铁路空心墩抗震性能的拟静力试验研究

Pseudo static Test Research on Seismic Performance of Railway Hollow Pier

摘要:

铁路桥梁空心墩在铁路建设中普遍使用，空心墩与实体墩有较大差异，空心墩塑性铰区域的长度能否直接采用实体墩的研究结果尚不明确，采用缩尺模型进行模拟试验是一种比较理想的手段。本文以大瑞铁路的空心桥墩为原型，制作了3个大比例尺的缩尺模型，采用拟静力试验方法进行了截面合理配筋、地震破坏模式及塑性铰区域长度研究，得到了空心高墩在水平反复荷载作用下的骨架曲线、滞回曲线、塑性铰区长度及破坏特征。试验结果表明，现有设计配筋率下模型桥墩呈现延性破坏，破坏特征体现为混凝土的压碎，有明显的塑性铰区域；模型桥墩的塑性铰区域长度与墩底截面受力方向尺寸相近。采用数值模拟得到单调加载骨架曲线和试验骨架曲线，与试验得到曲线能较好地吻合。

Abstract:

Hollow piers are widely applied on railway bridges.In high intensity seismic regions，hollow piers and solid piers differ greatly in the arrangement of the longitudinal reinforcements and stirrups.In addition，plastic hinge mechanisms and positions of hollow piers are very different from those of solid piers.Experiments must be completed to examine solid piers on plastic hinges and then the findings applied to hollow piers.In this paper，methods of testing and numerical analysis are introduced and used to study the plastic hinge’s mechanism and position of hollow piers.Firstly，based on the hollow piers on the Dali Ruili railway，three large-scale models were made to study reasonable reinforcement arrangement，seismic damage model，and plastic hinge zone length by using pseudo-static test methods.Pseudo static test methods are the most widely used test methods for studying structural or component performances.This method maximizes the number of specimens and provides an abundance of information such as the bearing capacity，stiffness, deformation capacity，energy dissipation，and damage characteristics.From the scale model，hysteresis loop，plastic hinge zone length，and failure characteristics of hollow piers were obtained under the cyclic horizontal loads.The results show that under the design reinforcement arrangement，the model presents ductile failure whose characteristics are concrete crushing with obvious plastic hinge region.In addition，the plastic hinge zone length is similar to the dimension of the pier section （along the stress direction） at the bottom of the pier.Secondly，a fiber element model was made by using the software Opensees.During the finite element analysis，no constraint model was used for protective layer of concrete and Mander model was used for core concrete.Then，a monotonic loading skeleton curve and hysteresis loop were obtained through numerical modeling.Finally，after comparing the model results and test hysteresis curves，it was shown that numerical results were consistent with results obtained experimentally.