中央扣对大跨度悬索桥地震响应影响及机理研究

Study on Effect and Mechanism of Central Buckle on Seismic Responses of Long Span Suspension Bridge

为研究不同形式中央扣对悬索桥地震响应影响规律及机理,本文结合某三跨铁路悬索桥,基于ANSYS有限元分析软件建立三维空间有限元分析模型,对比分析不同中央扣设置形式对桥梁自振特性的影响。通过非线性时程分析,对在塔梁位置设置纵向黏滞液体阻尼器前后不同形式中央扣对悬索桥地震响应的影响规律进行研究。通过响应控制振型的研究,揭示中央扣对各响应产生不同影响的机理。研究结果表明:仅通过自振特性分析不能直接得到准确的中央扣对桥梁地震响应影响规律;不同中央扣设置形式下,主梁竖向位移及各项内力响应均大幅增加,塔底弯矩、剪力有所减小,以刚性中央扣为最优;考虑阻尼器后,不同形式中央扣对大跨度悬索桥地震响应的影响与无阻尼器情况基本一致,其原因是设置阻尼器并未改变桥梁各响应的控制振型。

To study the effects of different forms of central buckles on seismic responses of suspension bridges and their mechanism, depending on a three-span railway suspension bridge, this paper established the three-di- mensional space finite element analysis model based on finite element software ANSYS, to perform the comparative analysis of the effects of different forms of central buckles on self-vibration behavior of the bridge. Non-linear time-history analysis was conducted to study the effects of different forms of central buckles on seismic responses of the bridge before and after the longitudinal fluid viscous dampers were installed at the tower beams. The study of response control vibration mode revealed the mechanism of the influence of different forms of central buckles on seismic responses. The results showed that： exact influence of central buckle on seismic response on the bridge can not be derived directly through self-vibration behavior analysis alone. Under different forms of central buckles, the girder vertical displacement and internal force responses increased greatly while the bending moment and shear forces in the bottom of the tower decreased, with rigid central buckle being optimal in this research. With damper being considered, the effect of different forms of central buckles on the seismic response of the long span suspension bridge with and without dampers remains the same as the establishment of dampers did not change the response control vibration mode of the bridge.