非均匀地形的低矮建筑物风荷载干扰效应研究

For typical kinds of low-rise buildings with flat roofs, gable roofs and cylindrical roofs, the effects of the upstream terrains in long, near distance and nearby surrounding buildings on the atmospheric boundary layer near the ground and the wind loads on low-rise buildings are investigated through the wind tunnel measurements of wind velocity, pressure and PIV combined with CFD simulation. A method to calculate the peak wind pressure on roofs is proposed to consider the spatial correlation reduction effects, which is suitable to the wind characteristics of roofs. Wind velocity model of the atmospheric boundary layer near the ground and wind load model of typical kinds of roofs will be obtained. With wind tunnel tests and artificial neural network technology,interference effects in homogenious and inhomogenious upstream terrains on low-rise buildings in a city center surrounded by high-rise buildings or in an industrial region surrounded by low-rise buildings are investigated, considering changes of the terrain roughness length, wind direction, surrounding building distribution, building density and shape of the low-rise building itself. The wind flow modes, velocity turbulence and wind pressure will be studied to reflect the interference mechanism of the terrains and surrounding buildings on the low-rise building. Moreover, the wind-resistant method for cladings of typical kinds of low-rise buildings is proposed, where the wind interference is included.

针对平屋面、双坡屋面和柱状屋面等三种典型低矮建筑物，通过风洞实验的测速、测压和流场粒子显示技术，并结合CFD数值模拟，研究上游远距离地形、中距离地形和近距离附近建筑物，对近地边界层风场和低矮建筑物风荷载的影响机理，提出适合屋面风荷载特性、考虑空间相关性折减效应的极值风压计算方法，建立水平非均匀地形的近地边界层风速模型和典型形式单体低矮建筑物的平均与极值风荷载模型。通过风洞实验，并结合人工神经网络技术，针对工业园区低矮建筑群和处于城市中心区的低矮建筑物等两大类低矮建筑物，研究在水平均匀和非均匀地形条件下，地形粗糙度长度系数、风向、周围干扰物分布形式、建筑物密度、低矮建筑物自身几何形状等参数，对建筑群周围的气流流动模式、湍流特性、建筑物表面平均和极值风压的影响规律，揭示地形和周围建筑物对低矮建筑物的风荷载干扰机理，建立考虑干扰效应的低矮建筑物围护结构抗风设计方法。

低矮建筑房屋高度低，风荷载易受到周围建筑物的干扰效应影响，建筑物表面风压分布与单体建筑物存在较大区别。本项目通过风洞实验，并结合CFD数值模拟，针对工业园区低矮建筑群和处于城市中心区的低矮建筑物等两大类典型建筑群开展干扰效应研究；针对平屋面低矮建筑群，系统研究了风向、间距等对2个相同低矮建筑物、1排3列、3排1列以及多排多列低矮建筑群的风荷载干扰效应影响规律，给出了屋面平均风压和极值风压系数的干扰因子变化规律，建筑群角部建筑物风荷载放大效应明显，其建筑物屋面角部区域放大更为明显，中心区域建筑物主要呈现遮挡效应；给出了不同建筑群布置下，建筑物之间流动模式的界限，阻力系数曲线在不同流动模式间距界限处出现跳跃性变化，建筑物表面风压也呈现特殊分布形式；揭示了非均匀地形条件下单体建筑物和群体建筑物的风荷载变化规律，建筑物之间距离较近时干扰效应受非均匀地形影响比建筑物间距较大时的影响更为显著；研究了高层建筑对低矮建筑物风荷载的影响规律，高层建筑物对低矮建筑物的风压特性影响显著，当低矮建筑物位于高层建筑物迎风上游时，距离较近时出现明显的正压现象，当位于高层建筑物的迎风下游时，低矮建筑物表面负压出现明显的放大现象，且间距越近，高层建筑物高度越大时，影响越显著。