大跨度斜拉桥多维多点随机地震激励响应分析

为研究大跨度斜拉桥地震激励下的平稳随机响应规律，以某大跨度斜拉桥为例，用ANSYS软件建立了三维有限元分析模型.考虑地震动的多维性、行波效应、部分相干效应及局部场地效应对主梁及主塔位移和内力随机响应的影响，用该模型分析了大跨度斜拉桥在多维多点地震激励下的响应.研究结果表明:相对于一致激励，大跨度斜拉桥在多维多点激励下的结构响应显著增大，主梁的纵向位移增大了约2.3倍，①号塔顶的纵向位移和塔底横向弯矩分别增大了约2.2和2.3倍；仅考虑一致地震激励不能保证大跨度斜拉桥的结构安全；考虑行波效应时斜拉桥的地震响应减小，相干效应较小可忽略，软场地条件下结构的地震响应更大. 

Stochastic Seismic Response Analysis of Large-Span Cable-Stayed Bridge Subjected to Multi-dimensional and Multi-support Excitations

In order to investigate the stationary random response of large-span cable-stayed bridge under seismic excitations, a large-span cable-stayed bridge was employed for numerical simulation, and a three-dimensional finite element model in ANSYS software was used to study the response of large-span cable-stayed bridge subjected to multi-dimensional and multi-support seismic excitations (MDMSSE). The spatial variations of earthquake action including traveling wave effect (TWE), coherent effect (CE), and local site effect (LSE) were taken into account to analyze their effect on displacement and internal force responses of the main beam and the main tower. Results show that the structural seismic response increased remarkably under MDMSSE in comparison with uniform excitation: the main beam longitudinal displacement increased about 2.3 times; the top longitudinal displacement and bottom traverse moment of main tower ① increased about 2.2 and 2.3 times, respectively. Therefore, only considering uniform excitation is unsafe to a large-span cable-stayed bridge. In addition, the structural response will reduce when considering TWE and CE influence, and hence can be ignored. A soft site has a great influence on structural seismic response.