基于纤维模型的大跨连续梁桥隔震特性研究

Research On Seismic Isolation Characteristics of Large-span Continuous Girder Bridge Based on Fiber Element Model

分别应用纤维单元模拟梁墩桩构件,分层壳单元模拟承台,Bouc-Wen模型模拟铅芯橡胶隔震支座,建立某跨海大桥的一段引桥的有限元分析模型.通过进行动力弹塑性分析,探讨铅芯橡胶支座(LRB)屈服力和屈服后刚度两大参数对桥梁结构的动力特性及隔震效果的影响规律.分析结果表明,LRB对大跨连续梁桥具有明显的减震效果,可以大幅度减小各墩的相对位移和墩底剪力;LRB屈服力越小,其墩的位移和墩底剪力越小,隔震效果越好;LRB屈服后刚度越小,隔震效果越好;盲目减小LRB屈服力反而会增大支座位移,容易造成支座最先破坏,导致落梁.

In this paper,a finite element analysis model is established for an approach span of a cross-sea bridge with the beam,pier and pile simulated by fiber beam elements,the pile cap simulated by layered shell element,and the lead rubber bearings simulated by Bouc-Wen model.Through the dynamic elastic-plastic analysis,the influence rule of the dynamic characteristics and seismic isolation effect of the two parameters of the yield force of Lead Rubber Bearing(LRB)and post-yield stiffness on the bridge structure was discussed.The results show that LRB has obvious seismic reduction effects on large-span continuous girder bridge,such as the significant decrease of the relative displacement of the pier and the shear force at the bottom of the pier.The smaller the yield force of LRB,the displacement of the pier and the shear force at the bottom of the pier,the better the seismic reduction effect will be.The smaller the post-yield stiffness of LRB,the better the seismic isolation effect will be.Unreasonably reducing the yield strength of LRB may increase its displacement,causing its damage beforehand,even beam lowering.