不同密度人群行走作用下结构竖向振动响应分析

Vertical vibration response of a structure under different number pedestrians walking on it

行人密度的增加会引起步行速度、步行力的基频和一阶分量降低,从而导致结构振动响应随人数增长的规律发生改变。针对该问题,考虑了不同人群密度下步行速度的变化,引入已有经验关系获得相应步行速度下的步频,进一步结合相关试验结果确定相应的步行力频谱参数,在此基础上导出人员密度影响系数的计算表达式。结果表明:在人群密度不超过0.3人/m^2时,结构振动响应按人数平方根倍关系增长;在人群密度超过0.3人/m^2后,增长倍数按步行力频率与结构频率比的大小,可划分为非共振区和诱发共振区,在非共振区,增长倍数低于人数的平方根倍,在诱发共振区,步频改变可能诱发共振,从而导致增长倍数高于人数的平方根倍。

Increase in pedestrian density can lead to decrease in walking speed,and the first order component and its frequency of pedestrian loads. This can further change the variation law of structural vibration responses with increase in pedestrian number. Aiming at this problem,considering walking speeds varying under different crowd densities,introducing the existing empirical relationship to get the pedestrian ’s step frequency under the corresponding walking speed,combining with the related test results to determine the corresponding spectral parameters of pedestrian loads,based on these the formula for the influence coefficient of pedestrian density were derived. The results showed that the structural vibration response increases with increase in the square root of pedestrian number when the crowd density is less than 0. 3 persons/m^2; after the crowd density is larger than 0. 3 persons/m^2,according to the ratio of the pedestrian’s step frequency to the structure’s frequency,there are two regions including the non-resonance region and the induced resonance region; in the non-resonance region,the growth multiple of structural vibration response is less than that of the square root of pedestrian number; in the induced resonance region,the change of the pedestrian’s step frequency may induce resonance,thus the growth multiple of structural vibration response is higher than that of the square root of pedestrian number.