MTMD在钢箱梁悬索桥高阶涡激振动控制中的应用

Application of multiple tuned mass damper for higher-order vortex-induced vibration of suspension bridge with steel box girder

大跨度悬索桥模态密集,常遇风速下存在多个模态发生涡激共振的可能。鉴于多重调谐质量阻尼器(MTMD)在减振效率和鲁棒性方面的优点,探讨了MTMD理论在大跨度钢箱梁悬索桥高阶竖向涡激振动控制中的应用。首先从Scanlan线性涡激力模型出发,在不考虑气动刚度项和气动阻尼项的条件下得到安装MTMD后的加劲梁位移频响函数。然后以加劲梁位移频响函数峰值极小值为目标函数,运用基于Matlab的遗传算法完成MTMD方案的初步参数优化设计。最后,从结构固有频率波动和结构固有阻尼比变化两方面讨论了MTMD的控制效率和鲁棒性。计算结果表明,在MTMD的初步参数优化设计中忽略气动刚度项和气动阻尼项是可行的,适当扩大MTMD的频率范围和阻尼比可以使其在减振效率和鲁棒性上达到更好的平衡,比传统调谐质量阻尼器(STMD)更适合悬索桥涡激振动控制。

The vertical modes of long-span suspension bridges are usually closely spaced so that vortex--induced vibration may occur in more than one mode. To suppress highe^order vortex-induced vibration of suspension bridges, the application of MT- MD, which is demonstrated to be more effective and robust than TMDs, is investigated. Firstly, the displacement response function of the girder installed with MTMD was deduced, using the empirical linear model of vortex-induced force developed by Scanlan. However, the aerodynamic damping and aerodynamic stiffness were not considered. Then, the minimal peak value of the displacement response function of the girder was defined as the optimization objective function and preliminary parameter optimization was accomplished by Matlab-based Genetic Algorithm. Lastly, the effectiveness and robustness of MTMD was discussed from the aspects of possible error in structural natural frequency and possible variation in structural mechanical damp- ing ratio. The results indicated that it is acceptable to ignore the aerodynamic stiffness and the aerodynamic damping in the ini- tial procedure of parameter optimization, and MTMD with proper frequency range and damping ratio can reach good balance between effectiveness and robustness, which is more suitable for the vortex-induced vibration control of suspension bridge than the traditional tuned mass damper scheme （STMD）.