钢桁架人行桥人致振动控制设计

Design of Human-induced Vibration Control for Pedestrian Steel Truss Bridges

摘要:

我国现行规范明确要求人行桥竖向基频不低于 3 Hz，而大跨度人行桥受自身结构特性影响，往往难以满足该指标。参考德国《人行桥设计指南》（EN03—2007）发现，限制人致振动加速度更适合大跨度人行桥设计。以简支钢桁架人行桥为工程背景，根据《人行桥设计指南》（EN03—2007）规范规定的人行荷载模式，分析了结构振动加速度，评价了行人舒适度。通过参数分析优化了调谐质量阻尼器（tuned mass damper，TMD）与主体结构的质量比和频率比。结果表明，减振率随着TMD的质量比增大而增大，但并非线性关系，当质量比达到1.5%以上时，减振率的提升幅度明显变小；而TMD频率比的变化对振动加速度的影响较小，减振效果优化不明显。选取质量比为1.0%的TMD可使简支钢桁架人行桥人致振动减振率达到74.8%，达到《人行桥设计指南》（EN03—2007）规范的最好舒适度要求。

Abstract:

China's current codes clearly stipulate that the vertical fundamental frequency of footbridges shall not be less than 3 Hz. However, due to the influence of their own structural characteristics, long-span footbridges are often difficult to meet this requirement.With reference to the German design of footbridges guideline（EN03—2007）,it found that the method limiting vibration acceleration was more reasonable for the design of long-span footbridges. A simply-supported steel truss pedestrian bridge was taken as the engineering background in this paper. Based on the pedestrian load patterns specified in the EN03—2007 guideline, the structural vibration acceleration was analyzed and the comfort evaluation was conducted. The mass ratio and frequency ratio between the Tuned Mass Damper (TMD) and the main structure were optimized through parametric analysis.The calculated results indicate：The vibration reduction rate increases with the increase of the mass ratio of TMD, but the relationship is not linear; when the mass ratio exceeds 1.5%, the improvement amplitude of the vibration reduction rate decreases significantly. In contrast, the change of the frequency ratio of TMD has a minor impact on the vibration acceleration, and the optimization effect of vibration reduction is not obvious.Selecting a TMD with a mass ratio of 1.0% achieves a human-induced vibration reduction rate of 74.8% for the simply-supported steel truss footbridge, meeting the highest comfort level requirement specified by the EN03-2007 guideline.