高墩大跨矮塔斜拉桥主梁地震响应特性研究

Study on Seismic Response Characteristics of Main Girder of Extradosed Cable-stayed Bridge with High Pier and Long Span

为研究地震作用对高墩大跨桥梁主梁的影响规律、以及P-Δ效应对地震响应的影响,以一座高墩大跨矮塔斜拉桥为研究对象,采用有限元软件建立静动力模型,选取5条有代表性的地震波数据,同时分析了桥梁在活载、地震作用下的内力和应力响应,重点对主梁响应进行了对比分析;在此基础上深入研究了P-Δ效应对不同墩高桥梁主梁地震响应的影响规律,并结合位移谱对P-Δ效应的影响进行了分析。结果表明:高墩大跨桥梁主梁的地震内力响应与活载效应相当、甚至更大,因此区别于常规桥梁,应详细考虑高墩大跨结构主梁的地震效应大小;动力P-Δ效应会引起主梁位移和内力的增大,且其影响会超过10%,需要考虑其不利影响。因此,对于高墩大跨桥梁结构应考虑地震作用与P-Δ效应对其主梁的控制作用。

In order to study influences of earthquake on the main girder of high-pier long-span bridge and P-Δeffect on seismic response,aextradosed cable-stayed bridge with high pier and long span was taken as the research object,the static and dynamic model was established with finite element software.Five seismic waves data were selected to deeply analyze the internal force and stress response of the bridge under live load and earthquake respectively,and focused on the comparative analysis of the response of the main girder.As the same time,influences of P-Δeffect on the internal force of the main girder under different height bridges were studied,and influences of displacement spectrum on P-Δeffect were also analyzed.The results show that for the high pier and long span bridge,the internal force response of the main girder under earthquake is equal to or even exceeds that under live load,so the seismic effect of the main girder of long span structure should be considered in detail,which is different from the conventional bridge.P-Δeffect may increase the internal force and displacement of the main girder.Its influence may exceed 10%,so it is necessary to consider its adverse effects.Therefore,the control effect of the seismic response and the P-Δeffect should be considered for the main girder of high-pier long-span bridges.