EXPERIMENTAL STUDY ON SEISMIC PERFORMANCE OF HOLLOW PIERS WITH ROUNDED RECTANGULAR CROSS SECTION IN HIGH-SPEED RAILWAYS

Ten large-scale specimens were designed based on hollow pier prototypes with rounded rectangular cross section used in high-speed railways. Hysteresis curves and failure mechanisms were obtained from cyclic loading tests under constant axial loading. The influence of each design parameter on the energy dissipation capacity and ductility of the specimens was further analyzed, and the shear performance of piers was evaluated using two empirical seismic shear capacity equations. Test results show that all specimens failed in flexure with flexure-shear cracks commonly observed at the bottom of the piers. The hysteresis curves had significant pinch and the skeleton curves rose slowly from concrete cracking to yielding. The displacement ductility reduced and the bearing strength increased with the increment in axial-load ratio and longitudinal reinforcement ratio. No pronounced effects of the volume-stirrup ratio on the ductility were observed due to the relatively low volume-stirrup ratio of the specimens. The longitudinal reinforcement ratio had notable effects on the shapes of hysteretic curves. Furthermore, increasing the longitudinal reinforcement ratio significantly improved the energy dissipation capacity of the specimens.