行人荷载随机性对楼盖振动响应的影响研究

Influences of walking load randomness on vibration responses of long-span floors

首先基于大量实验数据构建了行人单步步行荷载模型,并利用频率拓展方法获得了连续步行荷载时程,通过引入步频变异系数反映个体内随机性,引入体重及均值步频的变化反映个体间随机性。采用概率密度演化方法对一典型大跨楼盖实例进行了行人作用下的振动响应分析,与蒙特卡洛模拟结果的对比说明了概率密度演化方法中所采用的代表点能够合理反映出所选随机参数的主要概率信息。在此基础上,采用极值概率密度演化方法获得了楼盖10s均方根加速度的概率分布,并给出了具有95%和75%保证水平的反应谱曲线。与不考虑荷载随机性的楼盖振动响应结果对比发现,对于95%保证水平,行人荷载随机性放大效应最大可超过4倍,对于75%保证水平最大也接近2.5倍。结果表明,行人荷载随机性对楼盖的振动响应具有显著的影响,在楼盖的舒适度评估中需要考虑行人荷载的随机性。

A single footfall load model of pedestrian has been developed based on a large number of experimental records.The continuous time history of walking load is then expanded from the single footfall load curve by assuming it is a periodic one.Intra-subject variability,such as variation of body weight and mean walking rate,is one source for randomness in walking load.The other source is inter-subject variability,which is represented by variation coefficient of mean walking frequency.The probability density evolution method（PDEM）is adopted to calculate the dynamic responses of a long-span floor subjected to random walking load.The probability distribution of 10-sec root-mean-square acceleration responses are obtained by using the extreme value probability density evolution method,and the response spectrum curves with 75% and 95% confidence level are given in the study.Comparison of responses with and without consideration of walking load randomness shows that the acceleration responses of the floor could be underestimated without considering the walking load randomness.The walking load randomness should be considered in the assessment of vibration serviceability of long-span floors.