Experimental study on the mechanical behavior of bridge concrete pile caps under lateral seismic loading

Abstract This paper investigates the mechanical behavior of bridge pile caps subjected to lateral seismic loading through loading tests and numerical analyses. Two pile cap specimens were designed with different pile layouts (2 × 2 and 2 × 3) to examine the influence of pile layout variation. Although both pile cap specimens failed in bending, the dominant bending cracks in specimen SV2 × 2 appeared in two directions. In contrast, the dominant bending cracks in specimen SV2 × 3 were observed only in the width direction of the pile cap with a relatively smaller crack width. Compared with specimen SV2 × 2, the centrally positioned pile in the width direction significantly restrained the vertical displacement at the center of the right side in specimen SV2 × 3, and the rotation behavior in the width direction was consistent with the distribution of the dominant bending cracks. Furthermore, based on the distribution of principal compressive strains of internal concrete of pile caps, it was confirmed that multiple load paths developed in the pile cap of specimen SV2 × 3 due to the centrally positioned pile in the width direction, thereby enhancing the load‐bearing capacity and delaying the stiffness degradation of the pile cap in specimen SV2 × 3. The maximum capacities recorded were 255 and 314 kN in specimen SV2 × 2 and SV2 × 3, respectively. However, the transfer efficiencies of these load paths in specimen SV2 × 3 were different. The load path near the additional centrally positioned piles was capable of transferring a larger proportion of the external load from pier to piles, decreasing the reaction forces of the corner piles and the surrounding reinforcement stress.