RESEARCH ON THE AERODYNAMIC DAMPING RATIOS OF SQUARE TALL BUILDINGS IN ACROSS -WIND DIRECTION UNDER STRONG WIND

A rigid body base pivoted aero-elastic model is designed with adjustable mass and damping ratio, which can sway in two perpendicular directions. The acceleration history response of the top of the model is acquired from aero-elastic model wind tunnel test. The aerodynamic damping ratios of square tall buildings in across-wind direction in turbulent flow field are evaluated by the improved random decrement technique. The laws of across-wind aerodynamic damping ratios changing with reduced velocities is discussed, which is affected by terrain categories, structural damping ratios, uniform equivalent masses and aspect ratios. Ultimately, the empirical formulas of across-wind aerodynamic damping ratios are proposed, which are proved to be correct and practical by comparing the calculated across-wind responses considering aerodynamic damping ratios with wind tunnel tests results.