基于TMD的大跨连续钢箱梁人致振动分析研究

一般大跨连续钢箱梁人行桥难以满足我国现行规范对人行桥竖向自振频率的严苛要求(不应小于3 Hz)。为了对此类桥梁的人致振动舒适性进行适合准确的评价及优化,并为我国人行桥有关规范的制定提供依据,以一座(58.6+110+58.6)m大跨连续钢箱梁人行桥为例,参照德国人行桥设计指南(EN03-2008),以人群动荷载作用下结构的加速度幅值为指标对该桥的人致振动舒适性进行评价,并对舒适性不满足要求的特定模态采用布置调质阻尼器(TMD)的方法进行减振处理。分析研究表明:TMD可有效地控制结构相关模态下的人致振动响应,在人行桥第1、第3阶模态峰值位置布置总重6000 kg TMD后,两阶模态的人致振动减振率分别为86.5%、86.3%,最大竖向加速度幅值在0.5 m/s^2以下,满足设计指南最好舒适性指标。

Study of Pedestrian-induced Vibration of Long-span Continuous Steel Box-girder Footbridge Based on TMD

Generally long-span continuous steel box-girder footbridges are difficult to meet the stringent requirements for the vertical natural frequency of footbridges in China's current codes(should not be less than 3 Hz).In order to properly and accurately evaluate and optimize the pedestrian-induced vibration comfort of such bridges,and to provide a basis for the formulation of relevant standards for pedestrian bridges in China,take a(58.6+110+58.6)m long-span continuous steel box-beam footbridge as an example,referring to the German's Design of Footbridges Guideline(EN03-2007),the acceleration amplitude of the structure under the dynamic load of the crowd is used as an index to evaluate the pedestrian-induced vibration comfort of the bridge,and the specific mode that the comfort does not meet the requirements,the vibration damping treatment is performed by using a tuned mass damper(TMD).Analysis and research show that:TMD can effectively control the pedestrian-induced vibration response in the structure-related modes.After the total weight of 6000kg TMD is arranged at the peak position of the first and third-order modes of the footbridge,the pedestrian-induced vibration reduction rate of the two-order mode Reaching 86.5% and 86.3% respectively,the maximum vertical acceleration peaks are below 0.5 m/s^2,which meets the best comfort requirements of the design guidelines.