摘要
通过对人群荷载的频谱分析,说明当人行桥的自振频率位于人群的激振频率范围内时,人行桥将产生共振。因而,对于此类人行桥,需要安装调谐质量阻尼器(TMD)对其进行减振控制。通过人群荷载功率谱密度分布求得人行桥的均方根加速度,然后将其作为目标函数提出了多重调谐质量阻尼器(MTMD)阻尼比和频率比任意分布的优化表达式,并采用遗传算法求解该问题。人群激励下人行桥的振动分析表明,人-桥共振时采用MTMD将比单个TMD具有更高的减振效率,通过保持MTMD中心频率不变而适当等比例扩大最优频率比可以有效提高人-桥-MTMD系统减振效率的鲁棒性。计算同时表明,MTMD的相对运动位移较小,完全可以满足人行桥对安装空间的要求。
This paper presents the basic principle of human-footbridge resonance and deals with the applicability of multiple tuned mass dampers（MTMD） to suppress crowds-induced vibration on footbridge.According to the crowd load frequency analysis,human-footbridge resonance occurs as the model frequencies of a footbridge are covered by the wide band of crowd excited frequency.An MTMD system is employed to improve the footbridge dynamic characteristics by suppressing the excessive acceleration of footbridge for human normal walking comfort.Vibration suppression for footbridges subjected to crowd excitation with centrally distributed Power Spectral Densities（PSDs） is studied,and optimal governing equations of the root mean square（rms） acceleration of footbridge is developed.Using the genetic algorithm,the optimized problem is solved to obtain the optimum values of the design variables（i.e.frequency ratios and damping ratios） of the MTMD system.Numerical results from several footbridges under crowds loads show that the optimal MTMD is more effective than a single TMD in reducing acceleration during resonance,and that the proper frequency spacing enlargement of optimal MTMD results in the better robustness and reliability when detuning effect of MTMD exists.In addition,the inner space of a footbridge box-girder is wide and deep enough for installation and movement of MTMD.
出处
《土木工程学报》
EI
CSCD
北大核心
2010年第8期73-80,共8页
China Civil Engineering Journal
基金
教育部新世纪优秀人才支持计划(NCET-08-0318)
长江学者和创新团队发展计划(IRT00736)
