Cracking in RC Bent Caps (1851-1)

This final project report documents the findings of a Texas Department of Transportation sponsored research program to determine the causes of unexpected cracking in reinforced concrete bent caps at outside column locations (cantilevered regions) during service load conditions. Sixteen full-scale bent cap specimens were constructed and tested under quasi-static monotonic loading up to service level loading and through failure. Researchers considered and evaluated the following bent cap parameters in regard to their influence on cracking: longitudinal reinforcement stress, size, and spacing; embedment of longitudinal reinforcement near the discontinuous end of the cap; transverse reinforcement detailing and shear strength; critical section for flexure; and skin reinforcement. Researchers measured and recorded cracks from initial cracking through failure, and reinforcement strain data was recorded continuously throughout the loading history for each specimen. The experimental program confirmed that the observed flexural cracking during service load conditions is directly proportional to the level of stress in the flexural reinforcement. In addition, enhancing the shear strength of the bent cap leads to a reduction in inclined flexure-shear cracks during service and ultimate load conditions.