重庆永川长江大桥涡激振动性能风洞试验研究

Wind Tunnel Test for Vortex-Induced Vibration Property of Yongchuan Changjiang River Bridge in Chongqing

为研究在常遇风速下混合梁斜拉桥的涡激振动性能及抑振措施,以半飘浮体系七跨连续双塔混合梁斜拉桥——重庆永川长江大桥为背景,设计基于1∶50主梁节段模型风洞试验,测试在不同阻尼体系下检修车轨道、导流板对涡激振动性能的影响,并对主梁外挂排水管道的形状进行了优化,最后提出了可显著改善主梁涡激振动性能的抑振措施。研究结果表明:主梁在-3°、0°和+3°攻角下均发生了明显的涡激振动现象,+3°攻角下的振幅最大,且远大于规范的容许振幅;向梁底内侧移动检修车轨道,并在其内侧布置导流板可大幅降低主梁的涡激振动振幅;位于斜腹板的圆形排水管道会削弱主梁的气动性能,改用120cm×20cm的扁状排水管道可有效提高颤振临界风速并降低涡激振动振幅。

To examine the vortex-induced vibration property and the measures to suppress the vibration of hybrid girder cable-stayed bridge under common wind speeds,the Yongchuan Changjiang River Bridge in Chongqing,a seven-span two-pylon continuous hybrid girder cablestayed bridge of half floating system,was taken as the study background.The wind tunnel test based on the 1∶50sectional model of the main girder was designed,to test the influence of overhauling car tracks and guide vanes on the property of vortex-induced vibration under different damping systems.The shape of the external draining pipes on the main girder was optimized,and vibration damping measures that can markedly improve the property of the vortex-induced vibration of the main girder was proposed.The results of the study show that distinct vortex-induced vibration was found in the main girder when the wind attacking angle was respectively at-3°,0°,and ＋3°.The maximum vibration amplitude appeared when the attacking angle was ＋3°,far greater than the allowable value in the code.The amplitude of the vortex-induced vibration of the main girder can be considerably deceased by moving the overhauling car tracks towards the inner side of the base of the main girder and installing guide vanes at the inner side of the main girder.The circular draining pipes at the diagonal webs will exacerbate the aerodynamic property of the main girder,therefore,the 120cm×20cm flat draining pipes are chosen,which can effectively improve the critical flutter speed and reduce the amplitude of vortex-induced vibration.