龙卷风作用下双坡屋面风压分布试验研究

为研究龙卷风作用下双坡屋面的风压分布，根据龙卷风的风场特点，设计了用于建筑风工程的多变量可调节龙卷风塔，并进行双坡屋面刚性模型的风塔测压试验。龙卷风塔可调节塔体高度、导流板的方向角、导流板的高度，可以模拟类似龙卷风的涡旋风场。对龙卷风塔的气动测试表明：风场的风速分布、风压分布及总气压降和兰金涡流模型理论结果吻合良好，龙卷风塔的设计是可行的，可用于龙卷风荷载的相关研究。采用刚性模型的风塔测压试验，研究双坡屋面的风压分布，为了使研究成果具有代表性，针对3种典型的屋面坡角（15°，30°和60°）制作刚性屋面模型。试验结果表明：建筑物位于龙卷风中心（r=0.0R_m，r为建筑物距风场中心距离，R_m为最大旋转风速半径）时，屋面风荷载为吸力，且呈中心对称分布；建筑物位于r=1.0R_m时，屋面的吸力更大，且迎风面和背风面呈现出明显的区别；建筑物位于r=3.0R_m时，屋面的吸力均远小于前两种工况。

Experimental study on pressure distribution of gable roof to tornado

In order to study pressure distribution of gable roof under tornado, a multivariate adjustable tornado tower was designed for wind engineering according to the structure of tornado. The tornado tower had three variables: height of tower body, angle of direction vane and height of direction vane. Adjusting these variables, a tornado-like vortex can be simulated. Good agreements were achieved between experimental results and theoretical results in distributions of velocity, surface pressure and total pressure drop. Wind tower tests for rigid models of gable roof were carried out. In order to make the research representative, three typical roof pitches (15°, 30° and 60°) were used in making rigid models. The experimental results show that wind loads on the gable roof are suction, and pressure distribution is centrosymmetric when the building is located in the center of tornado. Suction on the roof becomes larger, and the windward and leeward side show more significant differences when the building is located at r=1.0R_m. Wind loads on the roof are much smaller than the first two conditions when the building is located at r=3.0R_m