超高层建筑横风向气动阻尼比简化估算方法研究

ACROSS WIND AERODYNAMIC DAMPING OF SUPER TALL BUILDINGS

通过3种高宽比、3种粗糙度流场、多种质量-阻尼参数的多自由度气弹模型风洞试验,分析了折算风速、风场粗糙度、高宽比、结构质量、结构阻尼比和涡振位移等因素对横风向气动阻尼比的影响。分析表明,正气动阻尼比与结构阻尼比负相关,而负气动阻尼比绝对值与结构阻尼比正相关,结构质量与气动阻尼比绝对值负相关,风场越粗糙或模型高宽比越小负气动阻尼比越不显著。整体来看,气动阻尼比本身不足以评价气弹响应的显著程度,以气动阻尼比本身作为经验公式的拟合对象有很大局限性。最后提出了协调气动阻尼比的概念,在此基础上建立了改进的气动阻尼比经验拟合公式,该拟合公式考虑了以上各因素对气动阻尼比的影响,为气动阻尼比的估算方法提供了新的思路。

Based on the wind tunnel test of MDOF models with various aspect ratios and mass-damping parameters, the influence on the crosswind aerodynamic damping ratio was analyzed due to reduced wind speed, wind field roughness, aspect ratio, structural mass, structural damping, as well as VIV displacement. It was found that positive aerodynamic damping is usually negatively correlated with a structural damping ratio, but the negative aerodynamic damping is positively correlated with structural damping, while the absolute value of an aerodynamic damping ratio is negatively correlated with structural mass. Furthermore, the positive aerodynamic damping is less significant in airflow over smooth terrain than over terrain category. Therefore, an empirical formula based on aerodynamic damping data alone cannot be reliably established, because an aerodynamic damping ratio alone is insufficient to assess the significance of aerodynamic effect. Thusly, these considerations lead to the proposal of the concept of a converted damping ratio. This concept allows an empirical formula to be established for an improved aerodynamic damping ratio.