the period it takes for corrosion of the reinforcing bars to commence. In the analytical study, the resistance of the concrete structure against the internal forces caused by corrosion was evaluated with the finite element techniques. This resistance was used to evaluate the period defining the failure of the cover concrete. These two periods

  17. Anchorage and shear in concrete structures exposed to fire: A literature review

    NASA Astrophysics Data System (ADS)

    Grauers, Katarina; Cederwall, Krister; Gylltoft, Kent

    A literature study has been performed on bond and shear strength of concrete structures exposed to high temperature. Present knowledge and areas where more research is needed have been investigated. Selected results from small and large scale bond tests as well as large scale shear tests are presented. There is a need to investigate further the shear strength of concrete beams both during a fire and after a fire to be able to model the bearing capacity of a structure. Fracture mechanics and the finite element method is recommended to be used in advanced analyses.

  18. Impact of structural aging on seismic risk assessment of reinforced concrete structures in nuclear power plants

    SciTech Connect

    Ellingwood, B.; Song, J.

    1996-03-01

    The Structural Aging Program is addressing the potential for degradation of concrete structural components and systems in nuclear power plants over time due to aging and aggressive environmental stressors. Structures are passive under normal operating conditions but play a key role in mitigating design-basis events, particularly those arising from external challenges such as earthquakes, extreme winds, fires and floods. Structures are plant-specific and unique, often are difficult to inspect, and are virtually impossible to replace. The importance of structural failures in accident mitigation is amplified because such failures may lead to common-cause failures of other components. Structural condition assessment and service life prediction must focus on a few critical components and systems within the plant. Components and systems that are dominant contributors to risk and that require particular attention can be identified through the mathematical formalism of a probabilistic risk assessment, or PRA. To illustrate, the role of structural degradation due to aging on plant risk is examined through the framework of a Level 1 seismic PRA of a nuclear power plant. Plausible mechanisms of structural degradation are found to increase the core damage probability by approximately a factor of two.

  19. Numerical simulation of the effect of blast and penetration on reinforced concrete structures

    NASA Astrophysics Data System (ADS)

    Mencarelli, Andrea

    In this thesis a novel discrete meso-scale model for concrete, called Lattice Discrete Particle Model (LDPM) will be presented. This novel approach enables the computational investigation of the mechanical behavior of concrete structures subjected to blast and projectile impact. Under these loading conditions concrete behaves non-linearly, and the material behavior is strongly influenced by the heterogeneity of the internal structure and by the associated damage localization and fracture occurring at failure. In particular fragmentation phenomena and triaxial confined behavior are predominant in this type of problems. Concrete non-linearity has been investigated by both continuum and discrete models, but at this time there is no a model able to reproduce correctly concrete behavior under fragmentation and highly confined compression. To overcome this limitation of the current state-of-the-art, the goal of this research is to formulate a model able to simulate concrete subjected to both extensive fracture and triaxial state of stress. Herein an overview of typical discrete models for concrete will be presented. Models will be characterized considering the scale of the material heterogeneity discretization. Material discretization, kinematic and static modeling, simulated tests, advantages and disadvantages of each model, and future developments will be also discussed. The formulation of the new approach will be then presented and explained. The model reproduces the concrete mesostructure through polyhedral cells obtained by a 3D Delaunay tetrahedralization, and a dual domain tessellation. Facets, produced by the tessellation, exchange axial and shear forces following compatibility and equilibrium equations at the discrete level. Softening behavior is reproduced only in tension and hardening only in compression. Shear reproduces both cohesion and friction. The model is able to reproduce concrete damage and failure under direct tension, mode I and mixed mode fracture

  20. Development of in-structure design spectra for dome mounted equipment on underground waste storage tanks at the Hanford Site

    SciTech Connect

    Julyk, L.J.

    1995-09-01

    In-structure response spectra for dome mounted equipment on underground waste storage tanks at the Hanford Site are developed on the basis of recent soil-structure-interaction analyses. Recommended design spectra are provided for various locations on the tank dome.

  1. Yield Line Evaluation Methodology for Reinforced Concrete Structures

    1998-12-30

    Yield line theory is an analytical technique that can be used to determine the ultimate bending capacity of flat reinforced concrete plates subject to distributed and concentrated loadings. Alternately, yield line theory, combined with rotation limits can be used to determine the energy absorption capacity of plates subject to impulsive and impact loadings. Typical components analyzed by yield line theory are basemats, floor and roof slabs subject to vertical loads along with walls subject tomore » out of plane loadings. One limitation of yield line theory is that it is computationally difficult to evaluate some mechanisms. This problem is aggravated by the complex geometry and reinforcing layouts commonly found in practice. The program has the capability to either evaluate a single user defined mechanism or to iterate over a range of mechanisms to determine the minimum ultimate capacity. The program is verified by comparison to a series of yield line mechanisms with known solutions.« less

  2. State of Strength in Massive Concrete Structure Subjected to Non-Mechanical Loads

    NASA Astrophysics Data System (ADS)

    Łydźba, Dariusz; Sobótka, Maciej

    2015-02-01

    The paper deals with an impact of non-mechanical loads on the state of strength in massive concrete hydraulic structures. An example of hydroelectric plant subjected to the effect of water temperature annual fluctuation is considered. Numerical analysis of transient thermal-elasticity problem was performed. After determining the temperature distributions within the domain, the Duhamel-Neumann set of constitutive equations was employed to evaluate fields of mechanical quantities: displacement, strain and stress. The failure criterion proposed by Pietruszczak was adopted in assessing whether the load induces exceeding of strength of concrete within the structure volume. The primary finding is that the temperature effect can lead to damage of concrete in draft tubes and spirals, especially in winter months.

  3. DFB fiber laser sensor for simultaneous strain and temperature measurements in concrete structures

    NASA Astrophysics Data System (ADS)

    Hadeler, Oliver; Richards, D. J.; Dakin, John P.

    1999-05-01

    A distributed feedback (DFB) fiber laser sensor for simultaneously measuring strain and temperature has been developed. The DFB fiber laser consists of a single fiber Bragg grating written in a low birefringent rare-earth doped fiber. By measuring the rf beat frequency between the two orthogonal polarized lasing modes and the absolute wavelength of one mode, both strain and temperature can be determined simultaneously to an accuracy of plus or minus 3 (mu) (epsilon) and plus or minus 0.04 degrees Celsius. Multiplexing capabilities make this sensor ideal for monitoring several locations within a civil engineering structure. Three gauge protection systems were developed to prevent damage to the fiber during embedment and insulate it from the high alkaline environment of the concrete. This sensor is easy to install, provides excellent strain transfer from the concrete to the optical fiber and is thin enough not to degrade the concrete structure.

  4. Hybrid optical-fibre/geopolymer sensors for structural health monitoring of concrete structures

    NASA Astrophysics Data System (ADS)

    Perry, M.; Saafi, M.; Fusiek, G.; Niewczas, P.

    2015-04-01

    In this work, we demonstrate hybrid optical-fibre/geopolymer sensors for monitoring temperature, uniaxial strain and biaxial strain in concrete structures. The hybrid sensors detect these measurands via changes in geopolymer electrical impedance, and via optical wavelength measurements of embedded fibre Bragg gratings. Electrical and optical measurements were both facilitated by metal-coated optical fibres, which provided the hybrid sensors with a single, shared physical path for both voltage and wavelength signals. The embedded fibre sensors revealed that geopolymer specimens undergo 2.7 mɛ of shrinkage after one week of curing at 42 °C. After curing, an axial 2 mɛ compression of the uniaxial hybrid sensor led to impedance and wavelength shifts of 7 × 10-2 and -2 × 10-4 respectively. The typical strain resolution in the uniaxial sensor was 100 μ \\varepsilon . The biaxial sensor was applied to the side of a concrete cylinder, which was then placed under 0.6 mɛ of axial, compressive strain. Fractional shifts in impedance and wavelength, used to monitor axial and circumferential strain, were 3 × 10-2 and 4 × 10-5 respectively. The biaxial sensor’s strain resolution was approximately 10 μ \\varepsilon in both directions. Due to several design flaws, the uniaxial hybrid sensor was unable to accurately measure ambient temperature changes. The biaxial sensor, however, successfully monitored local temperature changes with 0.5 °C resolution.

  5. Qualification of a truly distributed fiber optic technique for strain and temperature measurements in concrete structures

    NASA Astrophysics Data System (ADS)

    Henault, J. M.; Salin, J.; Moreau, G.; Delepine-Lesoille, S.; Bertand, J.; Taillade, F.; Quiertant, M.; Benzarti, K.

    2011-04-01

    Structural health monitoring is a key factor in life cycle management of infrastructures. Truly distributed fiber optic sensors are able to provide relevant information on large structures, such as nuclear power plants or nuclear waste disposal facilities. The sensing chain includes an optoelectronic unit and a sensing cable made of one or more optical fibers. A new instrument based on Optical Frequency Domain Reflectometry (OFDR), enables to perform temperature and strain measurements with a centimeter scale spatial resolution over hundred of meters and with a level of precision equal to 1 μ strain and 0.1 °C. Several sensing cables are designed with different materials targeting to last for decades, either embedded in the concrete or attached to the surface of the structure. They must ensure an optimal transfer of temperature and strain from the concrete matrix to the optical fiber. Based on the European guide FD CEN/TR 14748 "Non-destructive testing - Methodology for qualification of non-destructive tests", a qualification method was developed. Tests were carried out using various sensing cables embedded in the volume or fixed to the surface of plain concrete specimens and representative-scale reinforced concrete structural elements. Measurements were performed with an OFDR instrument, while mechanical solicitations were imposed to the concrete element. Preliminary experiments seem very promising since measurements performed with distributed sensing systems are found comparable to values obtained with conventional sensors used in civil engineering and with the Strength of Materials Modelling. Moreover, the distributed sensing system makes it possible to detect and localize cracks appearing in concrete during the mechanical loading.

  6. Overview of activities in the U.S. related to continued service of nuclear power plant concrete structures

    NASA Astrophysics Data System (ADS)

    Naus, D. J.

    2011-04-01

    Safety-related nuclear power plant concrete structures are described and commentary on continued service assessments of these structures is provided. In-service inspection and testing requirements in the U.S. are summarized. The license renewal process in the U.S. is outlined and its current status noted. A summary of operating experience related to U.S. nuclear power plant concrete structures is presented. Several candidate areas are identified where additional research would be of benefit to aging management of NPP concrete structures. Finally current ORNL activities related to aging-management of concrete structures are outlined: development of operating experience database, application of structural reliability theory, and compilation of elevated temperature concrete material property data and information.

  7. Overview of Activities in U.S. Related to Continued Service of Nuclear Power Plant Concrete Structures

    SciTech Connect

    Naus, Dan J

    2011-01-01

    Safety-related nuclear power plant concrete structures are described and commentary on continued service assessments of these structures is provided. In-service inspection and testing requirements in the U.S. are summarized. The license renewal process in the U.S. is outlined and its current status noted. A summary of operating experience related to U.S. nuclear power plant concrete structures is presented. Several candidate areas are identified where additional research would be of benefit to aging management of NPP concrete structures. Finally current ORNL activities related to aging-management of concrete structures are outlined: development of operating experience database, application of structural reliability theory, and compilation of elevated temperature concrete material property data and information.

  8. Study on variability of modal parameters of concrete structure: humidity and moisture effect

    NASA Astrophysics Data System (ADS)

    Zhou, W.; Li, H.; Nasser, H.

    2008-03-01

    The complex external environment for civil engineering structures results in the structural vibration properties varying with external conditions, such as humidity and temperature. For the vibration-based structural health monitoring techniques, for example damage identification, modal updating etc., above characteristics will result in the vibration-based techniques invalid. Other researchers have reported that modal frequencies varied significantly due to temperature change, but the humidity affect structural vibration properties in another manner. This paper discusses the variation of frequencies and mode shapes with respect to humidity and temperature changes for concrete structures, for which the changing of moisture will affect the density of materials, and the changing of temperature will affect the stiffness of structures. This paper models these two factors with finite element model approach based on the theoretical analysis, and numerical results obtained on the FE model of a concrete bridge deck are reported.

  9. 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.

  10. Nuclear Technology. Course 29: Civil/Structural Inspection. Module 29-5, Concrete Testing and Inspection.

    ERIC Educational Resources Information Center

    Groseclose, Richard

    This fifth in a series of six modules for a course titled Civil/Structural Inspection introduces various test methods and equipment associated with concrete testing and provides a practical background for the actual inspection of the associated construction activities. The module follows a typical format that includes the following sections: (1)…

  11. Nuclear Technology. Course 29: Civil/Structural Inspection. Module 29-3, Concrete Materials.

    ERIC Educational Resources Information Center

    Groseclose, Richard

    This third in a series of six modules for a course titled Civil/Structural Inspection deals with concrete component materials and discusses their properties, methods of handling and storage, selection, uniformity, and methods of acceptance. The module follows a typical format that includes the following sections: (1) introduction, (2) module…

  12. Using Concrete & Representational Experiences to Understand the Structure of DNA: A Four-Step Instructional Framework

    ERIC Educational Resources Information Center

    Harrell, Pamela Esprivalo; Richards, Debbie; Collins, James; Taylor, Sarah

    2005-01-01

    A description of learning experience that uses a four-step instrumentational framework involving concrete and representational experiences to promote conceptual understanding of abstract biological concepts by a series of closely-related activities is presented. The students are introduced to the structure and implications of DNA using four…

  13. A&M. Outdoor turntable during demolition. Concrete structural supports radiate from ...

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

    A&M. Outdoor turntable during demolition. Concrete structural supports radiate from center towards outer edge of turntable. Detail of wheel. Date: February 3, 2003. INEEL negative no. HD-37-3-2 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

  14. A projective reconstruction method of underground or hidden structures using atmospheric muon absorption data

    NASA Astrophysics Data System (ADS)

    Bonechi, L.; D'Alessandro, R.; Mori, N.; Viliani, L.

    2015-02-01

    Muon absorption radiography is an imaging technique based on the analysis of the attenuation of the cosmic-ray muon flux after traversing an object under examination. While this technique is now reaching maturity in the field of volcanology for the imaging of the innermost parts of the volcanic cones, its applicability to other fields of research has not yet been proved. In this paper we present a study concerning the application of the muon absorption radiography technique to the field of archaeology, and we propose a method for the search of underground cavities and structures hidden a few metres deep in the soil (patent [1]). An original geometric treatment of the reconstructed muon tracks, based on the comparison of the measured flux with a reference simulated flux, and the preliminary results of specific simulations are discussed in details.

  15. Feasibility of using phase change materials to control the heat of hydration in massive concrete structures.

    PubMed

    Choi, Won-Chang; Khil, Bae-Soo; Chae, Young-Seok; Liang, Qi-Bo; Yun, Hyun-Do

    2014-01-01

    This paper presents experimental results that can be applied to select a possible phase change material (PCM), such as a latent heat material (LHM), to control the hydration heat in mass concrete structures. Five experimental tests (microconduction, simplified adiabatic temperature rise, heat, and compressive strength tests) were conducted to select the most desirable LHM out of seven types of inorganic PCM used in cement mortar and to determine the most suitable mix design. The results of these experimental tests were used to assess the feasibility of using PCM to reduce hydration heat in mass concrete that was examined. The experimental results show that cement mortar containing barium- [Ba(OH)2 · 8H2O] based PCM has the lowest amount of total hydration heat of the cement pastes. The barium-based PCM provides good latent heat properties that help to prevent volume change and microcracks caused by thermal stress in mass concrete.

  16. Relationship between pore structure and mechanical properties of ordinary concrete under bending fatigue

    SciTech Connect

    Zhang, B.

    1998-05-01

    Progressive macro damage of concrete under fatigue loading is caused by the change of its internal micro-meso properties such as pore structure. In this study, porosity, pore size distribution, and specific surface area of ordinary concrete at different fatigue stages were investigated using mercury intrusion, helium flow, and nitrogen adsorption (BET) methods. These properties changed with increasing loading cycles and could be taken as micro-meso damage parameters to evaluate macro fatigue damage of concrete. Test results showed that both porosity in mortar (mainly macro pores) and interface between mortar and coarse aggregates (interfacial cracks) developed at a similar rate. The corresponding residual bending fatigue strength and dynamic bending Young`s modulus were also obtained and their relationships with these micro-meso properties were established. The intrinsic bending strength and intrinsic bending Young`s modulus were predicted from these relationships.

  17. Customization and calibration of BOTDR sensors for underground structural health monitoring

    NASA Astrophysics Data System (ADS)

    Sham, Wai Lun; Yang, Yaowen; Pravin, Muley

    2011-04-01

    In recent years, it is becoming more common to use fiber optic sensors (FOS) in the structural health monitoring (SHM) sector, especially in the civil engineering field. A number of surface-mountable sensor system for FOS have been developed in the past years, the recent development of Brillouin Optical Time Domain Reflectometry (BOTDR) was a great evolution towards the SHM system development, it inspired the new edge of FOS SHM system. Different from the traditional monitoring instruments, it provides distributed, long distance, real-time, interference free and high accuracy/precision measurement data. It is now possible to achieve "continuous" measurement data and this SHM technique is applicable in area that is inaccessible. The research aims to solve the problems which exist in the convergence measurement using the conventional measuring methods, however, there is still a gap between the lab experiments and field applications. Limited research has been conducted on how to maximize its possible applications due to its brittle and fragile material nature. A number of additional considerations for a successful pairing of these two must be taken into account for successful field applications. This article provides a short review on underground monitoring techniques and FOS SHM systems. The focuses is on examine (i) the feasibility and effectiveness of different BOTDR sensors installation methods (ii) the suitable commercially-available o sensing cable for underground application (iii) the sensing performance of customized sensor protection package BOTDR sensor that manufactured involving layers of fiber reinforced composites. This research serves a bridge in between the technology advancement to the creation of a structure health monitoring system with practical application, numerical simulation and theoretical analysis aspects, and also to provide the insights into the mechanisms of BOTDR.

  18. Behavior and evaluation of an existing underground structure subjected to impulsive loads from an internal explosion

    SciTech Connect

    Keller, M.D.; Khan, P.K.

    1997-12-01

    An explosion is the result of a rapid chemical reaction which generates transient air pressure waves called blast waves. There has been much research on the processes of blast wave formation, propagation of blast waves, and quantification of the incident and reflected blast overpressures. The magnitude of blast overpressure, in a partially vented environment, is mainly a function of the type and quantity of detonating material, the amount of available venting, and the orientation and configuration of the reflecting surfaces. In addition to blast overpressure, an explosion can also generate high energy missiles (such as fragments), shock loads, and rapid rise of temperature in the confined space. This study concentrates on the effects of blast overpressure on a 40 feet diameter reinforced concrete cylinder with a hemispherical dome roof, supported on a 3 feet thick reinforced concrete pad, and buried under a minimum of 15 feet of soil used for radiation shielding at the top of the dome. The scope of this study is to determine whether the structure can withstand the blast overpressure generated by the postulated explosion without exceeding allowable design criteria.

  19. Stiffness analysis of glued connection of the timber-concrete structure

    NASA Astrophysics Data System (ADS)

    Daňková, Jana; Mec, Pavel; Majstríková, Tereza

    2016-01-01

    This paper presents results of experimental and mathematical analysis of stiffness characteristics of a composite timber-concrete structure. The composite timberconcrete structure presented herein is non-typical compared to similar types of building structures. The interaction between the timber and concrete part of the composite cross-section is not based on metal connecting elements, but it is ensured by a glued-in perforated mesh made of plywood. The paper presents results of experimental and mathematical analysis for material alternatives of the solution of the glued joint. The slip modulus values were determined experimentally. Data obtained from the experiment evaluated by means of regression analysis. Test results were also used as input data for the compilation of a 3D model of a composite structure by means of the 3D finite element model. On the basis of result evaluation, it can be stated that the stress-deformation behaviour at shear loading of this specific timber-concrete composite structure can be affected by the type of glue used. Parameters of the 3D model of both alternative of the structure represent well the behaviour of the composite structure and the model can be used for predicting design parameters of a building structure.

  20. Distributed Long-Gauge Optical Fiber Sensors Based Self-Sensing FRP Bar for Concrete Structure

    PubMed Central

    Tang, Yongsheng; Wu, Zhishen

    2016-01-01

    Brillouin scattering-based distributed optical fiber (OF) sensing technique presents advantages for concrete structure monitoring. However, the existence of spatial resolution greatly decreases strain measurement accuracy especially around cracks. Meanwhile, the brittle feature of OF also hinders its further application. In this paper, the distributed OF sensor was firstly proposed as long-gauge sensor to improve strain measurement accuracy. Then, a new type of self-sensing fiber reinforced polymer (FRP) bar was developed by embedding the packaged long-gauge OF sensors into FRP bar, followed by experimental studies on strain sensing, temperature sensing and basic mechanical properties. The results confirmed the superior strain sensing properties, namely satisfied accuracy, repeatability and linearity, as well as excellent mechanical performance. At the same time, the temperature sensing property was not influenced by the long-gauge package, making temperature compensation easy. Furthermore, the bonding performance between self-sensing FRP bar and concrete was investigated to study its influence on the sensing. Lastly, the sensing performance was further verified with static experiments of concrete beam reinforced with the proposed self-sensing FRP bar. Therefore, the self-sensing FRP bar has potential applications for long-term structural health monitoring (SHM) as embedded sensors as well as reinforcing materials for concrete structures. PMID:26927110

  1. Distributed Long-Gauge Optical Fiber Sensors Based Self-Sensing FRP Bar for Concrete Structure.

    PubMed

    Tang, Yongsheng; Wu, Zhishen

    2016-02-25

    Brillouin scattering-based distributed optical fiber (OF) sensing technique presents advantages for concrete structure monitoring. However, the existence of spatial resolution greatly decreases strain measurement accuracy especially around cracks. Meanwhile, the brittle feature of OF also hinders its further application. In this paper, the distributed OF sensor was firstly proposed as long-gauge sensor to improve strain measurement accuracy. Then, a new type of self-sensing fiber reinforced polymer (FRP) bar was developed by embedding the packaged long-gauge OF sensors into FRP bar, followed by experimental studies on strain sensing, temperature sensing and basic mechanical properties. The results confirmed the superior strain sensing properties, namely satisfied accuracy, repeatability and linearity, as well as excellent mechanical performance. At the same time, the temperature sensing property was not influenced by the long-gauge package, making temperature compensation easy. Furthermore, the bonding performance between self-sensing FRP bar and concrete was investigated to study its influence on the sensing. Lastly, the sensing performance was further verified with static experiments of concrete beam reinforced with the proposed self-sensing FRP bar. Therefore, the self-sensing FRP bar has potential applications for long-term structural health monitoring (SHM) as embedded sensors as well as reinforcing materials for concrete structures.

  2. Structure formation of aerated concrete containing waste coal combustion products generated in the thermal vortex power units

    NASA Astrophysics Data System (ADS)

    Ivanov, A. I.; Stolboushkin, A. Yu; Temlyanstev, M. V.; Syromyasov, V. A.; Fomina, O. A.

    2016-10-01

    The results of fly ash research, generated in the process of waste coal combustion in the thermal vortex power units and used as an aggregate in aerated concrete, are provided. It is established that fly ash can be used in the production of cement or concrete with low loss on ignition (LOI). The permitted value of LOI in fly ash, affecting the structure formation and operational properties of aerated concrete, are defined. During non-autoclaved hardening of aerated concrete with fly ash aggregate and LOI not higher than 2%, the formation of acicular crystals of ettringite, reinforcing interporous partitions, takes place.

  3. Mixed formulation for seismic analysis of composite steel-concrete frame structures

    NASA Astrophysics Data System (ADS)

    Ayoub, Ashraf Salah Eldin

    This study presents a new finite element model for the nonlinear analysis of structures made up of steel and concrete under monotonic and cyclic loads. The new formulation is based on a two-field mixed formulation. In the formulation, both forces and deformations are simultaneously approximated within the element through independent interpolation functions. The main advantages of the model is the accuracy in global and local response with very few elements while maintaining rapid numerical convergence and robustness even under severe cyclic loading. Overall four elements were developed based on the new formulation: an element that describes the behavior of anchored reinforcing bars, an element that describes the behavior of composite steel-concrete beams with deformable shear connectors, an element that describes the behavior of reinforced concrete beam-columns with bond-slip, and an element that describes the behavior of pretensioned or posttensioned, bonded or unbonded prestressed concrete structures. The models use fiber discretization of beam sections to describe nonlinear material response. The transfer of forces between steel and concrete is described with bond elements. Bond elements are modeled with distributed spring elements. The non-linear behavior of the composite element derives entirely from the constitutive laws of the steel, concrete and bond elements. Two additional elements are used for the prestressed concrete models, a friction element that models the effect of friction between the tendon and the duct during the posttensioning operation, and an anchorage element that describes the behavior of the prestressing tendon anchorage in posttensioned structures. Two algorithms for the numerical implementation of the new proposed model are presented; an algorithm that enforces stress continuity at element boundaries, and an algorithm in which stress continuity is relaxed locally inside the element. Stability of both algorithms is discussed. Comparison

  4. Application of petrographic examination techniques to the assessment of fire-damaged concrete and masonry structures

    SciTech Connect

    Ingham, Jeremy P.

    2009-07-15

    The number of building fires has doubled over the last 50 years. There has never been a greater need for structures to be assessed for fire damage to ensure safety and enable appropriate repairs to be planned. Fortunately, even after a severe fire, concrete and masonry structures are generally capable of being repaired rather than demolished. By allowing direct examination of microcracking and mineralogical changes, petrographic examination has become widely used to determine the depth of fire damage for reinforced concrete elements. Petrographic examination can also be applied to fire-damaged masonry structures built of materials such as stone, brick and mortar. Petrography can ensure accurate detection of damaged geomaterials, which provides cost savings during building repair and increased safety reassurance. This paper comprises a review of the role of petrography in fire damage assessments, drawing on a range of actual fire damage investigations.

  5. Performance of corrosion inhibiting admixtures for structural concrete -- assessment methods and predictive modeling

    SciTech Connect

    Yunovich, M.; Thompson, N.G.

    1998-12-31

    During the past fifteen years corrosion inhibiting admixtures (CIAs) have become increasingly popular for protection of reinforced components of highway bridges and other structures from damage induced by chlorides. However, there remains considerable debate about the benefits of CIAs in concrete. A variety of testing methods to assess the performance of CIA have been reported in the literature, ranging from tests in simulated pore solutions to long-term exposures of concrete slabs. The paper reviews the published techniques and recommends the methods which would make up a comprehensive CIA effectiveness testing program. The results of this set of tests would provide the data which can be used to rank the presently commercially available CIA and future candidate formulations utilizing a proposed predictive model. The model is based on relatively short-term laboratory testing and considers several phases of a service life of a structure (corrosion initiation, corrosion propagation without damage, and damage to the structure).

  6. Field application of cathodic prevention on reinforced concrete structures

    SciTech Connect

    Bazzoni, A.; Bazzoni, B.; Lazzari, L.; Bertolini, L.; Pedeferri, P.

    1996-11-01

    This paper illustrates the results gained during the first three years of cathodic protection application to Frejus highway viaducts in northern Italy. CP applications deal with corrosion control of chloride contaminated structures (cathodic protection application properly said) and the corrosion prevention of new non-contaminated structures, constructed with incorporated cathodic protection systems (so-called cathodic prevention). Both normal and post-tensioned structures are present: in the latter case the problems connected with the risk of hydrogen embrittlement of the tendons are discussed. The paper illustrates also the computerized system for gathering and monitoring data and the criteria adopted to evaluate and control the cathodic protection and cathodic prevention conditions as well as to avoid overprotection.

  7. 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

  8. Characterization of radon entry rates and indoor concentrations in underground structures

    SciTech Connect

    Borak, T.B.; Whicker, F.W.; Fraley, L.; Gadd, M.S.; Ibrahim, S.A.; Monette, F.A.; Morris, R.; Ward, D.C.

    1992-12-31

    An experimental facility has been designed to comprehensively determine the influence of soil and meterological conditions on the transport of radon into underground structures. Two identical basements are equipped to continuously monitor pressure differentials, temperatures, soil moisture, precipitation, barometric pressure, wind speed, wind direction, natural ventiliation rates, and radon concentrations. A computerized data acquisition system accumulates and processes data at the rate of 6000 points per day. The experimental design is based on performing experiments in one structure, with the other used as a control. Indoor radon concentrations have temporal variations ranging from 150 to 1400 Bq m{sup -3}. The corresponding entry rate of radon ranges from 300 to 10,000 Bq h{sup -1}. When the radon entry rate is high, the indoor radon concentration decreases, whereas elevated radon concentrations seem to be associated with slow but persistent radon entry rates. This inverse relationship is partially due to compensation from enhanced natural ventilation during periods when the radon entry rate is high. Correlations between measured variables in the soil and indoor-outdoor atmospheres are used to interpret these data. This laboratory has the capability to generate essential data required for developing and testing radon transport models.

  9. Damage detection monitoring applications in self-healing concrete structures using embedded piezoelectric transducers and recovery

    NASA Astrophysics Data System (ADS)

    Karaiskos, G.; Tsangouri, E.; Aggelis, D. G.; Deraemaeker, A.; Van Hemelrijck, D.

    2015-07-01

    The ageing, operational and ambient loadings have a great impact in the operational and maintenance cost of concrete structures. Their service life prolongation is of utmost importance and this can be efficiently achieved by using reliable and low-cost monitoring and self-healing techniques. In the present study, the ultrasonic pulse velocity (UPV) method using embedded small-size and low-cost piezoelectric PZT (lead zirconate titanate) ceramic transducers in concrete with self-healing properties is implemented for monitoring not only the setting and hardening phases of concrete since casting time, but also for the detection of damage initiation, propagation and recovery of integrity after healing. A couple of small-scale notched unreinforced concrete beams are subjected to mode-I fracture through three-point bending tests. After a 24-hour healing agent curing period, the beams are reloaded using the same loading scenario. The results demonstrate the excellent performance of the proposed monitoring technique during the hydration, damage generation and recovery periods.

  10. Development of ductile hybrid fiber reinforced polymer (D-H-FRP) reinforcement for concrete structures

    NASA Astrophysics Data System (ADS)

    Somboonsong, Win

    The corrosion of steel rebars has been the major cause of the reinforced concrete deterioration in transportation structures and port facilities. Currently, the Federal Highway Administration (FHWA) spends annually $31 billion for maintaining and repairing highways and highway bridges. The study reported herein represents the work done in developing a new type of reinforcement called Ductile Hybrid Fiber Reinforced Polymer or D-H-FRP using non-corrosive fiber materials. Unlike the previous FRP reinforcements that fail in a brittle manner, the D-H-FRP bars exhibit the stress-strain curves that are suitable for concrete reinforcement. The D-H-FRP stress-strain curves are linearly elastic with a definite yield point followed by plastic deformation and strain hardening resembling that of mild steel. In addition, the D-H-FRP reinforcement has integrated ribs required for concrete bond. The desirable mechanical properties of D-H-FRP reinforcement are obtained from the integrated design based on the material hybrid and geometric hybrid concepts. Using these concepts, the properties can be tailored to meet the specific design requirements. An analytical model was developed to predict the D-H-FRP stress-strain curves with different combination of fiber materials and geometric configuration. This model was used to optimize the design of D-H-FRP bars. An in-line braiding-pultrusion manufacturing process was developed at Drexel University to produce high quality D-H-FRP reinforcement in diameters that can be used in concrete structures. A series of experiments were carried out to test D-H-FRP reinforcement as well as their individual components in monotonic and cyclic tensile tests. Using the results from the tensile tests and fracture analysis, the stress-strain behavior of the D-H-FRP reinforcement was fully characterized and explained. Two series of concrete beams reinforced with D-H-FRP bars were studied. The D-H-FRP beam test results were then compared with companion

  11. Abstraction and Concreteness in the Everyday Mathematics of Structural Engineers.

    ERIC Educational Resources Information Center

    Gainsburg, Julie

    The everyday mathematics processes of structural engineers were studied and analyzed in terms of abstraction. A main purpose of the study was to explore the degree to which the notion of a gap between school and everyday mathematics holds when the scope of practices considered "everyday" is extended. J. Lave (1988) promoted a methodology that…

  12. Deterministic modelling of the cumulative impacts of underground structures on urban groundwater flow and the definition of a potential state of urban groundwater flow: example of Lyon, France

    NASA Astrophysics Data System (ADS)

    Attard, Guillaume; Rossier, Yvan; Winiarski, Thierry; Cuvillier, Loann; Eisenlohr, Laurent

    2016-08-01

    Underground structures have been shown to have a great influence on subsoil resources in urban aquifers. A methodology to assess the actual and the potential state of the groundwater flow in an urban area is proposed. The study develops a three-dimensional modeling approach to understand the cumulative impacts of underground infrastructures on urban groundwater flow, using a case in the city of Lyon (France). All known underground structures were integrated in the numerical model. Several simulations were run: the actual state of groundwater flow, the potential state of groundwater flow (without underground structures), an intermediate state (without impervious structures), and a transient simulation of the actual state of groundwater flow. The results show that underground structures fragment groundwater flow systems leading to a modification of the aquifer regime. For the case studied, the flow systems are shown to be stable over time with a transient simulation. Structures with drainage systems are shown to have a major impact on flow systems. The barrier effect of impervious structures was negligible because of the small hydraulic gradient of the area. The study demonstrates that the definition of a potential urban groundwater flow and the depiction of urban flow systems, which involves understanding the impact of underground structures, are important issues with respect to urban underground planning.

  13. Structures and Opportunities to Supply the Telecommunication Systems in Underground Mines

    NASA Astrophysics Data System (ADS)

    Wojaczek, Antoni

    2016-06-01

    Telecommunication systems in underground mines require reliable power supply both of stationary and underground devices. Special problems connected with power supply occur in a case when subscriber devices are located in explosion hazard areas. The paper presents the basic problems connected with power supply of stationary elements of safety systems as well as subscriber devices located in explosion hazard areas that are significantly distant from stationary elements. Acceptable methods of supplying the subscribers devices under technical environment conditions of mine undergrounds have been determined.

  14. 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

  15. Concrete modelling for expertise of structures affected by alkali aggregate reaction

    SciTech Connect

    Grimal, E.; Sellier, A.; Multon, S.; Le Pape, Y.; Bourdarot, E.

