摘要
为了研究大跨度斜拉桥超长拉索在不同流场特性下的高阶多模态涡激振动问题,以牛顿定律为基础,建立了考虑张力变化以及垂度效应的拉索结构振子方程,引入改进的Van Der Pol式尾流振子模型,以加速度耦合两非线性振子,提出了一种简便的拉索涡激振动流固耦合预报模型;采用二阶中心差分法,对两振子方程在空间域和时间域进行离散迭代求解,编制了拉索涡激振动的MATLAB计算程序,并验证了其可靠性。该方法为研究拉索涡激振动提供了一种新思路,可解决风洞试验和数值软件(CFD)不便模拟大长细比拉索结构的问题。基于提出的预报模型,以1根330 m超长拉索为研究对象,分析了拉索多模态涡激振动特性,探讨了不同流场特性对拉索涡激振动的影响。研究结果表明:均匀流作用下,拉索发生涡激锁定现象,以单一模态发生振动,随着风速的增加,拉索涡激锁定区间增大而最大振幅不发生改变;剪切流作用下,拉索发生多模态涡激振动,位移响应呈现"拍"的特点,振动频率分布在Strouhal涡脱频率范围内,存在2个或3个主导频率,主导频率全程参与振动,非主导频率间歇参与振动;拉索多模态涡激振动位移响应表现为行波-驻波并存的状态,随着风剖面指数的增加,涡激振动行波效应显著。
To investigate the high-order, multimode, vortex-induced vibration of ultra-long cables of long-span cable-stayed bridges under different flow fields, the structural vibration equation of the cable considering the change of tension and the effect of sag was established based on Newton’s laws, and a modified Van Der Pol wake oscillator model was adopted. Then, a fast and convenient fluid-solid coupled prediction model for vortex-induced vibration of cables was developed by coupling the two nonlinear vibration equations with acceleration. Based on the second-order central difference method, the two equations of the oscillator were discretized in the time domain and space domain. A MATLAB program for vortex-excited cable vibration was developed, and its reliability was verified. The problem of vortex-induced vibration of a cable with large length-to-diameter ratio being difficult to simulate by wind tunnel tests and numerical software(CFD) can be addressed by the new method proposed in this paper. A 330 m ultra-long cable was selected as an example. The characteristics of the multimode vortex-induced vibration of the cable were analyzed, and the effects of different flow field characteristics on the vortex-induced vibration of the cable were evaluated. The results showed that there is a vortex-lock and single-mode vibration of the cable for the uniform flow field. Multimode vortex-induced vibration of the cable occurs under shear flow. The displacement response is provided with the characteristic of "beat," and the vibration frequency is distributed within the range of the Strouhal vortex frequency. There are two or three orders of dominant frequencies, which participate in the whole vibration, and non-dominant frequencies that participate in the vibration intermittently. Additionally, the displacement response of multimode vortex-induced vibration of cables shows the coexistence of traveling waves and standing waves, and the effect of the traveling waves of the vortex-induced vibration of the cable is significant with increase of the wind profile index.
作者
周旭辉
韩艳
王磊
蔡春声
廖楚峰
ZHOU Xu-hui;HAN Yan;WANG Lei;CAI C S;LIAO Chu-feng(School of Civil Engineering,Changsha University of Science&Technology,Changsha 410114,Hunan,China;Louisiana State University,Baton Rouge LA70803,Louisiana,USA)
出处
《中国公路学报》
EI
CAS
CSCD
北大核心
2019年第10期257-265,共9页
China Journal of Highway and Transport
基金
国家自然科学优秀青年基金项目(51822803)
国家自然科学基金项目(51678079,51778073)
湖南省杰出青年基金项目(2018JJ1027)
湖南省教育厅科学优秀青年基金项目(16B011)
关键词
桥梁工程
超长拉索
尾流振子模型
多模态涡激振动
二阶中心差分法
行波效应
bridge engineering
ultra-long cable
wake oscillator model
multimode vortex-induced vibration
second-order central difference method
traveling wave effect
