根据交通流和生物力学的研究成果，将人体视为具有质量、刚度、阻尼的两自由度系统，建立了人群过桥时人群 － 桥梁耦合系统的动力学模型，分析了人群对耦合系统动力特性的影响，研究了不同行走模式时人群 － 桥梁耦合系统的动力响应和人致振动参数敏感性．结果表明:人群使耦合系统产生了附加振型;人群集度和位置对耦合系统的动力特性影响较大;行走人群对桥梁动力响应的影响主要取决于人群行走的频率是否与结构竖向基频相接近，以及人群行走步调是否相接近;人群集度和行走速度对人群 － 桥梁耦合系统的动力特性均有不同程度的影响．文中模型避免了计算人群与桥梁的耦合振动时参数取值的任意性．

According to the findings of traffic flow and biomechanics,a human body is considered to be a 2- DOF(Degree of Freedom) system with mass,stiffness and damping.A dynamic model of crowd- bridge coupling systemwith crowd being on the bridge is thus constructed.Moreover,the dynamic characteristics of the coupling systemaffected by the crowd are analyzed,and the dynamic response as well as the pedestrian- induced vibration parametersensitivity of the coupling system in different walking modes is investigated.The results show that (1) an additionalvibration mode of the coupling system may occur due to the presence of crowd; (2) crowd density and locationgreatly affect the dynamic characteristics of the coupling system; (3) the influence of walkers on bridge's dynamicresponse mainly depends on two factors such as whether the walking frequency is close to the vertical fundamentalfrequency of the structure and whether the crowd is of the same walking pace; and (4) both crowd density andwalking speed influence the dynamic characteristics of the crowd- bridges coupling system to different degrees.Theproposed model helps avoid the randomness of parameter selection for calculating the coupling vibration of crowdand structure.