    2010-04-15

    Alkali aggregate reaction (AAR) affects numerous civil engineering structures and causes irreversible expansion and cracking. In order to control the safety level and the maintenance cost of its hydraulic dams, Electricite de France (EDF) must reach better comprehension and better prediction of the expansion phenomena. For this purpose, EDF has developed a numerical model based on the finite element method in order to assess the mechanical behaviour of damaged structures. The model takes the following phenomena into account: concrete creep, the stress induced by the formation of AAR gel and the mechanical damage. A rheological model was developed to assess the coupling between the different phenomena (creep, AAR and anisotropic damage). Experimental results were used to test the model. The results show the capability of the model to predict the experimental behaviour of beams subjected to AAR. In order to obtain such prediction, it is necessary to take all the phenomena occurring in the concrete into consideration.

  16. Quantitative ultrasonic evaluation of concrete structures using one-sided access

    NASA Astrophysics Data System (ADS)

    Khazanovich, Lev; Hoegh, Kyle

    2016-02-01

    Nondestructive diagnostics of concrete structures is an important and challenging problem. A recent introduction of array ultrasonic dry point contact transducer systems offers opportunities for quantitative assessment of the subsurface condition of concrete structures, including detection of defects and inclusions. The methods described in this paper are developed for signal interpretation of shear wave impulse response time histories from multiple fixed distance transducer pairs in a self-contained ultrasonic linear array. This included generalizing Kirchoff migration-based synthetic aperture focusing technique (SAFT) reconstruction methods to handle the spatially diverse transducer pair locations, creating expanded virtual arrays with associated reconstruction methods, and creating automated reconstruction interpretation methods for reinforcement detection and stochastic flaw detection. Interpretation of the reconstruction techniques developed in this study were validated using the results of laboratory and field forensic studies. Applicability of the developed methods for solving practical engineering problems was demonstrated.

  17. DETERMINING THE EFFECTS OF RADIATION ON AGING CONCRETE STRUCTURES OF NUCLEAR REACTORS

    SciTech Connect

    Serrato, M.

    2010-01-29

    The U.S. Department of Energy Office of Environmental Management (DOE-EM) is responsible for the Decontamination and Decommissioning (D&D) of nuclear facilities throughout the DOE Complex. Some of these facilities will be completely dismantled, while others will be partially dismantled and the remaining structure will be stabilized with cementitious fill materials. The latter is a process known as In-Situ Decommissioning (ISD). The ISD decision process requires a detailed understanding of the existing facility conditions, and operational history. System information and material properties are need for aged nuclear facilities. This literature review investigated the properties of aged concrete structures affected by radiation. In particular, this review addresses the Savannah River Site (SRS) isotope production nuclear reactors. The concrete in the reactors at SRS was not seriously damaged by the levels of radiation exposure. Loss of composite compressive strength was the most common effect of radiation induced damage documented at nuclear power plants.

  18. Online monitoring of cracking in concrete structures using embedded piezoelectric transducers

    NASA Astrophysics Data System (ADS)

    Dumoulin, C.; Karaiskos, G.; Sener, J.-Y.; Deraemaeker, A.

    2014-10-01

    Online damage detection is of great interest in the field of concrete structures and, more generally, within the construction industry. Current economic requirements impose the reduction of the operating costs related to such inspection while the security and the reliability of structures must constantly be improved. In this paper, nondestructive testing is applied using piezoelectric transducers embedded in concrete structures. These transducers are especially adapted for online ultrasonic monitoring, due to their low cost, small size, and broad frequency band. These recent transducers are called smart aggregates. The technique of health monitoring developed in this study is based on a ultrasonic pulse velocity test with an embedded ultrasonic emitter-receiver pair (pitch-catch). The damage indicator focuses on the early wave arrival. The Belgian company MS3 takes an interest in evaluating the quality of the concrete around the anchorage system of highway security barriers after important shocks. The failure mechanism can be viewed as a combination of a bending and the failure of the anchorages. Accordingly, the monitoring technique has been applied both on a three-points bending test and several pull-out tests. The results indicate a very high sensitivity of the method, which is able to detect the crack initiation phase and follow the crack propagation over the entire duration of the test.

  19. Comprehension and retention: The effect of concrete details and causal structure in scientific narrative

    NASA Astrophysics Data System (ADS)

    Wilcken, Wendi M.

    The purpose of this study was to examine two of the salient elements of instructional narratives as a guide to instructional practice. The literature summarized in this report discusses the theoretical basis for narrative impact on comprehension and retention, enumerates and defines possible salient narrative elements from the literature, and examines the instructional impact of two of these elements: concrete details and causal structure. This is intended to help provide guidance to instructional designers and teachers who desire to use narrative in science instruction. Participants included 94 high school physics students. An experimental research design of 2 (Gender) x 2 (Concreteness) x 2 (Causal Structure) x 2 (Comprehension as within-subjects) ANCOVA was used to analyze the effects of the narrative elements. It was found that concrete details improved comprehension and retention but that causal structure had no statistically significant impact on comprehension or retention. There were no significant gender differences in comprehension or retention though there were two- and three-way interactions between the independent variables.

  20. Final report of LDRD project: Electromagnetic impulse radar for detection of underground structures

    SciTech Connect

    Loubriel, G.; Aurand, J.; Buttram, M.; Zutavern, F.; Brown, D.; Helgeson, W.

    1998-03-01

    This report provides a summary of the LDRD project titled: Electromagnetic impulse radar for the detection of underground structures. The project met all its milestones even with a tight two year schedule and total funding of $400 k. The goal of the LDRD was to develop and demonstrate a ground penetrating radar (GPR) that is based on high peak power, high repetition rate, and low center frequency impulses. The idea of this LDRD is that a high peak power, high average power radar based on the transmission of short impulses can be utilized effect can be utilized for ground penetrating radar. This direct time-domain system the authors are building seeks to increase penetration depth over conventional systems by using: (1) high peak power, high repetition rate operation that gives high average power, (2) low center frequencies that better penetrate the ground, and (3) short duration impulses that allow for the use of downward looking, low flying platforms that increase the power on target relative to a high flying platform. Specifically, chirped pulses that are a microsecond in duration require (because it is difficult to receive during transmit) platforms above 150 m (and typically 1 km) while this system, theoretically could be at 10 m above the ground. The power on target decays with distance squared so the ability to use low flying platforms is crucial to high penetration. Clutter is minimized by time gating the surface clutter return. Short impulses also allow gating (out) the coupling of the transmit and receive antennas.

  1. Simulations of Underground Structures Subjected to Dynamic Loading Using the Distinct Element Method

    NASA Astrophysics Data System (ADS)

    Morris, J. P.; Glenn, L. A.; Heuze, F. E.; Bonner, M. P.

    2004-07-01

    We present preliminary results from a parameter study investigating the stability of underground structures in response to explosion-induced strong ground motions. In practice, even the most sophisticated site characterization may lack key details regarding precise joint properties and orientations within the rock mass. Thus, in order to place bounds upon the predicted behavior of a given facility, an extensive series of simulations representing different realizations may be required. The influence of both construction parameters (reinforcement, rock bolts,liners) and geological parameters (joint stiffness, joint spacing and orientation, and tunnel diameter to block size ratio) must be considered. We will discuss the distinct element method (DEM) with particular emphasis on techniques for achieving improved computational efficiency, including the handling of contact detection and approaches to parallelization. We also outline the continuum approaches we employ to obtain boundary conditions for the distinct element simulations. Finally, our DEM code is used to simulate dynamic loading of a generic subterranean facility in hardrock, demonstrating the suitability of the DEM for this application.

  2. Simulations of Underground Structures Subjected to Dynamic Loading using the Distinct Element Method

    SciTech Connect

    Morris, J P; Glenn, L A; Heuze, F E; Bonner, M P

    2003-07-14

    We present preliminary results from a parameter study investigating the stability of underground structures in response to explosion-induced strong ground motions. In practice, even the most sophisticated site characterization may lack key details regarding precise joint properties and orientations within the rock mass. Thus, in order to place bounds upon the predicted behavior of a given facility, an extensive series of simulations representing different realizations may be required. The influence of both construction parameters (reinforcement, rock bolts,liners) and geological parameters (joint stiffness, joint spacing and orientation, and tunnel diameter to block size ratio) must be considered. We will discuss the distinct element method (DEM) with particular emphasis on techniques for achieving improved computational efficiency, including the handling of contact detection and approaches to parallelization. We also outline the continuum approaches we employ to obtain boundary conditions for the distinct element simulations. Finally, our DEM code is used to simulate dynamic loading of a generic subterranean facility in hardrock, demonstrating the suitability of the DEM for this application.

  3. 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

  4. Application of shearography to crack detection in concrete structures subjected to traffic loading

    NASA Astrophysics Data System (ADS)

    Muzet, V.; Blain, P.; Przybyla, D.

    2010-09-01

    Early detection of defects in concrete structures, such as bridges or dams, is essential to optimize the maintenance of civil engineering facilities. Optical methods constitute non-destructive means of control and measurement but they are generally confined in laboratories where both the setup and environnement are controlled. The method of shearography is especially well adapted to detect damages due to both its capacity to distinctly visualize strain concentration zones and its robustness. The experimental set-up is relatively compact, which enables to examine an extensive surface area by simply moving the shearographic head. In this paper, the application of this methodology for the detection of cracks is presented on concrete samples and circulated outside concrete structures. Due to its sensitivity to strain concentration, shearography is able to detect structural cracks, even when they were not through-cracks. Operational implementation is made on two circulated structures with experts in manual cracks detection. No stimulation device is used. In the first structure, cracks are detected on the bridge deck and on the bridge abutment. In the second structure, cracks on the intrados of the bridge deck are detected and also beginning of cracks which have not been detected by the visual inspection. Different areas are scanned and the results are in agreement with the visual inspection. This technique enables detecting cracks on structures subjected to traffic load. The natural loading of an engineering structure, i.e. the rolling traffic it bears, proves well suited for cracks detection by means of shearography, provided traffic patterns are regular enough.

  5. Use of slurry infiltrated fiber concrete (SIFCON) in hinge regions of earthquake resistant structures

    NASA Astrophysics Data System (ADS)

    Wood, Bryan Thane

    This dissertation reports on an experimental and analytical study of the use of precast slurry infiltrated fiber concrete (SIFCON) flexural hinges to improve the seismic resistance of reinforced concrete moment frames. The main thrust of the research was to investigate how different variables effect the nonlinear, cyclic, flexural behavior of reinforced SIFCON hinges, and to determine how to optimize hinge performance. In addition, a conceptual analysis was performed to evaluate the improvement in seismic resistance from using SIFCON hinges in concrete structures. Seven 10″ wide, 16″ deep, and 26″ long reinforced SIFCON hinges were designed and fabricated, then tested under quasi-static loading. All specimens were fabricated using between 9 and 11%, by volume, Dramix 30/50 fibers, made by the Bekaert Corporation. Grade 60, Grade 75, and ASTM A722 (Dywidag) bars were used, in combination with three different SIFCON compression strengths. Additionally, various end connection details were used in testing three different reinforcing arrangements. It was shown that precast SIFCON hinges can exhibit better performance than reinforced concrete hinges. The maximum curvature ductility achieved was 26.4 over a 4″ inch long interior region of a specimen. The curvature ductility of this hinge specimen, when taken over the full 26 inch hinge length, was 10.5. SIFCON hinges absorb approximately 30% more energy than fiber-reinforced concrete hinges. SIFCON hinge ductility is limited by the ultimate tensile strain of the reinforcing steel. Grade 60 reinforcing resulted in the best hinge behavior seen in testing. Transverse ties may be required to prevent buckling of compression reinforcing. SIFCON flexural stiffness is approximately half that of comparable strength reinforced concrete beams. It was found that SIFCON material behavior is highly variable. Fiber orientation and size effects are the main variables that affect SIFCON behavior. Fabrication technique and skill of

  6. Water retention and gas relative permeability of two industrial concretes

    SciTech Connect

    Chen Wei; Liu Jian; Brue, Flore; Skoczylas, Frederic; Davy, C.A.; Bourbon, Xavier; Talandier, Jean

    2012-07-15

    This experimental study aims at identifying the water retention properties of two industrial concretes to be used for long term underground nuclear waste storage structures. Together with water retention, gas transfer properties are identified at varying water saturation level, i.e. relative gas permeability is assessed directly as a function of water saturation level S{sub w}. The influence of the initial de-sorption path and of the subsequent re-saturation are analysed both in terms of water retention and gas transfer properties. Also, the influence of concrete microstructure upon water retention and relative gas permeability is assessed, using porosity measurements, analysis of the BET theory from water retention properties, and MIP. Finally, a single relative gas permeability curve is proposed for each concrete, based on Van Genuchten-Mualem's statistical model, to be used for continuous modelling approaches of concrete structures, both during drying and imbibition.

  7. Advances in Chemical and Structural Characterization of Concretion with Implications for Modeling Marine Corrosion

    NASA Astrophysics Data System (ADS)

    Johnson, Donald L.; DeAngelis, Robert J.; Medlin, Dana J.; Carr, James D.; Conlin, David L.

    2014-05-01

    The Weins number model and concretion equivalent corrosion rate methodology were developed as potential minimum-impact, cost-effective techniques to determine corrosion damage on submerged steel structures. To apply the full potential of these technologies, a detailed chemical and structural characterization of the concretion (hard biofouling) that transforms into iron bearing minerals is required. The fractions of existing compounds and the quantitative chemistries are difficult to determine from x-ray diffraction. Environmental scanning electron microscopy was used to present chemical compositions by means of energy-dispersive spectroscopy (EDS). EDS demonstrates the chemical data in mapping format or in point or selected area chemistries. Selected-area EDS data collection at precise locations is presented in terms of atomic percent. The mechanism of formation and distribution of the iron-bearing mineral species at specific locations will be presented. Based on water retention measurements, porosity in terms of void volume varies from 15 v/o to 30 v/o (vol.%). The void path displayed by scanning electron microscopy imaging illustrates the tortuous path by which oxygen migrates in the water phase within the concretion from seaside to metalside.

  8. Calculating CO2 uptake for existing concrete structures during and after service life.

    PubMed

    Andersson, Ronny; Fridh, Katja; Stripple, Håkan; Häglund, Martin

    2013-10-15

    This paper presents a model that can calculate the uptake of CO2 in all existing concrete structures, including its uptake after service life. This is important for the calculation of the total CO2 uptake in the society and its time dependence. The model uses the well-documented cement use and knowledge of how the investments are distributed throughout the building sector to estimate the stock of concrete applications in a country. The depth of carbonation of these applications is estimated using two models, one theoretical and one based on field measurements. The maximum theoretical uptake potential is defined as the amount of CO2 that is emitted during calcination at the production of Portland cement, but the model can also, with some adjustments, be used for the other cement types. The model has been applied on data from Sweden and the results show a CO2 uptake in 2011 in all existing structures of about 300,000 tonnes, which corresponds to about 17% of the total emissions (calcination and fuel) from the production of new cement for use in Sweden in the same year. The study also shows that in the years 2030 and 2050, an increase in the uptake in crushed concrete, from 12,000 tonnes today to 200,000 and 500,000 tonnes of CO2, respectively, could be possible if the waste handling is redesigned. PMID:24007514

  9. Study on the Non-contact Acoustic Inspection Method for Concrete Structures by using Strong Ultrasonic Sound source

    NASA Astrophysics Data System (ADS)

    Sugimoto, Tsuneyoshi; Uechi, Itsuki; Sugimoto, Kazuko; Utagawa, Noriyuki; Katakura, Kageyoshi

    Hammering test is widely used to inspect the defects in concrete structures. However, this method has a major difficulty in inspect at high-places, such as a tunnel ceiling or a bridge girder. Moreover, its detection accuracy is dependent on a tester's experience. Therefore, we study about the non-contact acoustic inspection method of the concrete structure using the air borne sound wave and a laser Doppler vibrometer. In this method, the concrete surface is excited by air-borne sound wave emitted with a long range acoustic device (LRAD), and the vibration velocity on the concrete surface is measured by a laser Doppler vibrometer. A defect part is detected by the same flexural resonance as the hammer method. It is already shown clearly that detection of a defect can be performed from a long distance of 5 m or more using a concrete test object. Moreover, it is shown that a real concrete structure can also be applied. However, when the conventional LRAD was used as a sound source, there were problems, such as restrictions of a measurement angle and the surrounding noise. In order to solve these problems, basic examination which used the strong ultrasonic wave sound source was carried out. In the experiment, the concrete test object which includes an imitation defect from 5-m distance was used. From the experimental result, when the ultrasonic sound source was used, restrictions of a measurement angle become less severe and it was shown that circumference noise also falls dramatically.

  10. Estimation of Prestress Force Distribution in the Multi-Strand System of Prestressed Concrete Structures

    PubMed Central

    Cho, Keunhee; Park, Sung Yong; Cho, Jeong-Rae; Kim, Sung Tae; Park, Young-Hwan

    2015-01-01

    Prestressed concrete (PSC) is one of the most reliable, durable and widely used construction materials, which overcomes the weakness of concrete in tension by the introduction of a prestress force. Smart strands enabling measurement of the prestress force have recently been developed to maintain PSC structures throughout their lifetime. However, the smart strand cannot give a representative indication of the whole prestress force when used in multi-strand systems since each strand sustains a different prestress force. In this paper, the actual distribution of the prestress force in a multi-strand system is examined using elastomagnetic (EM) sensors to develop a method for tracking representative indicators of the prestress force using smart strands. PMID:26083230

  11. Seismic fragility of reinforced concrete structures and components for application to nuclear facilities

    SciTech Connect

    Gergely, P.

    1984-09-01

    The failure and fragility analyses of reinforced concrete structures and elements in nuclear reactor facilities within the Seismic Safety Margins Research Program (SSMRP) at the Lawrence Livermore National Laboratory are evaluated. Uncertainties in material modeling, behavior of low shear walls, and seismic risk assessment for nonlinear response receive special attention. Problems with ductility-based spectral deamplification and prediction of the stiffness of reinforced concrete walls at low stress levels are examined. It is recommended to use relatively low damping values in connection with ductility-based response reductions. The study of static nonlinear force-deflection curves is advocated for better nonlinear dynamic response predictions. Several details of the seismic risk analysis of the Zion plant are also evaluated. 73 references.

  12. 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.

  13. Influence of Geological Structure on Coal and Gas Outburst Occurrences in Turkish Underground Coal Mines

    NASA Astrophysics Data System (ADS)

    Esen, Olgun; Özer, Samet Can; Fişne, Abdullah

    2015-04-01

    Coal and gas outbursts are sudden and violent releases of gas and in company with coal that result from a complex function of geology, stress regime with gas pressure and gas content of the coal seam. The phenomena is referred to as instantaneous outbursts and have occurred in virtually all the major coal producing countries and have been the cause of major disasters in the world mining industry. All structures from faults to joints and cleats may supply gas or lead to it draining away. Most geological structures influence the way in which gas can drain within coal seams. From among all the geological factors two groups can be distinguished: parameters characterising directly the occurrence and geometry of the coal seams; parameters characterising the tectonic disturbances of the coal seams and neighbouring rocks. Also dykes may act as gas barriers. When the production of the coal seam is advanced in mine working areas, these barriers are failed mostly in the weak and mylonitized zones. Geology also plays a very important role in the outburst process. Coal seams of complex geological structure including faults, folds, and fractured rocks are liable to outbursts if coal seams and neighbouring rocks have high gas content level. The purpose of the study is to enlighten the coal industry in Turkey to improving mine safety in underground coal production and decrease of coal and gas outburst events due to increasing depth of mining process. In Turkey; the years between 1969 and 2013, the number of 90 coal and gas outbursts took place in Zonguldak Hard Coal Basin in both Kozlu and Karadon Collieries. In this study the liability to coal and gas outburst of the coal seams are investigated by measuring the strength of coal and the rock pressure. The correlation between these measurements and the event locations shows that the geological structures resulted in 52 events out of 90 events; 19 events close to the fault zones, 25 events thorough the fault zones and 8 events in

  14. Experimental characterization of ETDR sensors for crack monitoring in concrete structures

    NASA Astrophysics Data System (ADS)

    Danjaji, Musa B.; Abatan, Ayo O.; Lin, Mark W.

    1999-12-01

    A novel approach for health monitoring of civil infrastructural systems using electrical time domain reflectometry (ETDR) sensors has been established. In this paper, experimental characterization results obtained when a coaxial cable is used as an ETDR sensor to monitor cracks in reinforced concrete structures will be provided. The first part of the paper shows simulation of cracks due to high pressure on the sensor when it is embedded in concrete. The results show that as the pressure on the sensor increases, the ETDR technique was able to detect exactly the location on the sensor where the high pressure is applied. The technique is able to detect the crack location and magnitude of pressure to an application point in a harsh environment. Furthermore, the ETDR technique was able to distinctly detect the locations on the sensors when multiple compressive high-pressure forces were applied on the sensor within a spatial resolution of less than one inch. This multiple sensing ability confirms the ETDR sensing approach as a fully distributed sensing technique. The second part of the paper will show the simulated effect of high temperature on the sensor when embedded in concrete. The results show that the ETDR sensor is reliable and durable with significant increases in temperature variations.

  15. A Novel Optical Fiber Sensor for Steel Corrosion in Concrete Structures

    PubMed Central

    Leung, Christopher K.Y.; Wan, Kai Tai; Chen, Liquan

    2008-01-01

    Steel corrosion resulting from the penetration of chloride ions or carbon dioxide is a major cause of degradation for reinforced concrete structures,. The objective of the present investigation was to develop a low-cost sensor for steel corrosion, which is based on a very simple physical principle. The flat end of a cut optical fiber is coated with an iron thin film using the ion sputtering technique. Light is then sent into a fiber embedded in concrete and the reflected signal is monitored. Initially, most of the light is reflected by the iron layer. When corrosion occurs to remove the iron layer, a significant portion of the light power will leave the fiber at its exposed end, and the reflected power is greatly reduced. Monitoring of the reflected signal is hence an effective way to assess if the concrete environment at the location of the fiber tip may induce steel corrosion or not. In this paper, first the principle of the corrosion sensor and its fabrication are described. The sensing principle is then verified by experimental results. Sensor packaging for practical installation will be presented and the performance of the packaged sensors is assessed by additional experiments.

  16. Structural Aging Program approach to providing an improved basis for aging management of safety-related concrete structures

    SciTech Connect

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

    1993-11-01

    The Structural Aging (SAG) Program is being conducted at the Oak Ridge National Laboratory (ORNL) for the United States Nuclear Regulatory Commission (USNRC). The SAG Program is addressing the aging management of safety-related concrete structures in nuclear power plants for the purpose of providing improved technical bases for their continued service. The program is organized into four tasks: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technologies, and Quantitative Methodology for Continued Service Determinations. Objectives and a summary of recent accomplishments under each of these tasks are presented.

  17. 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.

  18. Study of the seismic response of a recycled aggregate concrete frame structure

    NASA Astrophysics Data System (ADS)

    Wang, Changqing; Xiao, Jianzhuang

    2013-12-01

    Based on six-degree-of-freedom three-dimensional shaking table tests, the seismic response of a recycled aggregate concrete (RAC) frame was obtained. The analysis results indicate that the maximum story shear force and overturning moment reduce proportionally along the height of the model under the same earthquake wave. The story shear force, base shear coefficient and overturning moment of the structure increase progressively as the acceleration amplitude increases. The base shear coefficient is primarily controlled by the peak ground acceleration (PGA). The relationships between the PGA and the shear coefficient as well as between the PGA and the dynamic amplification factor are obtained by mathematical fitting. The dynamic amplification factor decreases rapidly at the elastic-plastic stage, but decreases slowly with the development of the elastic-plasticity stage. The results show that the RAC frame structure has reasonable deformability when compared with natural aggregate concrete frame structures. The maximum inter-story drift ratios of the RAC frame model under frequent and rare intensity 8 test phases are 1/266 and 1/29, respectively, which are larger than the allowable value of 1/500 and 1/50 according to Chinese seismic design requirements. Nevertheless, the RAC frame structure does not collapse under base excitations with PGAs from 0.066 g up to 1.170 g.

  19. 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.

  20. Towards Practical Carbonation Prediction and Modelling for Service Life Design of Reinforced Concrete Structures

    NASA Astrophysics Data System (ADS)

    Ekolu, O. S.

    2015-11-01

    Amongst the scientific community, the interest in durability of concrete structures has been high for quite a long time of over 40 years. Of the various causes of degradation of concrete structures, corrosion is the most widespread durability problem and carbonation is one of the two causes of steel reinforcement corrosion. While much scientific understanding has been gained from the numerous carbonation studies undertaken over the past years, it is still presently not possible to accurately predict carbonation and apply it in design of structures. This underscores the complex nature of the mechanisms as influenced by several interactive factors. Based on critical literature and some experience of the author, it is found that there still exist major challenges in establishing a mathematical constitutive relation for realistic carbonation prediction. While most current models employ permeability /diffusion as the main model property, analysis shows that the most practical material property would be compressive strength, which has a low coefficient of variation of 20% compared to 30 to 50% for permeability. This important characteristic of compressive strength, combined with its merit of simplicity and data availability at all stages of a structure's life, promote its potential use in modelling over permeability. By using compressive strength in carbonation prediction, the need for accelerated testing and permeability measurement can be avoided. This paper attempts to examine the issues associated with carbonation prediction, which could underlie the current lack of a sound established prediction method. Suggestions are then made for possible employment of different or alternative approaches.

  1. Assessment of the effects of microbially influenced degradation on a massive concrete structure. Final report, Report 5

    SciTech Connect

    Rogers, R.D.

    1995-07-08

    There is a need to estimate the effect of environmental conditions on construction materials to be used in the repository at Yucca Mountain. Previous reports from this project have demonstrated that it is important to develop an understanding of microbially influenced degradation (MID) development and its influence on massive concrete structures. Further, it has been shown that the most effective way to obtain quantitative data on the effects of MID on the structural integrity of repository concrete is to study manmade, analog structures known to be susceptible to MID. The cooling tower shell located at the Ohaaki Power Station near Wairakei, New Zealand is such a structure.

  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. 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.

  4. Sub-Frequency Interval Approach in Electromechanical Impedance Technique for Concrete Structure Health Monitoring

    PubMed Central

    Yang, Yaowen; Divsholi, Bahador Sabet

    2010-01-01

    The electromechanical (EM) impedance technique using piezoelectric lead zirconate titanate (PZT) transducers for structural health monitoring (SHM) has attracted considerable attention in various engineering fields. In the conventional EM impedance technique, the EM admittance of a PZT transducer is used as a damage indicator. Statistical analysis methods such as root mean square deviation (RMSD) have been employed to associate the damage level with the changes in the EM admittance signatures, but it is difficult to determine the location of damage using such methods. This paper proposes a new approach by dividing the large frequency (30–400 kHz) range into sub-frequency intervals and calculating their respective RMSD values. The RMSD of the sub-frequency intervals (RMSD-S) will be used to study the severity and location of damage. An experiment is carried out on a real size concrete structure subjected to artificial damage. It is observed that damage close to the PZT changes the high frequency range RMSD-S significantly, while the damage far away from the PZT changes the RMSD-S in the low frequency range significantly. The relationship between the frequency range and the PZT sensing region is also presented. Finally, a damage identification scheme is proposed to estimate the location and severity of damage in concrete structures. PMID:22163548

  5. 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

  6. How Concrete Is Concrete?

    ERIC Educational Resources Information Center

    Gravemeijer, Koeno

    2011-01-01

    If we want to make something concrete in mathematics education, we are inclined introduce, what we call, "manipulatives", in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own,…

  7. Brillouin Corrosion Expansion Sensors for Steel Reinforced Concrete Structures Using a Fiber Optic Coil Winding Method

    PubMed Central

    Zhao, Xuefeng; Gong, Peng; Qiao, Guofu; Lu, Jie; Lv, Xingjun; Ou, Jinping

    2011-01-01

    In this paper, a novel kind of method to monitor corrosion expansion of steel rebars in steel reinforced concrete structures named fiber optic coil winding method is proposed, discussed and tested. It is based on the fiber optical Brillouin sensing technique. Firstly, a strain calibration experiment is designed and conducted to obtain the strain coefficient of single mode fiber optics. Results have shown that there is a good linear relationship between Brillouin frequency and applied strain. Then, three kinds of novel fiber optical Brillouin corrosion expansion sensors with different fiber optic coil winding packaging schemes are designed. Sensors were embedded into concrete specimens to monitor expansion strain caused by steel rebar corrosion, and their performance was studied in a designed electrochemical corrosion acceleration experiment. Experimental results have shown that expansion strain along the fiber optic coil winding area can be detected and measured by the three kinds of sensors with different measurement range during development the corrosion. With the assumption of uniform corrosion, diameters of corrosion steel rebars were obtained using calculated average strains. A maximum expansion strain of 6,738 με was monitored. Furthermore, the uniform corrosion analysis model was established and the evaluation formula to evaluate mass loss rate of steel rebar under a given corrosion rust expansion rate was derived. The research has shown that three kinds of Brillouin sensors can be used to monitor the steel rebar corrosion expansion of reinforced concrete structures with good sensitivity, accuracy and monitoring range, and can be applied to monitor different levels of corrosion. By means of this kind of monitoring technique, quantitative corrosion expansion monitoring can be carried out, with the virtues of long durability, real-time monitoring and quasi-distribution monitoring. PMID:22346672

  8. Structural concretes with waste-based lightweight aggregates: from landfill to engineered materials.

    PubMed

    De'Gennaro, Roberto; Graziano, Sossio Fabio; Cappelletti, Piergiulio; Colella, Abner; Dondi, Michele; Langella, Alessio; De'Gennaro, Maurizio

    2009-09-15

    This research provides possible opportunities in the reuse of waste and particularly muds, coming from both ornamental stone (granite sludges from sawing and polishing operations) and ceramic production (porcelain stoneware tile polishing sludge), for the manufacture of lightweight aggregates. Lab simulation of the manufacturing cycle was performed by pelletizing and firing the waste mixes in a rotative furnace up to 1300 degrees C, and determining composition and physicomechanical properties of lightweight aggregates. The best formulation was used to produce and test lightweight structural concretes according to standard procedures. Both granite and porcelain stoneware polishing sludges exhibit a suitable firing behavior due to the occurrence of SiC (an abrasive component) which, by decomposing at high temperature with gas release, acts as a bloating promoter, resulting in aggregates with particle density < 1 Mg/m3. However, slight variations of mixture composition produce aggregates with rather different properties, going from values close to those of typical commercial expanded clays (particle density 0.68 Mg/m3; strength of particle 1.2 MPa) to products with high mechanical features (particle density 1.25 Mg/m3; strength of particle 6.9 MPa). The best formulation (50 wt.% porcelain stoneware polishing sludge +50 wt.% granite sawing sludge) was used to successfully manufacture lightweight structural concretes with suitable properties (compressive strength 28 days > 20 MPa, bulk density 1.4-2.0 Mg/m3).

  9. 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.

  10. Impact load-induced micro-structural damage and micro-structure associated mechanical response of concrete made with different surface roughness and porosity aggregates

    SciTech Connect

    Erdem, Savas Dawson, Andrew Robert; Thom, Nicholas Howard

    2012-02-15

    The relationship between the nature of micro damage under impact loading and changes in mechanical behavior associated with different microstructures is studied for concretes made with two different coarse aggregates having significant differences mainly in roughness and porosity - sintered fly ash and uncrushed gravel. A range of techniques including X-ray diffraction, digital image analysis, mercury porosimetry, X-ray computed tomography, laser surface profilometry and scanning electron microscopy were used to characterize the aggregates and micro-structures. The concrete prepared with lightweight aggregates was stronger in compression than the gravel aggregate concrete due to enhanced hydration as a result of internal curing. In the lightweight concrete, it was deduced that an inhomogeneous micro-structure led to strain incompatibilities and consequent localized stress concentrations in the mix, leading to accelerated failure. The pore structure, compressibility, and surface texture of the aggregates are of paramount importance for the micro-cracking growth.

  11. Validation of mechanical models for reinforced concrete structures: Presentation of the French project ``Benchmark des Poutres de la Rance''

    NASA Astrophysics Data System (ADS)

    L'Hostis, V.; Brunet, C.; Poupard, O.; Petre-Lazar, I.

    2006-11-01

    Several ageing models are available for the prediction of the mechanical consequences of rebar corrosion. They are used for service life prediction of reinforced concrete structures. Concerning corrosion diagnosis of reinforced concrete, some Non Destructive Testing (NDT) tools have been developed, and have been in use for some years. However, these developments require validation on existing concrete structures. The French project “Benchmark des Poutres de la Rance” contributes to this aspect. It has two main objectives: (i) validation of mechanical models to estimate the influence of rebar corrosion on the load bearing capacity of a structure, (ii) qualification of the use of the NDT results to collect information on steel corrosion within reinforced-concrete structures. Ten French and European institutions from both academic research laboratories and industrial companies contributed during the years 2004 and 2005. This paper presents the project that was divided into several work packages: (i) the reinforced concrete beams were characterized from non-destructive testing tools, (ii) the mechanical behaviour of the beams was experimentally tested, (iii) complementary laboratory analysis were performed and (iv) finally numerical simulations results were compared to the experimental results obtained with the mechanical tests.

  12. 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.

  13. Damage detection of concrete masonry structures by enhancing deformation measurement using DIC

    NASA Astrophysics Data System (ADS)

    Bolhassani, Mohammad; Rajaram, Satish; Hamid, Ahmad A.; Kontsos, Antonios; Bartoli, Ivan

    2016-04-01

    This study focuses on deformability and damage detection of a concrete masonry wall. It employed point-to-point traditional strain gages and full-field measurement technique using digital image correlation (DIC) to investigate the damage and deformability of a partially grouted (PG) reinforced masonry wall. A set of ungrouted and grouted assemblages and full-scale concrete masonry shear wall were constructed and tested under displacement control loading. The wall was constructed according with masonry standards joint committee (MSJC 2013) and tested under constant vertical compression load and horizontal lateral load using quasi-static displacement procedure. The DIC method was used to determine non-uniform strain contours on the assemblages. This method was verified by comparing strains along the selected directions with traditional TML gage results. After a successful comparison, the method was used to investigate the state of damage and deformability of the wall specimen. Panel deformation, crack pattern, displacement at the top, and the base strain of the wall were captured using full-field measurement and results were in a good agreement with traditional strain gages. It is concluded that full-filed measurements using DIC is promising especially when the test specimens experience inelastic deformation and high degree of damage. The ability to characterize and anticipate failure mechanisms of concrete masonry systems by depicting strain distribution, categorizing structural cracks and investigating their effects on the behavior of the wall were also shown using DIC. In addition to monitoring strains across the gage length, the DIC method provided full-field strain behavior of the test specimens and revealed strain hotspots at locations that corresponded to failure.

