基于人群密度的随机人群荷载模型研究

A study on stochastic crowd load model based on crowd density

人群同步率与行走步频对人行桥的结构振动响应影响较大,但既有随机人群荷载模型仅由单人荷载模型组合而成,并未考虑人群密度对结构振动的影响,建立可描述人群行走特征的随机人群荷载模型尤为重要。以某钢桁架人行桥为研究对象,采用现场振动测试试验与数值模拟的方法,研究人群密度对人行桥振动响应的影响规律,在既有随机人群荷载模型的基础上,提出一种考虑人群同步率与行走步频随人群密度变化而改变的随机人群荷载模型,并采用其他学者的相关试验数据对本文建立随机人群荷载模型的正确性进行了验证。研究结果表明:人群同步率和行走步频都会随人群密度的变化而改变;当人群密度小于1人/m^(2)时,人行桥振动响应与人群密度呈正相关,当人群密度超过1人/m^(2),人行桥振动响应随人群密度呈负相关;基于人群密度的荷载模型所得到计算值与试验值的相对误差为5.0%~12.2%,这证明本文建立的随机人群荷载模型能够较好模拟人群行走所产生的荷载效应。

The existing stochastic crowd load model is only composed of a single load model,and the influence of crowd density on structural vibration is not considered.Therefore,it is very important to establish a stochastic crowd load model which can describe the walking characteristics of pedestrian.In this paper,a steel truss pedestrian bridge was taken as the research object.By using the method of field vibration test and numerical simulation,the influence of crowd density on the vibration response of the pedestrian bridge was studied.Based on the existing stochastic crowd load model,a crowd load model considering the change of crowd synchronization rate and walking frequency with the change of crowd density was proposed,and the relevant tests of other scholars were used,the validity and applicability of the model were verified by the test data.The results show that:the crowd synchronization rate and walking frequency will change with the crowd density;when the crowd density is less than 1 person/m^(2),the pedestrian bridge vibration response is positively correlated with the crowd density;when the crowd density is more than 1 person/m^(2),the pedestrian bridge vibration response is negatively correlated with the crowd density;the relative error between the calculated value and the test value based on the crowd density load model is 5.0%-12.2%,which proves that the stochastic crowd load model established in this paper can better simulate the load effect of crowd walking.