Investigation on wind-induced aero-elastic effects of tall buildings by wind tunnel test using a bi-axial forced vibration device

Abstract

Wind-induced vibrations of tall buildings certainly change wind effects on the structures, which is the so-called aero-elastic effect. To date, the approach to identify the aero-elastic effect is still sparse. In this paper, a bi-axial forced vibration device is developed to evaluate the aero-elastic effects of tall buildings via wind tunnel tests. The device can simulate the first-order bi-axial vibration of building models. Furthermore, the surface pressure and the top displacement of the oscillating model can be synchronously measured. The aerodynamic damping ratio and aerodynamic stiffness were identified through analyzing the aero-elastic force acting on the oscillating model. The effects of aero-elastic parameters on wind-induced responses and equivalent static wind loads of a 347 m tall building were examined and analyzed. The results show that for a return period of 100 years, the aerodynamic damping is positive while the aerodynamic stiffness is negative. Aerodynamic stiffness is much smaller than the structural stiffness and therefore it has a negligible effect on natural frequency of the building. Considering the aero-elastic effects, the maximum top displacement and acceleration decrease by approximately 4% and 10% respectively, and meanwhile, the base shear and base moment induced by equivalent static wind loads decrease by approximately 1%. This investigation indicates that wind tunnel test using such kind of bi-axial forced vibration device is an effective approach to identify aero-elastic parameters of tall buildings and even other tall slender structures.