  14. Application of lock-in data processing for thermographic NDT of concrete structures

    NASA Astrophysics Data System (ADS)

    Sakagami, Takahide; Kubo, Shiro; Nakamura, Shiro; Kawashima, Yasushi; Komiyama, Tatsuhito

    2002-03-01

    A new quantitative nondestructive testing technique for delamination defects in concrete structures was developed based on the phase delay measurement using a lock-in infrared thermography under the application of periodical heating. The lock-in thermography technique was developed based on the thermal insulation method thermographic NDT. Experimental studies were made on the applicability to the detection of artificial delamination defects in concrete blocks. Concrete blocks were periodically heated by quartz lamps combined with the light dimmer controller. The controller was operated by the same reference signal for the lock-in thermography. It was found that the delamination defects were detected by the localized contrast change in the phase delay images. It was also found that the location and size of the delamination defects can be estimated by the area of contrast change in the phase delay images which was clearly observed compared with conventional thermography techniques. The relationship between the values of phase delay and heating period was examined for several defect depths and several heating periods. It was found that the phase delay curve for certain defect depth shows the peak of the contrast in phase delay image at certain heating period and the depth of the delamination defects can be estimated from this relationship. Finally, the proposed lock-in thermographic NDT technique was applied for the quantitative measurement of the actual delamination defects found under railway bridge. It was fund that the depths of the delamination defects can be estimated using the master curve of the relationship between the values of phase delay and heating period made by the experiments for artificial delamination defects.

  15. Hybrid networking sensing system for structural health monitoring of a concrete cable-stayed bridge

    NASA Astrophysics Data System (ADS)

    Torbol, Marco; Kim, Sehwan; Chien, Ting-Chou; Shinozuka, Masanobu

    2013-04-01

    The purpose of this study is the remote structural health monitoring to identify the torsional natural frequencies and mode shapes of a concrete cable-stayed bridge using a hybrid networking sensing system. The system consists of one data aggregation unit, which is daisy-chained to one or more sensing nodes. A wireless interface is used between the data aggregation units, whereas a wired interface is used between a data aggregation unit and the sensing nodes. Each sensing node is equipped with high-precision MEMS accelerometers with adjustable sampling frequency from 0.2 Hz to 1.2 kHz. The entire system was installed inside the reinforced concrete box-girder deck of Hwamyung Bridge, which is a cable stayed bridge in Busan, South Korea, to protect the system from the harsh environmental conditions. This deployment makes wireless communication a challenge due to the signal losses and the high levels of attenuation. To address these issues, the concept of hybrid networking system is introduced with the efficient local power distribution technique. The theoretical communication range of Wi-Fi is 100m. However, inside the concrete girder, the peer to peer wireless communication cannot exceed about 20m. The distance is further reduced by the line of sight between the antennas. However, the wired daisy-chained connection between sensing nodes is useful because the data aggregation unit can be placed in the optimal location for transmission. To overcome the limitation of the wireless communication range, we adopt a high-gain antenna that extends the wireless communication distance to 50m. Additional help is given by the multi-hopping data communication protocol. The 4G modem, which allows remote access to the system, is the only component exposed to the external environment.

  16. Capillary transport of water through textile-reinforced concrete applied in repairing and/or strengthening cracked RC structures

    SciTech Connect

    Lieboldt, M.; Mechtcherine, V.

    2013-10-15

    The use of textile-reinforced concrete (TRC) has great potential for innovative solutions in repairing, protecting, and strengthening concrete and RC structures. The article at hand reports on an investigation on composite concrete specimens made of cracked ordinary concrete as substrate and textile-reinforced concrete (TRC) as a cover layer for its strengthening and repair. The TRC cover layer was assessed with regard to its effectiveness as a protective layer against the ingress of water through capillary action. Since in real applications such TRC layers may be cracked or presumed to be so, thereby activating the load-carrying function of the textile reinforcement, the TRC layer was cracked for purposes of this study. The water transport in the cracked ordinary concrete specimens without the TRC layer was used as a reference. Gravimetric measurements and neutron radiography served as the testing techniques. In ordinary concrete quick and deep ingress of water through relatively wide macro-cracks of approximately 100 μm width, followed by transport through the capillary pore system, caused saturation of large areas in a rather short time. TRC applied to the RC surface reduced the ingress of water to a large extent. Its small crack widths of 15 to 20 μm changed suction behaviour fundamentally. In the cracked substrate of ordinary concrete, capillary suction was prevented, and transport through the pore system of the matrix became the prevailing transport mechanism of capillary action. Not only was the mechanism altered, but the transport of water deep into inner regions was markedly retarded as well.

  17. Pounding Effects on the Earthquake Response of Adjacent Reinforced Concrete Structures Strengthened by Cable Elements

    NASA Astrophysics Data System (ADS)

    Liolios, Angelos; Liolios, Asterios; Hatzigeorgiou, George; Radev, Stefan

    2014-06-01

    A numerical approach for estimating the effects of pounding (seismic interaction) on the response of adjacent Civil Engineering structures is presented. Emphasis is given to reinforced concrete (RC) frames of existing buildings which are seismically strengthened by cable-elements. A double discretization, in space by the Finite Element Method and in time by a direct incremental approach is used. The unilateral behaviours of both, the cable-elements and the interfaces contact-constraints, are taken strictly into account and result to inequality constitutive conditions. So, in each time-step, a non-convex linear complementarity problem is solved. It is found that pounding and cable strengthening have significant effects on the earthquake response and, hence, on the seismic upgrading of existing adjacent RC structures.

  18. Analysis Techniques of Acoustic Emission Data for Damage Assessment of Reinforced Concrete Structures

    NASA Astrophysics Data System (ADS)

    Garilli, G.; Proverbio, E.; Marino, A.; de Domenico, D.; Termini, D.; Teramo, A.

    2010-12-01

    The aim of this work is the arrangement, through Acoustics Emission (AE) techniques, of a procedure aimed at early diagnosis of building diseases with the assessment of the causes that have produced a crack in a given structural element, in order to plan suitable structural adjustment works. To this end, bending tests were performed, divided into different cycles of increasing load on a concrete beam, to assess the damage level and response in relation to the stress change. Through the proposed procedure and different indicators of the damage level of material, such as b, Ib and Z-value, it was possible to identify in the study sample areas where cracks were detected, assessing the size, evolution process typology of microcraks. The recorded parameters of AE (Counts, Amplitude) are well related to the damage extent and applied load, providing a significant validation of the reliability analysis procedures used for monitoring and early detection of building diseases.

  19. Calcareous concretions and psammoma bodies in sputum smears: do these similar structures have different clinical significance?

    PubMed

    Martínez-Girón, Rafael; Martínez-Torre, Santiago; Tamargo-Peláez, María Luisa; López-Cabanilles, María Dolores; Torre-Bayón, Concepción

    2014-09-01

    Different noncellular elements, such as round concentric calcified laminated structures, may be found in sputum smears. If these structures appear isolated on the background of the smear, the term usually used to describe them is "calcareous concretions" (CC). On the contrary, when the structures are part of epithelial cell groups or small tissue fragments, the term used to describe them is "Psammoma bodies" (PB). The aim of this work is to establish the relationship between these structures and pulmonary disease, especially lung carcinoma, by searching for the presence of CC and/or PB in sputum smears. Our study has taken as a basis 16.716 sputum smears from 696 patients obtained during a 7-year period (2003-2009). After reviewing them, it was found that from the total, 66 cases (0.39%) contained round calcified structures, 57 of them (0.34%) corresponding to CC, and the remaining 9 ones (0.05%) corresponding to PB. From these 57 CC cases, 56 corresponded to benign entities, and only one was found with lung carcinoma. On the other hand, from the 9 PB cases all of them (100%) were related to lung adenocarcinoma. We conclude that, even having a similar morphological structure, these aforementioned calcified structures we have observed in sputum smears have different and relevant clinical significance.

  20. Radio frequency tomography for the investigation of cracks in reinforced concrete structures

    NASA Astrophysics Data System (ADS)

    Negishi, Tadahiro; Gennarelli, Gianluca; Soldovieri, Francesco; Erricolo, Danilo

    2016-04-01

    We are interested in investigating the presence of cracks inside reinforced concrete structures using Radio Frequency Tomography (RFT). RFT applies electromagnetic waves to probe the environment and is based on the use of multiple transmitting and receiving antennas. RFT is a multistatic system where the volume under investigation is illuminated and observed from different directions, which results into an increase in resolution. In an application of RFT there are two main phases: the forward problem and the inverse reconstruction. The forward problem consists in the determination of the electromagnetic field scattered by the volume under investigation, which is illuminated by the transmitters. The scattered field depends on the spatial distribution of the dielectric permittivity in the volume under investigation. This distribution determines the contrast function. The inverse problem consists of the reconstruction of the contrast function from the scattered electromagnetic field. One of the challenges in RFT is the determination of the best approach to solve the inverse problem. In order to focus solely on the behavior of the inverse approach, we consider simplified geometries for the volume under investigation, such as a cylindrical concrete pillar with a metallic steel bar that is coaxial to the cylinder. In this way, it is possible to analytically evaluate the scattered electromagnetic field in an exact way. We then investigate the behavior of the reconstruction approach from the point of view of (1) geometry of the illumination and observation antennas; (2) frequency used to illuminate the volume under interest; (3) fusion of the results obtained at various frequencies.

  1. A galvanic zinc-hydrogel system for cathodic protection of reinforced concrete structures

    SciTech Connect

    Wehling, J.E.

    1999-07-01

    Installations of galvanic cathodic protection anodes have been completed on bridge structures in Illinois, Virginia, Florida, Wisconsin, and Oregon, on parking garages in Illinois and Wisconsin, on high voltage transmission tower footings in California, and on condominium balconies in Florida. Some of these installations involve prestressed concrete. The installation of these systems will be described in detail and monitoring data will be presented for at least six months of active service. The system consists of a 10 mil zinc foil bonded to an ionically conductive hydrogel adhesive, which is applied directly to the surface of the steel-reinforced concrete. A copper wire connects the zinc anode to multiple steel rebars and/or strands. The performance is monitored by measuring the current flow in the wire, by measuring the amount of zinc consumed or, more generally, by taking depolarization readings at regular intervals. All of these measurements are an indication of the performance of the galvanic system and the corrosion of the steel rebars that is being prevented.

  2. Considerations in the evaluation of concrete structures for continued service in aged Nuclear Power Plants (NPPs)

    SciTech Connect

    Naus, D.; Marchbanks, M.; Oland, B.; Arndt, G.; Brown, T.

    1989-01-01

    Currently, there are /approximately/119 commercial nuclear power plants (NPPs) in the US either under construction, operating at low-to-full power, or awaiting an operating license. Together, these units have a net generating capacity of /approximately/110 GW(e). Assuming no life extension of present facilities, the operating licenses for these plants will start to expire in the middle of the next decade with Yankee Rowe being the first plant to attain this status. Where it is noted that with no life extension of facilities, a potential loss of electrical generating capacity in excess of 75 GW(e) could occur during the time period 2006 to 2020 when the operating licenses of 80 to 90 NPPs are scheduled to expire. A potential timely and cost-effective solution to meeting future electricity demand, which has worked well for non-nuclear generating plants, is to extend the service life (operating licenses) of existing NPPs. Since the concrete components in these plants provide a vital safety function, any continued service considerations must include an in-depth assessment of the safety-related concrete structures. 7 refs.

  3. Nonlinear FE simulations of structural behavior parameters of reinforced concrete beam with epoxy-bonded FRP

    NASA Astrophysics Data System (ADS)

    Sasmal, Saptarshi; Kalidoss, S.

    2015-05-01

    In the present study, investigations on fiber-reinforced plastic (FRP) plated-reinforced concrete (RC) beam are carried out. Numerical investigations are performed by using a nonlinear finite element analysis by incorporating cracking and crushing of concrete. The numerical models developed in the present study are validated with the results obtained from the experiment under monotonic load using the servo-hydraulic actuator in displacement control mode. Further, the validated numerical models are used to evaluate the influence of different parameters. It is found from the investigations that increase in the elastic modulus of adhesive layer and CFRP laminate increases the interfacial stresses whereas increase in laminate modulus decreases the displacement and reinforcement strain of the beam. It is also observed that increase in the adhesive layer can largely reduce the interfacial stresses, whereas increase in laminate thickness increases it. However, increase in laminate thickness decreases the displacement and reinforcement strain of the beam significantly. It is mention worthy that increase in laminate length reduces the interfacial stresses, whereas CFRP width change does not affect the interfacial stresses. The study will be useful for the design and practicing engineers for arriving at the FRP-based strengthening schemes for RC structures judiciously.

  4. Consumable and non-consumable thermal spray anodes for impressed current cathodic protection of reinforced concrete structures

    SciTech Connect

    Covino, B.S. Jr.; Cramer, S.D.; Bullard, Sophie J.; Holcomb, Gordon R.; Collins, Wesley K.; McGill, G.E.

    1998-01-01

    A comparison is presented of some of the differences between thermal spray Zn, a consumable anode, and catalyzed thermal spray Ti, a non-consumable anode, used for impressed current cathodic protection of reinforced concrete structures. The thermal spray process for both Ti and Zn is compared using the spray parameters, atomizing gases, spray rate, and cost. The thermal spray Ti and Zn coatings are compared in terms of physical properties, composition, and structure. Results of accelerated laboratory experiments are presented and comparisons between Ti and Zn are made on the effect of electrochemical aging on voltage requirements, bond strength, coating resistivity, water permeability, and anode-concrete interracial composition.

  5. Structural implications of underground coal mining in the Mesaverde Group in the Somerset Coal Field, Delta and Gunnison Counties, Colorado

    SciTech Connect

    Christopher J. Carroll; Eric Robeck; Greg Hunt; Wendell Koontz

    2004-07-01

    Paleogene and Neogene faults and fractures on the eastern edge of the Colorado Plateau are present in Mesaverde Group coal and sandstone beds. Recent observations of coal cleat orientation in relation to faults in coal mines have significant impacts for mine planning in the area. Faults, coal cleats, and natural fractures are interpreted to show a structural evolution of the Mesaverde Group through time. This field trip included a visit to two active underground coal mines, the Bowie Resources' Bowie No. 2 Mine, and Mountain Coal's West Elk Mine. Mine geologists discussed structural styles including fault orientations and timing, cleat development, and rotation. Geologic encounters ranging from fault flooding, subsidence, mine fires, methane gas problems, and land use restrictions were also discussed. Coal cleat development and open-mode fractures in adjacent sandstones were observed on outcrops and compared to underground measurements in coal mines in the Somerset Coal Field, Colorado's most productive. Coal cleat orientations along a reverse fault in one mine showed rotation in relation to possible Neogene age displacement.

  6. Structural Stability Monitoring of a Physical Model Test on an Underground Cavern Group during Deep Excavations Using FBG Sensors.

    PubMed

    Li, Yong; Wang, Hanpeng; Zhu, Weishen; Li, Shucai; Liu, Jian

    2015-08-31

    Fiber Bragg Grating (FBG) sensors are comprehensively recognized as a structural stability monitoring device for all kinds of geo-materials by either embedding into or bonding onto the structural entities. The physical model in geotechnical engineering, which could accurately simulate the construction processes and the effects on the stability of underground caverns on the basis of satisfying the similarity principles, is an actual physical entity. Using a physical model test of underground caverns in Shuangjiangkou Hydropower Station, FBG sensors were used to determine how to model the small displacements of some key monitoring points in the large-scale physical model during excavation. In the process of building the test specimen, it is most successful to embed FBG sensors in the physical model through making an opening and adding some quick-set silicon. The experimental results show that the FBG sensor has higher measuring accuracy than other conventional sensors like electrical resistance strain gages and extensometers. The experimental results are also in good agreement with the numerical simulation results. In conclusion, FBG sensors could effectively measure small displacements of monitoring points in the whole process of the physical model test. The experimental results reveal the deformation and failure characteristics of the surrounding rock mass and make some guidance for the in situ engineering construction.

  7. Structural Stability Monitoring of a Physical Model Test on an Underground Cavern Group during Deep Excavations Using FBG Sensors

    PubMed Central

    Li, Yong; Wang, Hanpeng; Zhu, Weishen; Li, Shucai; Liu, Jian

    2015-01-01

    Fiber Bragg Grating (FBG) sensors are comprehensively recognized as a structural stability monitoring device for all kinds of geo-materials by either embedding into or bonding onto the structural entities. The physical model in geotechnical engineering, which could accurately simulate the construction processes and the effects on the stability of underground caverns on the basis of satisfying the similarity principles, is an actual physical entity. Using a physical model test of underground caverns in Shuangjiangkou Hydropower Station, FBG sensors were used to determine how to model the small displacements of some key monitoring points in the large-scale physical model during excavation. In the process of building the test specimen, it is most successful to embed FBG sensors in the physical model through making an opening and adding some quick-set silicon. The experimental results show that the FBG sensor has higher measuring accuracy than other conventional sensors like electrical resistance strain gages and extensometers. The experimental results are also in good agreement with the numerical simulation results. In conclusion, FBG sensors could effectively measure small displacements of monitoring points in the whole process of the physical model test. The experimental results reveal the deformation and failure characteristics of the surrounding rock mass and make some guidance for the in situ engineering construction. PMID:26404287

  8. Structural Stability Monitoring of a Physical Model Test on an Underground Cavern Group during Deep Excavations Using FBG Sensors.

    PubMed

    Li, Yong; Wang, Hanpeng; Zhu, Weishen; Li, Shucai; Liu, Jian

    2015-01-01

    Fiber Bragg Grating (FBG) sensors are comprehensively recognized as a structural stability monitoring device for all kinds of geo-materials by either embedding into or bonding onto the structural entities. The physical model in geotechnical engineering, which could accurately simulate the construction processes and the effects on the stability of underground caverns on the basis of satisfying the similarity principles, is an actual physical entity. Using a physical model test of underground caverns in Shuangjiangkou Hydropower Station, FBG sensors were used to determine how to model the small displacements of some key monitoring points in the large-scale physical model during excavation. In the process of building the test specimen, it is most successful to embed FBG sensors in the physical model through making an opening and adding some quick-set silicon. The experimental results show that the FBG sensor has higher measuring accuracy than other conventional sensors like electrical resistance strain gages and extensometers. The experimental results are also in good agreement with the numerical simulation results. In conclusion, FBG sensors could effectively measure small displacements of monitoring points in the whole process of the physical model test. The experimental results reveal the deformation and failure characteristics of the surrounding rock mass and make some guidance for the in situ engineering construction. PMID:26404287

  9. A thermal active restrained shrinkage ring test to study the early age concrete behaviour of massive structures

    SciTech Connect

    Briffaut, M.; Benboudjema, F.; Nahas, G.

    2011-01-15

    In massive concrete structures, cracking may occur during hardening, especially if autogenous and thermal strains are restrained. The concrete permeability due to this cracking may rise significantly and thus increase leakage (in tank, nuclear containment...) and reduce the durability. The restrained shrinkage ring test is used to study the early age concrete behaviour (delayed strains evolution and cracking). This test shows, at 20 {sup o}C and without drying, for a concrete mix which is representative of a French nuclear power plant containment vessel (w/c ratio equal to 0.57), that the amplitude of autogenous shrinkage (about 40 {mu}m/m for the studied concrete mix) is not high enough to cause cracking. Indeed, in this configuration, thermal shrinkage is not significant, whereas this is a major concern for massive structures. Therefore, an active test has been developed to study cracking due to restrained thermal shrinkage. This test is an evolution of the classical restrained shrinkage ring test. It allows to take into account both autogenous and thermal shrinkages. Its principle is to create the thermal strain effects by increasing the temperature of the brass ring (by a fluid circulation) in order to expand it. With this test, the early age cracking due to restrained shrinkage, the influence of reinforcement and construction joints have been experimentally studied. It shows that, as expected, reinforcement leads to an increase of the number of cracks but a decrease of crack widths. Moreover, cracking occurs preferentially at the construction joint.

  10. 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.

  11. Characterizing the Nano and Micro Structure of Concrete toImprove its Durability

    SciTech Connect

    Monteiro, P.J.M.; Kirchheim, A.P.; Chae, S.; Fischer, Peter; MacDowell, Alastair; Schaible, Eirc; Wenk, H.R.; Macdowell, Alastair A.

    2009-01-13

    New and advanced methodologies have been developed to characterize the nano and microstructure of cement paste and concrete exposed to aggressive environments. High resolution full-field soft X-ray imaging in the water window is providing new insight on the nano scale of the cement hydration process, which leads to a nano-optimization of cement-based systems. Hard X-ray microtomography images of ice inside cement paste and cracking caused by the alkali?silica reaction (ASR) enables three-dimensional structural identification. The potential of neutron diffraction to determine reactive aggregates by measuring their residual strains and preferred orientation is studied. Results of experiments using these tools are shown on this paper.

  12. Characterizing the nano and micro structure of concrete to improve its durability

    SciTech Connect

    Monteiro, P.J.M.; Kirchheim, A.P.; Chae, S.; Fischer, P.; MacDowell, A.A.; Schaible, E.; Wenk, H.R.

    2008-10-22

    New and advanced methodologies have been developed to characterize the nano and microstructure of cement paste and concrete exposed to aggressive environments. High resolution full-field soft X-ray imaging in the water window is providing new insight on the nano scale of the cement hydration process, which leads to a nano-optimization of cement-based systems. Hard X-ray microtomography images on ice inside cement paste and cracking caused by the alkali-silica reaction (ASR) enables three-dimensional structural identification. The potential of neutron diffraction to determine reactive aggregates by measuring their residual strains and preferred orientation is studied. Results of experiments using these tools will be shown on this paper.

  13. EVALUATION OF THE DURABILITY OF THE STRUCTURAL CONCRETE OF REACTOR BUILDINGS AT SRS

    SciTech Connect

    Duncan, A.; Reigel, M.

    2011-02-28

    The Department of Energy (DOE) intends to close 100-150 facilities in the DOE complex using an in situ decommissioning (ISD) strategy that calls for grouting the below-grade interior volume of the structure and leaving the above-grade interior open or demolishing it and disposing of it in the slit trenches in E Area. These closures are expected to persist and remain stable for centuries, but there are neither facility-specific monitoring approaches nor studies on the rate of deterioration of the materials used in the original construction or on the ISD components added during closure (caps, sloped roofs, etc). This report will focus on the evaluation of the actual aging/degradation of the materials of construction used in the ISD structures at Savannah River Site (SRS) above grade, specifically P & R reactor buildings. Concrete blocks (six 2 to 5 ton blocks) removed from the outer wall of the P Reactor Building were turned over to SRNL as the first source for concrete cores. Larger cores were received as a result of grouting activities in P and R reactor facilities. The cores were sectioned and evaluated using microscopy, x-ray diffraction (XRD), ion chromatography (IC) and thermal analysis. Scanning electron microscopy shows that the aggregate and cement phases present in the concrete are consistent with the mix design and no degradation mechanisms are evident at the aggregate-cement interfaces. Samples of the cores were digested and analyzed for chloride ingress as well as sulfate attack. The concentrations of chloride and sulfate ions did not exceed the limits of the mix design and there is no indication of any degradation due to these mechanisms. Thermal analysis on samples taken along the longitudinal axis of the cores show that there is a 1 inch carbonation layer (i.e., no portlandite) present in the interior wall of the reactor building and a negligible carbonation layer in the exterior wall. A mixed layer of carbonate and portlandite extends deeper into the

  14. 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.

  15. Nuclear Technology. Course 29: Civil/Structural Inspection. Module 29-6, Pre-Stressed Concrete Materials, Fabrication and Inspection.

    ERIC Educational Resources Information Center

    Groseclose, Richard

    This sixth in a series of six modules for a course titled Civil/Structural Inspection describes inspection activities associated with pre-stressed concrete such as reviewing material certifications and test reports, inspecting construction operations, performing materials testing, and preparing records and reports of inspection and testing…

  16. Nuclear Technology. Course 29: Civil/Structural Inspection. Module 29-4, Concrete Preparation, Production, Placement and Finishing.

    ERIC Educational Resources Information Center

    Groseclose, Richard

    This fourth in a series of six modules for a course titled Civil/Structural Inspection describes concrete preparation, production, placement, and finishing. The module follows a typical format that includes the following sections: (1) introduction, (2) module prerequisites, (3) objectives, (4) notes to instructor/student, (5) subject matter, (6)…

  17. Health monitoring of reinforced concrete structures based on PZT admittance signal

    NASA Astrophysics Data System (ADS)

    Wang, Dansheng; Zhu, Hongping; Shen, Danyan; Ge, Dongdong

    2009-07-01

    Reinforced concrete (RC) structure is one of most familiar engineering structure styles in the civil engineering community, which often suffer crack damage during their service life because of some factors such as overloading, excessive use, and bad environmental conditions. Thus early detection of crack damage is of special concern for RC structures. Piezoelectric materials have direct and converse piezoelectric effects and can serve as actuators or sensors. A health monitoring method based on PZT admittance signals is addressed in this paper, which use the electromechanical coupling property of piezoelectric materials. An experimental study on health monitoring of a RC beam is implemented based on the PZT admittance signals. In this experiment, the electrical admittances of distributed PZT sheets are measured when the host beams are suffering from variable loads. From the obtained PZT admittance curves one can find that the presence of incipient crack can be captured and the cracking load of the RC beam can also generally determined. By the experimental study it is concluded that the health monitoring technique is quite effective and sensitive for RC structures, which indicates its favorable application foreground in civil engineering field.

  18. The application of 1-3 cement-based piezoelectric transducers in active and passive health monitoring for concrete structures

    NASA Astrophysics Data System (ADS)

    Qin, Lei; Huang, Shifeng; Cheng, Xin; Lu, Youyuan; Li, Zongjin

    2009-09-01

    1-3 cement-based piezoelectric composite has been developed for health monitoring of concrete structures. Transducers made of this type of composite have broadband frequency response. Plain concrete and engineered cement composite (ECC) beams with embedded 1-3 cement-based piezoelectric transducers were prepared and tested. During experiments, the transducers were used to perform active and passive detection of the damage evolution of the beams. In active detection, a damage index based on the average energy of the received waves was proposed and used. In passive detection, acoustic emission (AE) events were recorded and the accumulated AE event number was analyzed with the loading history. Crack localization was also accomplished in the passive monitoring. The results of the two methods demonstrated similar trends in interpreting the damage evolution of the concrete beam. The results were also consistent with each material's characteristics.

  19. Improved synthetic aperture focusing technique by Hilbert-Huang transform for imaging defects inside a concrete structure.

    PubMed

    Tong, Jian-Hua; Chiu, Chin-Lung; Wang, Chung-Yue

    2010-11-01

    A useful nondestructive testing tool for civil engineering should immediately reveal defects inside concrete structures at the construction sites. To date, there are few effective methods to image defects inside concrete structures. In this paper, a new nondestructive testing method using elastic waves for imaging possible defects inside concrete is developed. This method integrates the point-source/point receiver scheme with the synthetic aperture focusing technique (SAFT) to increase functioning depth and enhance received signals. To improve image quality, received signals are processed by Hilbert-Huang transform (HHT) to get time-frequency curves for the SAFT process. Compared with conventional SAFT method processing with time-amplitude signals, this new method is capable of providing a better image of defects not only in the numerical simulation but also in the experimental result. The image can reveal the number of defects and their locations and front-end profiles. The results shown in this paper indicate that this new elastic-wave-based method exhibits high capability in imaging the defects of in situ concrete structures.

  20. Geological features that contribute to ground control problems in underground coal mines. Information circular/1993

    SciTech Connect

    Shea-Albin, V.R.

    1993-01-01

    A major portion of ground control problems encountered in underground coal mines can be attributed to geologic features in the strata surrounding the extracted coal seam. The U.S. Bureau of Mines has compiled information from several sources on the geological features that contribute to ground control problems in underground coal mines. The compilation includes sedimentary features such as paleochannels, crevasse splays, clastic dikes, mold and cast structures, concretions, lithologic factors, and structural features, such as folds, fractures, joints, cleat, and faults. The compiled information will aid in identifying the features, predicting their occurrence in advance of mining, and controlling or minimizing roof failure when these features are encountered in an underground coal mine.

  1. The Factor Structure of Concrete and Formal Operations: A Confirmation of Piaget.

    ERIC Educational Resources Information Center

    Gray, William M.

    Piaget has hypothesized that concrete and formal operations can be described by specific logical models. The present study focused on assessing various aspects of four concrete operational groupings and two variations of two formal operational characteristics. Six hundred twenty-two 9-14 year old students participating in the Human Sciences…

  2. Analysis of the status of pre-release cracks in prestressed concrete structures using long-gauge sensors

    NASA Astrophysics Data System (ADS)

    Abdel-Jaber, H.; Glisic, B.

    2015-02-01

    Prestressed structures experience limited tensile stresses in concrete, which limits or completely eliminates the occurrence of cracks. However, in some cases, large tensile stresses can develop during the early age of the concrete due to thermal gradients and shrinkage effects. Such stresses can cause early-age cracks, termed ‘pre-release cracks’, which occur prior to the transfer of the prestressing force. When the prestressing force is applied to the cross-section, it is assumed that partial or full closure of the cracks occurs by virtue of the force transfer through the cracked cross-section. Verification of the closure of the cracks after the application of the prestressing force is important as it can either confirm continued structural integrity or indicate and approximate reduced structural capacity. Structural health monitoring (SHM) can be used for this purpose. This paper researches an SHM method that can be applied to prestressed beam structures to assess the condition of pre-release cracks. The sensor network used in this method consists of parallel long-gauge fiber optic strain sensors embedded in the concrete cross-sections at various locations. The same network is used for damage detection, i.e. detection and characterization of the pre-release cracks, and for monitoring the prestress force transfer. The method is validated on a real structure, a curved continuous girder. Results from the analysis confirm the safety and integrity of the structure. The method and its application are presented in this paper.

  3. Comparative study between structural and electrical properties of geopolymers applied to a green concrete

    NASA Astrophysics Data System (ADS)

    Montaño, A. M.; González, C. P.; Pérez, J.; Royero, C.; Sandoval, D.; Gutiérrez, J.

    2013-11-01

    This work shows a comparative analysis of geopolymers obtained by alkaline activation of two aluminosilicates: bentonite and metakaolin. With the goal of to replace some cement percentage, both aluminosilicates were added in several proportions (10, 20 and 30%) to concrete mixes. Portland Type I cement was used to prepare the reference concrete (without geopolymer). X-ray diffraction of geopolymers allowed to find new crystallographic phases that was not present in precursor's minerals. To evaluate mechanical properties of concrete prepared with geopolymers, test tubes with 7, 14, 28 and 90 days as setting time were used. Chemical resistance and Electrical impedance of concrete mixes were also measured. Results shows that cementitious material obtained from metakaolin exhibit the best compressive strength. On the other hand, those materials derived from bentonite, have a high electrical resistance so that, they protected reinforced concrete better that Portland does.

  4. Dual-band infrared imaging for concrete bridge deck inspection

    SciTech Connect

    Durbin, P.; Del Grande, N.

    1994-02-01

    Dual-band infrared (DBIR) imaging methods and unique image-correction algorithms used successfully for underground and obscured object imaging and detection (of buried mines, archaeological structures, geothermal aquifers and airframe defects) are adapted for inspection of concrete highways and bridge decks to provide early warnings of subsurface defects. To this end, we prepared small concrete test slabs with defects (embedded plastic layers). We used selective DBIR (3--5 {mu}m and 8--12 {mu}m) image ratios to depict the defect sites and remove the effects of surface clutter. We distinguish true temperature-difference signals (at surrogate delamination sites) from emissivity noise (at sites with oil stains, sand, gravel, metal parts and roughness differences) towards improved concrete bridge deck inspections.

  5. Cementitious Barriers Partnership (CBP): Using the CBP Software Toolbox to Simulate Sulfate Attack and Carbonation of Concrete Structures - 13481

    SciTech Connect

    Brown, K.G.; Kosson, D.S.; Garrabrants, A.C.; Sarkar, S.; Flach, G.; Langton, C.; Smith, F.G.III; Burns, H.; Van der Sloot, H.; Meeussen, J.C.L.; Seignette, P.F.A.B.; Samson, E.; Mallick, P.; Suttora, L.; Esh, D.; Fuhrmann, M.; Philip, J.

