ACROSS WIND AERODYNAMIC DAMPING OF SUPER TALL BUILDINGS

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.