悬索桥桥塔挂缆前后动态特性分析与测试

通过有限元分析和基于环境激励的模态试验分析,研究了润扬长江公路大桥南汊悬索桥挂缆前后桥塔的动态特性。在分析挂缆后桥塔动态特性时,将上部结构的作用转化为弹性约束,建立了等效模型进行分析,推导了主缆等效约束刚度的近似计算公式。结果表明:挂缆前后桥塔顺桥向动态特性变化较大,横桥向变化较小;等效有限元模型是合理的,悬索桥的振动可以分为2种体系运动,塔的振动特性可以单独取出进行分析。该结论为验证设计理论和后期维护提供了重要依据。

Dynamic Analysis and Test of Bridge Tower of Suspension Bridge Before and After Cable Installed

The dynamic properties of the tower of Runyang Yangtze River Nancha Suspension Bridge were studied before and after installing cable by finite element method and the modal experiment analysis based on environmental stimulation.A model of the tower-cable system with solid element and combine element was built,and the dynamic interactions between tower and cable,the changes in dynamic characteristics from the free-standing towers to tower-cable system were obtained.Results demonstrate that the cable has more significant effect on in-plane vibration than that on out-plane.The analytical results of the finite element model were verified by the testing results.The dynamic behaviour of the suspension bridge can be seperated into two parts,and the main tower's dynamic properties can be analyzed independently.The conclusions provide essential reference for the verification of design theory and the maintenance of bridges.