Seismic performance analysis of self-centering rocking bridge piers based on the endurance time method

Posttensioning self-centering rocking bridge piers utilize unbonded posttensioning (PT) tendons to provide self-centering capacity, while energy dissipation (ED) bars enable flag-shaped hysteresis behavior. The rocking interface at the pier base releases rotational constraints, achieving both high ED and self-centering characteristics, thereby effectively reducing residual displacements under strong seismic excitations. To evaluate their seismic performance and the influence of key design parameters, this study conducts a systematic validation and parametric analysis based on the endurance time method (ETM). A refined finite element model capable of accurately capturing the rocking behavior was developed and validated. The effects of initial PT force, ED reinforcement ratio, and contact interface stiffness on pier response under a specific seismic hazard level were examined. Representative ETM ground motion records were synthesized, and numerical simulations were carried out. The influence of design parameters under different seismic hazard levels was comparatively assessed, and the applicability of ETM in predicting the seismic response of self-centering rocking piers was verified. Results indicate that ETM is effective in evaluating the seismic performance of self-centering rocking piers with varying design parameters. Increasing initial PT force significantly suppresses base uplift and reduces displacement response, although excessive PT force may increase axial and shear forces in the pier. A moderate increase in ED amount controls displacement, but excessive ED amount can reduce strain response and ED capacity. While flexible contact materials reduce shear force in the pier body, they increase the displacement of the mass center. As interface stiffness increases, both shear force and PT force also increase, eventually stabilizing beyond a certain stiffness threshold. The findings provide an efficient and simplified analytical approach for seismic design and rapid performance assessment of self-centering rocking piers.