屋盖结构脉动风压非高斯特性分析的极限流线方法

Limiting streamline method for analysis of non-Gaussian property of roof structures' fluctuating wind pressure

非高斯脉动风压对围护结构及局部结构构件有较大影响,在设计中应引起足够重视。目前,非高斯风压场的分区研究主要是建立在对实验数据的统计量分析基础上,并非普遍适用,且随机性较强,区内统计特征值亦相差很大,不足以显示不同区域的非高斯程度,故须结合其形成机理加以分析。考虑到在特定风场条件下分离流动及旋涡作用范围具有时均定常的特点,利用稳态数值方法求解的极限流线和粘性流动分离理论的基本结论,结合实验结果分析了典型屋盖结构脉动风压非高斯特性的形成和分布机理。结果表明,极限流线的分布形态与实验统计的偏度及峰态值分布高度相关,可以被很好地应用于风压场非高斯特性的生成及分布机理研究。

The non-Gaussian fluctuating wind pressure greatly affects a building envelope and its local structural elements,it should be paid attention to in the design.Currently,the identification of a non-Gaussian wind pressure field is mainly based on the statistical analysis of the measured data,but its results are not universally suitable.Besides,the method is highly random and the characteristic values of the non-Gaussian area are quite different,so they are not enough to show the non-Gaussian distribution levels in different areas.To overcome this difficulty,the mechanism of non-Gaussian property should also be considered.Here,considering that under conditions of a certain wind field the flow separation and the vortex action sphere were time-averaged stationary,the limiting streamline solved with the steady CFD and the basic conclusions of the viscous flow separation theory were used here,combined with the experimental results,the mechanisms of formation and distribution of the non-Gaussian properties of fluctuating wind pressure for typical roof structures were analyzed.The results showed that the distribution pattern of the limiting streamline is highly relevant to the distributions of skewness and kurtosis calculated from the experimental results,it can be reasonably applied in the analysis of the formation and distribution mechanism of the non-Gaussian properties of wind pressure fields.