冲击风作用下大跨屋盖多模态随机风致响应研究

Random wind-induced dynamic response of long-span roof to thunderstorm downbursts in the time domain

雷暴冲击风是一种近地面短时产生的瞬态强风,它与传统的边界层风场特征具有明显的差别,冲击风将会引起屋盖的强烈振动,甚至发生破坏。本文根据混合随机模型,详细研究了冲击风风场的数值模拟方法。应用Wood竖直风剖面方程与Holmes经验模型模拟平均风场,使用稳态高斯随机过程模拟脉动风场,模拟的风场与实际的雷暴冲击风较为一致。结合多阶模态加速度法和等效风荷载原理,详细推导了大跨屋盖随机风致响应的计算方法。结合边界层风洞试验,比较冲击风产生的表面风压特性,计算得到屋盖冲击风致动力响应时程,并研究了冲击风作用下大跨屋盖荷载风效应系数和位移风效应系数的分布特点。研究结果可作为评估大跨屋盖冲击风致响应的一种参考。

Thunderstorm downbursts, which are known that the wind characteristics differ significantly from boundary layer winds, are defined as an outburst of damaging strong winds on or near the ground. When such events occur, the roofs will induce a large amount of buffeting responses and cause failures. This paper presents a deterministic-stochastic hybrid model to simulate a downburst. Wood＇s velocity profile for the vertical profile and Holmes＇ empirical model are utilized to generate the mean wind. The fluctuation is generated by stationary Gaussian stochastic process. Based on the multi-modal acceleration method and the theory of equivalent wind load, a new method is provided to estimate the wind-inducod response of long-span roofs. Through the rigid and aeroclastic model wind tuunel test, the pressure field on roof is researched and compared. Using the time histories of downburst wind loads, the dynamic responses of structure can be obtained in the time domain. The distribution of gust load factor and gust displacement factor on the flexible roof surface has been studied and compared, respectively. In practice, the procedure and the results presented here may be used to estimate the dynamic response of long-span roof subjected to severe downburst winds.