Investigation on wind-induced responses and aeroelastic effect of a square-sectional super high-rise building under twisted wind flow

The aeroelastic effect is very significant for super high-rise buildings under the action of strong winds, due to their lightweight nature and high flexibility. The angle of horizontal winds varies with the height, which leads to significant changes to the wind loads and wind-induced responses of super high-rise buildings. Therefore, aeroelastic model tests of a square-sectional thousand-meter-scale super high-rise building under twisted wind flow with a total wind twist angle of 25° and the equivalent straight wind flow were conducted in a boundary wind tunnel. Based on the experimental time history of the top acceleration of the aeroelastic model, the aerodynamic damping ratio was identified by using the Hilbert-Huang transform and the revised random decrement technique. The effects of the wind direction angle, reduced wind speed and wind twist angle on the aerodynamic damping ratio, extreme acceleration, critical wind speed of the wind-induced resonance and lock-in region were comparatively analyzed, and the characteristics of the wind-induced responses, aeroelastic effect and vortex-induced vibration of the thousand-meter-scale super high-rise building under twisted wind flow were investigated. The results show that, the effects of the wind direction angle on the aerodynamic damping ratio and extreme acceleration are very obvious, and it can significantly change the influencing law of these results and the critical wind speed of the wind-induced resonance. The critical wind speed based on the frequency analysis is less than that determined by the aerodynamic damping ratio or the extreme acceleration, suggesting that the vortex-induced resonance characteristic reflected by the latter two methods shows a wind speed lag and may lead to the unsafety of structures. Compared to those under straight wind flow, the horizontal aerodynamic damping ratios under twisted wind flow are larger and the extreme top acceleration is less. The maximum reduction of the extreme top corner acceleration can reach 38.3%.