近断层地震动作用下减隔震桥梁空间动力分析

采用非线性时程分析法, 分析了减隔震桥梁和非减隔震桥梁的三维地震响应。通过对比减隔震桥梁在不同地震动激励下的动力响应, 研究了减隔震桥梁承受近断层地震动的响应特性。
通过对比减隔震和非减隔震桥梁纵向地震位移, 研究了近断层地震动对铅销橡胶支座的减震性能的影响。研究结果表明: 与普通地震动激励相比, 在近断层长周期脉冲型地震动激励下, 减隔震桥梁减震率由54.4%降低为18.3%, 隔震支座的减震效果降低了; 在近断层脉冲地震动作用下, 减隔震桥梁梁体纵向位移为179.6mm, 非减隔震桥梁为151.6mm, 铅销橡胶支座增大了梁体的纵向位移, 易造成相邻梁体的碰撞或落梁, 因此, 近断层地区桥梁不宜采用铅销橡胶支座隔震。

Spatial dynamic analysis of isolated bridges subjected to near-fault ground motion

With nonlinear dynamic time-history method, 3D dynamic responses of isolated bridge and non-isolated bridge were analyzed.Through comparing the dynamic responses of isolate bridge under the excitations of earthquakes with different frequency spectrums, the dynamic characteristic of isolated bridge was studied.Through comparing the longitudinal responses of isolated bridge with non-isolated bridge, the influence of near-fault ground motions on the seismic absorption ability of LRB(lead rubber bearing) was investigated.The result indicates that in contrast with common ground motion, the ratio of seismic absorption decreases from 54.4% to 18.
3%, and the absorption effect of LRB reduces under near-fault ground motion.The longitudinal displacements of girders for isolated bridge and non-isolated bridge are 179.6 mm and 151.6 mm respectively.Obviously, LRB enlarges the displacement of girder and easily makes girder collide and fall, so LRB is not suitable isolated device for the bridges near fault area.