景区大跨径人行索桥人致振动响应研究

Research on Human-induced Vibration of Long-span Cable-supported Footbridge in Scenic Spot

大跨人行桥的结构频率往往落在行人步频敏感范围之内,这使得人致振动成为该类桥梁设计所需重点考虑的问题之一,人流密集的景区人行索桥更是如此。以某座景区大跨径人行索桥为例,参考国外人行桥规范,基于不同行人同步率和人群密度下的4种人群荷载形式,应用直接共振理论选择典型竖弯和侧弯振型,通过有限元时程分析方法,计算获得不同荷载激励下主梁跨中的竖向和侧向加速度响应时程曲线。比较分析得出:(1)结构峰值加速度响应在一定范围内与行人同步率成线性关系;(2)竖向锁定现象有可能发生在此类景区大跨径人行索桥;(3)现有国外人行桥规范的荷载取值不完全适用于此类高人流密度的景区大跨径人行索桥。

The structure frequency of long-span footbridge often falls within the scope of pedestrian sensitive frequency, which makes human-induced vibration become one of the key design considerations required for this kind of bridge, especially for the footbridge in the crowed scenic spot. Based on a long-span scenic spot cable-supported footbridge, with reference to foreign footbridge codes and using the direct resonance theory to select typical vertical and horizontal modes, the vertical and horizontal acceleration time-history curves of girder mid-span are calculated by FEA time-history analysis method under 4 kinds of crowd＇s form of load at different rates of pedestrian synchronization and population density. The result of comparative analysis shows that （ 1 ） in a certain range, there is a linear relationship between peak acceleration response of the structure and the pedestrian synchronization rate; （2） the vertical ＂Lock-in＂ phenomenon may probably happen at the long-span footbridge in scenic spot; （ 3 ） the load values in code of existing foreign footbridge is not completely suitable for such footbridges in the site of high population density.