非对称单侧混合梁斜拉桥多点激励地震响应分析

Seismic Performance of a Cable-stayed Bridge with Asymmetric Single-side Mixed Girders under Multi-support Excitation

摘要:

以一座主跨为820 m的双塔非对称单侧混合梁斜拉桥为研究对象，对其进行动力特性分析。运用相对运动法进行多点激励地震响应计算，分析行波效应对塔顶、主梁、塔底等关键位置动力响应的影响，同时对比分析入射角方向（即斜拉桥两侧相对方向）对其动力响应的影响。结果表明：与一致激励分析结果相比，多点激励使得主塔内力结果偏小，而使得主梁内力结果偏大；不同入射角地震激励对非对称大跨度斜拉桥的内力也会产生较大影响，内力变化可达20%。因此，在进行该类型非对称混合梁斜拉桥设计中，应考虑非一致激励效应和地震动输入方向的影响因素。

Abstract:

The dynamic characteristics of a twin-tower asymmetric single-side mixed girder cable-stayed bridge with a main span of 820 meters were analyzed. First, we calculated the seismic response of the bridge under multi-point excitation with the relative motion method to analyze the influence of a traveling wave effect on the dynamic response of some key points, i.e., the tower top, main girder, and the tower bottom. At the same time, we compared and analyzed the dynamic responses under different incident angles. Results showed that, compared with the results of uniform excitation analysis, under multi-point excitation, the internal force of the main tower was smaller, but that of the main girder was larger. Earthquake excitation with different incident angles also had a great influence on the internal force of the cable-stayed bridge, which made the internal force increase (or decrease) up to 20%. Therefore, in the design of this type of asymmetrical hybrid beam cable-stayed bridge, the influences of non-uniform excitation and input direction of ground motions should be considered.