Research On Wind Comfort Of Super Tall Buildings With Large Aspect Ratios

The continuous development of cities and the increasing population have led to the emergence of a large number of high-rise buildings that exceed 100 meters in height,known as supertall buildings.In recent decades,the development of supertall buildings has been rapid,both in terms of quantity and height.Wind load is the main controlling load for supertall buildings,and comfort is an important indicator for studying the effects of wind load on supertall buildings.In this paper,a series of wind tunnel tests were conducted on supertall buildings with aspect ratios of 9:1,to investigate the effects of facade linear contraction,setback contraction,corner chamfer,and local openings on the peak acceleration at the top of the building.Furthermore,aerodynamic schemes were analyzed for a case study of a cruciform cross-section supertall building with an aspect ratio of 12:1.The main contributions of this study are as follows:(1)The wedge shape is unfavorable to the top acceleration control of square supertall buildings: compared with the standard square model,the top peak acceleration of buildings with wedge shape will increase,and the change pattern is not the same at different recurrence periods;at the 1-year recurrence period,the top peak acceleration increases with the increase of cone rate;at the 10-year recurrence period,the top peak acceleration of buildings decreases with the increase of cone rate.(2)Beveling treatment is beneficial for acceleration control in square-shaped super-tall buildings: After performing beveling treatment on the building corners,the peak acceleration of the beveled model at the top is reduced compared to the same taper ratio model without beveling.At a 1-year recurrence interval,the models with taper ratios of 0%,2.2%,and 4.4%reduced the peak acceleration by 24.29%,7.64%,and 16.80%,respectively.At a 10-year recurrence interval,the models with taper ratios of 0%,2.2%,and 4.4% reduced the peak acceleration by 33.06%,63.95%,and 51.46%,respectively.(3)Local openings are beneficial to the top acceleration control of super tall buildings with square cross-section: the top peak acceleration is reduced to different degrees in the corner area of the building compared with the fully closed building,and the reduction of the top peak acceleration is better in the middle and upper corner area of the building with local openings,while the reduction of the top peak acceleration is worse in the lower corner area of the building with local openings.(4)The change in peak acceleration with the use of setback and shrinkage aerodynamic measures varies at different recurrence intervals.At a 1-year recurrence interval,the peak acceleration gradually decreases with the increase of setback steps but remains higher than that of the standard square model.At a 10-year recurrence interval,the peak acceleration gradually increases with the increase of setback steps.At this time,the peak acceleration of the three-step setback scheme is lower than that of the standard square model,while the peak acceleration of other schemes is higher than that of the standard square model.(5)The use of facade rotation aerodynamic measures on the setback model results in a significant reduction in peak acceleration at various recurrence intervals compared to the setback and shrinkage model.Compared to the standard square model,the peak acceleration slightly increases at 1-year and 3-year recurrence intervals,but decreases significantly at 5-year and 10-year recurrence intervals.(6)The research results of a case study on a cross-shaped section with an aspect ratio of12:1 of a super-tall building show that upper openings in the cross-shaped section can reduce the peak acceleration at the top of the building.The pattern of peak acceleration at different recurrence intervals varies when beveling treatment is applied to the corner angles of the section wings.These research results can provide references for comfort research in super-tall buildings with large aspect ratios.