大跨悬索桥多维多点非平稳随机地震响应分析

Non-stationary Random Seismic Response Analysis of Long-span Suspension Bridges under Multi-support and Multi-dimensional Seismic Excitations

以湖北四渡河大跨悬索桥为工程背景,建立了悬索桥精细有限元模型,采用多维多点非平稳随机地震响应分析方法,数值仿真了该桥在单维与三维非平稳随机地震动的一致激励、行波效应、部分相干效应、部分相干+行波效应以及多点激励下的地震响应,分析了多维多点地震激励下视波速及地震非平稳性对结构随机地震响应的影响.研究结果表明:考虑地震动的空间效应对悬索桥结构响应有很大影响,地震动的行波效应对结构响应的影响比部分相干效应的影响大的多;三维地震作用下的结构响应比单维地震的作用明显增加;随着视波速的增大,行波效应对结构响应的影响减弱;按照平稳地震激励所作的随机地震响应分析,计算结果是偏安全的.

Take a long-span suspension bridge across Sidu river as an engineering background,a precise finite element model of suspension bridges was established. The seismic response of the sus- pension bridge subject to the uniform excitation, traveling-wave effect, partial coherence effect, com- bination effect of traveling waves and partial coherence effects and multi-support excitations under one-dimensional and three-dimensional non-stationary random seismic ground motions were numeri- cally simulated by a method for seismic anaiysis of the multi-support excitations under the three-dimensional non-stationary random seismic ground motions. The effect of apparent wave velocities and seismic non-stationarity on random seismic responses of structures is analyzed under multi-support and multi-dimensional seismic excitations. The results show that the spatial variation of seismic motions has a great influence on the structure seismic response. The influence of traveling wave effects is much larger than that of partial coherence effect on the structure seismic response. The structure seismic response under three-dimensional seismic excitations is greater than that under one-dimensional excitations. The effect of traveling waves on structure seismic response becomes weak with the apparent wave velocity increasing. The random seismic response analysis is secure when the stationarity of seismic ground motion is considered.