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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。
In order to study the wind pressure distribution of double-slope roof under the effect of tornado, a multivariable adjustable tornado tower for the construction wind engineering was designed according to the wind field characteristics of the tornado. The wind tower pressure test of the double-slope rigid roof model was carried out. Tornado tower height adjustable tower, the direction of the deflector angle, the height of the deflector, you can simulate a similar tornado wind field. The aerodynamic test of the tornado tower shows that the wind speed distribution, the wind pressure distribution and the total pressure drop are in good agreement with the Rankine vortex model theory. The design of the tornado tower is feasible and can be used to study the tornado load. In order to make the research results representative, a rigid roofing model was built for three typical roof slope angles (15 °, 30 ° and 60 °) by using wind tower pressure test of rigid model. The test results show that the roof wind load is suction and the center is symmetrical when the building is located in the center of the tornado (r = 0.0R m, where r is the distance from the wind center to the center of the building and R m is the radius of the maximum rotation speed) When r = 1.0Rm, the suction of the roof is bigger, and the windward and leeward are obviously different. When the building is located at r = 3.0Rm, the suction of the roof is far less than that of the former two.