复杂屋盖结构表面风压的非高斯特性研究

对一具有复杂曲面形状的开敞式大跨屋盖结构进行了风洞模型测压试验,对获得的屋面平均风压系数、脉动风压系数及其偏度和峰度值进行了计算和分析;提出并运用三种概率分布混合模型:对数正态分布和Weibull分布组合(LW)、双对数正态分布组合(LL)、双Weibull分布组合(WW)模型,对屋盖的非高斯风压分布特性进行了拟合和计算。结果显示,这类复杂屋盖除了在迎风屋檐、角区等出现吸力极大值外,还会在跨中凸起区域产生依次排列的多个极值区,这主要与复杂曲面所引起的气流多次分离与再附着有关;屋盖不同部位的风压呈现不同程度的非高斯特性,其中气流分离区的风压非高斯特性比较显著;三种概率分布混合模型对屋盖风压系数概率分布的拟合效果有所差别,其中LW混合模型的拟合效果最佳,适用于不同偏度的风压分布情况。

Non-Gaussian characteristics of the wind pressure on a roof with irregular shape

The rigid model wind tunnel experiments on an open-type roof with irregular shape were conducted.The mean wind-pressure coefficients,fluctuating wind-pressure coefficients,skewness and kurtosis were analyzed.The lognormal-Weibull mixture distribution model,lognormal-lognormal mixture distribution model and Weibull-Weibull mixture distribution model were adopted to fit the probability distribution of pressure coefficient time series of the taps.The data analysis shows that the maximum negative pressures appear on the eaves,and corners of the roof on the windward.What’s more,several extreme value areas are arranged in a line on the bulge part of the roof due to its irregular shape.The wind pressure in different parts of the roof presents different degrees of non-Gaussian properties and it shows strong non-Gaussian property when the taps are in flow separation regions.The three mixture models show some difference in the fitting results.The lognormal-Weibull mixture distribution model is appropriate for fitting the probability distribution of pressure coefficients with various skewness.