    2013-07-01

    The Cementitious Barriers Partnership (CBP) Project is a multi-disciplinary, multi-institutional collaboration supported by the U.S. Department of Energy Office of Tank Waste Management. The CBP project has developed a set of integrated modeling tools and leaching test methods to help improve understanding and prediction of the long-term hydraulic and chemical performance of cementitious materials used in nuclear applications. State-of-the-art modeling tools, including LeachXS{sup TM}/ORCHESTRA and STADIUM{sup R}, were selected for their demonstrated abilities to simulate reactive transport and degradation in cementitious materials. The new U.S. Environmental Protection Agency leaching test methods based on the Leaching Environmental Assessment Framework (LEAF), now adopted as part of the SW-846 RCRA methods, have been used to help make the link between modeling and experiment. Although each of the CBP tools has demonstrated utility as a standalone product, coupling the models over relevant spatial and temporal solution domains can provide more accurate predictions of cementitious materials behavior over relevant periods of performance. The LeachXS{sup TM}/ORCHESTRA and STADIUM{sup R} models were first linked to the GoldSim Monte Carlo simulator to better and more easily characterize model uncertainties and as a means to coupling the models allowing linking to broader performance assessment evaluations that use CBP results for a source term. Two important degradation scenarios were selected for initial demonstration: sulfate ingress / attack and carbonation of cementitious materials. When sufficient sulfate is present in the pore solution external to a concrete barrier, sulfate can diffuse into the concrete, react with the concrete solid phases, and cause cracking that significantly changes the transport and structural properties of the concrete. The penetration of gaseous carbon dioxide within partially saturated concrete usually initiates a series of carbonation

  6. Experimental evaluation of natural period of masonry and reinforced concrete structures during operative conditions

    NASA Astrophysics Data System (ADS)

    Carlo Ponzo, Felice; Ditommaso, Rocco; Auletta, Gianluca; Nigro, Antonella; Iacovino, Chiara; Salvatore Nigro, Domenico

    2016-04-01

    This work focuses on the experimental evaluation of the fundamental period of buildings of various types (masonry and reinforced concrete) using measurements of ambient vibrations on real buildings located in Basilicata (Italy) and numerical analyses. The results are compared with the simplified formula provided by the Seismic Italian Code (NTC2008), that is function of structural typology and height for both near collapse and limited damage limit states and experimental results provided by the recent scientific literature. With the intention of proposing simplified relationships to evaluate the fundamental period of buildings, several numerical and experimental campaigns, on different structures all around the world, have been carried out in the last years in order to calibrate different kind of formulas. Most of formulas retrieved from both numerical and experimental analyses provides vibration periods smaller than those suggested by the NTC2008. However, it is well known that the fundamental period of a structure play a key role in the correct evaluation of the spectral acceleration for seismic static analyses. Generally, simplified approaches impose the use of safety factors greater than those related to in depth nonlinear analyses with the aim to cover possible unexpected uncertainties. Using the simplified formula proposed by the Italian seismic code the fundamental period is quite higher than fundamental periods experimentally evaluated on real structures, with the consequence that the spectral acceleration adopted in the seismic static analysis may be significantly different than real spectral acceleration. This approach could produces a decreasing in safety factors obtained using linear seismic static analyses. Based on numerical and experimental evidences, the authors suggest a possible update of the seismic codes formula for the simplified estimation of the fundamental period of vibration of existing masonry and RC buildings. Acknowledgements This study

  7. The Performance Analysis of Distributed Brillouin Corrosion Sensors for Steel Reinforced Concrete Structures

    PubMed Central

    Wei, Heming; Zhao, Xuefeng; Kong, Xianglong; Zhang, Pinglei; Cui, Yanjun; Sun, Changsen

    2014-01-01

    The Brillouin optical time-domain analysis (BOTDA)-based optical fiber method has been proposed to measure strain variations caused by corrosion expansion. Spatial resolutions of 1 m can be achieved with this kind of Brillouin sensor for detecting the distributed strain. However, when the sensing fiber is wound around the steel rebar in a number of circles in a range of several meters, this spatial resolution still has limitations for corrosion monitoring. Here, we employed a low-coherent fiber-optic strain sensor (LCFS) to survey the performance of Brillouin sensors based on the fact that the deformation measured by the LCFS equals the integral of the strains obtained from Brillouin sensors. An electrochemical accelerated corrosion experiment was carried out and the corrosion expansion was monitored by both BOTDA and the LCFS. Results demonstrated that the BOTDA can only measure the expansion strain of about 1,000 με, which was generated by the 18 mm steel rebar corrosion, but, the LCFS had high sensitivity from the beginning of corrosion to the destruction of the structure, and no obvious difference in expansion speed was observed during the acceleration stage of the corrosion developed in the reinforced concrete (RC) specimens. These results proved that the BOTDA method could only be employed to monitor the corrosion inside the structure in the early stage. PMID:24379048

  8. ASSESSMENT OF RADIONUCLIDE RELEASE FROM INTACT STRUCTURES BACKFILLED WITH CONTAMINATED CONCRETE AT THE YANKEE NUCLEAR POWER STATION.

    SciTech Connect

    SULLIVAN, T.

    2004-09-30

    This calculation determines the release of residual radioactivity (including H-3, C-14, Co-60, Ni-63, Sr-90, and Cs-137), from subsurface structures filled with concrete debris at the Yankee Nuclear Power Station. Analyses were performed to assess the rate of release from the source of contamination and the resulting dose in the groundwater pathway. Two mechanisms were considered, diffusive release from the concrete structures (walls and floors) that remain intact and sorption onto concrete backfill placed within these structures. RESRAD was used to calculate the predicted maximum dose assuming a unit loading of 1 pCi/g on the intact structures. To the extent possible, the same assumptions in the soil DCGL calculations performed for Yankee Atomic were used in the calculation. However, modifications to some input parameter values were needed to represent the geometry of the subsurface facilities, flow through these facilities, and releases from the backfill and intact structures. Input parameters specific to these calculations included the leach rate, disposal geometry, pumping rate, porosity and bulk density. The dose results for a unit loading of 1 pCi/g on intact structures showed that Sr-90 had the highest dose (3.67E-02 mrem/yr).

  9. A Case for Underground Schools.

    ERIC Educational Resources Information Center

    Oklahoma State Dept. of Education, Oklahoma City.

    The underground school offers several advantages. Preliminary studies in Oklahoma have shown that these schools perform exceptionally well as learning environments. The lack of noise and distractions helps teachers keep the attention of their students. Underground structures can protect people against a broad range of natural and man-made…

  10. Underground Mathematics

    ERIC Educational Resources Information Center

    Hadlock, Charles R

    2013-01-01

    The movement of groundwater in underground aquifers is an ideal physical example of many important themes in mathematical modeling, ranging from general principles (like Occam's Razor) to specific techniques (such as geometry, linear equations, and the calculus). This article gives a self-contained introduction to groundwater modeling with…

  11. Self-centering seismic retrofit scheme for reinforced concrete frame structures: SDOF system study

    NASA Astrophysics Data System (ADS)

    Zhang, Yunfeng; Hu, Xiaobin

    2010-06-01

    This paper presents the results of a parametric study of self-centering seismic retrofit schemes for reinforced concrete (RC) frame buildings. The self-centering retrofit system features flag-shaped hysteresis and minimal residual deformation. For comparison purpose, an alternate seismic retrofit scheme that uses a bilinear-hysteresis retrofit system such as buckling-restrained braces (BRB) is also considered in this paper. The parametric study was carried out in a single-degree-of-freedom (SDOF) system framework since a multi-story building structure may be idealized as an equivalent SDOF system and investigation of the performance of this equivalent SDOF system can provide insight into the seismic response of the multi-story building. A peak-oriented hysteresis model which can consider the strength and stiffness degradation is used to describe the hysteretic behavior of RC structures. The parametric study involves two key parameters — the strength ratio and elastic stiffness ratio between the seismic retrofit system and the original RC frame. An ensemble of 172 earthquake ground motion records scaled to the design basis earthquake in California with a probability of exceedance of 10% in 50 years was constructed for the simulation-based parametric study. The effectiveness of the two seismic retrofit schemes considered in this study is evaluated in terms of peak displacement ratio, peak acceleration ratio, energy dissipation demand ratio and residual displacement ratio between the SDOF systems with and without retrofit. It is found from this parametric study that RC structures retrofitted with the self-centering retrofit scheme (SCRS) can achieve a seismic performance level comparable to the bilinear-hysteresis retrofit scheme (BHRS) in terms of peak displacement and energy dissipation demand ratio while having negligible residual displacement after earthquake.

  12. Corrosion Assessment of Steel Bars Used in Reinforced Concrete Structures by Means of Eddy Current Testing.

    PubMed

    de Alcantara, Naasson P; da Silva, Felipe M; Guimarães, Mateus T; Pereira, Matheus D

    2015-12-24

    This paper presents a theoretical and experimental study on the use of Eddy Current Testing (ECT) to evaluate corrosion processes in steel bars used in reinforced concrete structures. The paper presents the mathematical basis of the ECT sensor built by the authors; followed by a finite element analysis. The results obtained in the simulations are compared with those obtained in experimental tests performed by the authors. Effective resistances and inductances; voltage drops and phase angles of wound coil are calculated using both; simulated and experimental data; and demonstrate a strong correlation. The production of samples of corroded steel bars; by using an impressed current technique is also presented. The authors performed experimental tests in the laboratory using handmade sensors; and the corroded samples. In the tests four gauges; with five levels of loss-of-mass references for each one were used. The results are analyzed in the light of the loss-of-mass and show a strong linear behavior for the analyzed parameters. The conclusions emphasize the feasibility of the proposed technique and highlight opportunities for future works.

  13. Structural use of polymer concrete made with resins based on recycled PET

    SciTech Connect

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

    1995-08-01

    Recycled poly(ethylene terephthalate), PET, plastic waste can be used to produce unsaturated polyester resins. The PET waste is typically found in used beverage bottles that are collected after use in many localities. This research investigated the use of suitable unsaturated polyester resins based on recycled PET for the production of polymer concrete (PC) materials. The properties and structural behavior of unreinforced and steel-reinforced PC materials using resins based on recycled PET were found to be comparable to those obtained with PC materials using virgin resins. Resins based on recycled PET can also relatively easily be altered to achieve a wide variety of properties and performances in the PC. An experimental design also showed that the effect of the level of PET in the resin did not adversely affect the neat resin and the PC mechanical properties. Resins based on recycled PET help in decreasing the cost of PC products, saving energy, and alleviating an environmental problem posed by plastics waste.

  14. Corrosion Assessment of Steel Bars Used in Reinforced Concrete Structures by Means of Eddy Current Testing

    PubMed Central

    de Alcantara, Naasson P.; da Silva, Felipe M.; Guimarães, Mateus T.; Pereira, Matheus D.

    2015-01-01

    This paper presents a theoretical and experimental study on the use of Eddy Current Testing (ECT) to evaluate corrosion processes in steel bars used in reinforced concrete structures. The paper presents the mathematical basis of the ECT sensor built by the authors; followed by a finite element analysis. The results obtained in the simulations are compared with those obtained in experimental tests performed by the authors. Effective resistances and inductances; voltage drops and phase angles of wound coil are calculated using both; simulated and experimental data; and demonstrate a strong correlation. The production of samples of corroded steel bars; by using an impressed current technique is also presented. The authors performed experimental tests in the laboratory using handmade sensors; and the corroded samples. In the tests four gauges; with five levels of loss-of-mass references for each one were used. The results are analyzed in the light of the loss-of-mass and show a strong linear behavior for the analyzed parameters. The conclusions emphasize the feasibility of the proposed technique and highlight opportunities for future works. PMID:26712754

  15. 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.

  16. Structural resistance of reinforced concrete buildings under pyroclastic flows: a study of the Vesuvian area

    NASA Astrophysics Data System (ADS)

    Petrazzuoli, S. M.; Zuccaro, G.

    2004-05-01

    The analysis of the effects of pyroclastic flows on humans and on buildings represents the main tool to define the boundary of the most hazardous area around an active volcano such as Somma-Vesuvius. Estimation of the lateral pressure on buildings derived from analogies with the damages observed after a nuclear explosion [Valentine (1998) J. Volcanol. Geotherm. Res. 87, 117-140] lead to pressure values and/or structural resistance which are not realistic (too high). Recent evidence [Baxter (2000) Human and Structural Vulnerability Assessment for Emergency Planning in a Future Eruption of Vesuvius. Final Report EC Project ENV4-CT98-0699; Young et al. (1997) EOS, Trans. Am. Geophys. Union, 78, 401] have shown that beyond 2-3 km from the vent, even after a great eruption, resistance to collapse of buildings affected by a pyroclastic flow is still possible. Neri et al. [(2000) Numerical simulation of pyroclastic flows. In: Human and Human and Structural Vulnerability Assessment for Emergency Planning in a Future Eruption of Vesuvius. Final Report EC Project ENV4-CT98-0699], by means of a numerical model of a collapsing column, show that the peak overpressures of the pyroclastic flows range from 1 to 2 kPa at a distance from the vent of about 4-5 km, where important historical centres of the Vesuvian area are located. A detailed analysis of urban settlement of the area [Cherubini et al. (2001) Vulnerabilita' Sismica dell'Area Vesuviana. Gruppo Nazionale per la Difesa dai Terremoti, CNR, Roma] has shown that most of the people live in reinforced concrete (r.c.) structures, not designed to resist horizontal seismic actions. The present work is aimed at analyzing the collapse limit load of r.c. structures to horizontal pressure for different structural design typologies (strong aseismic, weak aseismic, strong non-aseismic, weak non-aseismic). The simulations performed have also taken into account the specific features of the r.c. structures of the area (local building

  17. DENA: A finite element program for the non-linear stress analysis of two-dimensional, metallic and reinforced concrete, structures

    NASA Astrophysics Data System (ADS)

    Ranjbaran, A.; Phipps, M. E.

    1994-04-01

    A finite element program for the nonlinear stress analysis of two-dimensional problems is introduced. Both metallic and reinforced concrete structures are considered. In the case of metals plasticity is taken into account. For reinforced concrete structures cracking of concrete in tension, plasticity and crushing of concrete in compression, and plasticity of reinforcement is accounted for. A new and unified model for embedding reinforcement in concrete elements is proposed. The proposed model is quite general in the sense that it can be used both for two- and three-dimensional problems. The theoretical basis of the program is presented. The accuracy, efficiency and robustness of the program and its implementation is verified through the analysis of two-dimensional problems.

  18. Influence of Steel Reinforcement on In-Situ Stress Evaluation in Concrete Structures by the Core-Drilling Method

    SciTech Connect

    McGinnis, M. J.; Pessiki, S.

    2006-03-06

    The core-drilling method is an emerging technique for evaluating in-situ stress in a concrete structure. A small hole is drilled into the structure, and the deformations in the vicinity of the hole are measured and related via elasticity theory to the stress. The method is similar to the ASTM hole-drilling strain-gauge method excepting that displacements rather than strains are the measured quantities. The technique may be considered nondestructive since the ability of the structure to perform its function is unaffected, and the hole is easily repaired. Displacement measurements in the current work are performed using 3D digital image correlation and industrial photogrammetry. The current paper addresses perturbations in the method caused by steel reinforcement within the concrete. The reinforcement is significantly stiffer than the surrounding concrete, altering the expected displacement field. A numerical investigation performed indicates an under-prediction of stress by as much as 18 percent in a heavily reinforced structure, although the effect is significantly smaller for more common amounts of reinforcement.

  19. Characterization of atomic structure of oxide films on carbon steel in simulated concrete pore solutions using EELS

    NASA Astrophysics Data System (ADS)

    Gunay, H. Burak; Ghods, Pouria; Isgor, O. Burkan; Carpenter, Graham J. C.; Wu, Xiaohua

    2013-06-01

    The atomic structure of oxide films formed on carbon steel that are exposed to highly alkaline simulated concrete pore solutions was investigated using Electron Energy Loss Spectroscopy (EELS). In particular, the effect of chloride exposure on film structure was studied in two types of simulated pore solutions: saturated calcium hydroxide (CH) and a solution prepared to represent typical concrete pore solutions (CP). It was shown that the films that form on carbon steel in simulated concrete pore solutions contained three indistinct layers. The inner oxide film had a structure similar to that of FeIIO, which is known to be unstable in the presence of chlorides. The outer oxide film mainly resembled Fe3O4 (FeIIO·Fe2IIIO3) in the CH solution and α-Fe2IIIO3/Fe3O4 in the CP solution. The composition of the transition layer between the inner and outer layers of the oxide film was mainly composed of Fe3O4 (FeIIO·Fe2IIIO3). In the presence of chloride, the relative amount of the FeIII/FeII increased, confirming that chlorides induce valence state transformation of oxides from FeII to FeIII, and the difference between the atomic structures of oxide film layers diminished.

  20. CP of new post-tensioned concrete structures. Monitoring and operating data at start-up

    SciTech Connect

    Bazzoni, B.; Lazzari, L.; Grandi, M.; Delfrate, A.

    1994-12-31

    A series of new post-tensioned concrete viaducts of the Frejus Highway, Italy, have been constructed with incorporated cathodic protection systems to prevent chloride contamination of the concrete and corrosion of reinforcements. The paper illustrates the computerized data gathering and monitoring system installed, and the criteria adopted to evaluate and control the cathodic protection conditions as well as to avoid overprotection of the post-tensioned tendons. Operating data gathered during the commissioning phase of the CP systems are reported and discussed.

  1. Carbonation and CO{sub 2} uptake of concrete

    SciTech Connect

    Yang, Keun-Hyeok; Seo, Eun-A; Tae, Sung-Ho

    2014-04-01

    This study developed a reliable procedure to assess the carbon dioxide (CO{sub 2}) uptake of concrete by carbonation during the service life of a structure and by the recycling of concrete after demolition. To generalize the amount of absorbable CO{sub 2} per unit volume of concrete, the molar concentration of carbonatable constituents in hardened cement paste was simplified as a function of the unit content of cement, and the degree of hydration of the cement paste was formulated as a function of the water-to-cement ratio. The contribution of the relative humidity, type of finishing material for the concrete surface, and the substitution level of supplementary cementitious materials to the CO{sub 2} diffusion coefficient in concrete was reflected using various correction factors. The following parameters varying with the recycling scenario were also considered: the carbonatable surface area of concrete crusher-runs and underground phenomena of the decreased CO{sub 2} diffusion coefficient and increased CO{sub 2} concentration. Based on the developed procedure, a case study was conducted for an apartment building with a principal wall system and an office building with a Rahmen system, with the aim of examining the CO{sub 2} uptake of each structural element under different exposure environments during the service life and recycling of the building. As input data necessary for the case study, data collected from actual surveys conducted in 2012 in South Korea were used, which included data on the surrounding environments, lifecycle inventory database, life expectancy of structures, and recycling activity scenario. Ultimately, the CO{sub 2} uptake of concrete during a 100-year lifecycle (life expectancy of 40 years and recycling span of 60 years) was estimated to be 15.5%–17% of the CO{sub 2} emissions from concrete production, which roughly corresponds to 18%–21% of the CO{sub 2} emissions from the production of ordinary Portland cement. - Highlights: • CO

  2. 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.

  3. Reliability-based design optimization of reinforced concrete structures including soil-structure interaction using a discrete gravitational search algorithm and a proposed metamodel

    NASA Astrophysics Data System (ADS)

    Khatibinia, M.; Salajegheh, E.; Salajegheh, J.; Fadaee, M. J.

    2013-10-01

    A new discrete gravitational search algorithm (DGSA) and a metamodelling framework are introduced for reliability-based design optimization (RBDO) of reinforced concrete structures. The RBDO of structures with soil-structure interaction (SSI) effects is investigated in accordance with performance-based design. The proposed DGSA is based on the standard gravitational search algorithm (GSA) to optimize the structural cost under deterministic and probabilistic constraints. The Monte-Carlo simulation (MCS) method is considered as the most reliable method for estimating the probabilities of reliability. In order to reduce the computational time of MCS, the proposed metamodelling framework is employed to predict the responses of the SSI system in the RBDO procedure. The metamodel consists of a weighted least squares support vector machine (WLS-SVM) and a wavelet kernel function, which is called WWLS-SVM. Numerical results demonstrate the efficiency and computational advantages of DGSA and the proposed metamodel for RBDO of reinforced concrete structures.

  4. 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.

  5. Alkali-silica reactivity of expanded glass granules in structure of lightweight concrete

    NASA Astrophysics Data System (ADS)

    Bumanis, G.; Bajare, D.; Locs, J.; Korjakins, A.

    2013-12-01

    Main component in the lightweight concrete, which provides its properties, is aggregate. A lot of investigations on alkali silica reaction (ASR) between cement and lightweight aggregates have been done with their results published in the academic literature. Whereas expanded glass granules, which is relatively new product in the market of building materials, has not been a frequent research object. Therefore lightweight granules made from waste glass and eight types of cement with different chemical and mineralogical composition were examined in this research. Expanded glass granules used in this research is commercially available material produced by Penostek. Lightweight concrete mixtures were prepared by using commercial chemical additives to improve workability of concrete. The aim of the study is to identify effect of cement composition to the ASR reaction which occurs between expanded glass granules and binder. Expanded glass granules mechanical and physical properties were determined. In addition, properties of fresh and hardened concrete were determined. The ASR test was processed according to RILEM AAR-2 testing recommendation. Tests with scanning electron microscope and microstructural investigations were performed for expanded glass granules and hardened concrete specimens before and after exposing them in alkali solution.

  6. 30 CFR 75.1903 - Underground diesel fuel storage facilities and areas; construction and safety precautions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... percent of the maximum capacity of the fuel storage system; and (7) Provided with a competent concrete... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Underground diesel fuel storage facilities and...-UNDERGROUND COAL MINES Diesel-Powered Equipment § 75.1903 Underground diesel fuel storage facilities and...

  7. 30 CFR 75.1903 - Underground diesel fuel storage facilities and areas; construction and safety precautions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... percent of the maximum capacity of the fuel storage system; and (7) Provided with a competent concrete... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Underground diesel fuel storage facilities and...-UNDERGROUND COAL MINES Diesel-Powered Equipment § 75.1903 Underground diesel fuel storage facilities and...

  8. 30 CFR 75.1903 - Underground diesel fuel storage facilities and areas; construction and safety precautions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... percent of the maximum capacity of the fuel storage system; and (7) Provided with a competent concrete... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Underground diesel fuel storage facilities and...-UNDERGROUND COAL MINES Diesel-Powered Equipment § 75.1903 Underground diesel fuel storage facilities and...

  9. 30 CFR 75.1903 - Underground diesel fuel storage facilities and areas; construction and safety precautions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... percent of the maximum capacity of the fuel storage system; and (7) Provided with a competent concrete... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Underground diesel fuel storage facilities and...-UNDERGROUND COAL MINES Diesel-Powered Equipment § 75.1903 Underground diesel fuel storage facilities and...

  10. 30 CFR 75.1903 - Underground diesel fuel storage facilities and areas; construction and safety precautions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... percent of the maximum capacity of the fuel storage system; and (7) Provided with a competent concrete... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Underground diesel fuel storage facilities and...-UNDERGROUND COAL MINES Diesel-Powered Equipment § 75.1903 Underground diesel fuel storage facilities and...

  11. Installation and verification of high precision mechanics in concrete structures at the example of ALMA antenna interfaces

    NASA Astrophysics Data System (ADS)

    Heinz, Volker; Kraus, Max; Orellana, Eduardo

    2012-09-01

    For the ALMA interferometer at the array operation facility near San Pedro de Atacama at 5.000 meters asl 192 concrete antenna foundations had to be equipped with coupling points for 66 antennas. These antennas will be frequently moved between the foundations and placed on these interfaces without further adjustment. To position the ALMA antennas with the required accuracy, high precision inserts need to be installed in previously casted concrete foundations. Very tight mechanical tolerances have to be applied to civil structures, with standard tolerances of not less than millimeters. This is extremely difficult considering the material (mortar and steel in a concrete slab) to be used and the environmental conditions on site. Special tools had to be designed and an installation and alignment procedure developed, tested and improved. Important was to have a robust process, which allows highest precision installation without major re-machining for approx 600 interface blocks. Installation material, which could cope with the conditions, was specially tested for these requirements. The geometry of the interface and other parameters such as horizontal and vertical stiffness must be verified after the installation. Special metrology tools to measure reliable at micron level at high altitude had been selected. The experience and knowledge acquired will be beneficial for the installation of any opto-mechanical device in civil engineering structures, such as telescope and dome track rails, but also in optical interferometer installations. Metrology requirements and environmental conditions in most of these cases are equally challenging.

  12. Full-scale laboratory validation of a wireless MEMS-based technology for damage assessment of concrete structures

    NASA Astrophysics Data System (ADS)

    Trapani, Davide; Zonta, Daniele; Molinari, Marco; Amditis, Angelos; Bimpas, Matthaios; Bertsch, Nicolas; Spiering, Vincent; Santana, Juan; Sterken, Tom; Torfs, Tom; Bairaktaris, Dimitris; Bairaktaris, Manos; Camarinopulos, Stefanos; Frondistou-Yannas, Mata; Ulieru, Dumitru

    2012-04-01

    This paper illustrates an experimental campaign conducted under laboratory conditions on a full-scale reinforced concrete three-dimensional frame instrumented with wireless sensors developed within the Memscon project. In particular it describes the assumptions which the experimental campaign was based on, the design of the structure, the laboratory setup and the results of the tests. The aim of the campaign was to validate the performance of Memscon sensing systems, consisting of wireless accelerometers and strain sensors, on a real concrete structure during construction and under an actual earthquake. Another aspect of interest was to assess the effectiveness of the full damage recognition procedure based on the data recorded by the sensors and the reliability of the Decision Support System (DSS) developed in order to provide the stakeholders recommendations for building rehabilitation and the costs of this. With these ends, a Eurocode 8 spectrum-compatible accelerogram with increasing amplitude was applied at the top of an instrumented concrete frame built in the laboratory. MEMSCON sensors were directly compared with wired instruments, based on devices available on the market and taken as references, during both construction and seismic simulation.

  13. Application of Micro-Electro-Mechanical Sensors Contactless NDT of Concrete Structures

    PubMed Central

    Ham, Suyun; Popovics, John S.

    2015-01-01

    The utility of micro-electro-mechanical sensors (MEMS) for application in air-coupled (contactless or noncontact) sensing to concrete nondestructive testing (NDT) is studied in this paper. The fundamental operation and characteristics of MEMS are first described. Then application of MEMS sensors toward established concrete test methods, including vibration resonance, impact-echo, ultrasonic surface wave, and multi-channel analysis of surface waves (MASW), is demonstrated. In each test application, the performance of MEMS is compared with conventional contactless and contact sensing technology. Favorable performance of the MEMS sensors demonstrates the potential of the technology for applied contactless NDT efforts. Objective: To illustrate the utility of air-coupled MEMS sensors for concrete NDT, as compared with conventional sensor technology. PMID:25897497

  14. Hydrogeological Processes and Structure of the Rio Tinto Mars Analog: Some Insights for Mars Underground Water Fluxes

    NASA Astrophysics Data System (ADS)

    Gómez-Ortiz, D.; Fernández-Remolar, D. C.; Prieto-Ballesteros, O.; Gómez, F.

    2007-03-01

    The tectonic pattern that controls Rio Tinto Mars analog aquifer has been studied. Faults that define the groundwater flow have been identified. Similar faults affecting to the Mars basement probably played an essential role in transporting underground fl

  15. Solidification/stabilization of used abrasive media for non-structural concrete using portland cement. Interim research report

    SciTech Connect

    Webster, M.T.; Carrasquillo, R.L.; Loehr, R.C.; Fowler, D.W.

    1994-11-01

    Highway bridges in the United States are painted to resist corrosion and to help maintain the structural integrity of the bridge. Periodically, it is necessary to remove the existing paint so that the surface can be repainted. Most often the removal process consists of blasting the surface with an abrasive such as sand or slag. The blast media then contains elements present in the paint, such as cadmium, chromium and lead. The spent media may be a hazardous waste as defined by EPA`s Toxicity Characteristic (TC) criterion. This criterion uses the Toxicity Characteristic Leaching Procedure (TCLP) to determine whether a waste is classified as a hazardous waste. This procedure subjects the waste to a highly acidic environment in which chemicals can leach out of the waste. The leachate enviornment is then analyzed to determine the concentration of chemical leached, which must fall within the TC criterion. Some spent blasting material has been shown to have TCLP metal concentrations exceeding the TC criterion. The Texas Department of Transportation (TxDOT) has begun to recycle spent abrasive media in portland cement-based concrete using solidification/stabilization (S/S) techniques. This technology is designed to immobilize the metals while recycling the spent abrasive media as a component in non-structural concrete. The study has revealed the effectiveness of portland cement-based S/S systems in recycling contaminated spent abrasive media in portland cement-based concrete. The long-term leaching behavior of metals from these concrete products was examined using sequential extraction leaching tests.

  16. Design and installation of a cathodic protection system for a large reinforced concrete intake structure in the Arabian Gulf

    SciTech Connect

    Ali, M.; Al-Ghannam, H.

    1997-09-01

    The paper describes the condition survey methodology, design and installation of a cathodic protection (C.P.) system for a large reinforced concrete reservoir and sea water intake structure. The structure is critical for the supply of cooling water for a 2.4 million metric ton steel plant. The C.P. System consisting of mixed metal oxide coating on titanium mesh type anodes and automatic voltage/current controlled rectifiers was successfully installed and has been operating within design guidelines for the past 15 months.

  17. PLUTONIUM CONTAMINATION VALENCE STATE DETERMINATION USING X-RAY ABSORPTION FINE STRUCTURE PERMITS CONCRETE RECYCLE

    SciTech Connect

    Ervin, P. F.; Conradson, S. D.

    2002-02-25

    This paper describes the determination of the speciation of plutonium contamination present on concrete surfaces at the Rocky Flats Environmental Technology Site (RFETS). At RFETS, the plutonium processing facilities have been contaminated during multiple events over their 50 year operating history. Contamination has resulted from plutonium fire smoke, plutonium fire fighting water, milling and lathe operation aerosols, furnace operations vapors and plutonium ''dust'' diffusion.

  18. Effects of local underground structure and surface topography on waveforms from explosions recorded at the Source Physics Experiments site

    NASA Astrophysics Data System (ADS)

    Pitarka, A.; Mellors, R. J.; Rodgers, A.; Ford, S. R.; Harben, P. E.; Walter, W. R.; Wagoner, J. L.; Pasyanos, M. E.; Myers, S. C.; Vorobiev, O.; Xu, H.

    2012-12-01

    The far-field ground motions recorded along five radial lines during the first three SPE explosions are characterized by complex features, such as large azimuthal variations in P- and S-wave amplitudes, as well as substantial energy on the tangential component of motion. Shear wave energy is also observed on the tangential component of the near-field motion (epicentral distance < 20 m) suggesting that shear waves were also generated at or very near the source. These features become more pronounced as the waves propagate away from the source. In this study we investigate the effects of underground structure, including large-scale geologic features, a weathered granite surface layer and surface topography on wave propagation near the source region by modeling and analyzing the SPE waveforms. Anelastic finite-difference synthetic seismograms were calculated using WPP program and a 3D model. The 3D model is based on a regional geological model developed in EarthVision, with material properties constrained by shallow borehole data and tomography. By progressively including various geological features into the 3D model we were able to analyze separately their effects on wave propagation and scattering as well as their contributions to S-wave generation. In addition to modeling results obtained with an isotropic explosion source we will also show results of WPP simulations that use near-field synthetic motion calculated with GEODYN-L a Lagrangian hydrodynamic code for modeling the response of earth materials to explosion loading. The GEODYN-to-WPP coupling allows for a better representation of the physics of seismic energy generation and its propagation in the earth's crust.

  19. Design and operating characteristics of cathodic protection systems associated with large seawater intake reinforced concrete structures in the Arabian Gulf

    SciTech Connect

    Ali, M.; Chaudhary, Z.; Al-Muhid, T.M.M.

    1999-07-01

    The large reinforced concrete seawater intake structures, which are part of a cooling system in several petrochemical plants located in the Arabian Gulf, have been catholically protected to arrest chloride-induced corrosion of the steel reinforcement. The cathodic protection systems have an operating history of 1--5 years. The design and operating features of the cathodic protection systems are described and discussed. Monitoring data of each system collected over the years since commissioning of the systems are described and discussed to evaluate performance of each system.

  20. Zinc/hydrogel system for cathodic protection of reinforced concrete structures

    SciTech Connect

    Bennett, J.; Firlotte, C.

    1997-03-01

    Zinc, aluminum, and several aluminum alloys were tested as anodes in contact with hydrogel adhesives. Zinc was found to offer the best combination of working potential, resistance to passivation, cost, and availability. Several hydrogels used for medical applications were found to be inadequate for this use, but a hydrogel adhesive was developed specifically to bond sacrificial anodes to concrete. This hydrogel achieve a total charge in accelerated testing equal to 12 years of life at current densities normally used for cathodic protection (CP).

  1. A zinc/hydrogel system for cathodic protection of reinforced concrete structures

    SciTech Connect

    Bennett, J.; Firlotte, C.

    1996-11-01

    A zinc/hydrogel system has been developed for the cathodic protection of steel in reinforced concrete. This system consists of a thin foil of zinc which is attached to the concrete surface by an ionically conductive hydrogel adhesive. A direct electrical connection between the zinc and the reinforcing steel allows the zinc to function galvanically, polarizing the steel and protecting it from corrosion. Zinc, aluminum, and several aluminum alloys were tested as anodes in contact with hydrogel adhesives, and zinc was found to offer the best combination of working potential, resistance to passivation, cost and availability. Several hydrogels used for medical applications were found to be inadequate for this use, but a hydrogel adhesive was developed specifically to bond sacrificial anodes to concrete. This hydrogel achieved a total charge in accelerated testing equal to 12 years of life at current densities normally used for cathodic protection. Zinc/hydrogel was installed on about 1000 ft{sup 2} (100 m{sup 2}) of a fishing pier in Ft. Pierce, Florida on members including prestressed pilings, conventionally reinforced pile caps, and prestressed beams. Installation of this system was relatively easy, and initial performance is encouraging. After 5 months of service, adhesion is good and current densities remain high.

  2. Dual-band infrared imaging to detect corrosion damage within airframes and concrete structures

    SciTech Connect

    Del Grande, N.K.; Durbin, P.F.

    1994-01-01

    We are developing dual-band infrared (DBIR) imaging and detection techniques to inspect air frames and concrete bridge decks for hidden corrosion damage. Using selective DBIR image ratios,, we enhanced surface temperature contrast and removed surface emissivity noise associated with clutter. Our surface temperature maps depicted defect sites, which heat and cool at different rates than their surroundings. Our emissivity-ratio maps tagged and removed the masking effects of surface clutter. For airframe inspections, we used time-resolved DBIR temperature, emissivity-ratio and composite thermal inertia maps to locate corrosion-thinning effects within a flash-heated Boeing 737 airframe. Emissivity-ratio maps tagged and removed clutter sites from uneven paint, dirt and surface markers. Temperature and thermal inertia maps characterized defect sites, types, sizes, thicknesses, thermal properties and material-loss effects from air frame corrosion. For concrete inspections, we mapped DBIR temperature and emissivity-ratio patterns to better interpret surrogate delamination sites within naturally-heated, concrete slabs and remove the clutter mask from sand pile-up, grease stains, rocks and other surface objects.

  3. 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).

  4. Functional and structural failure mode overpressurization tests of 1:4-scale prestressed concrete containment vessel model.

    SciTech Connect

    Costello, James F. (United States Nuclear Regulatory Commission, Washington, DC); Shibata, Satoru (Nuclear Power Engineering Corporation, Tokyo, Japan); Hessheimer, Michael F.

