防振锤抑制拉索振动的实桥试验研究

Field study of cable vibration mitigation using Stockbridge damper

文章针对拉索采用防振锤减振开展实桥试验研究,根据某桥的2根较长斜拉索的参数,通过防振锤的优化设计,使防振锤针对拉索一阶振动进行频率调谐。试验中,通过人工激励使拉索按单阶模态振动,记录拉索安装防振锤前后的振动加速度时程数据,对数据进行处理得到拉索的模态阻尼比。试验结果表明:防振锤可以显著提高拉索的模态阻尼,并具有较好的鲁棒性,因此其用于斜拉索的振动控制是可行的;所测试防振锤的启动加速度较大,其对于低阶(一阶)的小振幅振动抑制效果不佳;锤头振幅过大可能使防振锤碰撞拉索,需要加以解决。研究结果可以为实际桥梁拉索防振锤的设计、应用提供参考。

This paper studies the damping effect of the Stockbridge damper(SD)for cable vibration control through field tests on an existing bridge.Based on the parameters of two long stay cables of the bridge,the SD is designed to tune the SD frequency to the first-order cable vibration mode.In the tests,the cable is vibrated by manual excitation and the vibration acceleration time history data before and after the installation of the SD is recorded,and then the modal damping ratio of the cable is calculated.The test results show that the SD can significantly improve the modal damping of the cable and has good robustness,and therefore it is feasible for cable vibration control.It is also found that the SD is activated only when the cable acceleration exceeds a certain,and its effect on suppressing low-order(first-order)cable vibration with small amplitude is compromised.Besides,the mass block of the SD may impact the cable in large-amplitude cable vibrations,which needs to be considered in practical design.The results can provide reference for the design and application of SDs.