考虑行人随机性的人行桥人致横向振动稳定性分析  

STABILITY ANALYSIS ON PEDESTRIAN-INDUCED LATERAL VIBRATION OF FOOTBRIDGES CONSIDERING PEDESTRIAN STOCHASTIC EXCITATION

作　　者：贾布裕[1] 颜全胜[1] 余晓琳[1] 杨铮[1] JIA Bu-yu;YAN Quan-sheng;YU Xiao-lin;YANG Zheng(School of Civil Engineering and Transportation, South China University of Technology, Guangdong, Guangzhou 510640, China)

机构地区：[1]华南理工大学土木与交通学院,广东510640

出　　处：《工程力学》2019年第1期155-164,共10页Engineering Mechanics

基　　金：国家自然科学基金项目(51478193,51608207);桥梁工程结构动力学国家重点实验室基金项目(201507);中央高校基本科研业务费专项资金项目(2015ZM114);福建省交通运输科技基金项目(201527)

摘　　要：2000年英国千禧桥大幅横向振动事件的发生,揭示了在人行桥的人致横向振动中,存在着振动发散不稳定现象:人群数目的小额增加会导致有限振幅的桥梁振动突变为大幅桥梁振动。这个现象已被证实为是由人-桥的相互作用引起,但其中机理仍未得到明确的解释。众多学者包括目前已有的规范所提出的模型,大部分基于确定性的思路或者单个试验观测结果,忽略了行人荷载中明显存在的随机性。行人荷载实质是一个复杂的窄带随机过程,包含行人不同步伐间的作用随机性以及不同行人之间的作用随机性,这些随机性导致的行人荷载将明显不同于按确定性考虑的情况。因此,该文提出了考虑人桥相互作用以及行人横向荷载随机性的非线性随机模型,将行人横向荷载划分为两部分:与桥梁振动无关的横向荷载以及与桥梁振动(振幅)相关的荷载,并考虑了单个行人不同步伐间的荷载随机性造成的激励过程窄带性。基于随机平均法推导得到的It?方程,进行了随机P-分叉分析和随机D-分叉分析,并以此得到人行桥横向振动发散失稳临界状态。最后利用所提方法对伦敦千禧桥北边跨进行了算例分析,验证了该文所提方法的有效性,并得到了一些有益的结论。The infamous incident of large lateral vibration on the London Millennium Bridge in2000reveals that divergence of instability exists in pedestrian-induced vibration:a small increase in the number of pedestrians will cause the amplitude of vibration of the footbridge to become divergent.Such divergence of an instability phenomenon has been proven to be caused by the interaction between the pedestrian and the footbridge,although the mechanisms still have not been clearly explored.Most existing models are based on deterministic methods or results of a single test,ignoring the obvious randomness in the pedestrian load.In fact,pedestrian load is a complex stochastic process characteristized by narrow-band,including the large intra-subject and inter-subject randomness,which cause the real pedestrian load to be significantly different from that of a deterministic case.A nonlinear stochastic model for footbridges considering the pedestrian-bridge interaction and the randomness among the pedestrian lateral load was proposed.The pedestrian lateral load was considered as a narrow-band excitation process caused by the intra-subject variability,and was divided into a static load independent offootbridge vibration and vibration amplitude–dependent load.Based on the It?equations derived by the stochasticaveraging method,the stochastic P-bifurcation and stochastic D-bifurcation were analyzed to gain the criticalcondition for triggering a large lateral vibration of footbridge.Finally,through the case study of the northern spanof the London Millennium Bridge,the availability of the proposed method was confirmed and meaningfulconclusions were obtained.

关 键 词：人行桥 人致横向振动 随机平均法 It.方程 稳定 

分 类 号：TU311[建筑科学—结构工程]