多塔斜拉桥纵向跨度大,进行地震反应分析时应考虑行波效应对结构地震响应的影响.阐述了相对位移法、绝对位移法及大质量法的基本原理,以某六塔斜拉桥为工程背景,采用大质量法计算了该桥在不同行波输入方向及不同视波速下的地震响应,并与一致激励的结果进行比较.研究表明,行波效应对结构地震响应的影响程度与地震波的频谱特性有关;行波效应基本不控制结构的内力设计,但对支座和伸缩缝的变形能力提出更高的要求.
Multi-span cable-stayed bridges have extended longitudinal length.The travelling wave effect should be considered in analysising earthquake responses of multi-span cable-stayed bridges.In this paper,basic principles of the relative displacement method,the absolute displacement method and the large mass method were introduced.A cable-stayed bridge with six towers was taken as an example.The seismic responses of the bridge under different spreading directions of the earthquake wave with different wave velocities were calculated using the large mass method.A major finding is that the influence of travelling wave effect is related to the spectral characteristics of earthquake waves.Traveling wave effect does not control the internal force design of the structure,demanding higher deformation capacity of bearings and expansion joints