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A finite element model capable of tracing the nonlinear response of coupled shear walls to earthquake motions is proposed. The walls are idealized as an assembly of quadrilateral elements with three degrees of freedom, two translational and one-rotational, at each corner, and nonlinearities, such as cracking, crushing of concrete, and yielding of steel, are included in the model. The coupling beams are idealized as line elements, and the nonlinearities are confined to element ends through inelastic experimentally based moment-rotation relationships. Allowance has been made for stiffness degradation and bond slippage. The rotational degree of freedom to the plane stress element makes the compatibility of rotations at the coupling-beam-wall interface possible, the evaluation of coupling beams rotation straightforward and the mathematical model elegant. The model was applied to trace the response of two coupled shear walls tested elsewhere and the results achieved were in good agreements with experimental results.

A fatigue study was performed on two commercial highstrength concretes of 70 MPa and 95 MPa with water/cementitious material ratios of 0.28 and 0.23, respectively. Specimens were cast at the construction site and cured in the laboratory. Tests were performed under constant amplitude, and strains were measured continuously using strain gauges. The McCall model for fatigue life prediction was found to be satisfactory, and safer than the usual Wöhler curves. Strain evolution and stiffness degradation with the number of cycles in highstrength concrete were found to be similar to those of normal concrete. Strain at failure under cyclic loading was found to be of the same order as the strain at peak load under static loading. Interesting correlations between strain rate and number of cycles to failure and between stiffness decrease rate and number of cycles to failure were found. Evolution of the hysteresis loop was studied. Energy dissipated was found to decrease after the first cycles, and increased steadily thereafter up to failure. Finally, the differences in deformation characteristics between the two highstrength concretes studied in this investigation were analyzed.

A recent advancement in the field of structural rehabilitation consists of fiber-reinforced plastic (FRP) composites used to strengthen structural elements. Since a significant portion of the infrastructure in North America is in need of a rapidly applied strengthening and rehabilitation solution, much interest in this method has developed. FRP systems provide the advantage of increasing ductility and shear and flexural strength, whereas they are lightweight and can be applied relatively quickly and easily. Guidelines that the engineer can use to recommend construction specifications involved in FRP applications are provided. The results are based on numerous field applications and will help provide an efficient and proper repair method.

A recent advancement in the field of structural rehabilitation consists of fiber-reinforced plastic (FRP) composites used to strengthen structural elements. Since a significant portion of the infrastructure in North America is in need of a rapidly applied strengthening and rehabilitation solution, much interest in this method has developed. FRP systems provide the advantage of increasing ductility and shear and flexural strength, whereas they are lightweight and can be applied relatively quickly and easily. Guidelines that the engineer can use to recommend construction specifications involved in FRP applications are provided. The results are based on numerous field applications and will help provide an efficient and proper repair method.

A fatigue study was performed on two commercial high‐strength concretes of 70 MPa and 95 MPa with water/cementitious material ratios of 0.28 and 0.23, respectively. Specimens were cast at the construction site and cured in the laboratory. Tests were performed under constant amplitude, and strains were measured continuously using strain gauges. The McCall model for fatigue life prediction was found to be satisfactory, and safer than the usual Wo¨hler curves. Strain evolution and stiffness degradation with the number of cycles in high‐strength concrete were found to be similar to those of normal concrete. Strain at failure under cyclic loading was found to be of the same order as the strain at peak load under static loading. Interesting correlations between strain rate and number of cycles to failure and between stiffness decrease rate and number of cycles to failure were found. Evolution of the hysteresis loop was studied. Energy dissipated was found to decrease after the first cycles, and increased steadily thereafter up to failure. Finally, the differences in deformation characteristics between the two high‐strength concretes studied in this investigation were analyzed.

The objectives of this study are to evaluate the parameters that affect the behavior of flexible pipes for culverts and storm sewers and to examine the strength-limit states of such pipes proposed by the AASHTO bridge-design specifications. The flexible pipes investigated in the study are high-density polyethylene (HDPE), PVC, and metal pipes. The pipe diameters considered are 914 mm (36 in.) and 1,219 mm (48 in.). A three-dimensional finite-element (FE) model has been developed to simulate the behavior of buried pipes under truck load. Results from field tests conducted by the authors for large-diameter pipes under 2D, 1D, and 0.5Dburial depths, where Dis the pipe diameter, were used to evaluate the accuracy of the numerical model. Extensive parametric studies were then carried out to examine the effect of burial depth, backfill soil quality, and compaction level on the buried pipes, and their results are reported in this paper. The effect of these parameters has been evaluated in terms of thrust values at the pipe shoulder and springline, vertical diameter changes, and longitudinal strains. Regression analysis was carried out based on the FE model predictions for the first load pass and on results from a research study available in literature to predict the behavior of buried pipes with multiple load passes. The parametric study has shown that the performance of buried pipes varies with the soil type, and the increase of compaction level and soil cover reduces the stresses on buried pipes. The numerical predictions indicate that the provisions of AASHTO bridge-design specifications for HDPE pipes need to be reassessed for very shallow burial depths.