高速铁路圆端形空心桥墩抗震性能试验研究
EXPERIMENTAL STUDY ON SEISMIC PERFORMANCE OF HOLLOW PIERS WITH ROUNDED RECTANGULAR CROSS SECTION IN HIGH-SPEED RAILWAYS
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摘要: 以高速铁路中采用的圆端形空心桥墩为原型, 设计了10根大比例模型。考虑恒定轴向力的作用, 进行低周反复荷载试验, 得到不同桥墩模型的破坏特性、滞回曲线, 依此分析各参数下桥墩的延性及耗能性能, 并利用两种典型的抗剪公式对模型的抗剪承载力进行评估。试验结果表明, 该类桥墩均为弯曲型破坏, 墩底普遍有弯剪斜裂缝。滞回曲线捏缩效应明显并且骨架曲线从开裂到屈服上升缓慢。随着轴压比的提高, 模型的弯曲强度有所增大, 延性下降。由于模型的体积配箍率均较低, 其对延性的影响不明显。纵筋率对滞回曲线形状影响较大, 增加纵筋率耗能能力随之增大。Abstract: 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.