步行荷载的功率谱模型及其应用研究

Power spectral density model for pedestrian walking load and its application

基于傅里叶级数的步行荷载确定性模型,由于忽略了荷载的随机性,会高估人行桥、大跨度楼板在共振作用下的动力响应。为此,应考虑行人步行荷载的随机性,在1007条连续步行荷载记录的基础上,提出了前4阶主谐波和次谐波局部区域的功率谱建模方式。各阶谱线经行人体重、各阶能量、步行频率和阶数归一化后可统一表达为两项高斯函数之和的形式,模型中参数由试验数据统计分析得到。结合随机振动理论,给出了由步行功率谱计算楼板加速度响应的方法。通过理论计算值与10m×6m楼板模型的试验值以及火车站楼板实测对比,可知,所建议的功率谱模型的预测结果合理。

Deterministic models of pedestrian walking load proposed on the basis of Fourier series neglect the stochastic characteristics of human walking,and will overestimate dynamic responses at resonance case of structures like footbridges and long-span floors.In this paper,pedestrian walking load is regarded as a stochastic process.Based on the analysis of 1007 load records collected from an experiment,a power spectral density(PSD)model for the first four harmonics and sub-harmonics within a certain frequency range around each harmonic is proposed.The PSD is normalized step by step to pedestrian body weight,energy of each harmonic,mean pacing rate and order of each harmonic,and the PSD models for harmonic and sub-harmonic are suggested as two-term Gaussian functions fitting with four parameters obtained from the statistical analysis of the experimental data.Via stationary and non-stationary stochastic vibration theory,the proposed PSD model is used to predict the vertical structural acceleration response.The framework is finally tested via field measurements on a 10m×6m floor model and a long-span floor of a train station.It is indicated that the model is reasonable in practical design work.