Influence Of Surrounding Buildings On Wind Load Of A Super High-rise Building

Super high-rise building is a wind sensitive structure,which has the characteristics of large height width ratio,small stiffness,low damping and long basic natural vibration period.With the continuous development of urban buildings,the change of wind environment of urban buildings can not be ignored.In recent years,engineering accidents of excessive vibration of super high-rise buildings are frequent because of the change of wind environment.The existent research of wind load on single storey super high-rise buildings is not suitable for those in dense buildings.Based on the actual project,combined with the wind tunnel rigid pressure measurement experiment and SAP2000 finite element model,this paper studies the influence of surrounding buildings on the wind load of a super high-rise building.The main research contents are as follows:(1)Based on the wind tunnel rigid model pressure measurement experiment,the average wind pressure coefficient,fluctuating wind pressure correlation and aerodynamic spectrum of single building and two cases with different typical measuring points with surrounding buildings are compared,and the influence of surrounding buildings on the wind pressure distribution of high-rise buildings is obtained.(2)The calculation process of time domain method is briefly introduced,and the wind-induced vibration response of the SAP2000 model which including the wind load time histories of three working conditions obtained from wind tunnel experiment is analyzed by Newmark-β,and compared with each other;At the same time,the calculation principle of frequency domain method is introduced.The peak acceleration and peak displacement of the top floor under each wind direction angle are calculated by frequency domain method,and the influence of surrounding buildings on the wind-induced vibration response of super high-rise buildings is analyzed;The wind-induced vibration response analysis results of time domain method and frequency domain method verify the accuracy of the results by each other.(3)This paper introduces the principles of several mature equivalent static wind load calculation methods.Firstly,the average wind load of three working conditions is researched comparatively.Secondly,the equivalent static wind load of three working conditions is calculated by the inertia force method of China’s current code,and the different influence mechanisms of surrounding buildings on the average wind load and equivalent static wind load are analyzed.The research results show that the surrounding buildings change the wind field environment,and the shielding of the buildings upstream of the incoming wind will reduce the incoming wind speed at its interference height,so as to further reduce the average wind load on the windward side of the building structure,which is beneficial to the design of the envelope,but due to the influence of the flow around,the average wind load on the crosswind and leeward sides will increase,which will be more unfavorable to the design of the envelope,However,the value of the most unfavorable wind load of the retaining structure shall refer to the wind load on the leeward side;The surrounding short buildings have little influence on the wind load of super high-rise buildings.Because the surrounding buildings will increase the fluctuating wind load of the wind field,resulting in the increase of the dynamic response of the structure,which has an adverse impact on the design of the main structure.Considering comprehensively that the most unfavorable load of the enclosure structure and the main structure is the condition of surrounding buildings,the design wind load shall take the condition of surrounding buildings.