不同地震激励下大跨度斜拉桥的地震反应分析

考虑地震波的行波效应、部分相干效应和局部场地效应,建立了不同机制的地震激励下大跨度斜拉桥地震反应的分析方法并以正在建设的主跨1 018 m的香港某大跨度斜拉桥为例,数值仿真了大跨度斜拉桥在确定性地震波一致激励、行波激励以及随机地震动场多点激励下的地震反应。结果表明:与确定性地震波一致激励相比,在确定性地震波行波激励以及考虑空间变化的随机地震动场激励下,斜拉桥的纵向位移反应明显减小,而其主跨跨中竖向位移反应明显增大。由此得出结论:对于大跨度斜拉桥,一致地震激励不能控制其抗震设计,应考虑行波激励和随机地震动场多点激励对其地震响应的影响。

Seismic responses of long-span cable-stayed bridges under different patterns of earthquake excitations

In this paper,the methods for the seismic response analysis of the long-span cable-stayed bridges excited by different patterns of earthquakes are built.Taking a cable-stayed bridge with main span of 1018 m under construction as an example,the numerical simulation for the seismic responses of the long-span cable-stayed bridges is performed under the uniform excitation and the travelling wave excitation of the deterministic earthquake or the multi-support excitation of the random earthquake ground motion.The results show that under the excitations,the travelling wave of the deterministic earthquake and the random earthquake ground motion with spatial variability by comparing with the uniform excitation of the deterministic earthquake,the longitudinal displacement of the cable-stayed bridge is clearly decreased,and its vertical displacement at the midpoint of the main span is significantly increased.A conclusion is given that the uniform seismic excitation is not able to control the seismic design for the long-span cable-stayed bridge,and the influence of the travelling wave excitation and the multi-support excitation of the random earthquake ground motion on the seismic responses of the long-span cable-stayed bridge must be considered.