人群步行荷载等效动载因子及应用

Equivalent dynamic load factor for pedestrian loads and its application

人群步行荷载是大跨楼盖、人行桥等工程结构人致振动分析的基础。现有时域模型缺乏对人-人相互作用的考虑,频域模型形式复杂难以用于工程设计。对此,研究提出了一种简单有效的人群步行荷载等效动载因子模型,该模型基于二阶傅里叶级数,充分考虑人-人相互作用且适用于人群密度相关的多种交通状态。首先利用基于实测的人群步行荷载互功率谱模型进行了不同人数、主导步频、结构阻尼比下的单自由度系统响应模拟,进而依据结构响应等效的原则,由模拟结果拟合确定等效动载因子计算公式。利用已建成大跨结构的实测响应进行了验证,结果表明该模型相比国内外现有规范方法具有更低的预测误差,可为大跨结构设计中人致振动舒适度和安全性评估提供参考。

Pedestrian loads are the basis for human-induced vibration analysis for structures like large-span floors and footbridges.Existing load models in time domain lack the consideration of human-human interaction,while those in frequency domain are too complicated to be used in engineering design.In this regard,a simple and effective equivalent dynamic load factor model for pedestrian loads in the form of the second-order Fourier series is proposed,which considers human-human interaction and is applicable to different traffic conditions related to crowd density.Firstly,the structural responses of single-degree-of-freedom systems under different crowd sizes,dominant walking frequencies and structural damping ratios were simulated via the experiment-based power spectral density model for pedestrian loads.Then following the structural response equivalence principle,the expressions for equivalent dynamic load factor were determined by fitting the simulation results.The model was validated using the measured responses of as-built large-span structures,and the results showed that the model had lower prediction errors compared to existing domestic and international codified methods,and can serve as a reference for human-induced vibration serviceability analysis and safety assessment in the design of large-span structures.