The Experts below are selected from a list of 126 Experts worldwide ranked by ideXlab platform
Daniel S Crovo - One of the best experts on this subject based on the ideXlab platform.
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field monitoring of integral abutment bridge in massachusetts
Transportation Research Record, 2004Co-Authors: Scott A Civjan, Sergio F Brena, David A. Butler, Daniel S CrovoAbstract:Integral abutment bridges are increasingly being used to eliminate undesirable bridge joint effects on the long-term performance of bridges. Although many states use this type of construction, common design guidelines are lacking, and nonuniform limitations on integral abutment design are imposed by different agencies. Data from the field monitoring of an existing three-span integral abutment bridge in central Massachusetts are presented. Resulting data are valuable in evaluating existing design provisions and understanding structural behavior. The results presented for a 16-month period of monitoring include recorded ambient temperature from -4°F to 99°F (-20°C to 37°C). Longitudinal movements induced by thermal expansion and contraction of the bridge are consistent with temperature changes. However, Earth Pressure Cell data indicate that the maximum Pressures generated behind the abutment walls occur in early spring. Lower Pressures measured in the summer indicate some dissipation of soil Pressures with...
Scott A Civjan - One of the best experts on this subject based on the ideXlab platform.
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field monitoring of integral abutment bridge in massachusetts
Transportation Research Record, 2004Co-Authors: Scott A Civjan, Sergio F Brena, David A. Butler, Daniel S CrovoAbstract:Integral abutment bridges are increasingly being used to eliminate undesirable bridge joint effects on the long-term performance of bridges. Although many states use this type of construction, common design guidelines are lacking, and nonuniform limitations on integral abutment design are imposed by different agencies. Data from the field monitoring of an existing three-span integral abutment bridge in central Massachusetts are presented. Resulting data are valuable in evaluating existing design provisions and understanding structural behavior. The results presented for a 16-month period of monitoring include recorded ambient temperature from -4°F to 99°F (-20°C to 37°C). Longitudinal movements induced by thermal expansion and contraction of the bridge are consistent with temperature changes. However, Earth Pressure Cell data indicate that the maximum Pressures generated behind the abutment walls occur in early spring. Lower Pressures measured in the summer indicate some dissipation of soil Pressures with...
Joseph F. Labuz - One of the best experts on this subject based on the ideXlab platform.
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Soil-structure interaction of an Earth Pressure Cell
Journal of Geotechnical and Geoenvironmental Engineering, 2011Co-Authors: Gregory S. Wachman, Joseph F. LabuzAbstract:The output from an Earth Pressure Cell (EPC) is usually related to the normal stress in soil through fluid calibration, where a known Pressure is applied to the EPC and the output is recorded. However, distribution of normal stress within a soil is not uniform, and the EPC is not an ideal membrane—bending stiffness affects the response. These factors complicate the performance of the EPC. A calibration procedure for an EPC is reviewed, and it is shown that these controversial sensors can provide an accurate measure of average normal stress if calibrated in soil at a given density. In addition, a soil-structure interaction model is proposed to explain why soil calibration is necessary.
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Discussion of "Performance of a Cantilever
2007Co-Authors: Joseph G. Bentler, Joseph F. LabuzAbstract:The authors’ Earth Pressure and displacement measurements on acast-in-place reinforced concrete cantilever retaining wall showthat significant residual lateral stresses were created by compac-tion of the backfill, but at the end of construction, sufficient trans-lation of the wall had occurred to develop an active Earth-Pressurecondition.To examine the Earth Pressure measurements in detail, it wouldbe helpful if the authors could provide the following information.First, details of the smooth-wheel vibratory roller—includingstatic weight, centrifugal force if operated in the vibratorymode , length of roller drum, and the distance between the edgeof the drum and the back of the wall during the compactionprocess—would make it possible to compare measured residuallateral stresses with those estimated by using Duncan and Seed’s 1986 procedure. Second, complete dimensions for the wall stemand the supporting footing are needed for evaluating stabilityagainst overturning and sliding resistance. Finally, it would beinteresting to compare the Earth Pressure measurements on EPC10 on the back of the wall with those on Cell EPC bf, located1.5 m behind EPC 10 in the vertical plane through the heel of thefooting.The authors report that the maximum lateral force on the wallstem, as determined from the Earth Pressure Cell measurements,occurred at a backfill height of 6.1 m and was approximatelyequal to the design value based on the theoretical active Pressuredistribution for the 7.9 m high wall. With 6.1 m of backfill inplace, the maximum lateral force of 159.2 kN/m was about 1.8times the theoretical value assuming fully active conditions, i.e.,
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FIELD INSTALLATION OF AN Earth Pressure Cell
Transportation Research Record, 2001Co-Authors: Brent Theroux, Joseph F. Labuz, Shongtao DaiAbstract:An Earth Pressure Cell (EPC) is a device designed to provide an estimate of normal stress in soil. The practice of designing and manufacturing stress-measurement devices revolves around the study of the interaction between the measuring device and the host material. However, distribution of normal stress is not necessarily uniform across a given surface. Consequently, output from an EPC may be different under soil-loading conditions than under fluid Pressure. In addition, depending on the design, as the Cell deflects, an arching-type phenomenon may develop. A study was conducted to devise a scheme for calibration of EPCs and to recommend a procedure for field installation. A new testing device was designed to permit the application of uniaxial soil Pressure to the EPC by using various types of soil and load configurations. Sensitivities computed from soil calibrations varied from those determined from fluid calibrations by as much as 30 percent. A field installation procedure was developed from model test...