    2003-02-01

    A 1:4-scale model of a prestressed concrete containment vessel (PCCV), representative of a pressurized water reactor (PWR) plant in Japan, was constructed by NUPEC at Sandia National Laboratories from January 1997 through June, 2000. Concurrently, Sandia instrumented the model with nearly 1500 transducers to measure strain, displacement and forces in the model from prestressing through the pressure testing. The limit state test of the PCCV model, culminating in functional failure (i.e. leakage by cracking and liner tearing) was conducted in September, 2000 at Sandia National Laboratories. After inspecting the model and the data after the limit state test, it became clear that, other than liner tearing and leakage, structural damage was limited to concrete cracking and the overall structural response (displacements, rebar and tendon strains, etc.) was only slightly beyond yield. (Global hoop strains at the mid-height of the cylinder only reached 0.4%, approximately twice the yield strain in steel.) In order to provide additional structural response data, for comparison with inelastic response conditions, the PCCV model filled nearly full with water and pressurized to 3.6 times the design pressure, when a catastrophic rupture occurred preceded only briefly by successive tensile failure of several hoop tendons. This paper summarizes the results of these tests.

  5. Testing of concrete by laser ablation

    DOEpatents

    Flesher, D.J.; Becker, D.L.; Beem, W.L.; Berry, T.C.; Cannon, N.S.

    1997-01-07

    A method is disclosed for testing concrete in a structure in situ, by: directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete; detecting a characteristic of energy which has been transferred to the concrete; determining, separately from the detecting step, the total quantity of concrete removed by the succession of pulses; and calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed. 1 fig.

  6. Testing of concrete by laser ablation

    DOEpatents

    Flesher, Dann J.; Becker, David L.; Beem, William L.; Berry, Tommy C.; Cannon, N. Scott

    1997-01-01

    A method of testing concrete in a structure in situ, by: directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete; detecting a characteristic of energy which has been transferred to the concrete; determining, separately from the detecting step, the total quantity of concrete removed by the succession of pulses; and calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed.

  7. Development of an advanced, high-frequency GPR technique for the assessment of concrete structures: from modeling predictions to experimental results

    NASA Astrophysics Data System (ADS)

    Cheilakou, Eleni; Matikas, Theodore E.

    2016-04-01

    The main objective of this paper is to develop a portable, advanced and high operating frequency GPR prototype system, which will be able to provide an increased sensitivity and resolution in terms of defects detectability at a penetration depth range up to 40-50 cm in concrete. For this purpose, the theoretical assessment of multiple GPR antenna-frequency approaches was initially performed using electromagnetic wave simulation tools for the propagation of radar waves within concrete, aiming to predict the required antenna frequency and characteristics that are most effective in detecting internal concrete elements and defects of interest found in realistic structures. Form the modeling results obtained, which are described in this paper, a portable, advanced, single-channel GPR system was developed, which uses a highfrequency shielded dipole antenna in monostatic arrangement and operates at a central operating frequency of 2600 MHz. Finally, the evaluation of the performance of the developed GPR technology was carried out under laboratory conditions, where concrete samples of varying dimensions and with different embedded structural features of known characteristics were tested. The validation results produced from this study indicated the high potential and efficiency of the developed GPR device to accurately detect internal concrete features with superior resolution and with sufficient penetration for concrete to be adequately resolved in depths up to 40 cm.

  8. Closure Report for Corrective Action Unit 135: Areas 25 Underground Storage Tanks, Nevada Test Site, Nevada

    SciTech Connect

    D. H. Cox

    2001-06-01

    Corrective Action Unit (CAU) 135, Area 25 Underground Storage Tanks, was closed in accordance with the approved Corrective Action Plan (DOE/NV, 2000). CAU 135 consists of three Corrective Action Sites (CAS). Two of these CAS's were identified in the Corrective Action Investigation Data Quality Objective meeting as being improperly identified as underground storage tanks. CAS 25-02-03 identified as the Deluge Valve Pit was actually an underground electrical vault and CAS 25-02-10 identified as an Underground Storage Tank was actually a former above ground storage tank filled with demineralized water. Both of these CAS's are recommended for a no further action closure. CAS 25-02-01 the Underground Storage Tanks commonly referred to as the Engine Maintenance Assembly and Disassembly Waste Holdup Tanks and Vault was closed by decontaminating the vault structure and conducting a radiological verification survey to document compliance with the Nevada Test Site unrestricted use release criteria. The Area 25 Underground Storage Tanks, (CAS 25-02-01), referred to as the Engine Maintenance, Assembly, and Disassembly (E-MAD) Waste Holdup Tanks and Vault, were used to receive liquid waste from all of the radioactive and cell service area drains at the E-MAD Facility. Based on the results of the Corrective Action Investigation conducted in June 1999, discussed in ''The Corrective Action Investigation Plan for Corrective Action Unit 135: Area 25 Underground Storage Tanks, Nevada Test Site, Nevada'' (DOE/NV, 199a), one sample from the radiological survey of the concrete vault interior exceeded radionuclide preliminary action levels. The analytes from the sediment samples exceeded the preliminary action levels for polychlorinated biphenyls, Resource Conservation and Recovery Act metals, total petroleum hydrocarbons as diesel-range organics, and radionuclides. The CAU 135 closure activities consisted of scabbling radiological ''hot spots'' from the concrete vault, and the drilling

  9. Application of micro X-ray diffraction to investigate the reaction products formed by the alkali silica reaction in concrete structures

    SciTech Connect

    Dähn, R.; Arakcheeva, A.; Schaub, Ph.; Pattison, P.; Chapuis, G.; Grolimund, D.; Wieland, E.; Leemann, A.

    2015-12-21

    Alkali–silica reaction (ASR) is one of the most important deterioration mechanisms in concrete leading to substantial damages of structures worldwide. Synchrotron-based micro-X-ray diffraction (micro-XRD) was employed to characterize the mineral phases formed in micro-cracks of concrete aggregates as a consequence of ASR. This particular high spatial resolution technique enables to directly gain structural information on ASR products formed in a 40-year old motorway bridge damaged due to ASR. Micro-X-ray-fluorescence was applied on thin sections to locate the reaction products formed in veins within concrete aggregates. Micro-XRD pattern were collected at selected points of interest along a vein by rotating the sample. Rietveld refinement determined the structure of the ASR product consisting of a new layered framework similar to mountainite and rhodesite. Furthermore, it is conceivable that understanding the structure of the ASR product may help developing new technical treatments inhibiting ASR.

  10. Stability analyses of the mass abrasive projectile high-speed penetrating into concrete target. Part II: Structural stability analyses

    NASA Astrophysics Data System (ADS)

    Wu, Hao; Chen, Xiao-Wei; Fang, Qin; He, Li-Lin

    2014-12-01

    The initial oblique and attacking angles as well as the asymmetrical nose abrasion may lead to bending or even fracture of a projectile, and the penetration efficiency decreases distinctly. The structural stability of a high-speed projectile non-normally penetrating into concrete and the parametric influences involved are analyzed with the mass abrasion taken into account. By considering the symmetrical or asymmetrical nose abrasion as well as the initial oblique and attacking angles, both the axial and the transverse drag forces acting on the projectile are derived. Based on the ideal elastic-plastic yield criterion, an approach is proposed for predicting the limit striking velocity (LSV) that is the highest velocity at which no yielding failure has occurred and the projectile can still maintain its integral structural stability. Furthermore, some particular penetration scenarios are separately discussed in detail. Based on the engineering model for the mass loss and nose-blunting of ogive-nose projectiles established in Part I of this study, the above approach is validated by several high-speed penetration tests. The analysis on parametric influences indicates that the LSV is reduced with an increase in the asymmetrical nose abrasion, the length-diameter-ratio, and the concrete strength, as well as the oblique and attacking angles. Also, the LSV raises with an increase in the initial caliber-radius-head (CRH) and the dimensionless cartridge thickness of a projectile.

  11. Analyzing environmental and structural charactersitics of concrete for carbon mitigation and climate adaptation in urban areas: A case study in Rajkot, India

    NASA Astrophysics Data System (ADS)

    Solis, Andrea Valdez

    Increasing temperatures, varying rain events accompanied with flooding or droughts coupled with increasing water demands, and decreasing air quality are just some examples of stresses that urban systems face with the onset of climate change and rapid urbanization. Literature suggests that greenhouse gases are a leading cause of climate change and are of a result of anthropogenic activities such as infrastructure development. Infrastructure development is heavily dependent on the production of concrete. Yet, concrete can contribute up to 7% of total CO29 emissions globally from cement manufacturing alone. The goal of this dissertation was to evaluate current concrete technologies that could contribute to carbon mitigation and climate adaptation in cities. The objectives used to reach the goal of the study included (1) applying a material flow and life cycle analysis (MFA-LCA) to determine the environmental impacts of pervious and high volume fly ash (HVFA) concrete compared to ordinary portland cement (OPC) concrete in a developing country; (2) performing a comparative assessment of pervious concrete mixture designs for structural and environmental benefits across the U.S. and India; and (3) Determining structural and durability benefits from HVFA concrete mixtures when subjected to extreme hot weather conditions (a likely element of climate change). The study revealed that cities have a choice in reducing emissions, improving stormwater issues, and developing infrastructure that can sustain higher temperatures. Pervious and HVFA concrete mixtures reduce emissions by 21% and 47%, respectively, compared to OPC mixtures. A pervious concrete demonstration in Rajkot, India showed improvements in water quality (i.e. lower levels of nitrogen by as much as 68% from initial readings), and a reduction in material costs by 25%. HVFA and OPC concrete mixtures maintained compressive strengths above a design strength of 27.6 MPa (4000 psi), achieved low to moderate permeability

  12. Behavior of full-scale concrete segmented pipelines under permanent ground displacements

    NASA Astrophysics Data System (ADS)

    Kim, Junhee; O'Connor, Sean; Nadukuru, Srinivasa; Lynch, Jerome P.; Michalowski, Radoslaw; Green, Russell A.; Pour-Ghaz, Mohammed; Weiss, W. Jason; Bradshaw, Aaron

    2010-03-01

    Concrete pipelines are one of the most popular underground lifelines used for the transportation of water resources. Unfortunately, this critical infrastructure system remains vulnerable to ground displacements during seismic and landslide events. Ground displacements may induce significant bending, shear, and axial forces to concrete pipelines and eventually lead to joint failures. In order to understand and model the typical failure mechanisms of concrete segmented pipelines, large-scale experimentation is necessary to explore structural and soil-structure behavior during ground faulting. This paper reports on the experimentation of a reinforced concrete segmented concrete pipeline using the unique capabilities of the NEES Lifeline Experimental and Testing Facilities at Cornell University. Five segments of a full-scale commercial concrete pressure pipe (244 cm long and 37.5 cm diameter) are constructed as a segmented pipeline under a compacted granular soil in the facility test basin (13.4 m long and 3.6 m wide). Ground displacements are simulated through translation of half of the test basin. A dense array of sensors including LVDT's, strain gages, and load cells are installed along the length of the pipeline to measure the pipeline response while the ground is incrementally displaced. Accurate measures of pipeline displacements and strains are captured up to the compressive and flexural failure of the pipeline joints.

  13. State-of-the-art of non-destructive testing methods and technologies for application to nuclear power plant safety-related concrete structures

    SciTech Connect

    Wiggenhauser, Herbert; Naus, Dan J.

    2014-02-18

    The inspection of nuclear power plant concrete structures presents challenges different from conventional civil engineering structures. Wall thicknesses can be in excess of one meter and the structures often have increased steel reinforcement density with more complex detailing. The accessibility for any testing method may be limited due to the presence of liners and other components and there can be a number of penetrations or cast-in-place items present. The objective of the report is to present the state-of-the art of non-destructive testing methods and technologies for the inspection of thick, heavily-reinforced nuclear power plant concrete cross-sections with particular respect to: •locating steel reinforcement and identification of its cover depth •locating tendon ducts and identification of the condition of the grout materials •detection of cracking, voids, delamination, and honeycombing in concrete structures •detection of inclusions of different materials or voids adjacent to the concrete side of the containment liner •methods capable of identification of corrosion occurrence on the concrete side of the containment liner.

  14. State-of-the-Art of Non-Destructive Testing Methods and Technologies for Application to Nuclear Power Plant Safety-Related Concrete Structures

    SciTech Connect

    Wiggenhauser, Dr. Herbert; Naus, Dan J

    2014-01-01

    The inspection of nuclear power plant concrete structures presents challenges different from conventional civil engineering structures. Wall thicknesses can be in excess of one meter and the structures often have increased steel reinforcement density with more complex detailing. The accessibility for any testing method may be limited due to the presence of liners and other components and there can be a number of penetrations or cast-in-place items present. The objective of the report is to present the state-of-the art of non-destructive testing methods and technologies for the inspection of thick, heavily-reinforced nuclear power plant concrete cross-sections with particular respect to: locating steel reinforcement and identification of its cover depth locating tendon ducts and identification of the condition of the grout materials detection of cracking, voids, delamination, and honeycombing in concrete structures detection of inclusions of different materials or voids adjacent to the concrete side of the containment liner methods capable of identification of corrosion occurrence on the concrete side of the containment liner

  15. Optimal seismic design of reinforced concrete structures under time-history earthquake loads using an intelligent hybrid algorithm

    NASA Astrophysics Data System (ADS)

    Gharehbaghi, Sadjad; Khatibinia, Mohsen

    2015-03-01

    A reliable seismic-resistant design of structures is achieved in accordance with the seismic design codes by designing structures under seven or more pairs of earthquake records. Based on the recommendations of seismic design codes, the average time-history responses (ATHR) of structure is required. This paper focuses on the optimal seismic design of reinforced concrete (RC) structures against ten earthquake records using a hybrid of particle swarm optimization algorithm and an intelligent regression model (IRM). In order to reduce the computational time of optimization procedure due to the computational efforts of time-history analyses, IRM is proposed to accurately predict ATHR of structures. The proposed IRM consists of the combination of the subtractive algorithm (SA), K-means clustering approach and wavelet weighted least squares support vector machine (WWLS-SVM). To predict ATHR of structures, first, the input-output samples of structures are classified by SA and K-means clustering approach. Then, WWLS-SVM is trained with few samples and high accuracy for each cluster. 9- and 18-storey RC frames are designed optimally to illustrate the effectiveness and practicality of the proposed IRM. The numerical results demonstrate the efficiency and computational advantages of IRM for optimal design of structures subjected to time-history earthquake loads.

  16. The Shock and Vibration Bulletin. Part 3: Structure Medium Interaction, Case Studies in Dynamics

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Structure and medium interactions topics are addressed. Topics include: a failure analysis of underground concrete structures subjected to blast loadings, an optimization design procedure for concrete slabs, and a discussion of the transient response of a cylindrical shell submerged in a fluid. Case studies in dynamics are presented which include an examination of a shock isolation platform for a seasparrow launcher, a discussion of hydrofoil fatigue load environments, and an investigation of the dynamic characteristics of turbine generators and low tuned foundations.

  17. Some considerations in the evaluation of concrete as a structural material for alternative LLW (low-level radioactive waste) disposal technologies

    SciTech Connect

    MacKenzie, D.R.; Siskind, B.; Bowerman, B.S.; Piciulo, P.L.

    1987-01-01

    The objective of this study was to develop information needed to evaluate the long-term performance of concrete and reinforced concrete as a structural material for alternative LLW disposal methods. The capability to carry out such an evaluation is required for licensing a site which employs one of these alternative methods. The basis for achieving the study objective was the review and analysis of the literature on concrete and its properties, particularly its durability. In carrying out this program characteristics of concrete useful in evaluating its performance and factors that can affect its performance were identified. The factors are both intrinsic, i.e., associated with composition of the concrete (and thus controllable), and extrinsic, i.e., due to external environmental forces such as climatic conditions and aggressive chemicals in the soil. The testing of concrete, using both accelerated tests and long-term non-accelerated tests, is discussed with special reference to its application to modeling of long-term performance prediction. On the basis of the study's results, conditions for acceptance are recommended as an aid in the licensing of disposal sites which make use of alternative methods.

  18. Water Underground

    NASA Astrophysics Data System (ADS)

    de Graaf, I. E. M.

    2014-12-01

    The world's largest accessible source of freshwater is hidden underground. However it remains difficult to estimate its volume, and we still cannot answer the question; will there be enough for everybody? In many places of the world groundwater abstraction is unsustainable: more water is used than refilled, leading to decreasing river discharges and declining groundwater levels. It is predicted that for many regions in the world unsustainable water use will increase in the coming decades, due to rising human water use under a changing climate. It would not take long before water shortage causes widespread droughts and the first water war begins. Improving our knowledge about our hidden water is the first step to prevent such large water conflicts. The world's largest aquifers are mapped, but these maps do not mention how much water these aquifers contain or how fast water levels decline. If we can add thickness and geohydrological information to these aquifer maps, we can estimate how much water is stored and its flow direction. Also, data on groundwater age and how fast the aquifer is refilled is needed to predict the impact of human water use and climate change on the groundwater resource. Ultimately, if we can provide this knowledge water conflicts will focus more on a fair distribution instead of absolute amounts of water.

  19. Water underground

    NASA Astrophysics Data System (ADS)

    de Graaf, Inge

    2015-04-01

    The world's largest assessable source of freshwater is hidden underground, but we do not know what is happening to it yet. In many places of the world groundwater is abstracted at unsustainable rates: more water is used than being recharged, leading to decreasing river discharges and declining groundwater levels. It is predicted that for many regions of the world unsustainable water use will increase, due to increasing human water use under changing climate. It would not be long before shortage causes widespread droughts and the first water war begins. Improving our knowledge about our hidden water is the first step to stop this. The world largest aquifers are mapped, but these maps do not mention how much water they contain or how fast water levels decline. If we can add a third dimension to the aquifer maps, so a thickness, and add geohydrological information we can estimate how much water is stored. Also data on groundwater age and how fast it is refilled is needed to predict the impact of human water use and climate change on the groundwater resource.

  20. A viscoelastic Unitary Crack-Opening strain tensor for crack width assessment in fractured concrete structures

    NASA Astrophysics Data System (ADS)

    Sciumè, Giuseppe; Benboudjema, Farid

    2016-09-01

    A post-processing technique which allows computing crack width in concrete is proposed for a viscoelastic damage model. Concrete creep is modeled by means of a Kelvin-Voight cell while the damage model is that of Mazars in its local form. Due to the local damage approach, the constitutive model is regularized with respect to finite element mesh to avoid mesh dependency in the computed solution (regularization is based on fracture energy). The presented method is an extension to viscoelasticity of the approach proposed by Matallah et al. (Int. J. Numer. Anal. Methods Geomech. 34(15):1615-1633, 2010) for a purely elastic damage model. The viscoelastic Unitary Crack-Opening (UCO) strain tensor is computed accounting for evolution with time of surplus of stress related to damage; this stress is obtained from decomposition of the effective stress tensor. From UCO the normal crack width is then derived accounting for finite element characteristic length in the direction orthogonal to crack. This extension is quite natural and allows for accounting of creep impact on opening/closing of cracks in time dependent problems. A graphical interpretation of the viscoelastic UCO using Mohr's circles is proposed and application cases together with a theoretical validation are presented to show physical consistency of computed viscoelastic UCO.

  1. Microwave NDE for Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Arunachalam, Kavitha; Melapudi, Vikram R.; Rothwell, Edward J.; Udpa, Lalita; Udpa, Satish S.

    2006-03-01

    Nondestructive assessment of the integrity of civil structures is of paramount importance for ensuring safety. In concrete imaging, radiography, ground penetrating radar and infrared thermography are some of the widely used techniques for health monitoring. Other emerging technologies that are gaining impetus for detecting and locating flaws in steel reinforcement bar include radioactive computed tomography, microwave holography, microwave and acoustic tomography. Of all the emerging techniques, microwave NDT is a promising imaging modality largely due to their ability to penetrate thick concrete structures, contrast between steel rebar and concrete and their non-radioactive nature. This paper investigates the feasibility of a far field microwave NDE technique for reinforced concrete structures.

  2. Biodecontamination of concrete

    SciTech Connect

    Hamilton, M.A.; Rogers, R.D.; Benson, J.

    1996-12-31

    A novel technology for biologically decontaminating concrete is being jointly developed by scientists at the Idaho National Engineering Laboratory (INEL) and British Nuclear Fuels plc (BNFL). The technology exploits a naturally occurring phenomenon referred to as microbially influenced degradation (MID) in which bacteria produce acids that dissolve the cement matrix of concrete. Most radionuclide contamination of concrete is fixed in the outer few mm of the concrete surface. By capturing and controlling this natural process, a biological method of removing the surface of concrete to depths up to several mm is being developed. Three types of bacteria are known to be important in MID of concrete: nitrifying bacteria that produce nitric acid, sulfur oxidizing bacteria that produce sulfuric acid, and certain heterotrophic bacteria that produce organic acids. An investigation of natural environments demonstrated with scanning electron microscopy the presence of bacteria on concrete surfaces of a variety of structures, such as bridges and dams, where corrosion is evident. Enumeration of sulfur oxidizing and nitrifying bacteria revealed their presence and activity on structures to varying degrees in different environments. Under ideal conditions, Thiobacillus thiooxidans, a sulfur oxidizing bacteria, attached to and colonized the surface of concrete specimens. Over 1mm depth of material from a 10 cm x 10 cm square surface was removed in 68 days in the Thiobacillus treated specimen compared to a sterile control. Laboratory and field demonstrations are currently being conducted using experimental chambers designed to be mounted directly to concrete surfaces where radionuclide contamination exists. Data is being obtained in order to determine actual rates of surface removal and limitations to the system. This information will be used to develop a full scale decontamination technology.

  3. Effects of fertilizer and pesticides on concrete

    SciTech Connect

    Broder, M.F.; Nguyen, D.T.; Harner, A.L.

    1994-12-31

    Concrete is the most common material of construction for secondary containment of fertilizers and pesticides because of its relative low cost and structural properties. Concrete, however, is porous to some products it is designed to contain and is subject to corrosion. In this paper, concrete deterioration mechanisms and corrosion resistant concrete formulation are discussed, as well as exposure tests of various concrete mixes to some common liquid fertilizers and herbicides.

  4. Examples of Solutions for Steel-Concrete Composite Structures in Bridge Engineering / Przykłady Konstrukcji Zespolonych W Budownictwie Mostowym

    NASA Astrophysics Data System (ADS)

    Flaga, Kazimierz; Furtak, Kazimierz

    2015-03-01

    The aim of the article [1] was to discuss the application of steel-concrete composite structures in bridge engineering in the aspect of structural design, analysis and execution. It was pointed out that the concept of steel-concrete structural composition is far from exhausted and new solutions interesting from the engineering, scientific and aesthetic points of view of are constantly emerging. These latest trends are presented against the background of the solutions executed in Poland and abroad. Particular attention is focused on structures of double composition and steel-concrete structures. Concrete filled steel tubular (CFST) structures are highlighted. W artykule [1] omówiono problemy konstrukcyjne, obliczeniowe i realizacyjne, związane z zastosowaniem konstrukcji zespolonych stal-beton w mostownictwie. Wskazano tam, że idea konstrukcyjnego zespolenia stali z betonem jest jeszcze daleka do wyczerpania i że wciąż pojawiają się nowe rozwiązania interesujące z inżynierskiego, naukowego i estetycznego punktu widzenia. W artykule niniejszym pokazano te nowoczesne trendy na tle rozwiązań zrealizowanych w Polsce i na świecie. Szczególną uwagę poświęcono konstrukcjom podwójnie zespolonym oraz konstrukcjom stalowobetonowym. Wyeksponowano tu szczególnie konstrukcje z rur stalowych wypełnionych betonem, typu CFST. Dają one nadzieję na ich szersze zastosowanie w warunkach polskich.

  5. 36. VAL, DETAIL OF TYPICAL INTERIOR OF CONCRETE 'A' FRAME ...

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

    36. VAL, DETAIL OF TYPICAL INTERIOR OF CONCRETE 'A' FRAME STRUCTURE SHOWING PAINTED CONCRETE WALLS, CONCRETE STAIRS AND INTERIOR WOOD DOOR. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  6. To What Degree Does Handling Concrete Molecular Models Promote the Ability to Translate and Coordinate between 2D and 3D Molecular Structure Representations? A Case Study with Algerian Students

    ERIC Educational Resources Information Center

    Mohamed-Salah, Boukhechem; Alain, Dumon

    2016-01-01

    This study aims to assess whether the handling of concrete ball-and-stick molecular models promotes translation between diagrammatic representations and a concrete model (or vice versa) and the coordination of the different types of structural representations of a given molecular structure. Forty-one Algerian undergraduate students were requested…

  7. Integrated model for assessing the cost and CO2 emission (IMACC) for sustainable structural design in ready-mix concrete.

    PubMed

    Hong, Taehoon; Ji, Changyoon; Park, Hyoseon

    2012-07-30

    Cost has traditionally been considered the most important factor in the decision-making process. Recently, along with the consistent interest in environmental problems, environmental impact has also become a key factor. Accordingly, there is a need to develop a method that simultaneously reflects the cost and environmental impact in the decision-making process. This study proposed an integrated model for assessing the cost and CO(2) emission (IMACC) at the same time. IMACC is a model that assesses the cost and CO(2) emission of the various structural-design alternatives proposed in the structural-design process. To develop the IMACC, a standard on assessing the cost and CO(2) emission generated in the construction stage was proposed, along with the CO(2) emission factors in the structural materials, based on such materials' strengths. Moreover, using the economic and environmental scores that signify the cost and CO(2) emission reduction ratios, respectively, a method of selecting the best design alternative was proposed. To verify the applicability of IMACC, practical application was carried out. Structural designs were assessed, each of which used 21, 24, 27, and 30 MPa ready-mix concrete (RMC). The use of IMACC makes it easy to verify what the best design is. Results show the one that used 27 MPa RMC was the best design. Therefore, the proposed IMACC can be used as a tool for supporting the decision-making process in selecting the best design alternative. PMID:22436837

  8. Investigation of Deterioration Behavior of Hysteretic Loops in Nonlinear Static Procedure Analysis of Concrete Structures with Shear Walls

    SciTech Connect

    Ghodrati Amiri, G.; Amidi, S.; Khorasani, M.

    2008-07-08

    In the recent years, scientists developed the seismic rehabilitation of structures and their view points were changed from sufficient strength to the performance of structures (Performance Base Design) to prepare a safe design. Nonlinear Static Procedure analysis (NSP) or pushover analysis is a new method that is chosen for its speed and simplicity in calculations. 'Seismic Rehabilitation Code for Existing Buildings' and FEMA 356 considered this method. Result of this analysis is a target displacement that is the base of the performance and rehabilitation procedure of the structures. Exact recognition of that displacement could develop the workability of pushover analysis. In these days, Nonlinear Dynamic Analysis (NDP) is only method can exactly apply the seismic ground motions. In this case because it consumes time, costs very high and is more difficult than other methods, is not applicable as much as NSP. A coefficient used in NSP for determining the target displacement is C2 (Stiffness and Strength Degradations Coefficient) and is applicable for correcting the errors due to eliminating the stiffness and strength degradations in hysteretic loops. In this study it has been tried to analysis three concrete frames with shear walls by several accelerations that scaled according to FEMA 273 and FEMA 356. These structures were designed with Iranian 2800 standard (vers.3). Finally after the analyzing by pushover method and comparison results with dynamic analysis, calculated C2 was comprised with values in rehabilitation codes.

  9. Effects of Cylindrical Charge Geometry and Secondary Combustion Reactions on the Internal Blast Loading of Reinforced Concrete Structures

    SciTech Connect

    Price, Matthew A.

    2005-05-01

    An understanding of the detonation phenomenon and airblast behavior for cylindrical high-explosive charges is essential in developing predictive capabilities for tests and scenarios involving these charge geometries. Internal tests on reinforced concrete structures allowed for the analysis of cylindrical charges and the effect of secondary reactions occurring in confined structures. The pressure profiles that occur close to a cylindrical explosive charge are strongly dependent on the length-to-diameter ratio (L/D) of the charge. This study presents a comparison of finite-element code models (i.e., AUTODYN) to empirical methods for predicting airblast behavior from cylindrical charges. Current finite element analysis (FEA) and blast prediction codes fail to account for the effects of secondary reactions (fireballs) that occur with underoxidized explosives. Theoretical models were developed for TNT and validated against literature. These models were then applied to PBX 9501 for predictions of the spherical fireball diameter and time duration. The following relationships for PBX 9501 were derived from this analysis (units of ft, lb, s). Comparison of centrally located equivalent weight charges using cylindrical and spherical geometries showed that the average impulse on the interior of the structure is ~3%–5% higher for the spherical charge. Circular regions of high impulse that occur along the axial direction of the cylindrical charge must be considered when analyzing structural response.

  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. Underground Layout Configuration

    SciTech Connect

    A. Linden

    2003-09-25

    The purpose of this analysis was to develop an underground layout to support the license application (LA) design effort. In addition, the analysis will be used as the technical basis for the underground layout general arrangement drawings.

  12. Modeling, Analysis, and Preservation Techniques for Historic Reinforced Concrete Structures in Seismic Prone Regions Case Study: Augusta Airship Hangar, Sicily

    SciTech Connect

    Cronin, Kelly; Whyte, Catherine; Reiner, Tom

    2008-07-08

    also can be used as an example for the rehabilitation of other historic structures. The techniques and processes discussed in this paper can be applied to other historic reinforced concrete structures and can be expanded upon in future investigations.

  13. Nonlinear ultrasonic guided waves for prestress level monitoring in prestressing strands for post-tensioned concrete structures

    NASA Astrophysics Data System (ADS)

    Nucera, Claudio; Lanza di Scalea, Francesco

    2011-04-01

    Monitoring load levels in multi-wire steel strands is crucial to ensuring the proper structural performance of post-tensioned concrete structures, suspension bridges and cable-stayed bridges. The post-tensioned box-girder structural scheme is widely used in several bridges, including 90% of the California inventory. In this structural typology, prestressing tendons are the main load-carrying components. Therefore loss of prestress as well as the presence of structural defects (e.g. corrosion and broken wires) affecting these elements are critical for the performance of the entire structure and may conduct to catastrophic failures. Unfortunately, at present there is no well-established methodology for the monitoring of prestressing (PS) tendons able to provide simultaneous and continuous information about the presence of defects as well as prestress levels. In this paper the authors develop a methodology to assess the level of load applied to the strands through the use of ultrasonic nonlinearity. Since an axial load on a multi-wire strand generates proportional contact stresses between adjacent wires, ultrasonic nonlinearity from the inter-wire contact must be related to the level of axial load. The work presented shows that the higher-harmonic generation of ultrasonic guided waves propagating in individual wires of the strand varies monotonically with the applied load, with smaller higher-harmonic amplitudes with increasing load levels. This trend is consistent with previous studies on higher-harmonic generation from ultrasonic plane waves incident on a contact interface under a changing contact pressure. The paper presents the results of experimental researches on free strands and embedded strands, and numerical studies (nonlinear Finite Element Analysis) on free strands.

  14. Mossbauer Spectroscopic Study of Gamma Irradiation on the Structural Properties of Hematite, Magnetite and Limonite Concrete for Nuclear Reactor Shielding

    NASA Astrophysics Data System (ADS)

    Eissa, N. A.; Kany, M. S. I.; Mohamed, A. S.; Sallam, A. A.; El Fouly, M. H.

    1998-12-01

    This work investigate the effect of gamma irradiation on a heavy type of concrete, constructed for nuclear reactor shield. The effect of gamma irradiation was studied after annealing the concrete samples at 300°C for 24 hours in air.

  15. Bacterial concrete

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, Venkataswamy; Ramesh, K. P.; Bang, S. S.

    2001-04-01

    Cracks in concrete are inevitable and are one of the inherent weaknesses of concrete. Water and other salts seep through these cracks, corrosion initiates, and thus reduces the life of concrete. So there was a need to develop an inherent biomaterial, a self-repairing material which can remediate the cracks and fissures in concrete. Bacterial concrete is a material, which can successfully remediate cracks in concrete. This technique is highly desirable because the mineral precipitation induced as a result of microbial activities is pollution free and natural. As the cell wall of bacteria is anionic, metal accumulation (calcite) on the surface of the wall is substantial, thus the entire cell becomes crystalline and they eventually plug the pores and cracks in concrete. This paper discusses the plugging of artificially cracked cement mortar using Bacillus Pasteurii and Sporosarcina bacteria combined with sand as a filling material in artificially made cuts in cement mortar which was cured in urea and CaCl2 medium. The effect on the compressive strength and stiffness of the cement mortar cubes due to the mixing of bacteria is also discussed in this paper. It was found that use of bacteria improves the stiffness and compressive strength of concrete. Scanning electron microscope (SEM) is used to document the role of bacteria in microbiologically induced mineral precipitation. Rod like impressions were found on the face of calcite crystals indicating the presence of bacteria in those places. Energy- dispersive X-ray (EDX) spectra of the microbial precipitation on the surface of the crack indicated the abundance of calcium and the precipitation was inferred to be calcite (CaCO3).

  16. Evaluation of ilmenite serpentine concrete and ordinary concrete as nuclear reactor shielding

    NASA Astrophysics Data System (ADS)

    Abulfaraj, Waleed H.; Kamal, Salah M.

    1994-07-01

    The present study involves adapting a formal decision methodology to the selection of alternative nuclear reactor concretes shielding. Multiattribute utility theory is selected to accommodate decision makers' preferences. Multiattribute utility theory (MAU) is here employed to evaluate two appropriate nuclear reactor shielding concretes in terms of effectiveness to determine the optimal choice in order to meet the radiation protection regulations. These concretes are Ordinary concrete (O.C.) and Ilmenite Serpentile concrete (I.S.C.). These are normal weight concrete and heavy heat resistive concrete, respectively. The effectiveness objective of the nuclear reactor shielding is defined and structured into definite attributes and subattributes to evaluate the best alternative. Factors affecting the decision are dose received by reactor's workers, the material properties as well as cost of concrete shield. A computer program is employed to assist in performing utility analysis. Based upon data, the result shows the superiority of Ordinary concrete over Ilmenite Serpentine concrete.

  17. 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

  18. 49 CFR 192.325 - Underground clearance.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... installed with enough clearance from any other underground structure to allow proper maintenance and to... prevent the heat from impairing the serviceability of the pipe. (d) Each pipe-type or bottle-type...

  19. 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.

