马鞍屋盖表面面积平均风压特性研究

Area-averaged wind pressure on a saddle roof

为完善我国建筑结构荷载规范中有关围护结构和覆面材料的设计,提出了面积平均风压的概念。通过刚性模型风洞测压试验,研究了马鞍屋盖表面的面积平均风压特性。①以锥形涡为引,确定各矢跨比马鞍屋盖表面出现锥形涡的来流工况,以涡核吸力和涡核互相关性为依据,确定了马鞍屋盖的最不利风向为沿高点连线方向。②在一定附属区域内对单点风压进行集合,得到面积平均风压(时程);在马鞍屋盖表面实行各种分区,探讨了最不利风向下各面积平均风压时程的峰值吸力随附属面积的变化趋势,得到了相应的拟合公式;通过各区域内单点风压时程的累积概率分布,验证了该拟合公式的准确性与有效性;根据偏度和峰度值大小,分析了面积平均风压时程的非高斯特性,并与单点时程的风压特性进行了比较,结果表明面积平均风压时程曲线中风压脉动分布均匀,高频脉动减少,因而其非高斯特性并不如单点突出,且普遍偏向高斯分布。

In order to improve wind resistant design of enclosure structures and cladding elements,the concept of area-averaged wind pressure was proposed,and its characteristics were systematically studied with wind tunnel tests.Firstly,starting from conical vortex,the approaching flow conditions causing generation of conical vortex were identified.Based on suction and correlation coefficient of vortex cores,the most unfavorable attack angle for a saddle roof was confirmed to be along the connection of high points.Secondly,the area-averaged wind pressures were calculated by averaging all pressure taps within the area at each time instant.The relationships between peak loads over various tributary zones and increasing tributary area were presented and fitted,they were verified with the cumulative probability curve of single point pressure.Non-Gaussian feature of area-averaged wind pressure time series was analyzed and compared with that of point pressure according to skewness and kurtosis.Results indicated that area-averaged wind pressure,whose uniform fluctuations concentrate in low-frequency range,is more normally distributed than individual pressures.