矩形高层建筑顺风向脉动风荷载空间相关性

Spatial correlation analysis of fluctuating along-wind loads on high-rise buildings with rectangular section

为研究风场类别、结构特征尺寸及竖向间距等因素对矩形高层建筑顺风向脉动风荷载空间相关性的影响,采用矩形刚性模型表面压力同步测量试验,对顺风向脉动风荷载及脉动风速相干函数空间分布特性进行研究,对矩形模型表面脉动风荷载与脉动风速、迎风面与背风面脉动风压的相关性进行对比分析.根据试验结果,对传统脉动风速相干函数模型进行改进,提出了可计及风场类别、结构迎风面宽度及竖向间距等流场和结构参数的矩形建筑顺风向脉动风荷载相干函数表达式.结果表明:顺风向脉动风荷载的相关性要明显强于脉动风,当矩形断面长边迎风时,迎风面脉动风压相关性低于断面整体风荷载的相关性,背风面脉动风压的弱相关性在间距较小时并不能完全忽略,采用传统脉动风速相干函数模型可能导致脉动风荷载取值偏不安全.

To investigate the influence of turbulence characteristic, structure dimension and separation distance on spanwise correlation characteristics of fluctuating along-wind loads acting on the rectangular building, the surface pressure fluctuations on a rigid model with rectangular cross-section were measured synchronically in the simulated atmospheric boundary layers.The distribution characteristics of coherence function of fluctuating along wind loads and oncoming turbulence were also studied.The correlation of unsteady along-wind loads and wind fluctuations, and the fluctuating pressures acting on windward side and leeward side were compared through present experiments.A modified expression of a coherence function of fluctuating along-wind loads on rectangular high-rise building was proposed by considering various parameters, including windward width of structure, spatial spacing and incoming wind characteristics.The measured results show that the fluctuating along-wind loads are more correlated than the wind fluctuation.The correlation of fluctuating pressures on windward side is weaker than that of overall unsteady drag forces in the case of model whose width exceeds the stream wise dimension.The weak correlation of fluctuating wind pressure on leeward side can＇t be ignored at a small separation distance.So the conventional coherence model of turbulence is unsafe for predicting the fluctuating along-wind loads of the high-rise buildings.