π型开口截面斜拉桥涡激振动的气动抑振措施试验研究

Experimental study on vortex-induced vibration suppression measures ofπ-shaped open section cable-stayed bridge

涡激振动是大跨度桥梁主梁在低风速下容易发生的一种风致振动现象,会影响行车安全性、舒适性和桥梁疲劳寿命,避免涡激振动的发生或抑制涡激振动振幅是桥梁抗风设计的热点问题。基于涡激振动对主梁气动外形敏感的特性,通过设计不同气动措施改善主梁的涡激振动性能,探究单个气动措施和多个气动措施组合的涡激振动抑制效果。以某π型开口截面斜拉桥工程为依托,对几何缩尺比为1∶37的刚性节段模型开展涡激振动研究,进行了风洞测振试验,并对下稳定板、检修车轨道位置和导流板等典型气动措施的抑振效果进行了测试。研究结果表明:主梁原设计断面存在明显的竖弯涡激振动现象,最大竖弯涡激振动振幅已超过规范限值;安装1道下稳定板可有效抑制竖弯涡激振动,安装多道下稳定板后,竖弯涡激振动振幅被限制,但同时会造成扭转涡激振动振幅增大,使用稳定板措施时应兼顾竖弯涡激振动和扭转涡激振动振幅的变化;检修车轨道的有无及位置变化对此截面的涡激振动性能影响较小,内移检修车轨道不能有效减小涡激振动振幅;在安装1道下稳定板的基础上增设导流板可进一步抑制涡激振动,安装下稳定板与导流板的组合措施可达到最优抑振效果。研究结果可为类似主梁断面涡激振动的气动控制措施选择提供参考。

Vortex-induced vibration is a common aeroelastic phenomenon of long-span bridge girder under low wind speed,which is easy to affect the driving safety,comfort and reduce the fatigue life of the bridge.How to avoid vortex-induced vibration or suppress its amplitude is a hot issue in wind resistant design of bridges.Based on the characteristic that vortex-induced vibration is sensitive to the aerodynamic shape of the girder,different aerodynamic measures are designed to improve the vortex-induced vibration performance of the girder.And the suppression effect of vortex-induced vibration of a lot of aerodynamic measures and a combination of multiple aerodynamic measures are explored.Based on aπ-shaped open section cable-stayed bridge project,the vortex induced vibration of the rigid segment model with a geometric scale ratio of 1:37 was studied by using the wind tunnel vibration tests.The vibration suppression effect of aerodynamic measures such as the track position of the lower stabilizer plate,the maintenance vehicle and deflector were tested.The results show that there is obvious vertical bending vortex induced vibration in the original design section of the main beam.The maximum amplitude of vertical bending vortex-induced vibration has exceeded the specification limit.A lower stabilizer plate can effectively suppress vertical bending vortex induced vibration.When the multiple stabilizer plates are used,the amplitude changes of vertical bending vortex-induced vibration and torsional vortex-induced vibration should be considered.The presence and the change of track position of maintenance vehicle have little effect on the vortex vibration performance of this section.Moving the maintenance vehicle track inward cannot effectively reduce the amplitude of vortex-induced vibration.After installing the lower stabilizer plate,the amplitude of vortex induced vibration in vertical bending is limited,and the amplitude of torsional vortex vibration increases.Adding a deflector based on installing the lower stabilizer plate can further suppress vortex-induced vibration.The combined measures of installing the lower stabilizer plate and deflector can achieve the optimal vibration suppression effect.The present results can provide reference for the selection of aerodynamic control measures for vortex-induced vibration of similar girder sections.