Title: Strut-and-Tie-Based Design and Testing of Reinforced Concrete Pier Caps
Author(s): Indu Geevar, Devdas Menon, and Meher Prasad A.
Publication: Structural Journal
Appears on pages(s): 211-223
Keywords: corbel; cracking; disturbed regions; pier cap; serviceability; shear; strut and tie
This study was motivated by the observation of unexpected cracking in an actual reinforced concrete (RC) pier cap, consisting of a pair of two secondary corbels, supported on a primary corbel with the pier at its center. The pier cap was analyzed using the strut-and-tie method (STM) by considering a three-dimensional (3-D) model. Tests were carried out on two scaled-down pier cap specimens to assess safety and serviceability performance. The load-carrying capacity of the pier cap was under-predicted by approximately 75% by STM using ACI 318 and AASHTO codes. The test results presented in the paper include evolution of cracking and strains in the steel reinforcing bars, along with load-deflection plots. It was observed that concentrating reinforcing bars near the bearings resulted in an increase in strength by approximately 8.5% without adversely affecting serviceability. In summary, STM is found to provide an effective basis for the design and detailing of such complex pier caps.