Longitudinal Wind Effects Of Large-aspect-ratio Featured High-rise Buildings With Different Aerodynamic Measures

Wind loads and wind effects are the control factors of structural safety and usability for supertall buildings in the strong typhoon areas.It is difficult to meet the requirements of wind-resistant design through strengthening the stiffness and strength of structures.The aerodynamic measure now is a hot spot of research.The focus of research is mainly on the reducing the cross-wind effects of supertall buildings by aerodynamic measures.However,some studies have shown that the wind-induced vortex-induced vibration is not very obvious under certain aerodynamic shapes and the control direction of the structure is still along-wind direction.Therefore,it is significance to study the effects of aerodynamic measures on the along-wind loads and responses of supertall buildings.In this paper,a standard square model with an aspect ratio of 9:1 is used as the based model.The effects of shrinking of section along height(linear and set-back),chamfering and opening ventilation slots at the equipment and refuge floors are studied.Some important conclusions are listed as follow:1.The mean and fluctuating wind loads of tap-layers: the linear shrinking and set-back of section have a significant reduction effect,and the reduced value increases with the increase of the taper ratio.The mean load at top of building is reduced by 50% and the fluctuating wind loads at 0.8H is reduced by 60% for model with taper ratio 6.6%.The chamfered corner can significantly reduce the along-wind loads.The mean loads of tap-layers are reduced from 8.5~14 to 6.5~8.5.The reduced rule of four models with opening ventilation slots is consistent.The reduction effects from small to large are opening the lower slot,the middle slot,the upper slot,and all slots.2.The wind-induced based bending moment: The linear shrinking and set-back of section have obvious reduction effects.Compared to the based bending moment of square model,those of the models with taper ratio 2.2%,4.4% and 6.6% are decreased by 22.7%,36.5%,and 44.8%,respectively.The reduction effect of the retractable table model is 2 times,and the value is reduced to 37.4%.The chamfering corners can further reduce the based bending moment response of the structure.The corresponding bending moment response of the three chamfered models decreases by 22.7%,22.5%,and 19.5%,respectively.Two set-back model has the most reduced effect in the set-back models and it is reduced by 37.4%.The reduction effects of four models with opening ventilation slots from small to large are opening the lower slot,the middle slot,the upper slot,and all slots.3.The wind-induced acceleration at the top building: The linear shrinking has unfavorable effect and the response of the acceleration value increases.Compared to the wind-induced acceleration of square model,those of the models with taper ratio 2.2%,4.4%and 6.6% are increased by are 15.6%,25%,and 41.7%,respectively.Set-back has a slight reduction effect.Chamfered corner has no effect on the acceleration.Similar to the non-chamfered models,linear shrinking of section increases the wind-induced acceleration for chamfered models.The reduction effects of four models with opening ventilation slots from small to large are opening the lower slot,the middle slot,the upper slot,and all slots.The above related results can provide some suggestions for the wind-resistant design enhance the wind-resistant performance of supertall buildings.