高速铁路桥梁圆端形墩地震反应数值分析

Numerical Analysis of the Seismic Responses of Round-ended Piers of High-speed Railway Bridges

以高速铁路简支桥梁圆端型实体墩为工程背景,建立了2种有限元模型计算桥墩的弹塑性地震反应,一种是包括桥墩的杆系单元全桥体系模型,可以考虑列车荷载的影响;另一种是单墩实体模型,用以分析桥墩的地震响应;基于2种有限元模型和弯矩-曲率关系程序,分别计算了不同车速、墩高、地震作用组合和有车/无车等工况下桥墩的弹塑性地震响应.计算结果表明,随着地震强度的增加,桥墩的地震响应呈上升趋势,车速、墩高的增加对桥墩地震响应的影响不呈线性增长关系,地震频谱特性对桥墩地震反应影响较大;罕遇地震作用下墩底进入弹塑性状态,给出了适合低配筋率桥墩塑性铰区箍筋加密长度简化计算公式.

For round-ended piers of high-speed railway bridges,two kinds of finite element model were set up to calculate the elastic-plastic seismic responses of piers：one was beam element model of the whole bridge which includes the piers and could take into account the influence of vehicle load,and the other was solid model of the piers which could explain the seismic responses of piers.According to the two models and the bending moment-curvature relationship program,the elastic-plastic seismic responses of piers were computed at different earthquake load combination,pier height and vehicle speed.The calculation results have shown that the seismic responses of piers will increase with increment seismic intensity,the influence of vehicle speed and pier height on the responses of the piers is not in a linearly increasing manner,the frequency characteristics of earthquake wave have great influence on the seismic responses of the piers,the piers step into the state of elastic-plasticity and the plastic hinge will be developed at the bottom of piers under rare earthquake.The simplified calculation formula of plastic hinge region length suited to high-speed railway bridge round-ended piers where stirrups are encrypted was presented.