高铁简支梁桥横向地震碰撞效应及减震研究

Transverse Seismic Pounding Effect and Pounding Reduction of Simply-Supported Girder Bridge for High-Speed Railway

为了研究高铁简支梁桥横向地震碰撞效应及减隔震装置的减碰效果,以7跨32m标准跨径简支梁桥为例,通过试验测定挡块的实际力-变形曲线,并基于SAP2000建立了考虑地震碰撞效应的有限元模型.在此基础之上,分析了轨道系统、挡块-垫石初始间距及挡块钢板厚度对桥梁地震响应的影响,并进一步探讨了橡胶垫层、铅芯橡胶支座(LRB)、摩擦摆支座(FPB)、高阻尼橡胶支座(HDR)及液体粘滞阻尼器的减碰效果.研究结果表明:轨道系统的约束作用会显著改变各桥跨之间的地震力分配;在所考虑的最大地震激励下,碰撞力峰值达2.18MN,挡块的非线性效应显著;对于本文算例而言,挡块-垫石间距设为3cm,挡块钢板厚度取32mm是一个较为合理的配置;减隔震装置能够有效地改善桥梁结构抗震性能,且其防碰减震效果受地震波频谱特性及自身作用机理的影响,其中,FPB支座具有较强的适用性,且安装FPB支座后各桥跨之间的地震力分配更加均匀.

A 32 m standard-span simply-supported girder bridge with 7 spans for high-speed railway was used as a prototype to study the effects of the earthquake-induced transverse pounding,as well as the pounding reduction effects of various isolation devices.The actual force-deformation curves of shear keys were determined experimentally and a finite element model considering pounding was established using SAP2000.On this basis,influences of the rail system,the initial gap between the shear keys and bearing padstones,and the thickness of shear-key plates on seismic responses of the bridge were analyzed.Then,the pounding reduction effects of rubber bumpers,lead rubber bearings(LRBs),friction pendulum bearings(FPBs),high damping rubber bearings(HDRs),and fluid viscous dampers were discussed.The results are as follows:the rail system can significantly alter the distribution of seismic forces between bridge spans.Under excitations of the maximum earthquakes considered,the nonlinear effect of shear keys is significant,with the maximum pounding force of 2.18 MN.For the sample bridge presented in this paper,it is a reasonable configuration to set the initial gap between the pounding members as 3 cm and the thickness of shear-key plates as 32 mm.The seismic isolation devices can improve the seismic performance of the bridge;their pounding reduction effects are affected by spectral characteristics of ground motions as well as their own mechanisms.Among them,the FPB has better applicability and the seismic forces between different spans become more uniform after the installation of FPBs.