大跨结构的振动舒适度与TMD减振频域分析

Frequency domain analysis for pedestrian induced vibration of long-span structure and TMD mitigation

将大跨结构的动力特性转化到广义坐标系并结合频率响应函数,计算有或无调谐质量阻尼器(TMD)的多阶模态结构在人行荷载的多阶谐波激振下的加速度反应谱。通过引入结构频率调整系数,能够预测结构实际频率与计算频率产生偏差的情况。利用有或无TMD的结构频响函数得到窄带激振下的TMD减振率,分析TMD频率比和阻尼比偏离最优解对TMD减振率的影响。结合一个实际工程算例,比较了该频域分析法和传统的时域分析法,采用最优参数设计TMD,研究了人群行走荷载下考虑实际频率偏差工况的有或无TMD结构加速度反应谱、反应谱曲面及TMD设计要点等问题。研究结果表明了该方法准确、全面、高效的优越性。

By transforming the dynamic properties of long-span structure to generalized coordinates and along with frequency response function, the acceleration response spectrums of a structure with multiple modes with and without tuned mass damper(TMD) under multiple orders of harmonic components of pedestrian load were calculated. The deviation of as-built structural frequency from calculated frequency can be taken into account by introducing a structural frequency adjustment coefficient. Utilizing the TMD reduction rate under narrow band excitation obtained from the structural frequency response function with and without TMD, the impact of TMD frequency ratio and damping ratio deviating from the optimal solution on the TMD reduction rate was analyzed. With an example analysis of a real project, this frequency domain method and traditional time domain method were compared, the optimal parameters were employed to design the TMD, the structural acceleration response spectrum and response spectrum surface of the structure with and without TMD under crowd walking load considering the structural frequency deviation, the key points of TMD design, and other problems were studied. This study reflects the advantages of accuracy, comprehensiveness and efficiency comparing to the frequency domain method.