缆塔自平衡悬索桥边跨长度敏感性分析

Sensitivity Analysis of Side Span Length of Cable Tower Self-balancing Suspension Bridge

为确定某主跨2300 m缆塔自平衡悬索桥的边跨长度,建立悬索桥有限元模型,研究了边跨长度参数对悬索桥结构动力特性和结构静力性能的影响规律,结果表明:悬索桥设置边跨后,主跨一阶对称侧弯振型频率有所提高,一阶反对称竖弯振型频率有所下降;设置边跨可以减小索塔附近主梁转角,边跨902 m悬索桥主梁竖向转角比无边跨悬索桥减小34.0%,主梁横向转角减小66.1%;随着边跨长度增加,悬索桥主缆缆力变化不大,但是索塔附近吊索索力逐渐减小;悬索桥索塔横向弯矩逐渐增大,但是轴力几乎没有变化;边跨长度参数对悬索桥索塔塔顶纵向位移影响显著,边跨902m悬索桥的塔顶纵向位移比边跨502 m悬索桥增大116.3%。可见,悬索桥设置边跨可以提高悬索桥的结构横向刚度,但是会降低结构竖弯刚度,同时边跨长度参数对悬索桥大部分静力响应参数影响较为明显。研究成果为该桥以及同类桥型设计提供参考。

In order to determine the side span length of a cable tower self-balancing suspension bridge with 2300 m main span,the finite element model of the suspension bridge was established,and the influence of the side span length parameters on the structural dynamic characteristics and structural static properties of the suspension bridge structure was studied.The results show that:the frequency of the first order symmetric lateral bending mode of the main span increases and the frequency of the first order antisymmetric vertical bending mode of the main span decreases after the side span of the suspension bridge is set;setting side span can reduce the angle of main beam near the cable tower.The vertical angle of main beam of suspension bridge with side span of 902 m is 34.0% less than that of suspension bridge without side span,and the transverse angle of main beam is 66.1% less;with the increase of the side span length,the main cable force of the suspension bridge does not change much,but the cable force of the suspension cables near the cable tower gradually decreases.The transverse bending moment of suspension bridge cable tower gradually increases,but the axial force hardly changes;the side span length parameter has a significant impact on the longitudinal displacement of the top of the cable tower of the suspension bridge,and the longitudinal displacement of the top of the tower of the side span 902 m suspension bridge is 116.3% higher than that of the side span 502 m suspension bridge.It can be seen that the lateral stiffness of the structure of suspension bridge can be improved by setting side span,but the vertical bending stiffness of the structure will be reduced.At the same time,the length parameters of side span have obvious influence on most of the static response parameters of suspension bridge.The research results provide reference for the design of this bridge and similar bridges.