  20. Methodology for reliability based condition assessment. Application to concrete structures in nuclear plants

    SciTech Connect

    Mori, Y.; Ellingwood, B.

    1993-08-01

    Structures in nuclear power plants may be exposed to aggressive environmental effects that cause their strength to decrease over an extended period of service. A major concern in evaluating the continued service for such structures is to ensure that in their current condition they are able to withstand future extreme load events during the intended service life with a level of reliability sufficient for public safety. This report describes a methodology to facilitate quantitative assessments of current and future structural reliability and performance of structures in nuclear power plants. This methodology takes into account the nature of past and future loads, and randomness in strength and in degradation resulting from environmental factors. An adaptive Monte Carlo simulation procedure is used to evaluate time-dependent system reliability. The time-dependent reliability is sensitive to the time-varying load characteristics and to the choice of initial strength and strength degradation models but not to correlation in component strengths within a system. Inspection/maintenance strategies are identified that minimize the expected future costs of keeping the failure probability of a structure at or below an established target failure probability during its anticipated service period.

  1. Molecular Survey of Concrete Biofilm Microbial Communities

    EPA Science Inventory

    Although several studies have shown that bacteria can deteriorate concrete structures, there is very little information on the composition of concrete microbial communities. To this end, we studied different microbial communities associated with concrete biofilms using 16S rRNA g...

  2. Lateral Force Distribution and Behavior of Mixed Structure of Wood and Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Tsuji, Takuya; Isoda, Hiroshi

    In this paper, modal analysis has been carried out to study lateral force distribution caused by the difference between stiffness and the weight to hybrid structure of upper wooden story and lower RC story, and the level of plastification and damages are discussed by referring to inelastic time history analysis.

  3. 30 CFR 75.811 - High-voltage underground equipment; grounding.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage underground equipment; grounding... COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution § 75.811 High-voltage underground equipment; grounding. Frames, supporting structures...

  4. 30 CFR 75.811 - High-voltage underground equipment; grounding.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false High-voltage underground equipment; grounding... COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution § 75.811 High-voltage underground equipment; grounding. Frames, supporting structures...

  5. 30 CFR 75.811 - High-voltage underground equipment; grounding.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false High-voltage underground equipment; grounding... COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution § 75.811 High-voltage underground equipment; grounding. Frames, supporting structures...

  6. 30 CFR 75.811 - High-voltage underground equipment; grounding.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false High-voltage underground equipment; grounding... COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution § 75.811 High-voltage underground equipment; grounding. Frames, supporting structures...

  7. Health monitoring of prestressing tendons in post-tensioned concrete structures

    NASA Astrophysics Data System (ADS)

    Salamone, Salvatore; Bartoli, Ivan; Nucera, Claudio; Phillips, Robert; Lanza di Scalea, Francesco

    2011-04-01

    Currently 90% of bridges built in California are post-tensioned box-girder. In such structures the steel tendons are the main load-carrying components. The loss of prestress, as well as the presence of defects or the tendon breakage, can be catastrophic for the entire structure. Unfortunately, today there is no well-established method for the monitoring of prestressing (PS) tendons that can provide simultaneous information related to the presence of defects and the level of prestress in a continuous, real time manner. If such a monitoring system were available, considerable savings would be achieved in bridge maintenance since repairs would be implemented in a timely manner without traffic disruptions. This paper presents a health monitoring system for PS tendons in post-tensioned structures of interest to Caltrans. Such a system uses ultrasonic guided waves and embedded sensors to provide simultaneously and in real time, (a) measurements of the level of applied prestress, and (b) defect detection at early grow stages. The proposed PS measurement technique exploits the sensitivity of ultrasonic waves to the inter-wire contact developing in a multi-wire strand as a function of prestress level. In particular the nonlinear ultrasonic behavior of the tendon under changing levels of prestress is monitored by tracking higher-order harmonics at (nω) arising under a fundamental guided-wave excitation at (ω). Moreover this paper also present real-time damage detection and location in post-tensioned bridge joints using Acoustic Emission techniques. Experimental tests on large-scale single-tendon PT joint specimens, subjected to multiple load cycles, will be presented to validate the monitoring of PS loads (through nonlinear ultrasonic probing) and the monitoring of damage progression and location (through acoustic emission techniques). Issues and potential for the use of such techniques to monitor post-tensioned bridges in the field will be discussed.

  8. Optimal Image Stitching for Concrete Bridge Bottom Surfaces Aided by 3d Structure Lines

    NASA Astrophysics Data System (ADS)

    Liu, Yahui; Yao, Jian; Liu, Kang; Lu, Xiaohu; Xia, Menghan

    2016-06-01

    Crack detection for bridge bottom surfaces via remote sensing techniques is undergoing a revolution in the last few years. For such applications, a large amount of images, acquired with high-resolution industrial cameras close to the bottom surfaces with some mobile platform, are required to be stitched into a wide-view single composite image. The conventional idea of stitching a panorama with the affine model or the homographic model always suffers a series of serious problems due to poor texture and out-of-focus blurring introduced by depth of field. In this paper, we present a novel method to seamlessly stitch these images aided by 3D structure lines of bridge bottom surfaces, which are extracted from 3D camera data. First, we propose to initially align each image in geometry based on its rough position and orientation acquired with both a laser range finder (LRF) and a high-precision incremental encoder, and these images are divided into several groups with the rough position and orientation data. Secondly, the 3D structure lines of bridge bottom surfaces are extracted from the 3D cloud points acquired with 3D cameras, which impose additional strong constraints on geometrical alignment of structure lines in adjacent images to perform a position and orientation optimization in each group to increase the local consistency. Thirdly, a homographic refinement between groups is applied to increase the global consistency. Finally, we apply a multi-band blending algorithm to generate a large-view single composite image as seamlessly as possible, which greatly eliminates both the luminance differences and the color deviations between images and further conceals image parallax. Experimental results on a set of representative images acquired from real bridge bottom surfaces illustrate the superiority of our proposed approaches.

  9. Underground laboratories in Asia

    SciTech Connect

    Lin, Shin Ted; Yue, Qian

    2015-08-17

    Deep underground laboratories in Asia have been making huge progress recently because underground sites provide unique opportunities to explore the rare-event phenomena for the study of dark matter searches, neutrino physics and nuclear astrophysics as well as the multi-disciplinary researches based on the low radioactive environments. The status and perspectives of Kamioda underground observatories in Japan, the existing Y2L and the planned CUP in Korea, India-based Neutrino Observatory (INO) in India and China JinPing Underground Laboratory (CJPL) in China will be surveyed.

  10. Wing walls for enhancing the seismic performance of reinforced concrete frame structures

    NASA Astrophysics Data System (ADS)

    Yang, Weisong; Guo, Xun; Xu, Weixiao; Yuan, Xin

    2016-06-01

    A building retrofitted with wing walls in the bottom story, which was damaged during the 2008 M8.0 Wenchuan earthquake in China, is introduced and a corresponding 1/4 scale wing wall-frame model was subjected to shake table motions to study the seismic behavior of this retrofitted structural system. The results show that wing walls can effectively protect columns from damage by moving areas that bear reciprocating tension and compression to the sections of the wing walls, thus achieving an extra measure of seismic fortification. A `strong column-weak beam' mechanism was realized, the flexural rigidity of the vertical member was strengthened, and a more uniform distribution of deformation among all the stories was measured. In addition, the joint between the wing walls and the beams suffered severe damage during the tests, due to an area of local stress concentration. A longer area of intensive stirrup is suggested in the end of the beams.

  11. Molecular Survey of Concrete Sewer Biofilm Microbial Communities

    EPA Science Inventory

    Although bacteria are implicated in deteriorating concrete structures, there is very little information on the composition of concrete microbial communities. To this end, we studied different concrete biofilms by performing sequence analysis of 16S rDNA concrete clone libraries. ...

  12. 29 CFR 1926.704 - Requirements for precast concrete.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 8 2014-07-01 2014-07-01 false Requirements for precast concrete. 1926.704 Section 1926..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Concrete and Masonry Construction § 1926.704 Requirements for precast concrete. (a) Precast concrete wall units, structural...

  13. 29 CFR 1926.704 - Requirements for precast concrete.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Requirements for precast concrete. 1926.704 Section 1926..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Concrete and Masonry Construction § 1926.704 Requirements for precast concrete. (a) Precast concrete wall units, structural...

  14. 29 CFR 1926.704 - Requirements for precast concrete.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 8 2012-07-01 2012-07-01 false Requirements for precast concrete. 1926.704 Section 1926..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Concrete and Masonry Construction § 1926.704 Requirements for precast concrete. (a) Precast concrete wall units, structural...

  15. 29 CFR 1926.704 - Requirements for precast concrete.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 8 2013-07-01 2013-07-01 false Requirements for precast concrete. 1926.704 Section 1926..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Concrete and Masonry Construction § 1926.704 Requirements for precast concrete. (a) Precast concrete wall units, structural...

  16. 29 CFR 1926.704 - Requirements for precast concrete.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 8 2011-07-01 2011-07-01 false Requirements for precast concrete. 1926.704 Section 1926..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Concrete and Masonry Construction § 1926.704 Requirements for precast concrete. (a) Precast concrete wall units, structural...

  17. Underground infrastructure damage for a Chicago scenario

    SciTech Connect

    Dey, Thomas N; Bos, Rabdall J

    2011-01-25

    Estimating effects due to an urban IND (improvised nuclear device) on underground structures and underground utilities is a challenging task. Nuclear effects tests performed at the Nevada Test Site (NTS) during the era of nuclear weapons testing provides much information on how underground military structures respond. Transferring this knowledge to answer questions about the urban civilian environment is needed to help plan responses to IND scenarios. Explosions just above the ground surface can only couple a small fraction of the blast energy into an underground shock. The various forms of nuclear radiation have limited penetration into the ground. While the shock transmitted into the ground carries only a small fraction of the blast energy, peak stresses are generally higher and peak ground displacement is lower than in the air blast. While underground military structures are often designed to resist stresses substantially higher than due to the overlying rocks and soils (overburden), civilian structures such as subways and tunnels would generally only need to resist overburden conditions with a suitable safety factor. Just as we expect the buildings themselves to channel and shield air blast above ground, basements and other underground openings as well as changes of geology will channel and shield the underground shock wave. While a weaker shock is expected in an urban environment, small displacements on very close-by faults, and more likely, soils being displaced past building foundations where utility lines enter could readily damaged or disable these services. Immediately near an explosion, the blast can 'liquefy' a saturated soil creating a quicksand-like condition for a period of time. We extrapolate the nuclear effects experience to a Chicago-based scenario. We consider the TARP (Tunnel and Reservoir Project) and subway system and the underground lifeline (electric, gas, water, etc) system and provide guidance for planning this scenario.

  18. Microbiologically induced deterioration of concrete - A Review

    PubMed Central

    Wei, Shiping; Jiang, Zhenglong; Liu, Hao; Zhou, Dongsheng; Sanchez-Silva, Mauricio

    2013-01-01

    Microbiologically induced deterioration (MID) causes corrosion of concrete by producing acids (including organic and inorganic acids) that degrade concrete components and thus compromise the integrity of sewer pipelines and other structures, creating significant problems worldwide. Understanding of the fundamental corrosion process and the causal agents will help us develop an appropriate strategy to minimize the costs in repairs. This review presents how microorganisms induce the deterioration of concrete, including the organisms involved and their colonization and succession on concrete, the microbial deterioration mechanism, the approaches of studying MID and safeguards against concrete biodeterioration. In addition, the uninvestigated research area of MID is also proposed. PMID:24688488

  19. A new, high current output, galvanic (sacrificial) anode, electrochemical rehabilitation system for reinforced and prestressed concrete structures

    SciTech Connect

    Clear, K.C.

    1999-07-01

    This paper summarizes 1995 through 1998 laboratory, outdoor exposure facility, and field data on the subject concrete rehab system. The system shows promise as a means of providing cathodic protection to the reinforcing, as a chloride removal process, as a re-alkalization process, and/or as a lithium injection procedure to minimize alkali-aggregate reactions in the concrete. Unique characteristics of the system include: (1) Surrounding each galvanic anode with a highly corrosive liquid which maintains it (the anode) at peak output voltage throughout its life; and (2) Placing an ionic transfer layer between the anode and the concrete surface that is high volume, low resistivity and deliquescent (i.e. pulls water vapor out of the air at relative humidities of 35% or higher). The ionic transfer layer typically consists of sponge, felt or sand loaded with calcium chloride (and/or other chemicals such as sodium hydroxide, potassium acetate, and lithium-salts). In some cases it also contains a wetting agent and is encapsulated (fully or partially) in vapor permeable, but water impermeable materials. The ionic transfer layer will not freeze at temperatures as low as {minus}20 C ({minus}5 F), and provides sufficient space for all anode corrosion products, thus preventing undesirable stresses on the concrete, the anode assembly and any cosmetic covering.

  20. Cooling tower with concrete support structure, fiberglass panels, and a fan supported by the liquid distribution system

    SciTech Connect

    Bardo, C. J.; Clark Jr., J. L.; Dylewski, A. J.; Seawell, J. Q.

    1985-09-24

    A liquid cooling tower includes precast concrete support legs and cross beams and fiberglass reinforced polyester resin side and top panels. A liquid distribution system is supplied with liquid by a vertically extending main pipe, and a fan and fan motor are supported by the main pipe.

  1. Testing of plain and fibrous concrete single cavity prestressed concrete reactor vessel models

    SciTech Connect

    Oland, C.B.

    1985-01-01

    Two single-cavity prestressed concrete reactor vessel (PCRV) models were fabricated and tested to failure to demonstrate the structural response and ultimate pressure capacity of models cast from high-strength concretes. Concretes with design compressive strengths in excess of 70 MPa (10,000 psi) were developed for this investigation. One model was cast from plain concrete and failed in shear at the head region. The second model was cast from fiber reinforced concrete and failed by rupturing the circumferential prestressing at the sidewall of the structure. The tests also demonstrated the capabilities of the liner system to maintain a leak-tight pressure boundary. 3 refs., 4 figs.

  2. Assessment of permeation quality of concrete through mercury intrusion porosimetry

    SciTech Connect

    Kumar, Rakesh; Bhattacharjee, B

    2004-02-01

    Permeation quality of laboratory cast concrete beams was determined through initial surface absorption test (ISAT). The pore system characteristics of the same concrete beam specimens were determined through mercury intrusion porosimetry (MIP). Data so obtained on the measured initial surface absorption rate of water by concrete and characteristics of pore system of concrete estimated from porosimetry results were used to develop correlations between them. Through these correlations, potential of MIP in assessing the durability quality of concrete in actual structure is demonstrated.

  3. Concrete using waste oil palm shells as aggregate

    SciTech Connect

    Basri, H.B.; Mannan, M.A.; Zain, M.F.M.

    1999-04-01

    Concrete with oil palm shells (OPS) as coarse aggregate was investigated for its workability, density, and compressive strength development over 56 days under three curing conditions. The effect of fly ash as partial cement replacement was also studied. Fresh OPS concrete was found to have better workability while its 28-day air-dry density was 19--20% lower than ordinary concrete. Compressive strength after 56 days was found to be 41--50% lower than ordinary concrete. These results were still within the normal range for structural lightweight concrete. Fly ash was found to lower the compressive strength of OPS concrete, which was the opposite of its effect on normal concrete.

  4. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, J.J.; Elling, D.; Reams, W.

    1990-03-13

    A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

  5. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, J.J.; Elling, D.; Reams, W.

    1988-05-26

    A sprayable electrically conductive polymer concrete coating for vertical and overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt% calcined coke breeze, 40 wt% vinyl ester resin with 3.5 wt% modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag. 4 tabs.

  6. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, Jack J.; Elling, David; Reams, Walter

    1990-01-01

    A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

  7. Diffusion of Radionuclides in Concrete and Soil

    SciTech Connect

    Mattigod, Shas V.; Wellman, Dawn M.; Bovaird, Chase C.; Parker, Kent E.; Recknagle, Kurtis P.; Clayton, Libby N.; Wood, Marcus I.

    2012-04-25

    One of the methods being considered for safely disposing of Category 3 low-level radioactive wastes is to encase the waste in concrete. Such concrete encasement would contain and isolate the waste packages from the hydrologic environment and would act as an intrusion barrier. Any failure of concrete encasement may result in water intrusion and consequent mobilization of radionuclides from the waste packages. The mobilized radionuclides may escape from the encased concrete by mass flow and/or diffusion and move into the surrounding subsurface environment. Therefore, it is necessary to assess the performance of the concrete encasement structure and the ability of the surrounding soil to retard radionuclide migration. The objective of our study was to measure the diffusivity of Re, Tc and I in concrete containment and the surrounding vadose zone soil. Effects of carbonation, presence of metallic iron, and fracturing of concrete and the varying moisture contents in soil on the diffusivities of Tc and I were evaluated.

  8. Dependence of expansion of a salt-saturated concrete on temperature and mixing and handling procedures. Final report

    SciTech Connect

    Wakeley, L.D.

    1987-07-01

    In experiments with an expansive salt-saturated concrete (ESC), time of setting was controlled by amount of sodium citrate used. The rheological and physical properties required of ESC were determined by its intended use, in an underground repository for radioactive wastes in bedded rock salt. These properties, including a long working time and low air content, could not be achieved using conventional high-range water-reducing admixtures, such as melamine or naphthalene formaldehyde condensates. Within a fixed range of citrate percentages, expansivity of the concrete was proportional to the amount of citrate used. The desired level of expansion resulted from delaying formation of ettringite until after formation of a rigid structure in the paste. Expansive potential was diminished by warmer temperatures of mixing curing, and by repeated episodes of mixing or disturbance during the extended period of workability (up to 4 hr). These variables should be considered in plans for field placement of this or any expansive concrete. The potential for durability of this concrete in the environment for which it was formulated cannot be gauged by those properties commonly used as indicators of durability for conventional concrete in surface environments. Low permeability and minimal reaction to brine are interrelated factors which may better indicate durability than do traditionally cited properties such as compressive strength or resistance to cyclic phenomena.

  9. Science Center Goes Underground

    ERIC Educational Resources Information Center

    Modern Schools, 1977

    1977-01-01

    A unique underground science center at Bluffton College, designed to save energy and preserve trees, rolling landscape, and other environmental features of the campus, is under construction in Bluffton, Ohio. (Author)

  10. ISST (Intercontinental Ballistic Missile Silo Superhardening Technology) structure with SIFCON (Slurry-Infiltrated Fiber Concrete) - HFC-2 test. Final report, November 1983-September 1984

    SciTech Connect

    Schneider, B.; Mondragon, R.; Kirst, J.; Berglund, J.

    1988-04-01

    In 1983 a new material, slurry-infiltrated fiber concrete (SIFCON), was brought to the attention of the Air Force Weapons Laboratory (AFWL) by Dr David Lankard of the Lankard Materials Laboratory (LML) in Columbus, Ohio. A review of both high strength and ductility indicated that the material had a potential use in a superhard silo structure. Because the material showed such promise, AFWL proposed a program to construct and test a scale model of a generic superhard silo structure using the SIFCON material. AFWL decided to place the structure in a scheduled calibration test that was part of the Intercontinental Ballistic Missile Silo Superhardening Technology (ISST) testing program in Yuma, Arizona. NMERI then began a program to develop a slurry mix design for use in the structure, as well as construction techniques for placing the SIFCON in the wall of the model.

  11. Determination of chlorine, sulfur and carbon in reinforced concrete structures by double-pulse laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Labutin, Timur A.; Popov, Andrey M.; Zaytsev, Sergey M.; Zorov, Nikita B.; Belkov, Mikhail V.; Kiris, Vasilii V.; Raikov, Sergey N.

    2014-09-01

    Accurate and reliable quantitative determination of non-metal corrosion agents in concrete is still an actual task of analytical use of LIBS. Two double-pulse LIBS systems were tested as a tool for the determination of chlorine, sulfur and carbon in concretes. Both systems had collinear configuration; a laboratory setup was equipped with an ICCD and two lasers (355/532 nm + 540 nm), but a CCD was a detector for a mobile system with one laser (1064 nm). Analytical lines of Cl I at 837.59 nm, S I at 921 nm and C I at 247.86 nm were used to plot calibration curves. Optimal interpulse delays for the laboratory setup were 4 μs for chlorine and 2.8 μs for carbon, while an interpulse delay of 2 μs was optimal for chlorine and sulfur determination with the mobile system. We suggested the normalization of the Cl I line at 837.59 nm to the Mg II line at 279.08 nm (visible at 837.23 nm in the third order) to compensate for pulse-to-pulse fluctuations of chlorine lines. It provided the decrease of the detection limit of chlorine from 400 ppm to 50 ppm. Therefore, we reported that LIBS can be used to determine main corrosive active substances under ambient conditions in concrete below critical threshold values. Moreover, the application of the mobile system for in-situ qualitative assessment of corrosion way of a steel cage of a swimming pool dome was also demonstrated. It was found that chloride corrosion due to the disinfection of water was the main way for corrosion of the open part steel and the steel rebar inside the concrete.

  12. Fiber Loop Ringdown Sensor for Potential Real-Time Monitoring of Cracks in Concrete Structures: An Exploratory Study

    PubMed Central

    Sahay, Peeyush; Kaya, Malik; Wang, Chuji

    2013-01-01

    A fiber loop ringdown (FLRD) concrete crack sensor is described for the first time. A bare single mode fiber (SMF), without using other optical components or chemical coatings, etc., was utilized to construct the sensor head, which was driven by a FLRD sensor system. The performance of the sensor was evaluated on concrete bars with dimensions 20 cm × 5 cm × 5 cm, made in our laboratory. Cracks were produced manually and the responses of the sensor were recorded in terms of ringdown times. The sensor demonstrated detection of the surface crack width (SCW) of 0.5 mm, which leads to a theoretical SCW detection limit of 31 μm. The sensor's response to a cracking event is near real-time (1.5 s). A large dynamic range of crack detection ranging from a few microns (μm) to a few millimeters is expected from this sensor. With the distinct features, such as simplicity, temperature independence, near real-time response, high SCW detection sensitivity, and a large dynamic range, this FLRD crack sensor appears promising for detections of cracks when embedded in concrete. PMID:23344372

  13. Concrete lunar base investigation

    NASA Technical Reports Server (NTRS)

    Lin, T. D.; Senseny, Jonathan A.; Arp, Larry D.; Lindbergh, Charles

    1992-01-01

    This paper presents results of structural analyses and a preliminary design of a precast, prestressed concrete lunar base subjected to 1-atm internal pressure. The proposed infrastructure measures 120 ft in diameter and 72 ft in height, providing 33,000 sq ft of work area for scientific and industrial operations. Three loading conditions were considered in the design (1) during construction, (2) under pressurization, and (3) during an air-leak scenario. A floating foundation, capable of rigid body rotation and translation as the lunar soil beneath it yields, was developed to support the infrastructure and to ensure the airtightness of the system. Results reveal that it is feasible to use precast, prestressed concrete for construction of large lunar bases on the Moon.

  14. Concrete lunar base investigation

    NASA Technical Reports Server (NTRS)

    Lin, T. D.; Senseney, Jonathan A.; Arp, Larry Dean; Lindbergh, Charles

    1989-01-01

    This paper presents results of structural analyses and a preliminary design of a precast, prestressed concrete lunar based subjected to one atmosphere internal pressure. The proposed infrastructure measures 120 ft in diameter and 72 ft in height, providing 33,000 sq ft of work area for scientific and industrial operations. Three loading conditions were considered in the design: (1) during construction; (2) under pressurization; and (3) during an air-leak scenario. A floating foundation, capable of rigid body rotation and translation as the lunar soil beneath it yields, was developed to support the infrastructure and to ensure the air-tightness of the system. Results reveal that it is feasible to use precast, prestressed concrete for construction of large lunar bases on the moon.

  15. Looking north from building 215. Notice two glass and concrete ...

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

    Looking north from building 215. Notice two glass and concrete monitors in middle of the field and the stairs at the left going to the pipelines. - Fitzsimons General Hospital, Underground Fuel Pipelines, North Page Street North of Building No. 215, Aurora, Adams County, CO

  16. 3. NORTHEAST REAR, SHOWING CONCRETE ENCASEMENT FOR STAIRWAY LEADING FROM ...

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

    3. NORTHEAST REAR, SHOWING CONCRETE ENCASEMENT FOR STAIRWAY LEADING FROM INSTRUMENT ROOM TO UNDERGROUND FIRING CONTROL ROOM. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Firing Control Building, Test Area 1-100, northeast end of Test Area 1-100 Road, Boron, Kern County, CA

  17. Refractory concretes

    DOEpatents

    Holcombe, Jr., Cressie E.

    1979-01-01

    Novel concrete compositions comprise particles of aggregate material embedded in a cement matrix, said cement matrix produced by contacting an oxide selected from the group of Y.sub.2 O.sub.3, La.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Sm.sub.2 O.sub.3, Eu.sub.2 O.sub.3 and Gd.sub.2 O.sub.3 with an aqueous solution of a salt selected from the group of NH.sub.4 NO.sub.3, NH.sub.4 Cl, YCl.sub.3 and Mg(NO.sub.3).sub.2 to form a fluid mixture; and allowing the fluid mixture to harden.

  18. Evaluating the integrity of the reinforced concrete structure repaired by epoxy injection using simulated transfer function of impact-echo response

    SciTech Connect

    Cheng, Chia-Chi; Yu, Chih-peng; Wu, Jiunn-Hong; Hsu, Keng-Tsan; Ke, Ying-Tsu

    2014-02-18

    Cracks and honeycombs are often found inside reinforced concrete (RC) structure caused by excessive external force, or improper casting of concrete. The repairing method usually involves epoxy injection. The impact-echo method, which is a sensitive for detecting of the interior voids, may not be applicable to assess the integrity of the repaired member as both air and epoxy are less in acoustic impedances. In this study, the repaired RC structure was evaluated by the simulated transfer function of the IE displacement waveform where the R-wave displacement waveform is used as a base of a simulated force-time function. The effect of different thickness of the epoxy layer to the amplitude corresponding to the interface is studied by testing on specimen containing repaired naturally delaminated cracks with crack widths about 1 mm, 3 mm and 5 mm. The impact-echo responses were compared with the drilling cores at the test positions. The results showed the cracks were not fully filled with epoxy when the peak amplitude corresponding to the interface dropped less than 20%. The peak corresponding to the thicker epoxy layer tends to be larger in amplitude. A field study was also performed on a column damaged by earthquake before and after repairing.

  19. Ethical considerations for a better collaboration between architects and structural engineers: design of buildings with reinforced concrete frame systems in earthquake zones.

    PubMed

    Hurol, Yonca

    2014-06-01

    Architects design building structures, although structural design is the profession of structural engineers. Thus, it is better for architects and structural engineers to collaborate starting from the initial phases of the architectural design. However, this is not very common because of the contradictory design processes and value systems held within the two professions. This article provides a platform upon which architects and structural engineers can resolve the value conflicts between them by analysing phases of the structural design of reinforced concrete frame systems in architecture, the criteria of the structural design for each phase and determining the conflicting values for each criterion. The results shown in the article demonstrate that the architectural design of structures is a complex process, which is based on contradictory values and value systems. Finally, the article suggests to architects and structural engineers to use Value Sensitive Design and to choose an appropriate team leader in order to resolve the unethical conflict between them and to avoid any unreasonable decision making.

  20. Underground mine communications: a survey

    SciTech Connect

    Yarkan, S.; Guzelgoz, S.; Arslan, H.; Murphy, R.R.

    2009-07-01

    After a recent series of unfortunate underground mining disasters, the vital importance of communications for underground mining is underlined one more time. Establishing reliable communication is a very difficult task for underground mining due to the extreme environmental conditions. Until now, no single communication system exists which can solve all of the problems and difficulties encountered in underground mine communications. However, combining research with previous experiences might help existing systems improve, if not completely solve all of the problems. In this survey, underground mine communication is investigated. Major issues which underground mine communication systems must take into account are discussed. Communication types, methods, and their significance are presented.

  1. Procedure for detecting underground utilities with specific shape

    NASA Astrophysics Data System (ADS)

    Ristic, Aleksandar; Vrtunski, Milan; Govedarica, Miro; Bugarinovic, Zeljko

    2016-04-01

    Nowadays GPR technology is acknowledged as a reliable, fast, non-destructive remote sensing technology whose area of applications is wider every day. One of its most common applications is underground utility detection. Not only it is possible to detect the utility in the field, but using certain algorithms utilities which haven't been detected in the field can be detected in radargrams. There is a number of procedures for automated detection of utility in the radargrams. Further, there are procedures that can estimate certain parameters such as propagation velocity, diameter or even characteristics of the material. However, the majority of these procedures is designed to detect cylindrical shape utilities, which, in a radargram, are represented with hyperbolic reflection. According to geometry of hyperbola, utility parameters can be estimated. In this paper we present a procedure that is designed to estimate characteristics of non-cylindrical utilities. It is worth mentioning that these utilities are not so rare. Some underground tanks and sewage collectors are among them. Heat line is consisted of two insulated pipes of the same diameter, often placed in a concrete channel and covered with plates made from reinforced concrete. Therefore, it can be considered as non-cylindrical utility and such structure has characteristic signature in a radargram. The main idea of the proposed procedure is to detect this signature, and then, based on standardized parameters for the heat lines, to estimate the diameter of the pipes. The proposed procedure is based on artificial neural network. As a training set we made a number of radargrams collected on different locations which contain heat lines of various dimensions. Pipe diameters were in a range from 65 to 250 mm. 400MHz antenna was used since the depth hasn't exceeded 2m. After the network is trained it is validated using radargrams that haven't been used in the training set. Further tests were done with radargrams that

  2. Cleaning up underground contaminants

    SciTech Connect

    Not Available

    1994-05-01

    At hundreds of industrial and government sites across the United States, environmental consulting firms are designing permanent containment systems for underground contaminants such as hydrocarbon fuels, cleaning solvents, and industrial chemicals. In quantities of thousands of liters or more, these chemicals threaten to contaminate drinking water supplies for hundreds of years. Typical containment systems (e.g., deep wells of cement or clay, or hydraulic pumping to control groundwater movement) can keep the chemicals from further contaminating groundwater if they are properly maintained for many years, but they do not remove the contaminants. Clearly, removing the contaminants from the soil is a much preferable solution than containing them and attempting to prevent their spread. A dynamic underground stripping process that combines steam and electrical heating of underground soils with vacuum extraction of vapors and fluids and guiding these processes by real-time monitoring methods is described.

  3. Underground mineral extraction

    NASA Technical Reports Server (NTRS)

    Miller, C. G.; Stephens, J. B.

    1980-01-01

    A method was developed for extracting underground minerals such as coal, which avoids the need for sending personnel underground and which enables the mining of steeply pitched seams of the mineral. The method includes the use of a narrow vehicle which moves underground along the mineral seam and which is connected by pipes or hoses to water pumps at the surface of the Earth. The vehicle hydraulically drills pilot holes during its entrances into the seam, and then directs sideward jets at the seam during its withdrawal from each pilot hole to comminute the mineral surrounding the pilot hole and combine it with water into a slurry, so that the slurried mineral can flow to a location where a pump raises the slurry to the surface.

  4. Underground physics with DUNE

    DOE PAGES

    Kudryavtsev, Vitaly A.

    2016-01-01

    The Deep Underground Neutrino Experiment (DUNE) is a project to design, construct and operate a next-generation long-baseline neutrino detector with a liquid argon (LAr) target capable also of searching for proton decay and supernova neutrinos. It is a merger of previous efforts of the LBNE and LBNO collaborations, as well as other interested parties to pursue a broad programme with a staged 40-kt LAr detector at the Sanford Underground Research Facility (SURF) 1300 km from Fermilab. This programme includes studies of neutrino oscillations with a powerful neutrino beam from Fermilab, as well as proton decay and supernova neutrino burst searches.more » In this study, we will focus on the underground physics with DUNE.« less

  5. Underground physics with DUNE

    SciTech Connect

    Kudryavtsev, Vitaly A.

    2016-01-01

    The Deep Underground Neutrino Experiment (DUNE) is a project to design, construct and operate a next-generation long-baseline neutrino detector with a liquid argon (LAr) target capable also of searching for proton decay and supernova neutrinos. It is a merger of previous efforts of the LBNE and LBNO collaborations, as well as other interested parties to pursue a broad programme with a staged 40-kt LAr detector at the Sanford Underground Research Facility (SURF) 1300 km from Fermilab. This programme includes studies of neutrino oscillations with a powerful neutrino beam from Fermilab, as well as proton decay and supernova neutrino burst searches. In this study, we will focus on the underground physics with DUNE.

  6. CASPAR - Nuclear Astrophysics Underground

    NASA Astrophysics Data System (ADS)

    Strieder, Frank; Robertson, Daniel; Couder, Manoel; Greife, Uwe; Wells, Doug; Wiescher, Michael

    2015-10-01

    The work of the LUNA Collaboration at the Laboratori Nationali del Gran Sasso demonstrated the research potential of an underground accelerator for the field of nuclear astrophysics. Several key reactions could be studied at LUNA, some directly at the Gamow peak for solar hydrogen burning. The CASPAR (Compact Accelerator System for Performing Astrophysical Research) Collaboration will implement a high intensity 1 MV accelerator at the Sanford Underground Research Facility (SURF) and overcome the current limitation at LUNA. The installation of the accelerator in the recently rehabilitated underground cavity at SURF started in Summer 2015 and first beam should be delivered by the end of the year. This project will primarily focus on the neutron sources for the s-process, e.g. 13C(α , n) 16O and 22Ne(α , n) 25Mg , and lead to unprecedented measurements compared to previous studies. A detailed overview of the science goals of CASPAR will be presented.

  7. Structure-integrated fiber-optic sensors for reliable static and dynamic analysis of concrete foundation piless

    NASA Astrophysics Data System (ADS)

    Schallert, Matthias; Hofmann, Detlef; Habel, Wolfgang R.; Stahlmann, Joachim

    2007-04-01

    Assessment of ultimate bearing capacity and bearing behavior of large concrete piles in existing foundations or during and after installation remains a difficult task. A common and widespread test method is high-strain dynamic load testing using the one dimensional theory of wave propagation to calculate bearing capacity. Another method of quality insurance based on this theory is low-strain dynamic pile integrity testing. Both testing methods use sensors attached onto or near the pile head. In order to get more precise information about the pile response over whose length, highly resolving fiber optic sensors based on Fabry-Perot technology have been developed for integration into concrete piles at several levels. Motivation is the monitoring of pile deformations during dynamic low-strain, high-strain and static load testing with only one measuring device. First small scale piles have been tested in model tests. All signal responses from integrated sensors have been recorded and compared to signals obtained from common methods of instrumentation. The paper describes the sensing principle, sensor head installation as well as test results.

