非一致激励下大跨斜拉桥的随机地震响应分析

基于平稳随机地震动场理论,对大跨度斜拉桥进行非一致激励下的平稳随机地震响应分析。以金塘大桥主通航孔桥为研究对象建立有限元模型,采用多点平稳随机地震响应分析方法,数值仿真了该斜拉桥在纵桥向、横桥向和竖向多点激励下的地震响应,研究了地震动的空间变化,包括部分相干效应和行波效应以及视波速变化对大跨度斜拉桥地震响应的影响。数值分析结果表明：非一致激励下斜拉桥的内力和位移有较大改变,地震动的行波效应影响比部分相干效应的影响更大,地震动的空间变化对纵桥向激励有利,对横桥向激励影响较小,对竖向激励影响很大且不利。对大跨度斜拉桥,必须进行多点地震激励的响应分析。

Random Seismic Response Analysis of Long-span Cable-stayed Bridges under Non-uniform Excitation

The stochastic vibration analysis of long-span cable-stayed bridge under non-uniform excitation was performed based on the stationary random ground motion theory.The finite element model of main navigable span of jintang bridge was established.The seismic response of the cable-stayed bridge under longitudinal,transverse and vertical excitation were numerically simulated by the method of the multi-support stationary random seismic response,and the influence of spatial variation of seismic ground motion,including traveling-wave effect,partial coherence effect and the variety of apparent wave velocity were studied.The results show that the internal forces and displacement of cable-stayed bridge may be greatly changed under non-uniform excitation.The influence of the traveling-wave effect of the earthquake motion is greater than the partial coherence effect.The spatial variation of seismic ground motion is beneficial to cable-stayed bridge under longitudinal excitation,has a little influence under transverse excitation and has great and disadvantageous influence under vertical excitation.The random seismic analysis under multi-support earthquake excitations must be performed for the long-span cable-stayed bridge.