桥塔尾流风作用下吊索尾流致振动模型与参数分析

Motion Model and Parameter Analysis of Flow-Induced Vibration of Suspender in Bridge Tower Wake

现场实测表明,大跨度悬索桥塔后吊索受桥塔尾流影响常发生大幅尾流致振。为研究该振动机理,同时为工程设计和应用实践提供理论指导,以某大跨悬索桥桥塔单根塔柱和塔后吊索为研究对象,首先进行了大比例尺节段模型的风洞试验。通过试验,再现吊索在桥塔尾流区内的尾流致振现象,研究吊索的振动特征与桥塔尾流风速特征。在此基础上,考虑尾流刚度作用,建立吊索的非定常气动力模型与吊索尾流致运动微分方程。利用四阶龙格库塔算法积分求解吊索尾流致运动微分方程。影响吊索运动的参数分为3种类别:结构参数、流场参数和位置参数。通过对各影响参数进行逐个分析,研究不同参数对桥塔尾流区中吊索振动特征的影响规律。结果表明:质量比这一参数对于吊索的振动模式的组成和占比起到关键性作用;而其他参数对于吊索振幅仅起到调节作用,对于吊索运动模式改变作用不显著;增大吊索阻尼比与减小尾流场风速脉动成分均可有效减小吊索振动幅值,这为吊索减振工程实际问题提供了解决思路。

Field observations indicate that for a large-span suspension bridge,the suspender influenced by the tower wake frequently experiences large-amplitude wake-induced vibrations.A single tower column and a suspender of a suspension bridge were investigated to reveal the vibration mechanism and provide theoretical guidance for engineering design and applications.First,wind tunnel tests of large-scale segment models were performed.The experiments replicated the wake-induced vibration of the suspender in the wake of the tower.The suspender displacement and the speed of the tower wake were analyzed.Based on the experimental results,an unsteady aerodynamic model of the suspender was developed,considering the wake stiffness effect,and a wake-induced vibration motion differential equation was derived.The fourth-order Runge-Kutta integration algorithm was used to solve the differential equations.The parameters appearing in the equation were divided into three categories:structural parameters,flow field parameters,and position parameters.The effect of each parameter on the motion characteristics of the suspender was analyzed.The mass ratio parameter plays a significant role in the composition and proportion of the suspender vibration mode.However,the other parameters regulate the vibration amplitude but are insignificant in changing the movement mode.Meanwhile,the large damping ratio of the suspender and the small fluctuation of wind speed in the wake flow can effectively suppress the suspender vibration.This paper presents a method for practical engineering applications for minimizing the amplitude of suspender vibrations.