人行桥人致振动分析及TMD减振设计

Analysis of Pedestrian-induced Vibration and Design of TMD Damping for Footbridge

大跨人行桥在行人荷载作用下容易出现剧烈振动,进而影响通行舒适度与桥梁安全。当舒适度评价不满足要求时,如何通过简单措施实现振动控制是工程设计人员关心的问题。以一座(50+100+50)m的连续钢箱梁人行悬索桥为例,借助于有限元数值模拟手段,以人群荷载作用下的竖向加速度峰值为指标评价行人舒适度,并对舒适度不满足要求的模态使用调谐质量阻尼器(TMD)进行减振设计;比较了经典单个TMD、并联双TMD、串联双TMD的减振效果。结果表明:对于单个TMD而言,减振效果随TMD质量增大而提高,但减振率增幅逐渐减缓,因此单纯依赖TMD质量增加不是经济有效的减振措施;在保持TMD质量相同的情况下,多TMD方式的减振效果优于单个TMD,串联双TMD比并联双TMD减振效果更佳。该研究结果可为类似结构的减振装置设计提供参考。

Under pedestrian loading action,large-span footbridge is susceptible to severe vibration which effects pedestrian comfort and bridge safety.When comfort evaluation is not satisfied,how to achieve vibration control by simple measures is practical concern for design engineers.Taking a(50+100+50)m pedestrian suspension bridge stiff-ened with a continuous steel box girder as an example,the maximum vertical acceleration value under the action of pedestrian loading was taken as the index to evaluate the pedestrian comfort by finite element simulation.The modes which didn't meet the requirements was damping designed by the tuned mass damper(TMD).The effects of classic single TMD,parallel dual TMD,and serial dual TMD on vibration control were compared.The damping effect of single TMD improves with the increase of TMD mass.However,the rate of increase decreases gradually indicates that the increase of TMD mass alone is ineffective damping;Under the same TMD mass,that multiple TMD has a better vibration attenuation effect than single TMD,and serial dual TMD performs better than parallel dual TMD.The research results can provide a guide for damping design of similar structures.