大跨度斜拉桥在多点随机地震激励作用下的响应分析

以南京第二长江大桥南汊桥为例,采用随机振动分析方法研究了地震动的空间变化特性,包括行波效应、部分相干效应以及局部场地效应对大跨度斜拉桥地震响应的影响.研究结果表明:与一致地震激励相比,地震动的空间变化特性可以使斜拉桥的地震响应改变30%;同时考虑行波效应、部分相干效应时的地震响应接近于仅考虑行波效应时的地震响应;行波效应对斜拉桥地震响应的影响明显大于部分相干效应的影响;在加速度均方根相同的随机地震作用下,斜拉桥在软场地条件下的地震响应明显大于在硬场地条件下的响应,中等场地条件下的地震响应介于两者之间.

Seismic response analysis of long-span cable-stayed bridge under multi-support random excitations

Seismic response analysis of a long-span cable-stayed bridge under random seismic excitations with spatial variations,including travelling effect, incoherence effect and local site effect, was made with stochastic method.Based on this study the following conclusions are drawn:The responses of cable-stayed bridge under seismic excitations with spatial variations differ from those under uniform seismic excitations up to 30%; The responses obtained by considering travelling effect as well as incoherence effect are close to those obtained by only considering travelling effect; Travelling effect has more significant effect on the seismic responses of cable-stayed bridge than incoherence effect; If r.m.s. (root-mean-square) of random seismic ground motions are equal,seismic responses are considerably greater for the case of soft soil than for the cases of firm soil or medium soil.