大跨度屋盖结构极值风压概率分布特征研究

对两类典型的大跨度屋盖结构形式（球面屋盖和柱面屋盖）分别进行了超过1 000次的重复采样风洞试验，基于所获得的大量极值风压样本，运用广义极值理论和极大似然估计方法系统分析了极值风压的概率分布特征。研究表明：广义极值分布是描述极值风压概率分布的理想模型，多数区域极值风压符合极值Ⅲ型分布，少数尾流区测点极值风压符合极值Ⅰ型和Ⅱ型分布，且极值Ⅱ型分布区域对应的极值风压离散性更强。利用概率分析方法对传统的极值风压估算方法，即峰值因子法的保证率进行了检验，结果表明：峰值因子法无法给出具有一致保证率的极值风压分布，且低估了极值Ⅱ型分布区的最不利负压，误差率在20%~30%之间；应用概率分析方法可以获得具有确定保证率的极值风压，进而从概率意义上对局部极值风压的取值进行合理评估。

Probability distribution characteristics of extreme wind pressure for large span roofs

Probability distribution characteristics of extreme wind pressure for two kinds of typical large span roofs-a spherical shell and a cylindrical shell were analysed systematically.Based on the wind pressure samples obtained from more than 1 000 independent runs of wind tunnel tests and the generalized extreme value theory, the probability distribution model of extreme wind pressure was established. The study indicates that the generalized extreme value distribution is the ideal model to describe the probability distribution of extreme wind pressure. The extreme wind pressures in most areas follow type Ⅲ distribution, while few in downwind part follows type Ⅰ and type Ⅱ distribution. The extreme pressures which follow type Ⅱ distribution show larger discreteness. The reliability of traditional peak factor method was examined and the results indicate that the peak factor method underestimates the unfavorable negative pressure in type Ⅱ distribution area, with a error ratio between 20%~30%. The probability analysis method could determine distribution of extreme wind pressure with a certain guaranty rate and can thus be used to estimate local extreme wind pressure reasonably.