雷暴冲击风作用下高层建筑风压幅值特性研究

采用冲击射流装置模拟雷暴冲击风，对4个不同深宽比的高层建筑模型进行测压试验，分析了各模型8个不同径向位置处的风压幅值特性，并与大气边界层风作用下的建筑表面风压系数进行了对比。结果表明：雷暴冲击风作用下，建筑迎风面为正压，侧面和背风面均为负压；迎风面平均和脉动风压受模型深宽比影响较小，侧面和背风面受深宽比影响较大；随着径向距离的增加，迎风面平均风压系数逐渐减小，脉动风压系数先增大后减小，侧面平均风压系数绝对值以及脉动风压系数先增大后减小，背风面平均和脉动风压系数变化较为平缓；各模型迎风面风压系数沿高度呈“鼻子”状分布，最大风压出现在0.25H(H为模型高度)；与大气边界层风作用下建筑表面风压幅值相比，雷暴冲击风作用下高层建筑模型的迎风面中下部区域以及侧面前缘部位风压系数较大，考虑雷暴冲击风作用的高层建筑设计时，应对这些区域的风荷载取值进行适当放大。

Study on wind pressure amplitude characteristics of high-rise buildings under thunderstorm downburst

Using the impinging jet device to simulate thunderstorm downburst, pressure test was carried out on four high-rise building models with different aspect ratios. The characteristics of pressure amplitude of each model at eight different radial positions were analyzed and compared with atmospheric boundary layer wind. The results indicate that the mean wind pressure coefficients on the windward wall are positive, while those on the side walls and leeward wall are negative. The mean and fluctuating wind pressure on windward wall are less affected by the aspect ratio of models, while on side walls and leeward wall they are greatly influenced. With the increase of radial distance, the mean wind pressure coefficients of windward wall gradually decrease while the fluctuating wind pressure coefficients increase first and then decrease, the absolute value of mean and fluctuating wind pressure coefficients of side walls increase first and then decrease, and the mean and fluctuating wind pressure coefficients of leeward wall change slowly. The profiles of mean wind pressure coefficients on windward wall are nose-shaped, and the maximum value appears at the height of 0.25H (H is the height of the building). Compared with the wind pressure amplitude of the building surface under the atmospheric boundary layer wind, the wind pressure coefficient at the middle and lower area of windward wall and the area close to leading edge of side walls under thunderstorm downburst is large, and the wind load should be properly amplified in these areas for wind resistance design considering thunderstorm downburst effect.