不同坡度双坡屋盖表面风压特性研究

Research of wind pressures on gable roofs with different pitch angles

通过提取东京工艺大学低矮建筑气动数据库中的风压数据,以点风压和面积平均风压为分析参数,研究了不同坡度双坡屋盖表面的风压特性。首先给出了正风向及斜风向作用下,屋盖表面的平均和脉动风压分布。其次,通过Hermite Model法计算了双坡屋盖表面各区格面积平均风压时程的峰值因子,进而计算得到各区格的风压统计峰值,并据此分析了双坡屋盖的最不利风向和易损位置。以迎风角区域为参考,计算了该区域与屋盖其余部位面积平均风压的相关特性。最后探讨了部分国家规范中双坡屋盖围护结构设计风荷载的相关条文,并针对GB 50009—2012《建筑结构荷载规范》给出了修订建议。研究结果表明,根据各坡度屋盖风压分布、风压相关性和风压统计峰值的特点,可将双坡屋盖分为3个坡度区间,即0°≤θ≤15°(低坡度)、15°<θ≤30°(中等坡度)和30°<θ≤45°(高坡度);在多数双坡屋盖表面,吸力统计极值的最大值均发生于斜风向作用下的迎风角区域;考虑最不利风向下不同部位风吸力幅值的差异,可将低坡度的屋盖表面分为角部、长边边缘、短边边缘和中部4个区域,中等坡度和高坡度的屋盖表面可在此基础上进一步细分出屋脊区域以及短边边缘与屋脊交接区域进行风压统计。

Based on the aerodynamic database of low-rise buildings of Tokyo Polytechnic University, wind pressures on gable roofs with different pitch angles were investigated via point pressures and area-averaged pressures. Firstly, mean and fluctuating pressures on gable roofs were presented under normal and oblique flow. Secondly, peak factors and statistic peak suctions of each panel were calculated by Hermite Model, on the basis of which, the most unfavorable wind direction and the most susceptible panel were deduced. Thirdly, the correlation between windward corner panel and other panels was analyzed. Lastly, provisions of wind pressures on gable roof claddings from different codes were discussed. In addition, suggestions to GB 50009--2012 ＇ Load code for the design of building structures＇ were given based on this study. Results indicate that gable roofs could be classified as low pitch angle （0°≤ θ ≤15°）, medium pitch angle （15°≤ θ ≤30°） and high pitch angle （30°≤ θ ≤45°） , according to the wind pressure distribution, correlation and statistic peaks. For most pitch angles, the unfavorable wind directions are oblique and the most susceptible panel is near the windward comer. Considering the difference of design wind pressures, gable roofs with low pitch angles can be divided into corner, longer edge, shorter edge and interior regions, while ridge and connection of shorter edge and ridge should be further divided as separated regions on gable roofs with medium and high pitch angles.