  8. Nanogranular origin of concrete creep.

    PubMed

    Vandamme, Matthieu; Ulm, Franz-Josef

    2009-06-30

    Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium-silicate-hydrates (C-S-H), the nano-meter sized particles that form the fundamental building block of Portland cement concrete. We show that C-S-H exhibits a logarithmic creep that depends only on the packing of 3 structurally distinct but compositionally similar C-S-H forms: low density, high density, ultra-high density. We demonstrate that the creep rate ( approximately 1/t) is likely due to the rearrangement of nanoscale particles around limit packing densities following the free-volume dynamics theory of granular physics. These findings could lead to a new basis for nanoengineering concrete materials and structures with minimal creep rates monitored by packing density distributions of nanoscale particles, and predicted by nanoscale creep measurements in some minute time, which are as exact as macroscopic creep tests carried out over years.

  9. Nanogranular origin of concrete creep

    PubMed Central

    Vandamme, Matthieu; Ulm, Franz-Josef

    2009-01-01

    Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium–silicate–hydrates (C–S–H), the nano-meter sized particles that form the fundamental building block of Portland cement concrete. We show that C–S–H exhibits a logarithmic creep that depends only on the packing of 3 structurally distinct but compositionally similar C–S–H forms: low density, high density, ultra-high density. We demonstrate that the creep rate (≈1/t) is likely due to the rearrangement of nanoscale particles around limit packing densities following the free-volume dynamics theory of granular physics. These findings could lead to a new basis for nanoengineering concrete materials and structures with minimal creep rates monitored by packing density distributions of nanoscale particles, and predicted by nanoscale creep measurements in some minute time, which are as exact as macroscopic creep tests carried out over years. PMID:19541652

  10. Mitigation of Hexavalent Chromium in Storm Water Resulting from Demolition of Large Concrete Structure at the East Tennessee Technology Park - 12286

    SciTech Connect

    Britto, Ronnie; Brown, Bridget; Hale, Timothy B.; Hensley, Janice L.; Johnson, Robert T.; Patel, Madhu; Emery, Jerry A.; Gaston, Clyde; Queen, David C.

    2012-07-01

    American Recovery and Reinvestment Act (ARRA) funding was provided to supplement the environmental management program at several DOE sites, including the East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee. Demolition of the ETTP K-33 Building, the largest building to be demolished to date in Oak Ridge, was awarded to LSRS in FY-2010 under the ARRA program. The K-33 building was an 82 foot tall 2-story structure covering approximately 32 acres. Once this massive building was brought down to the ground, the debris was segregated and consolidated into piles of concrete rubble and steel across the remaining pad. The process of demolishing the building, tracking across concrete debris with heavy equipment, and stockpiling the concrete rubble caused it to become pulverized. During and after storm events, hexavalent chromium leached from the residual cement present in the large quantities of concrete. Storm water control measures were present to preclude migration of contaminants off-site, but these control measures were not designed to control hexavalent chromium dissolved in storm water from reaching nearby receiving water. The following was implemented to mitigate hexavalent chromium in storm water: - Steel wool was distributed around K-33 site catch basins and in water pools as an initial step in addressing hexavalent chromium. - Since the piles of concrete were too massive and unsafe to tarp, they were placed into windrows in an effort to reduce total surface area. - A Hach colorimetric field meter was acquired by the K-33 project to provide realtime results of hexavalent chromium in site surface water. - Three hexavalent chromium treatment systems were installed at three separate catch basins that receive integrated storm water flow from the K-33 site. Sodium bisulfite is being used as a reducing agent for the immobilization of hexavalent chromium while also assisting in lowering pH. Concentrations initially were 310 - 474 ppb of hexavalent chromium in

  11. Immobilization of iodine in concrete

    DOEpatents

    Clark, Walter E.; Thompson, Clarence T.

    1977-04-12

    A method for immobilizing fission product radioactive iodine recovered from irradiated nuclear fuel comprises combining material comprising water, Portland cement and about 3-20 wt. % iodine as Ba(IO.sub.3).sub.2 to provide a fluid mixture and allowing the fluid mixture to harden, said Ba(IO.sub.3).sub.2 comprising said radioactive iodine. An article for solid waste disposal comprises concrete prepared by this method. BACKGROUND OF THE INVENTION This invention was made in the course of, or under a contract with the Energy Research and Development Administration. It relates in general to reactor waste solidification and more specifically to the immobilization of fission product radioactive iodine recovered from irradiated nuclear fuel for underground storage.

  12. Underground Tank Management.

    ERIC Educational Resources Information Center

    Bednar, Barbara A.

    1990-01-01

    The harm to human health and our environment caused by leaking underground storage tanks can be devastating. Schools can meet new federal waste management standards by instituting daily inventory monitoring, selecting a reliable volumetric testing company, locating and repairing leaks promptly, and removing and installing tanks appropriately. (MLH)

  13. Global Pursuits: The Underground Railroad

    ERIC Educational Resources Information Center

    School Arts: The Art Education Magazine for Teachers, 2004

    2004-01-01

    This brief article describes Charles T. Webber's oil on canvas painting, "The Underground Railroad, 1893." The subject of this painting is the Underground Railroad, which today has become an American legend. The Underground Railroad was not a systematic means of transportation, but rather a secretive process that allowed fugitive slaves to escape…

  14. Design criteria for an underground lunar mine

    NASA Technical Reports Server (NTRS)

    Siekmeier, John A.

    1992-01-01

    Underground excavation and construction techniques have been well developed terrestrially and provide an attractive option for lunar mining and habitat construction. The lunar mine, processing facilities and habitats could be located beneath the lunar surface in basaltic rock that would protect the crew and equipment from the hazardous surface environment. A terrestrial-like atmosphere would be created within the underground structures allowing more conventional technologies to be utilized. In addition, the basalt would likely contain higher quality mineral deposits than the regolith (lunar soil) since the minerals in the regolith have been degraded by meteorite bombardment. The conditions that would affect the design of an underground lunar mine are described and a lunar rock mass rated to assess its quality using terrestrial rock mass classification systems. Design criteria are established and a construction scenario proposed. Parameters having the greatest effect on stability are identified based on distinct element computer modeling and terrestrial experience.

  15. SA-based concrete seismic stress monitoring: a case study for normal strength concrete

    NASA Astrophysics Data System (ADS)

    Hou, S.; Zhang, H. B.; Ou, J. P.

    2016-09-01

    The stress history of concrete structures that have survived an earthquake can serve as a critical index to evaluate the health of the structure. There are currently few reliable monitoring methods to assess concrete stress after a seismic event. Piezoelectric-based smart aggregate (SA) provides an innovative experimental approach to monitor stress on concrete. The principle of SA-based concrete seismic stress monitoring is based on the assumption that concrete stress can be reliably predicted by the average output voltages of limited SAs with an acceptable margin of error. In this study, the meso-scale randomness of concrete was evaluated throughout the overall stress range of concrete and the influence of different load paths was considered. Four cylindrical specimens of normal strength concrete were embedded with a total of 24 SAs. The SA output sensitivity curve in the paths of loading-unloading with different amplitudes and monotonic loading up to failure was obtained. Monitoring errors were analyzed during pre- and post-peak stages from the experimental results. This research suggests that SA-based concrete seismic stress monitoring for normal strength concrete is reliable.

  16. SA-based concrete seismic stress monitoring: a case study for normal strength concrete

    NASA Astrophysics Data System (ADS)

    Hou, S.; Zhang, H. B.; Ou, J. P.

    2016-09-01

    The stress history of concrete structures that have survived an earthquake can serve as a critical index to evaluate the health of the structure. There are currently few reliable monitoring methods to assess concrete stress after a seismic event. Piezoelectric-based smart aggregate (SA) provides an innovative experimental approach to monitor stress on concrete. The principle of SA-based concrete seismic stress monitoring is based on the assumption that concrete stress can be reliably predicted by the average output voltages of limited SAs with an acceptable margin of error. In this study, the meso-scale randomness of concrete was evaluated throughout the overall stress range of concrete and the influence of different load paths was considered. Four cylindrical specimens of normal strength concrete were embedded with a total of 24 SAs. The SA output sensitivity curve in the paths of loading–unloading with different amplitudes and monotonic loading up to failure was obtained. Monitoring errors were analyzed during pre- and post-peak stages from the experimental results. This research suggests that SA-based concrete seismic stress monitoring for normal strength concrete is reliable.

  17. Detection and Inspection of Steel Bars in Reinforced Concrete Structures Using Active Infrared Thermography with Microwave Excitation and Eddy Current Sensors.

    PubMed

    Szymanik, Barbara; Frankowski, Paweł Karol; Chady, Tomasz; John Chelliah, Cyril Robinson Azariah

    2016-02-16

    The purpose of this paper is to present a multi-sensor approach to the detection and inspection of steel bars in reinforced concrete structures. In connection with our past experience related to non-destructive testing of different materials, we propose using two potentially effective methods: active infrared thermography with microwave excitation and the eddy current technique. In this article active infrared thermography with microwave excitation is analyzed both by numerical modeling and experiments. This method, based on thermal imaging, due to its characteriatics should be considered as a preliminary method for the assessment of relatively shallowly located steel bar reinforcements. The eddy current technique, on the other hand, allows for more detailed evaluation and detection of deeply located rebars. In this paper a series of measurement results, together with the initial identification of certain features of steel reinforcement bars will be presented.

  18. The benefit of 3D laser scanning technology in the generation and calibration of FEM models for health assessment of concrete structures.

    PubMed

    Yang, Hao; Xu, Xiangyang; Neumann, Ingo

    2014-01-01

    Terrestrial laser scanning technology (TLS) is a new technique for quickly getting three-dimensional information. In this paper we research the health assessment of concrete structures with a Finite Element Method (FEM) model based on TLS. The goal focuses on the benefits of 3D TLS in the generation and calibration of FEM models, in order to build a convenient, efficient and intelligent model which can be widely used for the detection and assessment of bridges, buildings, subways and other objects. After comparing the finite element simulation with surface-based measurement data from TLS, the FEM model is determined to be acceptable with an error of less than 5%. The benefit of TLS lies mainly in the possibility of a surface-based validation of results predicted by the FEM model. PMID:25414968

  19. Detection and Inspection of Steel Bars in Reinforced Concrete Structures Using Active Infrared Thermography with Microwave Excitation and Eddy Current Sensors

    PubMed Central

    Szymanik, Barbara; Frankowski, Paweł Karol; Chady, Tomasz; John Chelliah, Cyril Robinson Azariah

    2016-01-01

    The purpose of this paper is to present a multi-sensor approach to the detection and inspection of steel bars in reinforced concrete structures. In connection with our past experience related to non-destructive testing of different materials, we propose using two potentially effective methods: active infrared thermography with microwave excitation and the eddy current technique. In this article active infrared thermography with microwave excitation is analyzed both by numerical modeling and experiments. This method, based on thermal imaging, due to its characteriatics should be considered as a preliminary method for the assessment of relatively shallowly located steel bar reinforcements. The eddy current technique, on the other hand, allows for more detailed evaluation and detection of deeply located rebars. In this paper a series of measurement results, together with the initial identification of certain features of steel reinforcement bars will be presented. PMID:26891305

  20. Closure report for underground storage tank 141-R3U1 and its associated underground piping

    SciTech Connect

    Mallon, B.J.; Blake, R.G.

    1994-03-01

    Underground storage tank UST 141-R3U1 at Lawrence Livermore National Laboratory (LLNL), was registered with the State Water Resources Control Board on June 27, 1984. This tank system consisted of a concrete tank, lined with polyvinyl chloride, and approximately 100 feet of PVC underground piping. UST 141-R3U1 had a capacity of 450 gallons. The underground piping connected three floor drains and one sink inside Building 141 to UST 141-R3U1. The wastewater collected in UST 141-R3U1 contained organic solvents, metals, and inorganic acids. On November 30, 1987, the 141-R3U1 tank system failed a precision tank test. The 141-R3U1 tank system was subsequently emptied and removed from service pending further precision tests to determine the location of the leak within the tank system. A precision tank test on February 5, 1988, was performed to confirm the November 30, 1987 test. Four additional precision tests were performed on this tank system between February 25, 1988, and March 6, 1988. The leak was located where the inlet piping from Building 141 penetrates the concrete side of UST 141-R3U1. The volume of wastewater that entered the backfill and soil around and/or beneath UST 141-R3U1 is unknown. On December 13, 1989, the LLNL Environmental Restoration Division submitted a plan to close UST 141-R3U1 and its associated piping to the Alameda County Department of Environmental Health. UST 141-R3U1 was closed as an UST, and shall be used instead as additional secondary containment for two aboveground storage tanks.

  1. Concrete Finisher Program. Apprenticeship Training.

    ERIC Educational Resources Information Center

    Alberta Learning, Edmonton. Apprenticeship and Industry Training.

    This document presents information about the apprenticeship training program of Alberta, Canada, in general and the concrete finishing program in particular. The first part of the document discusses the following items: Alberta's apprenticeship and industry training system; the apprenticeship and industry training committee structure; local…

  2. Estimation of Prestress Force Distribution in Multi-Strand System of Prestressed Concrete Structures Using Field Data Measured by Electromagnetic Sensor.

    PubMed

    Cho, Keunhee; Cho, Jeong-Rae; Kim, Sung Tae; Park, Sung Yong; Kim, Young-Jin; Park, Young-Hwan

    2016-08-18

    The recently developed smart strand can be used to measure the prestress force in the prestressed concrete (PSC) structure from the construction stage to the in-service stage. The higher cost of the smart strand compared to the conventional strand renders it unaffordable to replace all the strands by smart strands, and results in the application of only a limited number of smart strands in the PSC structure. However, the prestress forces developed in the strands of the multi-strand system frequently adopted in PSC structures differ from each other, which means that the prestress force in the multi-strand system cannot be obtained by simple proportional scaling using the measurement of the smart strand. Therefore, this study examines the prestress force distribution in the multi-strand system to find the correlation between the prestress force measured by the smart strand and the prestress force distribution in the multi-strand system. To that goal, the prestress force distribution was measured using electromagnetic sensors for various factors of the multi-strand system adopted on site in the fabrication of actual PSC girders. The results verified the possibility to assume normal distribution for the prestress force distribution per anchor head, and a method computing the mean and standard deviation defining the normal distribution is proposed. This paper presents a meaningful finding by proposing an estimation method of the prestress force based upon field-measured data of the prestress force distribution in the multi-strand system of actual PSC structures.

  3. LUNA: Nuclear astrophysics underground

    SciTech Connect

    Best, A.

    2015-02-24

    Underground nuclear astrophysics with LUNA at the Laboratori Nazionali del Gran Sasso spans a history of 20 years. By using the rock overburden of the Gran Sasso mountain chain as a natural cosmic-ray shield very low signal rates compared to an experiment on the surface can be tolerated. The cross sectons of important astrophysical reactions directly in the stellar energy range have been successfully measured. In this proceeding we give an overview over the key accomplishments of the experiment and an outlook on its future with the expected addition of an additional accelerator to the underground facilities, enabling the coverage of a wider energy range and the measurement of previously inaccessible reactions.

  4. In focus: Underground haulage

    SciTech Connect

    Not Available

    1994-10-01

    New ideas to improve mining techniques and equipment play a vital part in achieving the productivity improvements and cost reductions necessary for the profitability, and often in hard times, for the survival of mining operations. This paper reviews the development and design of rubber-tired underground haulage equipment currently used in the US northwest. It then goes on to discuss new developments in communication and computerized control systems for these haulage units.

  5. Foam concrete with porous mineral and organic additives

    NASA Astrophysics Data System (ADS)

    Kudiakov, A.; Prischepa, I.; Tolchennickov, M.

    2015-01-01

    The article presents results of studies of structural heat insulating foam concrete with porous mineral and organic additives. By mixing additives with the concrete the speed of the initial structure formation increases. The additives of ash loss and thermal-modified peat TMT 600 provide a stable increase of strength by compression and bending of foam concrete. In the dried foam concrete with the addition of TMT and ash loss thermal conductivity decreases by 20% and 7% respectively. The regularities of changes in the thermal conductivity at various moisture of foam concrete have been investigated.

  6. Lunar concrete for construction

    NASA Technical Reports Server (NTRS)

    Cullingford, Hatice S.; Keller, M. Dean

    1992-01-01

    Feasibility of using concrete for lunar base construction was discussed recently without relevant data for the effects of vacuum on concrete. Our experimental studies performed earlier at Los Alamos have shown that concrete is stable in vacuum with no deterioration of its quality as measured by the compressive strength. Various considerations of using concrete successfully on the Moon are provided in this paper, along with specific conclusions from the existing database.

  7. Lunar concrete for construction

    NASA Technical Reports Server (NTRS)

    Cullingford, Hatice S.; Keller, M. Dean

    1988-01-01

    Feasibility of using concrete for lunar-base construction has been discussed recently without relevant data for the effects of vacuum on concrete. Experimental studies performed earlier at Los Alamos have shown that concrete is stable in vacuum with no deterioration of its quality as measured by the compressive strength. Various considerations of using concrete successfully on the moon are provided in this paper along with specific conclusions from the existing data base.

  8. Concrete Solution

    NASA Technical Reports Server (NTRS)

    1998-01-01

    A Space Act Agreement between Kennedy Space Center and Surtreat Southeast, Inc., resulted in a new treatment that keeps buildings from corroding away over time. Structural corrosion is a multi-billion dollar problem in the United States. The agreement merged Kennedy Space Center's research into electrical treatments of structural corrosion with chemical processes developed by Surtreat. Combining NASA and Surtreat technologies has resulted in a unique process with broad corrosion-control applications.

  9. Concrete radiation shielding

    SciTech Connect

    Kaplan, M.F.

    1989-01-01

    This book presents an introduction to the aspects of nuclear physics relevant to concrete technology. It covers a variety of materials that may be used to produce concrete for radiation shielding. Details of the physical, mechanical, and nuclear properties of these concretes are provided, and their applications in nuclear waste storage, shelter design, and reactor shielding are described. Radiation shield design considerations are addressed.

  10. Concrete Waste Recycling Process for High Quality Aggregate

    SciTech Connect

    Ishikura, Takeshi; Fujii, Shin-ichi

    2008-01-15

    Large amount of concrete waste generates during nuclear power plant (NPP) dismantling. Non-contaminated concrete waste is assumed to be disposed in a landfill site, but that will not be the solution especially in the future, because of decreasing tendency of the site availability and natural resources. Concerning concrete recycling, demand for roadbeds and backfill tends to be less than the amount of dismantled concrete generated in a single rural site, and conventional recycled aggregate is limited of its use to non-structural concrete, because of its inferior quality to ordinary natural aggregate. Therefore, it is vital to develop high quality recycled aggregate for general uses of dismantled concrete. If recycled aggregate is available for high structural concrete, the dismantling concrete is recyclable as aggregate for industry including nuclear field. Authors developed techniques on high quality aggregate reclamation for large amount of concrete generated during NPP decommissioning. Concrete of NPP buildings has good features for recycling aggregate; large quantity of high quality aggregate from same origin, record keeping of the aggregate origin, and little impurities in dismantled concrete such as wood and plastics. The target of recycled aggregate in this development is to meet the quality criteria for NPP concrete as prescribed in JASS 5N 'Specification for Nuclear Power Facility Reinforced Concrete' and JASS 5 'Specification for Reinforced Concrete Work'. The target of recycled aggregate concrete is to be comparable performance with ordinary aggregate concrete. The high quality recycled aggregate production techniques are assumed to apply for recycling for large amount of non-contaminated concrete. These techniques can also be applied for slightly contaminated concrete dismantled from radiological control area (RCA), together with free release survey. In conclusion: a technology on dismantled concrete recycling for high quality aggregate was developed

  11. 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

  12. Concrete "Waffle" Provides Laser Beam Accuracy

    ERIC Educational Resources Information Center

    Building Design and Construction, 1978

    1978-01-01

    A massive concrete "waffle," riding on a bed of specially treated gravel and sand inside another building, provides the structural rigidity needed by the University of Rochester's Laboratory for Laser Energetics. (Author)

  13. Numerical Modeling of Mixing and Venting from Explosions in Underground Chambers

    SciTech Connect

    Liu, B T; Lomov, I; Glenn, L A

    2005-06-22

    2D and 3D numerical simulations were performed to study the dynamic interaction of explosion products in an underground concrete chamber with ambient air, barrels of water, and the surrounding walls and structure. The simulations were carried out with GEODYN, a multi-material, Godunov-based Eulerian code that employs adaptive mesh refinement and runs efficiently on massively parallel computer platforms. Tabular equations of state were used to model materials under shock loading. An appropriate constitutive model was used to describe the concrete. Interfaces between materials were either tracked with a volume-of-fluid method that used high-order reconstruction to specify the interface location and orientation, or a capturing approach was employed with the assumption of local thermal and mechanical equilibrium. A major focus of the study was to estimate the extent of water heating that could be obtained prior to venting of the chamber. Parameters investigated included the chamber layout, energy density in the chamber and the yield-to-water mass ratio. Turbulent mixing was found to be the dominant heat transfer mechanism for heating the water.

  14. Recent biogenic phosphorite: Concretions in mollusk kidneys

    USGS Publications Warehouse

    Doyle, L.J.; Blake, N.J.; Woo, C.C.; Yevich, P.

    1978-01-01

    Phosphorite concretions have been detected in the kidneys of two widespread species ofmollusks, Mercenaria mercenaria and Argopecten irradians, which have relatively high population densities. These concretions are thefirst documentation of the direct biogenic formation of phosphorite grains. The concretions are principally amorphous calcium phosphate, which upon being heated yields an x-ray diffraction pattern which is essentially that of chlorapatite. These concretions appear to be a normal formation of the excretory process of mollusks under reproductive, environmental, or pollutant-induced stress. Biogenic production of phosphorite concretions over long periods of time and diagenetic change from amorphous to crystalline structure, coupled with secondary enrichment, may account for the formation of some marine phosphorite desposits which are not easily explained by the chemical precipitation- replacement hypothesis. Copyright ?? 1978 AAAS.

  15. Short Time Impulse Response Function (STIRF) for automatic evaluation of the variation of the dynamic parameters of reinforced concrete framed structures during strong earthquakes.

    NASA Astrophysics Data System (ADS)

    Carlo Ponzo, Felice; Ditommaso, Rocco

    2015-04-01

    the results provided in this study, the methodology seems to be able to evaluate fast variations (over time) of dynamic parameters of a generic reinforced concrete framed structure. Further analyses are necessary to better calibrate the length of the moving time-window (in order to minimize the spurious frequency within each Interferometric Response Function evaluated on both weak and strong motion phases) and to verify the possibility to use the STIRF to analyse the nonlinear behaviour of general systems. Acknowledgements This study was partially funded by the Italian Civil Protection Department within the project DPC-RELUIS 2014 - RS4 ''Seismic observatory of structures and health monitoring''. References R. Ditommaso, F.C. Ponzo (2015). Automatic evaluation of the fundamental frequency variations and related damping factor of reinforced concrete framed structures using the Short Time Impulse Response Function (STIRF). Engineering Structures, 82 (2015), 104-112. http://dx.doi.org/10.1016/j.engstruct.2014.10.023.

  16. Bypassing and tightening of an underground water retention system in permeable karst: case study of the hydropower plant (HPP) Bribin, Indonesia

    NASA Astrophysics Data System (ADS)

    Kudella, Peter; Loges, Iryna; Mutschler, Thomas; Eiche, Elisabeth; Ruppert, Julia; Neumann, Thomas

    2016-05-01

    In the framework of the Integrated Water Resources Management (IWRM) joint research project in the karst area of Gunung Kidul, Province of Yogyakarta Special Region on the Java Island, Indonesia, an underground hydropower driven water extraction facility in the cave "Bribin" was developed using pump-as-turbine-driven systems for freshwater supply of the rural area. As numerous other caves in the Gunung Kidul area, Bribin is part of a ramified system of all-season water-bearing subterraneous rivers and natural caves in karstic limestone. The elliptic cross section of the cave was completely closed with a concrete barrage, thus creating a year-round underground retention volume with an operational storage level of approx. 15 m. This contribution highlights the geotechnical and geohydraulic challenges handled within the sub-project "Short-time and long-time behaviour of karst rock surrounding pressure-bearing underground water-retaining structures". One key to the feasibility of an artificial water retention scheme in a natural cave is to ensure the mechanical stability of the cave roof and sidewalls. The necessary geotechnical investigations are described. Another key to the effectiveness of such a water retention concept is the control and minimization of "lost" seepage water bypassing the barrage structure through the karst rock mass. Measures to monitor and to explain the seepage phenomena are presented as well as grouting efforts to minimize them. The limitations of improving the overall tightness will be discussed. Interpretation includes the use of analytical and numerical methods.

  17. Bypassing and tightening of an underground water retention system in permeable karst: case study of the hydropower plant (HPP) Bribin, Indonesia

    NASA Astrophysics Data System (ADS)

    Kudella, Peter; Loges, Iryna; Mutschler, Thomas; Eiche, Elisabeth; Ruppert, Julia; Neumann, Thomas

    2016-09-01

    In the framework of the Integrated Water Resources Management (IWRM) joint research project in the karst area of Gunung Kidul, Province of Yogyakarta Special Region on the Java Island, Indonesia, an underground hydropower driven water extraction facility in the cave "Bribin" was developed using pump-as-turbine-driven systems for freshwater supply of the rural area. As numerous other caves in the Gunung Kidul area, Bribin is part of a ramified system of all-season water-bearing subterraneous rivers and natural caves in karstic limestone. The elliptic cross section of the cave was completely closed with a concrete barrage, thus creating a year-round underground retention volume with an operational storage level of approx. 15 m. This contribution highlights the geotechnical and geohydraulic challenges handled within the sub-project "Short-time and long-time behaviour of karst rock surrounding pressure-bearing underground water-retaining structures". One key to the feasibility of an artificial water retention scheme in a natural cave is to ensure the mechanical stability of the cave roof and sidewalls. The necessary geotechnical investigations are described. Another key to the effectiveness of such a water retention concept is the control and minimization of "lost" seepage water bypassing the barrage structure through the karst rock mass. Measures to monitor and to explain the seepage phenomena are presented as well as grouting efforts to minimize them. The limitations of improving the overall tightness will be discussed. Interpretation includes the use of analytical and numerical methods.

  18. Underground petroleum tanks

    SciTech Connect

    Not Available

    1990-07-01

    This book presents the results of a survey of 46 state underground storage tank program officials. The survey covers: Whether petroleum tank insurance (mandated by the EPA) is available in each state and whether category 3 and 4 owners can obtain it; state programs that help owners meet the financial responsibility and/or technical requirements of such insurance; and lending institutions' attitudes towards providing loans to storage tank owners. A survey of the number and terms of insurance policies offered to tank owners is also presented.

  19. Underground coal gasification. Presentations

    SciTech Connect

    2007-07-01

    The 8 presentations are: underground coal gasification (UCG) and the possibilities for carbon management (J. Friedmann); comparing the economics of UCG with surface gasification technologies (E. Redman); Eskom develops UCG technology project (C. Gross); development and future of UCG in the Asian region (L. Walker); economically developing vast deep Powder River Basin coals with UCG (S. Morzenti); effectively managing UCG environmental issues (E. Burton); demonstrating modelling complexity of environmental risk management; and UCG research at the University of Queensland, Australia (A.Y. Klimenko).

  20. RESEARCH INTO EVALUATIONS OF UNDERGROUND SPACE ACCORDING TO QOL - CENTERING ON THE NAGOYA UNDERGROUND METRO -

    NASA Astrophysics Data System (ADS)

    Yoshimoto, Naomi; Wake, Tenji; Mita, Takeshi; Wake, Hiromi

    The present research investigates issues concerning space underground and concerns itself with psychological evaluations of comfort in underground railway premises from the perspective of the users of such premises. The actual psychological evaluation was done on the premises of nine Nagoya City underground stations. Four factors were extracted from the results obtained. The first factor is transmission information, the second factor is the comfort of the environment, the third is sense of insecurity, and the fourth, convenience. A covariance structure analysis was carried out to see if there was any relationship between these factors and the research participants' age and frequency of underground usage. It was found from this that the first element is related to the frequency with which the participants in the research use the underground trains. When the frequency of use is high, transmission of information is high. A relationship was also found between aging and factors one and four. The older the person the worse information transmission is and the more dependent they are on convenience, such as, for example, in terms of elevators and escalators.

  1. Lunar concrete: Prospects and challenges

    NASA Astrophysics Data System (ADS)

    Khitab, Anwar; Anwar, Waqas; Mehmood, Imran; Kazmi, Syed Minhaj Saleem; Munir, Muhammad Junaid

    2016-02-01

    The possibility of using concrete as a construction material at the Moon surface is considered. Dissimilarities between the Earth and the Moon and their possible effects on concrete are also emphasized. Availability of constituent materials for concrete at lunar surface is addressed. An emphasis is given to two types of materials, namely, hydraulic concrete and sulfur concrete. Hydraulic concrete necessitates the use of water and sulfur concrete makes use of molten sulfur in lieu of cement and water.

  2. North American deep underground laboratories: Soudan Underground Laboratory, SNOLab, and the Sanford Underground Research Facility

    NASA Astrophysics Data System (ADS)

    Lesko, Kevin T.

    2015-08-01

    Over the past several decades, fundamental physics experiments have required access to deep underground laboratories to satisfy the increasingly strict requirements for ultra-low background environments and shielding from cosmic rays. In this presentation, I summarize the existing and anticipated physics programs and laboratory facilities of North America's deep facilities: The Soudan Underground Laboratory in Minnesota, SNOLab in Ontario, Canada, and the Sanford Underground Research Facility in Lead, South Dakota.

  3. Permeability and corrosion resistance of reinforced sulfur concrete

    SciTech Connect

    Wrzesinski, W.R.; McBee, W.C.

    1988-01-01

    This report presents the findings form a 1-yr Bureau of Mines program in which sulfur concrete reinforcing materials were tested and evaluated to determine their resistance to corrosion. It also summarizes the permeation characteristics of sulfur concrete and the exemplary of precast, reinforced sulfur concrete structures in various industrial environments. The Bureau is furthering the development of sulfur concrete technology as part of a larger effort to find uses for the Nation's plentiful sulfur resources in construction materials. Sulfur concrete is a corrosion-resistant material that can be used in acid and salt environments where conventional materials fail.

  4. Concrete decontamination by Electro-Hydraulic Scabbling (EHS)

    SciTech Connect

    1994-11-01

    EHS is being developed for decontaminating concrete structures from radionuclides, organic substances, and hazardous metals. EHS involves the generation of powerful shock waves and intense cavitation by a strong pulsed electric discharge in a water layer at the concrete surface; high impulse pressure results in stresses which crack and peel off a concrete layer of controllable thickness. Scabbling produces contaminated debris of relatively small volume which can be easily removed, leaving clean bulk concrete. Objective of Phase I was to prove the technical feasibility of EH for controlled scabbling and decontamination of concrete. Phase I is complete.

  5. A quantitative empirical analysis of the abstract/concrete distinction.

    PubMed

    Hill, Felix; Korhonen, Anna; Bentz, Christian

    2014-01-01

    This study presents original evidence that abstract and concrete concepts are organized and represented differently in the mind, based on analyses of thousands of concepts in publicly available data sets and computational resources. First, we show that abstract and concrete concepts have differing patterns of association with other concepts. Second, we test recent hypotheses that abstract concepts are organized according to association, whereas concrete concepts are organized according to (semantic) similarity. Third, we present evidence suggesting that concrete representations are more strongly feature-based than abstract concepts. We argue that degree of feature-based structure may fundamentally determine concreteness, and we discuss implications for cognitive and computational models of meaning.

  6. Microbiologically induced deterioration of concrete--a review.

    PubMed

    Wei, Shiping; Jiang, Zhenglong; Liu, Hao; Zhou, Dongsheng; Sanchez-Silva, Mauricio

    2013-12-01

    Microbiologically induced deterioration (MID) causes corrosion of concrete by producing acids (including organic and inorganic acids) that degrade concrete components and thus compromise the integrity of sewer pipelines and other structures, creating significant problems worldwide. Understanding of the fundamental corrosion process and the causal agents will help us develop an appropriate strategy to minimize the costs in repairs. This review presents how microorganisms induce the deterioration of concrete, including the organisms involved and their colonization and succession on concrete, the microbial deterioration mechanism, the approaches of studying MID and safeguards against concrete biodeterioration. In addition, the uninvestigated research area of MID is also proposed.

  7. Review of concrete biodeterioration in relation to nuclear waste.

    PubMed

    Turick, Charles E; Berry, Christopher J

    2016-01-01

    Storage of radioactive waste in concrete structures is a means of containing wastes and related radionuclides generated from nuclear operations in many countries. Previous efforts related to microbial impacts on concrete structures that are used to contain radioactive waste showed that microbial activity can play a significant role in the process of concrete degradation and ultimately structural deterioration. This literature review examines the research in this field and is focused on specific parameters that are applicable to modeling and prediction of the fate of concrete structures used to store or dispose of radioactive waste. Rates of concrete biodegradation vary with the environmental conditions, illustrating a need to understand the bioavailability of key compounds involved in microbial activity. Specific parameters require pH and osmotic pressure to be within a certain range to allow for microbial growth as well as the availability and abundance of energy sources such as components involved in sulfur, iron and nitrogen oxidation. Carbon flow and availability are also factors to consider in predicting concrete biodegradation. The microbial contribution to degradation of the concrete structures containing radioactive waste is a constant possibility. The rate and degree of concrete biodegradation is dependent on numerous physical, chemical and biological parameters. Parameters to focus on for modeling activities and possible options for mitigation that would minimize concrete biodegradation are discussed and include key conditions that drive microbial activity on concrete surfaces.