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CALIBRATION OF AN Earth Pressure Cell
2000Co-Authors: Brent Theroux, Joseph F. Labuz, Andrew DrescherAbstract:In this study, researchers devised a scheme for calibration of Earth Pressure Cells to observe their response to various loading configurations and to recommend a procedure for field installation. Transducers designed to provide an estimate of normal stress within a soil, Earth Pressure Cells have provided readings that conflict with known loading conditions. Initial calibration tests used hydraulic oil as the pressurizing medium in both hydrostatic and uniaxial Pressure conditions, which mimic the manufacturers' procedure for Pressure Cell calibration. Researchers designed a new testing device to permit the application of uniaxial soil Pressure to the Earth Pressure Cells using various types of soil and load configurations. As a result of calibration tests, a field installation procedure was developed and recommended. In the laboratory, a thin-walled steel cylinder with a geotextile bottom was filled with uniform silica sand of a known density, and the Earth Pressure Cell was placed within the sand. The entire apparatus was carried into the field and installed in the desired locations. Once in place, the steel cylinder was pulled up out of the ground, leaving the Cell and geotextile behind. Preliminary field data indicate that soil calibration and placement procedure provide reasonably accurate measurements.
Tsuyoshi Hirabayashi - One of the best experts on this subject based on the ideXlab platform.
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THE SIZE EFFECTS OF Earth Pressure CellS ON MEASUREMENT IN GRANULAR MATERIALS
Soils and Foundations, 2003Co-Authors: Kinya Miura, Natsuhiko Otsuka, Eiji Kohama, Chairat Supachawarote, Tsuyoshi HirabayashiAbstract:ABSTRACT This paper aims to reveal the size effects of Earth Pressure Cells on measurements in sand and gravels and propose a guideline for the selection of an appropriate size. In the case of gravel containing large particles, point loadings at several contact points in the Cell make it difficult to measure the Earth Pressure with sufficient accuracy and reliability. Four types of Earth Pressure Cells were used in this study with different sizes of sensitive panels and principles of measurements. A series of loading tests were conducted with sand and four types of gravels. The reliability of the test results was first examined ; the influence of parameters such as the stiffness of the Earth Pressure Cell, and the sidewall friction of the test container were investigated. From a comparative study of the measured data, the appropriate size of the Earth Pressure Cell was determined as a function of the grain size of the gravel and accuracy needed in the measurements.
Thomas L. Brandon - One of the best experts on this subject based on the ideXlab platform.
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Static and dynamic measurements using embedded Earth Pressure Cells
Transportation Research Record, 1994Co-Authors: George M Fitz, Thomas L. BrandonAbstract:As part of a research program to study lateral Earth Pressures on retaining walls, dynamic compactor forces were measured by two methods: (a) a direct instrumentation method that is thought to yield reliable measurements of dynamic compactor forces and (b) taking measurements of embedded Earth Pressure Cell responses that are converted to estimated compactor forces at the ground surface. Comparison of the compactor forces from the two methods disclosed the following: (a) Reflection of seismic waves from the boundaries of the backfill can create a standing wave at the embedded Pressure Cell location, which may cause Pressure Cells to overregister. (b) The Pressure distribution beneath the base of the compactor can influence the embedded Pressure Cell readings. (c) Use of a registration ratio of unity resulted in estimated compactor forces that were generally in as good, or better, agreement with the forces measured by the direct instrumentation as when in situ registration ratios were used. During the in situ calibration studies, several factors that can influence the response of embedded Pressure Cells to static loads were identified: the presence of clods in the backfill can influence Pressure Cell response, even when the diaphragm size to soil particle size criterion is well satisfied; compaction-induced lateral Earth Pressures can cause nonlinearity in Pressure Cell response because of the rotation of lateral stresses; and other factors, such as variations in Cell placement conditions, can influence Pressure Cell results.
