Response of Variable-Depth Reinforced Concrete Pier Cap Beams

Abstract

Four variable-depth pier cap beams were constructed and tested. These specimens were designed to have reinforcement details that had similar features to two different types of pier cap beams used in the Champlain Bridge in Montréal, Canada. The objectives were to examine the behavior of variable-depth cap beams at service loading and at failure to analyze the effectiveness of crack control reinforcement and inclined reinforcement, as well as to investigate the influence of added external horizontal post-tensioning. The observed cap beam responses were compared with two prediction models: sectional analyses and nonlinear finite-element analyses. The amount of crack control reinforcement was important in controlling crack widths at the service load level. The inclined shear reinforcement was found to be effective in resisting shear. Horizontal post-tensioning was effective in reducing crack widths and increasing the overall stiffness of the cap beams but did not lead to significant increases in shear strength. Failure shears predicted by the sectional analyses were conservative. Nonlinear finite element analyses gave good predictions of the complete behavior and strength of the cap beams.