板式橡胶支座梁桥横向抗震加固研究

Study of seismic retrofit for girder bridge supported on elastomeric pad bearings in the transverse direction

针对汶川地震中板式橡胶支座梁桥梁体横向移位严重的震害现象,提出了在原约束体系基础上增设X形板弹塑性挡块的抗震加固设计方法。以一座典型板式橡胶支座简支梁桥为研究对象,建立了可合理模拟支座滑动效应、挡块力学性能和墩柱滞回性能的全桥精细化有限元数值模型。选择国内外实际地震动进行横桥向非线性地震反应分析,研究了梁体与钢筋混凝土挡块横向间隙、X形板弹塑性挡块力学性能等两大参数对抗震加固效果的影响。研究表明:钢筋混凝土挡块与梁体间可预留一定横向间隙,X形板弹塑性挡块屈服强度可控制为上部结构恒载反力的5%;与抗震加固前相比,抗震加固设计能有效控制墩梁相对位移,同时减小桥墩结构地震反应,显著提高桥梁结构抗震性能。

Facing the transverse seismic damages of highway bridges on elastomeric pad bearings during Wenchuan earthquake,which were characterized by serious shifting or even unseating of girders,a seismic retrofit measure of introducing auxiliary X-shaped steel hysteretic dampers to the original seismic resisting system was proposed. Based on a typical simple-supported girder bridge,a refined model was set up,which could consider the bearing sliding effect,the nonlinear hysteretic behavior of column and the proper mechanical properties of the RC shear key and Xshaped steel hysteretic damper. The nonlinear time history analysis were carried out for bridge seismic response in the transverse direction under selected ground motions,and the influence of two parameters,transverse gap between girder and RC shear key and yield strength of X-shaped steel hysteretic damper,on the structural seismic performance was studied. The results show that it is suggested that certain transverse gap between girder and RC shear key could be put up,and the yield strength of X-shaped steel hysteretic damper could be determined as 5 percent of the vertical reaction of the superstructure at the support. The seismic retrofit measure could effectively restrain the displacement of girder,control the girder inertia force transmitted to substructure,and improve the seismic perform-ance of bridge structure.