The wind-induced responses of tall buildings are stochastic processes, and the peak factor is an important parameter to evaluate the extreme value of the wind-induced response in wind-resistant design. The existing research on the peak factor mainly focuses on the wind pressure on the building surface, but rarely concerns the wind-induced response peak factor of the structures. In view of this, the peak factor of the wind-induced response of super-high-rise buildings was studied in this paper. Firstly, a series of wind tunnel tests of the multi-degree-of-freedom aero-elastic models (MDOF) were carried out, wherein the along-wind and cross-wind responses were measured. Thereafter, the peak factor of wind-induced response was calculated using the peak factor method, classical extreme value theory, and the improved peak factor method. It was found that the peak factor calculated by the improved peak factor method is in good agreement with classical extreme value theory, which indicates that the improved peak factor method is applicable to calculate the peak factor of the wind-induced response of high-rise buildings. The results calculated using the improved peak factor method show that the peak factor of cross-wind response varies significantly with the wind speed, varying from about 2.5 to 5.5. The peak factor of cross-wind response first increases and then decreases with the increase in the wind speed, reaches the minimum near the critical wind speed of vortex-induced vibration (VIV), and increases again when the wind speed is larger than the VIV wind speed. Finally, an empirical formula for the cross-wind response peak factor was proposed as a function of the reduced wind speed, aspect ratio, and damping ratio of the structure.

This research investigates the cross-wind aeroelastic effects of tall buildings with hexagonal cross-sections by using aeroelastic models with multiple-degree-of-freedom (MDOF). Cross-wind displacement and acceleration responses at the top of each model are measured using the wind tunnel test. The aerodynamic damping ratios for the two representative wind directions are identified by analyzing the measured responses using the random decrement technique. Results show that large-amplitude vortex-induced vibrations occur for one of the representative wind directions where the vertex of the hexagonal model is against the approaching wind, while there is no significant VIV observed for the other representative wind direction where the face of the hexagonal model is perpendicular to the approaching wind. The most dangerous wind direction is then identified based on the discussion. Two expressions for the cross-wind aerodynamic damping ratio are established for the two wind representative wind directions. The two equations can be used in engineering practice to estimate the cross-wind aerodynamic damping ratio of hexagonal tall buildings.

Dynamic wind-induced vibrations of structures will cause cyclic stresses in structural elements, potentially leading to fatigue damage accumulation or structural failure. Existing research on wind-induced fatigue mainly focuses on tower and large-span steel structures, such as chimneys, signal towers, transmission towers, long-span bridges, and wind turbines. However, existing studies on wind-induced fatigue damage in tall steel buildings remain limited. To determine whether and under what conditions wind-induced fatigue damage needs to be considered in tall steel structures, this study investigates wind-induced fatigue failure through wind tunnel tests and numerical simulations. Specifically, six real tall steel buildings were examined to assess their fatigue life under dynamic wind loads. First, wind tunnel tests using synchronous pressure models were conducted to obtain wind load time histories of these six buildings. Subsequently, time histories of wind-induced displacements and component stresses were calculated. The wind-induced fatigue life of each building was evaluated using the rain-flow counting method and the Palmgren–Miner rule, revealing that the fatigue life generally exceeds 400 years. The results demonstrate that tall steel structures designed according to current standards perform well in resisting wind-induced fatigue damage. Furthermore, when the ratio of the wind-induced root mean square (RMS) stress to the ultimate strength of a structural element reaches 0.125–0.164, the fatigue life of components may fall below the design life, indicating the necessity of considering potential fatigue damage. The RMS stress ratio can be preliminarily compared with the RMS stress ratio threshold proposed in this study to determine whether wind-induced fatigue damage needs to be considered in tall steel buildings. Finally, a simplified fatigue life prediction formula is established to provide approximate estimates for the fatigue life of tall steel buildings.