Centrifugal Shaking Table Test and Numerical Analysis of Soil and Structure Interaction System Reproducing Shear Failure of RC Piles

Numerous reinforced concrete (RC) piles supporting building structures have suffered damage in past earthquake disasters. However, the influence of damage to pile foundations and surrounding soil on the seismic response of the superstructures remains insufficiently understood. This study investigates the ultimate behavior of a soil–RC pile–superstructure interaction system governed primarily by shear failure of the piles. Centrifuge shaking table tests were conducted to observe the response under strong ground motion, and a simplified numerical analysis model was developed to validate the experimental results. The experiments revealed that when the RC piles reached their ultimate shear capacity, pronounced differential settlement occurred, causing significant tilting of the superstructure. A beam–spring model was employed for simulation, with RC piles modeled as nonlinear beam elements and subgrade reaction represented by tetra-linear springs. The numerical analysis successfully reproduced the time histories of horizontal acceleration and inertial force observed in the experiments. However, the pinching behavior seen in the inertial force–foundation displacement relationship was not captured, likely due to underestimation of horizontal displacement at the pile heads and the limitations of the hysteresis model used, which was originally designed for ductile failure.