平屋盖围护构件设计风荷载研究

GB 50009-2012《建筑结构荷载规范》中未给出复杂体型且重要建筑物的风荷载局部体型系数，此类建筑物的风荷载需通过风洞试验确定。基于此，提出了基于风洞试验的围护构件设计风荷载计算方法，将规范中阵风系数与局部体型系数的乘积修改为局部体型系数与脉动风压系数极值之和的形式，称为风压系数极值。提出的围护构件设计风荷载计算方法不仅适用于迎风面围护构件设计风荷载的计算，也适用于气流分离区围护构件设计风荷载的计算。在脉动风压系数极值的计算中，考虑了气流分离区非正态风压时程的特性，采用非正态峰值因子的简化计算式，可简便确定非正态风压时程的峰值因子。以平屋盖围护构件设计风荷载的确定过程为例，对比了我国规范方法与文中方法的异同，提出了平屋盖围护构件风压系数极值的设计建议值。结果表明，采用文中提出的围护构件设计风荷载计算方法，基于风洞试验数据可确定气流分离区围护构件的设计风荷载，采用日本风荷载规范的屋盖风荷载分区方法是合理的；采用风洞试验得到的局部体型系数，套用GB 50009-2012规范方法确定气流分离区围护构件的设计风荷载，可能严重低估风荷载取值。

Research on design wind loads on cladding and components of flat roof

The shape factors of wind loads for the complex-shaped and important buildings are not specified in GB 50009-2012 ‘Load code for the design of building structures’. The wind loads of these buildings are frequently determined by wind tunnel tests. A method of determining the design wind loads for cladding and components based on the wind tunnel tests was presented in this paper. In this method, the peak pressure coefficient of wind load is expressed as the summation of shape factor and the peak fluctuating pressure coefficient, instead of the product of the gust factor and the shape factor in GB 50009-2012. The method can not only be applied to the windward cladding and components, but also to the leeward cladding and components which are located in the flow separation zones. After the non-Gaussian characteristics of wind pressure histories are considered, the peak fluctuating pressure coefficient can be simply calculated using the reduced formulae of non-Gaussian peak factor. As an example, the design wind loads on cladding and components of a large-span flat roof were investigated using both the presented method and the method in GB 50009-2012. The recommended peak pressure coefficients on cladding and components of flat roof were presented for the wind-resistant design. It is clear that the problem of design wind loads on cladding and components is solved effectively by the presented method and that the load panels specified in AIJ-RLB-2004 code are reasonable. It is illustrated that the design wind loads on cladding and components located in the flow separation zones may be underestimated by the national code if the shape factors are obtained by wind tunnel test.