考虑行人同步率的随机行走人群模型

为了研究行走人群协同性对结构人致振动的影响，基于考虑行人同步率的随机行走人群模型，对人群行走下人行天桥的竖向振动问题就行了分析. 首先通过行走人群随机性分析，提出了考虑行人同步率的随机行走人群集中模型和离散模型；其次在两类模型下考虑人-结构竖向耦合作用，建立了随机行走人群作用下结构竖向振动响应分析方法；最后对比分析了人行天桥在不同随机行走人群模型下的竖向加速度响应和动力特性参数的变化规律. 研究结果表明:两类模型行人行走下，人行天桥的1 s均方根加速度响应随人群密度的提高先增大后减小；人群密度超过0.2人/m2后，随机行走人群离散模型下的人行天桥1 s均方根加速度大于集中模型，且增大集中模型同步区行人间距有利于减小结构振动响应；随着人群密度的增大，人行天桥瞬时频率不断减小，瞬时阻尼比则先增大后减小，集中模型和离散模型下人行天桥瞬时阻尼比分别最大提高到6倍和7倍；考虑行人同步率的随机行走人群模型能准确反映人行天桥实际所受到的人群行走荷载作用，可为人行天桥人致振动响应分析与评估提供参考. 

Random Walking Crowd Model Considering Pedestrian Synchronization Rate

In order to study the influence of walking crowd synergy on the human-induced vibration of structures, the vertical vibration of a footbridge under the action of walking crowd was analyzed using the random walking crowd model considering pedestrian synchronization rate. Firstly, a random walking crowd centralized model and discrete model considering pedestrian synchronization rate were proposed by random analysis of the walking crowd. Secondly, a method for vertical vibration response analysis of structure subjected to random walking crowd was established by considering the vertical coupling effect between human and structure under the two models. Finally, change rules of vertical acceleration responses and dynamic characteristic parameters of the footbridge under the two different random walking crowd models were compared and analyzed. Results show that the 1-s root-mean-square (RMS) acceleration responses of the footbridge under the two pedestrian walking models both increase first and then decrease with the crowd density increasing. Beyond the crowd density of 0.2 person/m2, the 1-s RMS acceleration of the footbridge in the random walking crowd discrete model is greater than that in the centralized model, and increasing the pedestrian spacing in the synchronization zone of the centralized model is beneficial to reducing structural vibration responses. As crowd density increases, the instantaneous frequency of footbridge decreases constantly; the instantaneous damping ratio of the footbridge increases first and then decreases, with a maximum 6-fold and 7-fold increase under the centralized model and the discrete model, respectively. In short, the random walking crowd model considering pedestrian synchronization rate can accurately reflect the actual crowd walking load of footbridges and therefore provide reference for the analysis and evaluation of human-induced vibration responses of footbridges.