Research on seismic performance of high-speed railway segmental assembled round-end hollow pier with energy dissipation bar

Segmental assembled piers have gained increasing attention in bridge engineering due to their superior construction efficiency, shortened construction periods, and reduced on-site wet work. However, their application in high-seismic-intensity regions remains limited because the mechanical performance of segment joints is generally weaker than that of conventional monolithic piers. This concern is particularly critical for high-speed railway bridges, which demand exceptional structural stability and seismic safety. To address this issue, energy dissipation bars were introduced into a segmental assembled round-end hollow pier to enhance its seismic resilience. A nonlinear finite element model was developed and validated against experimental results to ensure the reliability of the numerical approach. Based on the validated model, the effects of key design parameters of the energy dissipation bars were systematically investigated, and dynamic time-history analyses were conducted to evaluate seismic responses under different earthquake motions. The results demonstrate that increasing the sectional contribution ratio of the energy dissipation bars markedly improves the lateral resistance, energy dissipation capacity, and loading-unloading stiffness of the pier. However, this enhancement also results in larger residual drift angles, indicating a trade-off between seismic robustness and post-earthquake recoverability. Compared with the diameter and quantity of the bars, their arrangement shows a relatively limited influence on seismic performance. Moreover, the vibration mitigation effectiveness becomes increasingly significant with rising peak ground acceleration (PGA), achieving reduction rates exceeding 60 %. Nevertheless, severe plastic deformation and damage to the energy dissipation bars were observed under strong earthquakes, which indirectly amplify residual displacements. Additionally, the pier exhibits substantially stronger seismic responses under near-field ground motions than under far-field motions. In particular, near-field pulse-like earthquakes significantly amplify the pier-top displacement, suggesting that special design considerations are necessary when deploying such piers in near-fault regions. This study provides important insights into the seismic performance and design optimization of segmental assembled hollow piers for high-speed railways, offering valuable theoretical support and practical guidance for their application in seismic regions.