  8. Review of concrete biodeterioration in relation to nuclear waste.

    PubMed

    Turick, Charles E; Berry, Christopher J

    2016-01-01

    Storage of radioactive waste in concrete structures is a means of containing wastes and related radionuclides generated from nuclear operations in many countries. Previous efforts related to microbial impacts on concrete structures that are used to contain radioactive waste showed that microbial activity can play a significant role in the process of concrete degradation and ultimately structural deterioration. This literature review examines the research in this field and is focused on specific parameters that are applicable to modeling and prediction of the fate of concrete structures used to store or dispose of radioactive waste. Rates of concrete biodegradation vary with the environmental conditions, illustrating a need to understand the bioavailability of key compounds involved in microbial activity. Specific parameters require pH and osmotic pressure to be within a certain range to allow for microbial growth as well as the availability and abundance of energy sources such as components involved in sulfur, iron and nitrogen oxidation. Carbon flow and availability are also factors to consider in predicting concrete biodegradation. The microbial contribution to degradation of the concrete structures containing radioactive waste is a constant possibility. The rate and degree of concrete biodegradation is dependent on numerous physical, chemical and biological parameters. Parameters to focus on for modeling activities and possible options for mitigation that would minimize concrete biodegradation are discussed and include key conditions that drive microbial activity on concrete surfaces. PMID:26397745

  9. Estimation of Prestress Force Distribution in Multi-Strand System of Prestressed Concrete Structures Using Field Data Measured by Electromagnetic Sensor

    PubMed Central

    Cho, Keunhee; Cho, Jeong-Rae; Kim, Sung Tae; Park, Sung Yong; Kim, Young-Jin; Park, Young-Hwan

    2016-01-01

    The recently developed smart strand can be used to measure the prestress force in the prestressed concrete (PSC) structure from the construction stage to the in-service stage. The higher cost of the smart strand compared to the conventional strand renders it unaffordable to replace all the strands by smart strands, and results in the application of only a limited number of smart strands in the PSC structure. However, the prestress forces developed in the strands of the multi-strand system frequently adopted in PSC structures differ from each other, which means that the prestress force in the multi-strand system cannot be obtained by simple proportional scaling using the measurement of the smart strand. Therefore, this study examines the prestress force distribution in the multi-strand system to find the correlation between the prestress force measured by the smart strand and the prestress force distribution in the multi-strand system. To that goal, the prestress force distribution was measured using electromagnetic sensors for various factors of the multi-strand system adopted on site in the fabrication of actual PSC girders. The results verified the possibility to assume normal distribution for the prestress force distribution per anchor head, and a method computing the mean and standard deviation defining the normal distribution is proposed. This paper presents a meaningful finding by proposing an estimation method of the prestress force based upon field-measured data of the prestress force distribution in the multi-strand system of actual PSC structures. PMID:27548172

  10. Estimation of Prestress Force Distribution in Multi-Strand System of Prestressed Concrete Structures Using Field Data Measured by Electromagnetic Sensor.

    PubMed

    Cho, Keunhee; Cho, Jeong-Rae; Kim, Sung Tae; Park, Sung Yong; Kim, Young-Jin; Park, Young-Hwan

    2016-01-01

    The recently developed smart strand can be used to measure the prestress force in the prestressed concrete (PSC) structure from the construction stage to the in-service stage. The higher cost of the smart strand compared to the conventional strand renders it unaffordable to replace all the strands by smart strands, and results in the application of only a limited number of smart strands in the PSC structure. However, the prestress forces developed in the strands of the multi-strand system frequently adopted in PSC structures differ from each other, which means that the prestress force in the multi-strand system cannot be obtained by simple proportional scaling using the measurement of the smart strand. Therefore, this study examines the prestress force distribution in the multi-strand system to find the correlation between the prestress force measured by the smart strand and the prestress force distribution in the multi-strand system. To that goal, the prestress force distribution was measured using electromagnetic sensors for various factors of the multi-strand system adopted on site in the fabrication of actual PSC girders. The results verified the possibility to assume normal distribution for the prestress force distribution per anchor head, and a method computing the mean and standard deviation defining the normal distribution is proposed. This paper presents a meaningful finding by proposing an estimation method of the prestress force based upon field-measured data of the prestress force distribution in the multi-strand system of actual PSC structures. PMID:27548172

  11. On the effectiveness of smart technologies in the seismic protection of existing buildings Part II: Reinforced concrete structures

    SciTech Connect

    Mandara, A.; Ramundo, F.; Spina, G.

    2008-07-08

    The second part of a study concerning innovative intervention techniques for seismic protection of existing buildings is presented in this paper. The case of an existing framed r.c. structure, not designed for horizontal forces and extremely vulnerable to seismic action, is analyzed both in terms of maximum response reduction and energy dissipation. The proposed intervention approach, based on steel braces linked to the existing structure by passive or smart devices comes out appropriate and effective in the case of this type of buildings. The adopted control strategy produces a significant reducing effect on the elastic strain energy transmitted by the external perturbation to the structure, which is itself a fundamental safeguard aspect. The results prove the significantly improved capability of the system to dissipate input energy without structural damage, regardless of the specific seismic input.

  12. Controlling chloride ions diffusion in concrete.

    PubMed

    Zeng, Lunwu; Song, Runxia

    2013-11-28

    The corrosion of steel in concrete is mainly due to the chemical reaction between the chloride ions and iron ions. Indeed, this is a serious threaten for reinforced concrete structure, especially for the reinforced concrete structure in the sea. So it is urgent and important to protect concrete against chloride ions corrosion. In this work, we report multilayer concrete can cloak chloride ions. We formulated five kinds of concrete A, B, C, D and E, which are made of different proportion of cement, sand and glue, and fabricated six-layer (ABACAD) cylinder diffusion cloak and background media E. The simulation results show that the six-layer mass diffusion cloak can protect concrete against chloride ions penetration, while the experiment results show that the concentration gradients are parallel and equal outside the outer circle in the diffusion flux lines, the iso-concentration lines are parallel outside the outer circle, and the concentration gradients in the inner circle are smaller than those outside the outer circle.

  13. Controlling chloride ions diffusion in concrete

    PubMed Central

    Zeng, Lunwu; Song, Runxia

    2013-01-01

    The corrosion of steel in concrete is mainly due to the chemical reaction between the chloride ions and iron ions. Indeed, this is a serious threaten for reinforced concrete structure, especially for the reinforced concrete structure in the sea. So it is urgent and important to protect concrete against chloride ions corrosion. In this work, we report multilayer concrete can cloak chloride ions. We formulated five kinds of concrete A, B, C, D and E, which are made of different proportion of cement, sand and glue, and fabricated six-layer (ABACAD) cylinder diffusion cloak and background media E. The simulation results show that the six-layer mass diffusion cloak can protect concrete against chloride ions penetration, while the experiment results show that the concentration gradients are parallel and equal outside the outer circle in the diffusion flux lines, the iso-concentration lines are parallel outside the outer circle, and the concentration gradients in the inner circle are smaller than those outside the outer circle. PMID:24285220

  14. Nuclear Physics Underground

    SciTech Connect

    Bemmerer, Daniel

    2010-08-04

    Precisely known nuclear cross sections are an essential ingredient for the modeling of nuclear processes in our Sun, in stars, and in the Big Bang. Uncertainties due to theoretical extrapolations can be avoided if experimental data are available directly at astrophysically relevant energies. Since such energies are typically far below the Coulomb barrier, this entails cross section measurements in the picobarn range.The Laboratory for Underground Nuclear Astrophysics (LUNA) inside the Gran Sasso mountain in Italy takes up this challenge by combining accelerator-based experiments with low-background measurement techniques. Using this approach, in recent years several reactions relevant to hydrogen burning have been studied, e.g. {sup 3}He({alpha},{gamma}){sup 7}Be and {sup 14}N(p,{gamma}){sup 15}O. The implications of the data range from an independent lower limit on the age of the universe to a precise solar thermometer.Based on this progress, currently there are efforts in several countries to construct new underground accelerators. The exciting science that can be probed with these new facilities will be highlighted.

  15. Multinational underground nuclear parks

    SciTech Connect

    Myers, C.W.; Giraud, K.M.

    2013-07-01

    Newcomer countries expected to develop new nuclear power programs by 2030 are being encouraged by the International Atomic Energy Agency to explore the use of shared facilities for spent fuel storage and geologic disposal. Multinational underground nuclear parks (M-UNPs) are an option for sharing such facilities. Newcomer countries with suitable bedrock conditions could volunteer to host M-UNPs. M-UNPs would include back-end fuel cycle facilities, in open or closed fuel cycle configurations, with sufficient capacity to enable M-UNP host countries to provide for-fee waste management services to partner countries, and to manage waste from the M-UNP power reactors. M-UNP potential advantages include: the option for decades of spent fuel storage; fuel-cycle policy flexibility; increased proliferation resistance; high margin of physical security against attack; and high margin of containment capability in the event of beyond-design-basis accidents, thereby reducing the risk of Fukushima-like radiological contamination of surface lands. A hypothetical M-UNP in crystalline rock with facilities for small modular reactors, spent fuel storage, reprocessing, and geologic disposal is described using a room-and-pillar reference-design cavern. Underground construction cost is judged tractable through use of modern excavation technology and careful site selection. (authors)

  16. Kimballton Underground Research Facility

    NASA Astrophysics Data System (ADS)

    Rountree, Steven Derek

    2014-03-01

    The Kimballton Underground Research Facility (KURF) is an operating deep underground research facility with six active projects, and greater than 50 trained researchers. KURF is 30 minutes from the Virginia Tech (VT) campus in an operating limestone mine with drive-in access (eg: roll-back truck, motor coach), over 50 miles of drifts (all 40' × 20 +' the current lab is 35' × 22' × 100'), and 1700' of overburden (1450m.w.e.). The laboratory was built in 2007 and offers fiber optic internet, LN2, 480/220/110 V power, ample water, filtered air, 55 F constant temp, low Rn levels, low rock background activity, and a muon flux of only ~0.004 muons per square meter, per second, per steradian. The current users are funded by NSF, DOE, and NNSA. Current user group: 1) mini-LENS (VT, Louisiana State University, BNL); 2) Double Beta Decay to Excited States (Duke University); 3) HPGe Low-Background Screening (University of North Carolina (UNC), VT); 4) MALBEK (UNC); 5&6) Watchman - 5) Radionuclide Detector and 6) MARS detector (LLNL, SNL, UC-Davis, UC-Berkeley, UH, Hawaii Pacific, UC-Irvine, VT).

  17. Underground storage tank program

    SciTech Connect

    Lewis, M.W.

    1994-12-31

    Underground storage tanks, UST`S, have become a major component of the Louisville District`s Environmental Support Program. The District`s Geotechnical and Environmental Engineering Branch has spear-headed an innovative effort to streamline the time, effort and expense for removal, replacement, upgrade and associated cleanup of USTs at military and civil work installations. This program, called Yank-A-Tank, creates generic state-wide contracts for removal, remediation, installation and upgrade of storage tanks for which individual delivery orders are written under the basic contract. The idea is to create a ``JOC type`` contract containing all the components of work necessary to remove, reinstall or upgrade an underground or above ground tank. The contract documents contain a set of generic specifications and unit price books in addition to the standard ``boiler plate`` information. Each contract requires conformance to the specific regulations for the state in which it is issued. The contractor`s bid consists of a bid factor which in the multiplier used with the prices in the unit price book. The solicitation is issued as a Request for Proposal (RPP) which allows the government to select a contractor based on technical qualification an well as bid factor. Once the basic contract is awarded individual delivery orders addressing specific areas of work are scoped, negotiated and awarded an modifications to the original contract. The delivery orders utilize the prepriced components and the contractor`s factor to determine the value of the work.

  18. A Course on Underground Processing.

    ERIC Educational Resources Information Center

    Miller, Clarence A.

    1981-01-01

    Discusses a one-semester course on recovering fossil fuels and minerals from underground formations. Includes course outline and information of its major divisions: (1) Geological Background; (2) Flow, Transport, and Interfacial Phenomena in Porous Media; and (3) Description of Underground Processes. (SK)

  19. The mathematical model of radon-222 accumulation in underground mines

    NASA Astrophysics Data System (ADS)

    Klimshin, A.

    2012-04-01

    Necessity to control underground mine air radon level arises during building and operating mines as well as auto and railway tunnels including those for metros. Calculation of underground mine air radon level can be fulfilled for estimation of potential radon danger of area for underground structure building. In this work the new mathematical model of radon accumulation in underground mines has been suggested. It takes into consideration underground mine dimensions, air exchange factor and soils ability to emanate radon. The following assumptions have been taken for model development. It is assumed that underground mine is a cylinder of length L and of base area S. Due to ventilation atmosphere air of volume activity Catm, is coming in through one cylinder base and is going out of volume activity Cind from underground mine. Diffusion radon flux is coming in through side surfaces of underground mine. The sources of this flux are radium-226 atoms distributed evenly in rock. For simplification of the task it considered possible to disregard radon emanation by loosened rock and underground waters. As a result of solution of the radon diffusion equation the following expression for calculation of radon volume activity in underground space air has been got: 2·r0 ·λv ·Catm-·l·K0(r0/l)-+D-·K1(r0/l)·C0- Cind = 2·(λ+ λv)·r0 ·l·K0 (r0/l)+ D ·K1(r0/l) . The following designations are used in this expression: Kν(r) - the second genus modified Bessel's function, C0 - equilibrium radon volume activity in soil air, l - diffusion radon length in soil, D - radon diffusion factor, r0 - radius of underground tunnel, λv - factor of air exchange. Expression found may be used for calculation of the minimum factor of necessary air exchange for ensuring safe radon levels in underground spaces. With this worked out model expected levels of radon volume activity were calculated for air in the second metro line underground spaces in the city of Yekaterinburg, Russia.

  20. 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.

  1. Underground-Energy-Storage Program, 1982 annual report

    SciTech Connect

    Kannberg, L.D.

    1983-06-01

    Two principal underground energy storage technologies are discussed--Seasonal Thermal Energy Storage (STES) and Compressed Air Energy Storage (CAES). The Underground Energy Storage Program objectives, approach, structure, and milestones are described, and technical activities and progress in the STES and CAES areas are summarized. STES activities include aquifer thermal energy storage technology studies and STES technology assessment and development. CAES activities include reservoir stability studies and second-generation concepts studies. (LEW)

  2. Methods for ultimate load analysis of concrete containments

    SciTech Connect

    Dunham, R.S.; Rashid, Y.R.; Yuan, K.A.; Lu, Y.M.

    1985-06-01

    The objective of the research project described in this interim report is to develop a qualified methodology for the ultimate load analysis of concrete containment structures. The EPRI-sponsored nonlinear finite element code ABAQUS-EPGEN, which has recently been modified to incorporate a constitutive model for plain concrete and modeling capabilities for reinforced and prestressed concrete containments, is utilized as the structural analysis tool in this development. The ABAQUS-EPGEN concrete modeling and analysis capabilities are first evaluated by comparing measured data with code predictions for full-scale reinforced concrete slab specimens tested under uniaxial and biaxial tension. These specimen tests simulate the behavior of the cylindrical wall of a typical concrete containment structure under internal pressure. The calculated and measured strain comparisons are used to improve the constitutive model and to qualify the code for concrete containment analysis. The second part of this effort deals with the ultimate load analysis of reinforced and prestressed containments to determine bounds on the global overpressure capacities of typical concrete containment structures. The third part of this effort further examines such local effects through a substructural analysis of the liner-concrete interaction at major concrete cracks.

  3. Deterioration of concrete structures by acid deposition — an assessment of the role of rainwater on deterioration by laboratory and field exposure experiments using mortar specimens

    NASA Astrophysics Data System (ADS)

    Okochi, Hiroshi; Kameda, Hideki; Hasegawa, Shin-ichi; Saito, Nobuhiko; Kubota, Ken; Igawa, Manabu

    Deterioration of concrete structures caused by acid deposition was investigated by laboratory and field exposure of portland cement mortar specimens to acid deposition. Laboratory exposure experiment showed that the dissolved amount of calcium hydrates, which were the major components in mortar, increased with the increase in the acidity of simulated acid rain solution and the decrease in the flow rate. There was little difference in their amount among different temperature treatments after each exposure to the solution with the same acidity, namely left at room temperature, heated at 70°C, and cooled at -2°C. The neutralization progressed more deeply under the heated and cooled condition and was accelerated by even acid rain with pH 4.7 during a long period (90 exposure cycles, which correspond to the rainfall amount of 15 years in Japan). A field exposure experiment for two years indicated that the carbonation of calcium hydrates and the formation of other corrosion products such as chloride, nitrate, and sulfate were limited to the surface of mortar specimens. The neutralization progressed more deeply in mortar specimens sheltered from rainwater than in those washed by rainwater.

  4. A 2.5-dimensional method for the prediction of structure-borne low-frequency noise from concrete rail transit bridges.

    PubMed

    Li, Qi; Song, Xiaodong; Wu, Dingjun

    2014-05-01

    Predicting structure-borne noise from bridges subjected to moving trains using the three-dimensional (3D) boundary element method (BEM) is a time consuming process. This paper presents a two-and-a-half dimensional (2.5D) BEM-based procedure for simulating bridge-borne low-frequency noise with higher efficiency, yet no loss of accuracy. The two-dimensional (2D) BEM of a bridge with a constant cross section along the track direction is adopted to calculate the spatial modal acoustic transfer vectors (MATVs) of the bridge using the space-wave number transforms of its 3D modal shapes. The MATVs calculated using the 2.5D method are then validated by those computed using the 3D BEM. The bridge-borne noise is finally obtained through the MATVs and modal coordinate responses of the bridge, considering time-varying vehicle-track-bridge dynamic interaction. The presented procedure is applied to predict the sound pressure radiating from a U-shaped concrete bridge, and the computed results are compared with those obtained from field tests on Shanghai rail transit line 8. The numerical results match well with the measured results in both time and frequency domains at near-field points. Nevertheless, the computed results are smaller than the measured ones for far-field points, mainly due to the sound radiation from adjacent spans neglected in the current model.

  5. Fly ash sulfur concrete

    SciTech Connect

    Head, W.J.; Liao, M.

    1981-05-01

    Two waste products, flyash and elemental sulfur, can be combined with a modifying agent to produce a potentially useful construction material, flyash sulfur concrete. Manufacturing processes and characteristics of this concrete are described. Compared with a conventional crushed stone aggregate, flyash sulfur concrete is a viable highway pavement base course material. The material's strength characteristics are analyzed. (1 diagram, 4 graphs, 2 photos, 9 references, 5 tables)

  6. RESRAD drinking water pathway: Probabilistic applications for underground storage tanks

    SciTech Connect

    Bauer, L.R. )

    1993-01-01

    The radioactive wastewater treatment system in place at the Mound plant uses four 129,000-[ell] (34 000-gal) concrete tanks to collect treated effluent prior to discharge. These effluent tanks are located partially below grade and are therefore components of the plant's active underground storage tank program (AUSTP). In support of AUSTP implementation and evaluation, a screening analysis of the potential radiological consequences of complete failure of these tanks was required. The analysis has been performed and is the subject of this paper.

  7. HTGR Base Technology Program. Task 2: concrete properties in nuclear environment. A review of concrete material systems for application to prestressed concrete pressure vessels

    SciTech Connect

    Naus, D.J.

    1981-05-01

    Prestressed concrete pressure vessels (PCPVs) are designed to serve as primary pressure containment structures. The safety of these structures depends on a correct assessment of the loadings and proper design of the vessels to accept these loadings. Proper vessel design requires a knowledge of the component (material) properties. Because concrete is one of the primary constituents of PCPVs, knowledge of its behavior is required to produce optimum PCPV designs. Concrete material systems are reviewed with respect to constituents, mix design, placing, curing, and strength evaluations, and typical concrete property data are presented. Effects of extreme loadings (elevated temperature, multiaxial, irradiation) on concrete behavior are described. Finally, specialty concrete material systems (high strength, fibrous, polymer, lightweight, refractory) are reviewed. 235 references.

  8. An Alternative Mechanism for Accelerated Carbon Sequestration in Concrete

    SciTech Connect

    Haselbach, Liv M.; Thomle, Jonathan N.

    2014-07-01

    The increased rate of carbon dioxide sequestration (carbonation) is desired in many primary and secondary life applications of concrete in order to make the life cycle of concrete structures more carbon neutral. Most carbonation rate studies have focused on concrete exposed to air under various conditions. An alternative mechanism for accelerated carbon sequestration in concrete was investigated in this research based on the pH change of waters in contact with pervious concrete which have been submerged in carbonate laden waters. The results indicate that the concrete exposed to high levels of carbonate species in water may carbonate faster than when exposed to ambient air, and that the rate is higher with higher concentrations. Validation of increased carbon dioxide sequestration was also performed via thermogravimetric analysis (TGA). It is theorized that the proposed alternative mechanism reduces a limiting rate effect of carbon dioxide dissolution in water in the micro pores of the concrete.

  9. Phyllanthus muellerianus and C6H15NO3 synergistic effects on 0.5 M H2SO4-immersed steel-reinforced concrete: Implication for clean corrosion-protection of wind energy structures in industrial environment

    NASA Astrophysics Data System (ADS)

    Okeniyi, Joshua Olusegun; Omotosho, Olugbenga Adeshola; Popoola, Abimbola Patricia Idowu; Loto, Cleophas Akintoye

    2016-07-01

    This paper investigates Phyllanthus muellerianus leaf-extract and C6H15NO3 (triethanolamine: TEA) synergistic effects on reinforcing-steel corrosion-inhibition and the compressive-strength of steel-reinforced concrete immersed in 0.5 M H2SO4. This is to assess suitability of the synergistic admixture usage for wind-energy steel-reinforced concrete structures designed for industrial environments. Steel-reinforced concrete specimens were admixed with individual and synergistic designs of Phyllanthus muellerianus leaf-extract and C6H15NO3 admixtures and immersed in the 0.5 M H2SO4. Electrochemical monitoring of corrosion potential, as per ASTM C876-91 R99, and corrosion current were obtained and statistically analysed, as per ASTM G16-95 R04, for modelling noise resistance. Post-immersion compressive-strength testing then followed, as per ASTM C39/C39M-03, for detailing the admixture effect on load-bearing strength of the steel-reinforced concrete specimens. Results showed that while individual Phyllanthus muellerianus leaf-extract concentrations exhibited better inhibition-efficiency performance than C6H15NO3, synergistic additions of C6H15NO3 to Phyllanthus muellerianus leaf-extract improved steel-rebar corrosion-inhibition. Thus, 6 g Phyllanthus muellerianus + 2 g C6H15NO3 synergistically improved inhibition-efficiency to η = 84.17%, from η = 55.28% by the optimal chemical or from η = 74.72% by the optimal plant-extract admixtures. The study also established that improved compressive strength of steel-reinforced concrete with acceptable inhibition of the steel-rebar corrosion could be attained through optimal combination of the Phyllanthus muellerianus leaf-extract and C6H15NO3 admixtures.

  10. Antifouling marine concrete

    NASA Astrophysics Data System (ADS)

    Mathews, C. W.

    1980-03-01

    Various toxic agents were investigated for their ability to prevent the attachment and growth of marine fouling organisms on concrete. Three methods of incorporating antifoulants into concrete were also studied. Porous aggregate was impregnated with creosote and bis-(tri-n-butyltin) oxide (TBTO) and then used in making the concrete. Cuprous oxide, triphenyltin hydroxide (TPTH), and 2-2-bis-(p-methoxyphenyl)-1,1,1-trichloroethane (methoxychlor) were used as dry additives. Two proprietary formulations were applied as coatings on untreated concrete. Test specimens were exposed at Port Hueneme, Calif. and Key Biscayne, Fla. Efficacy of toxicants was determined by periodically weighing the specimens and the fouling organisms that became attached. Concrete prepared with an aggregate impregnated with a TBTO/creosote mixture demonstrated the best antifouling performance of those specimens exposed for more than 1 year. The two proprietary coatings and the concrete containing methoxychlor, TPTH, and cuprous oxide as dry additives have exhibited good antifouling properties but have been exposed for a shorter time. Also, the strength of concrete prepared using the toxicants was acceptable and the corrosion rate of reinforcing rods did not increase. The concentration of organotin compounds was essentially unchanged in a concrete specimen exposed 6-1/2 years in seawater.

  11. Electrical conductivity of concrete containing silica fume

    SciTech Connect

    Abo El-Enein, S.A.; Kotkata, M.F.; Hanna, G.B.; Saad, M.; Abd El Razek, M.M.

    1995-12-01

    The influence of silica fume on concrete properties represents an important technical research. In general, silica fume tends to improve both mechanical characteristics and durability of concrete. Thus the electrical properties of concrete containing silica fume can be studied to clarify its physical performance during hydration. The electrical conductivity of neat cement, mortar and concrete pastes was measured during setting and hardening. The ordinary Portland cement was partially replaced by different amounts of silica fume by weight. The changes in the electrical conductivity were reported during setting and hardening after gauging with water. The results of this study showed that the electrical conductivity can be used as an indication for the setting characteristics as well as the structural changes of the hardened pastes made with and without silica fume.

  12. Ultrasonic testing of reactive powder concrete.

    PubMed

    Washer, Glenn; Fuchs, Paul; Graybeal, Benjamin A; Hartmann, Joseph Lawrence

    2004-02-01

    Concrete is a critical material for the construction of infrastructure facilities throughout the world. Traditional concretes consist of cement paste and aggregates ranging in size from 6 to 25 mm that form a heterogeneous material with substantial compressive strength and a very low tensile strength. Steel reinforcement is used to provide tensile strength for reinforced concrete structures and as a composite the material is useful for structural applications. A new material known as reactive powder concrete (RPC) is becoming available. It differs significantly from traditional concrete; RPC has no large aggregates, and contains small steel fibers that provide additional strength and, in some cases, can replace traditional steel reinforcement. Due to its high density and lack of aggregates, ultrasonic inspections at frequencies 10 to 20 times that of traditional concrete inspections are possible. This paper reports on the initial findings of research conducted to determine the applicability of ultrasonic testing techniques for the condition assessment of RPC. Pulse velocities for shear and longitudinal waves and ultrasonic measurement of the modulus of elasticity for RPC are reported. Ultrasonic crack detection for RPC also is investigated. PMID:15055809

  13. Fracture Mechanics Modelling of an In Situ Concrete Spalling Experiment

    NASA Astrophysics Data System (ADS)

    Siren, Topias; Uotinen, Lauri; Rinne, Mikael; Shen, Baotang

    2015-07-01

    During the operation of nuclear waste disposal facilities, some sprayed concrete reinforced underground spaces will be in use for approximately 100 years. During this time of use, the local stress regime will be altered by the radioactive decay heat. The change in the stress state will impose high demands on sprayed concrete, as it may suffer stress damage or lose its adhesion to the rock surface. It is also unclear what kind of support pressure the sprayed concrete layer will apply to the rock. To investigate this, an in situ experiment is planned in the ONKALO underground rock characterization facility at Olkiluoto, Finland. A vertical experimental hole will be concreted, and the surrounding rock mass will be instrumented with heat sources, in order to simulate an increase in the surrounding stress field. The experiment is instrumented with an acoustic emission system for the observation of rock failure and temperature, as well as strain gauges to observe the thermo-mechanical interactive behaviour of the concrete and rock at several levels, in both rock and concrete. A thermo-mechanical fracture mechanics study is necessary for the prediction of the damage before the experiment, in order to plan the experiment and instrumentation, and for generating a proper prediction/outcome study due to the special nature of the in situ experiment. The prediction of acoustic emission patterns is made by Fracod 2D and the model later compared to the actual observed acoustic emissions. The fracture mechanics model will be compared to a COMSOL Multiphysics 3D model to study the geometrical effects along the hole axis.

  14. Modeling and assessment of concrete and the energy infrastructure

    SciTech Connect

    Guthrie, G.; Carey, J.

    1998-01-01

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Concrete is an essential component of the energy infrastructure. The characteristics of concrete that determine its effectiveness in any application--be it construction (e.g., roads, bridges, dams) or waste isolation--result from the chemical and structural evolution of the particular concrete structure. Geochemical and mineralogical factors are among the most important, yet most overlooked, controls of this evolutionary process. This project is geared at using a combination of advanced geochemical and mineralogical experimentation, characterization, and modeling (much of which was developed to understand geological systems such as Yucca Mountain) to understand the evolution of concrete in a mechanistic way. The goal was to develop a systematic approach to problems ranging from premature degradation of concrete to the design of next-generation concretes.

  15. Neutron imaging of water penetration into cracked steel reinforced concrete

    NASA Astrophysics Data System (ADS)

    Zhang, P.; Wittmann, F. H.; Zhao, T.; Lehmann, E. H.

    2010-04-01

    Service life and durability of reinforced concrete structures have become a crucial issue because of the economical and ecological implications. Service life of reinforced concrete structures is often limited by penetration of water and chemical compounds dissolved in water into the porous cement-based material. By now it is well-known that cracks in reinforced concrete are preferential paths for ingress of aggressive substances. Neutron radiography was successfully applied to study the process of water penetration into cracked steel reinforced concrete. In addition, the effectiveness of integral water repellent concrete to prevent ingress of water and salt solutions was investigated. Results are described in detail in this contribution. It will be shown that neutron radiography is a powerful method to visualize the process of water penetration into cracked and uncracked cement-based materials. On the basis of the obtained experimental data, it is possible to quantify the time-dependent water distributions in concrete with high accuracy and spatial resolution. It is of particular interest that penetration of water and salt solutions into damaged interfaces between concrete and steel can be visualized by means of neutron radiography. Deteriorating processes in cracked reinforced concrete structures can be studied in a completely new way. This advanced technology will help and find adequate ways to improve durability and service life of reinforced concrete structures. This will mean at the same time an essential contribution to improved sustainability.

  16. Communications trends ease underground problems

    SciTech Connect

    Voige, R.C.

    1981-12-01

    New developments in underground mine communications include improved twisted-pair paging phones, selective paging phones and annunciator systems, multi-channel systems with data transmission capabilities, and wireless medium frequency radio systems.

  17. Drilling effect on subsurface microbial community structure in groundwater from the -250 m gallery at the Horonobe Underground Research Laboratory, Japan

    NASA Astrophysics Data System (ADS)

    Ise, K.; Amano, Y.; Sasaki, Y.; Yoshikawa, H.

    2014-12-01

    The deep geological disposal system is regarded as the most secure and practical disposal method of high-level radioactive waste in the world. In this disposal system, preservation of reducing condition is one of the key requirements, because most of radionuclides have low solubilities in such condition. However, the host rocks near the shafts and galleries would be affected by oxidization during the construction and operation period of a repository (for about 50 years). Therefore, the recovery of reducing condition after closing the repository should be verified. During the recovery processes, it is considered that microbial activities play important roles, but the mechanisms are poorly understood. In this study, we monitored the changes in microbial communities by molecular method to evaluate microbial response toward the oxygen stress. The groundwater samples were collected from a borehole of 250 m depth at the Horonobe Underground Research Laboratory, for two years immediately after drilling of a borehole without any contamination as much as possible. Immediately after drilling of the borehole, the phylotype related to Arcobacter spp. was dominated about 65 % of the total clone library. Arcobacter spp. is known as sulfide oxidizer and which can growth chemoautotrophically. Half a year later, the phylotype related to Azoarcus spp. and Pseudomonas spp. known as nitrate reducing bacteria increased, instead of the phylotype related to Arcobacter spp. One year later, in addition to nitrate reducing bacteria, phylotype related to Dethiobacterspp. known as thiosulfate reducing bacteria was dominantly detected. Two years later, most of detected clones were related to uncultured species such as candidate division WS6 and JS1 which are detected frequently in deep-sea sediments. Our results indicate that these redox sequential reactions could contribute to the recovery and maintenance of reducing conditions and provide a conceptual model for evaluating the capacity to

  18. Concrete sample point: 304 Concretion Facility

    SciTech Connect

    Rollison, M.D.

    1995-03-10

    This report contains information concerning the analysis of concretes for volatile organic compounds. Included are the raw data for these analysis and the quality control data, the standards data, and all of the accompanying chains-of-custody records and requests for special analysis.

  19. Kimballton Underground Research Facility

    NASA Astrophysics Data System (ADS)

    Rountree, S. Derek; Vogelaar, R. Bruce

    2012-03-01

    A new deep underground research facility is open and operating only 30 minutes from the Virginia Tech campus. It is located in an operating limestone mine, and has drive-in access (eg: roll-back truck, motor coach), over 50 miles of drifts (all 40' x 20+'; the current lab is 35' x 22' x 100'), and is located where there is a 1700' overburden. The laboratory was built in 2007 and offers fiber optic internet, LN2, 480/220/110 V power, ample water, filtered air, 55 F constant temp, low Rn levels, low rock background activity, and a muon flux of only ˜0.004 muons per square meter, per second, per steradian. There are currently six projects using the facility: mini-LENS - Low Energy Neutrino Spectroscopy (Virginia Tech, Louisiana State University, BNL); Neutron Spectrometer (University of Maryland, NIST); Double Beta Decay to Excited States (Duke University); HPGe Low-Background Screening (North Carolina State University, University of North Carolina, Virginia Tech); MALBEK - Majorana neutrinoless double beta decay (University of North Carolina); Ar-39 Depleted Argon (Princeton University). I will summarize the current program and exciting potential for the future.

  20. Kimballton Underground Research Facility

    NASA Astrophysics Data System (ADS)

    Vogelaar, R. Bruce

    2011-10-01

    A new deep underground research facility is open and operating only 30 minutes from the Virginia Tech campus. It is located in an operating limestone mine, and has drive-in access (eg: roll-back truck, motor coach), over 50 miles of drifts (all 40' x 20' x 100'; the current lab is 35'x100'x22'), and is located where there is a 1700' overburden. The laboratory was built in 2007 and offers fiber optic internet, LN2, 480/220/110 V power, ample water, filtered air, 55 F constant temp, low Rn levels, low rock background activity, and a muon flux of only ˜ 0.004 muons per square meter, per second, per steradian. There are currently six projects using the facility: mini-LENS - Low Energy Neutrino Spectroscopy (Virginia Tech, Louisiana State University, BNL); Neutron Spectrometer (University of Maryland, NIST); Double Beta Decay to Excited States (Duke University); HPGe Low-Background Screening (North Carolina State University, University of North Carolina, Virginia Tech); MALBEK - Majorana neutrinoless double beta decay (University of North Carolina); Ar-39 Depleted Argon (Princeton University). I will summarize the current program, and exciting plans for the future.