中央扣对三塔悬索桥地震反应的影响

Influence of central buckle on seismic response of triple-tower suspension bridge

针对三塔悬索泰州长江大桥这一特殊桥型,基于Abaqus台建立了该桥的空间动力有限元模型并进行非线性动力分析.研究了地震作用下,缆梁间刚性中央扣对三塔悬索桥塔梁位移、塔柱内力以及塔梁间弹性拉索的影响.研究结果表明:中央扣对三塔悬索桥动力特性有不可忽视的影响;由于中央扣增强了缆梁间相互作用,在地震作用下,中塔横向位移与加劲梁跨中竖向位移均有所增加,中塔柱纵桥向剪力有所减小;中央扣限制了加劲梁纵向位移并减小了加劲梁对中塔下横梁的作用,但边塔柱底扭矩有所增加.

As a special type of suspension bridge, Taizhou Bridge is a triple-tower suspension bridge. A spatial dynamic finite element model for it is established with finite element software Abaqus and the nonlinear dynamic analysis is performed. The influence of rigid central buckle be- tween main cables and stiffening girder on seismic response of this bridge is investigated in detail, including displacements of towers and girder, forces in tower columns and elastic cables between lower beam and girder at mid-tower. The central buckle has unneglectable influence on the dynamic behavior of the bridge. The results show that the central buckle enhances the interaction between main cables and stiffening girder. When the bridge is subjected to seismic loads, the central buckle may cause the increment of transverse displacement of mid-tower in the direction across bridge and the vertical displacement at mid-span. Moreover it decreases the shear force at the bottom of mid- tower in the longitudinal direction, and thus well limits the longitudinal displacement of stiffening girder, and reduces the interaction between stiffening girder and lower beam of mid-tower. However, the twisting moment at the end columns of side tower increases significantly.