深水库区铁路斜拉桥地震反应分析

Analysis on Seismic Response of a Railway Cable-stayed Bridge in Deep Reservoir Region

以某深水库区铁路大跨度斜拉桥为研究对象,建立考虑动水压力效应的全桥空间动力计算模型,分析动水压力对桥梁动力特性及弹性地震反应的影响程度。结果表明:桥塔附加水体质量对斜拉桥的体系纵漂及体系对称竖弯振型影响较明显;考虑塔身的水体附加质量时,塔身控制截面的地震反应增加较大,且顺桥向地震反应增加明显大于横桥向的地震反应。因此对处在深水库区的铁路大跨桥梁,应考虑水体附加质量对桥梁地震响应的增大效应,否则设计将偏于不安全。

This paper was based on a long-span railway cable-stayed bridge in deep reservoir region. The whole bridge＆#39;s spatial dynamic calculation model considering the influence of dynamic water pressure was established, so as to analyze the influence degree caused by dynamic water pressure upon bridge dynamic characteristic and elastic seismic response. The analysis results show that：（ a） the additional water mass at bridge pylon has more significant influences upon the cable-stayed bridge system＆#39;s longitudinal drift and symmetrical vertical bending-moment vibration mode;（ b） when considering the additional water mass at bridge pylon, there will be a large increasing of seismic response at the most critical cross-section, and the increasing of seismic response in longitudinal direction of the bridge is significantly larger than that in transverse direction of the bridge. So it is suggested in this paper that when designing a long-span railway bridge located in deep reservoir region, the increasing effect upon bridge seismic response caused by additional water mass should be taken into account;otherwise the design will tend to be unsafe.