钝体断面列车对斜拉桥涡振稳定性影响的试验研究

Experimental Study on Influence of Blunt-body Section Train on Vortex Vibration Stability of Cable-stayed Bridge

涡激振动是大跨柔性桥梁风致振动中最常发生的一种现象,对结构气动外形与局部构造的微小变化十分敏感,列车在桥梁上行驶势必会改变桥梁断面的气动外形,因此有必要研究列车对桥梁涡振性能的影响。文章在试验中采用弹性悬挂刚性节段模型车桥系统,在不同阻尼比条件下进行了桥面无车和桥面有车往返状态下的涡激振动风洞试验。研究表明:在桥面无车状态-3°风攻角时,主梁发生了明显的竖向涡激振动;主梁断面抗涡性能的最有利风攻角为+3°,而在桥面有车状态下则刚好相反;车桥系统断面的涡振稳定性由主梁断面本身具有的涡振性能与列车气动外形对主梁涡振性能的影响共同决定;在实际工程中,钝体断面列车对车桥系统涡激振动稳定性的影响是不可忽视的。

Vortex-induced vibration is the most common phenomenon in wind-induced vibration of large-span flexible bridges,it is very sensitive to the aerodynamic shape of structures and the small changes in local structures,and the trains driving on the bridges will inevitably change the aerodynamic shape of bridge sections,thus it is necessary to study the influence of trains on the vortex vibration performance of bridges.This article uses the elastic-suspension rigid-section model train-bridge system in the experiment to conduct the vortex-induced vibration wind tunnel test under the round-trip condition with and without train on bridge and under different damping ratio conditions.The research shows that the main beam has the obvious vertical vortex-induced vibration at -3° wind angle of attack without train on the bridge;the most favorable wind angle of attack for the vortex resistance of main beam section is +3°,while it is opposite when there is the train on the bridge;the vortex vibration stability of train-bridge system cross-section is jointly determined by its own vortex vibration performance of main beam section and the influence of train aerodynamic shape on the vortex vibration performance of main beam;in actual engineering,the blunt-body section train has a non-ignorable influence on vortex-induced vibration stability of train-bridge system.