1400 m斜拉桥方案颤振临界状态拍振现象分析

1400 m 斜拉桥方案全桥气弹模型试验过程中，其在颤振临界状态下出现了拍振现象，这种振动在其他跨径较小桥梁中较少发生。为探究其发生机制，证明其存在的合理性，首先对气弹模型动力特性展开分析，结果显示其模态分布更为密集，每两阶模态之间的频率间隔更为狭小，这些都增加了拍振发生的可能性。进一步的理论分析则表明，与苏通大桥相比，1400 m 斜拉桥方案有着更为复杂的结构动力特性，在颤振临界频率附近存在着能与之发生牵连运动的振型参与进来，从而最终发生了拍振。

Beat Vibration Analysis of 1 400 m Cable Stayed Bridge under Flutter Critical State

In the process of full bridge aeroelastic wind tunnel test of 1400m cable stayed bridge, beat vibration phenomenon was found under flutter critical state,which is rarely occurred in the other shorter bridges.For the purpose of exploring the mechanism and demonstrating the rationality of this phe-nomenon,some dynamic character analysis was carried out in this paper.The analysis result show that, mode distribution seems more intensive and the intervals between every tow modes become more narrow-ly.For all these above reasons,the occurrence possibility of beat vibration increases.Furthermore,the further research demonstrate that,comparing with Sutong Bridge,the dynamic characters of 1400m cable stayed bridge scheme presents to be more complex so that some vibration modes which are adjacent to the flutter critical frequency can be excited by flutter vibration.Thus,the beat vibration occurred under flut-ter critical state.