大跨度提篮式人行拱桥的振动病害分析与改造

针对柔性桥面系动力性能不佳,在行人步伐荷载作用下振动过大,甚至可能发生人桥共振的问题,对一实例桥梁进行自振特性分析,提出提篮式拱桥的前几阶竖向自振频率主要由拱肋性能决定,竖向高阶频率主要由桥面系性能决定,提高桥面系刚度不能有效错开行人步频和结构竖向自振频率,但能有效地减弱动力响应,提高桥梁的使用性能和安全性。根据此类桥梁的这一动力特性,可以有效地诊断出其振动病害并寻求合理的改造加固措施,通常有增加桥面系刚度或增设耗能减振系统两种方法,后者更有效,也可以将这两种方法结合使用。动力响应分析法能有效地进行人行桥振动病害分析和加固前后动力性能对比分析。

Analysis of Vibration Disease on a Long-span X-type Arch Footbridge and Reinforcement

The flexible deck has such bad dynamic performance that excessive vibration response to pedestrian loads will occur.Furthermore,resonant vibration may be induced by synchronized human walking.A conclusion was drawn from the dynamic properties analysis of a real bridge that(1)X-type arch bridges' first several orders vertical natural frequencies are determined by the properties of arch ribs and other frequencies by the properties of deck;(2) increasing the stiffness of the deck cannot move the natural frequencies of the structure out of pedestrian footfall frequency range,but it can effectively decrease the dynamic response to the pedestrian loads and improve the serviceability and safety of the bridge.Based on the dynamic properties of this kind of bridge,it is not difficult to effectively diagnose the vibration disease and choose reasonable reinforcement measures.There are usually two measures,i.e.,increasing the stiffness of the bridge deck and installing energy dissipation system.The latter is more effective,and both can be taken together.Dynamic response analysis method can effectively diagnose the disease due to human-induced vibration and compare the result of reinforcement with primary dynamic properties.