中央扣对大跨悬索桥动力特性和汽车车列激励响应的影响

Influence of Central Buckle on Dynamic Behavior and Response of Long-span Suspension Bridge Under Vehicle Group Excitation

为了探讨大跨悬索桥在动力激励下中央扣的作用,以四渡河悬索桥为研究背景,建立了该大跨钢桁架加劲梁悬索桥的3种中央扣模式的空间动力计算模型,对其动力特性和在移动汽车车列激励下的时程反应进行了空间非线性分析。研究结果表明:中央扣提高了结构的反对称抗扭刚度,限制了结构的纵飘特性;在静车列作用下,中央扣对全桥内力分布影响很小,但是在移动车列激励下,中央扣使得加劲梁的应力动响应显著增加,且随车列速度增加而增大;中央扣对加劲梁纵桥向位移的限制作用在常规速度车列激励下表现不明显;中央扣的设置方式宜采用刚性中央扣或3对柔性中央扣。

In order to investigate the function of central buckle of long-span suspension bridge under dynamic load excitation, taking Siduhe Bridge as an example which is a suspension bridge with steel truss stiffening girder, the spatial dynamic finite element models for the bridge with three types of central buckles were established with ANSYS software. Dynamic behavior analysis and a 3-D nonlinear time history analysis for the bridge under vehicle group excitation were carried out. Study results show that central buckle can raise the antisymmetrical torsion stiffness and restrict the longitudinal floating characteristic of suspension bridge; under moving vehicle group, central buckle has a little influence on static stress distribution of the bridge, but makes its dynamic stress response more and more obviously increase with the growth of vehicle speed; the effect that central buckle restricts the longitudinal displacement amplitude of stiffening girder can＇t be shown apparently under vehicle group excitation of normal speed; among the three types of central buckles, rigid central buckles and three pairs of flexible central buckles are advisable to be adopted.