三塔斜拉桥多点激励地震反应特性分析

Seismic Response Analysis for Three-pylon Cable Stayed Bridge under Multi Support Excitation

以某空间框架式索塔3塔连续梁支承体系斜拉桥为例,采用多点时程反应分析方法研究了纵向和横向多点激励(仅考虑行波效应)对该类型桥梁地震响应的影响。研究结果表明:纵向多点地震激励下,行波效应对3塔斜拉桥中塔受力影响较小,边塔较大;同样,行波效应对两中跨主梁影响相对较小,两边跨则较大。横向多点地震激励下,无论是对于3塔斜拉桥中塔还是边塔,行波效应对于主塔受力是有利的,随着行波波速的降低,主塔响应呈下降趋势,对主梁来说,则可能放大主梁地震响应;存在一个最不利行波波速,在该行波波速下,结构响应取最大值。

In this paper, time history response method is used to analyze the influence of longitudinal and transverse multi support excitation（only consider traveling wave effect） on seismic response of a cable stayed bridge with three spatial frame pylon and continuous beam support system. The results show that：（1） in case of longitudinal multi support excitation, the influence of traveling wave effect on seismic response of intermediate tower and main girder is small, while that of side tower and main girder is large;（2） in case of transverse multi support excitation, the traveling wave effect is benefit for the internal force of main tower, and the response of main tower is decrease with the reduction of traveling wave velocity while the seismic response of main girder is increase, and there is a worst raveling wave velocity which result in worst structure response condition.