基于虚拟激励法的大跨桥梁抖振内力分析

Pseudo-excitation method for internal forces analysis of long-span bridges induced by buffeting

桥梁抖振内力分析是大跨桥梁抗风设计中的一项重要课题。目前,通常采用等效静风荷载的方法来计算桥梁抖振内力。本文将虚拟激励法应用到桥梁抖振内力分析中来,考虑多模态耦合效应,建立了直接应用随机振动方法计算桥梁抖振内力的快速算法。最后,以主跨为628m的某大跨斜拉桥为例进行了多模态耦合抖振内力分析,结果表明:高阶模态的参与将使主梁抖振内力增大,主梁抖振内力的峰因子介于3.4至4.0之间。

The analysis of buffeting-induced internal forces for long-span bridges is one of the important tasks in wind resistant design. Currently, the structural buffeting-induced internal forces are usually computed with the static analysis approach by presenting buffeting loading in the form of equivalent static load. In this paper, the pseudo-excitation method (PEM) is applied in the buffeting-induced internal forces analysis, and a high effective computation method is established directly by the random vibration method, which naturally involves the effect of multi-mode coupled vibration. With a long-span cable-stayed bridge as an example, the analysis of the buffeting-induced internal forces is carried out. The computation results show that the internal forces increase when the contributions of high order modes is taken into account, and the peck factors of the internal forces are between 3.4 and 4.0.