Experimental Study On Torsional Dynamic Characteristics Of Tall Buildings

Wind load is the load that must be considered in the design load combination of structure,among which typhoon has a large geographical scale,a wide range of influence and a strong energy content,which will bring huge safety and economic losses to the society.The basic characteristic of the wind load is that the basic period is longer.As the high-rise building is developing towards lighter and more flexible direction,the basic period will also become larger.Therefore,the displacement and comfort of the top layer of the high-rise structure will be greatly tested,especially the amplification effect caused by the torsional wind vibration superimposed on the edge of the high-rise building.With the increase of high-rise building height,wind load will become the main control load.Therefore,under the background of wide range of typhoon,serious disasters,insufficient research on wind-induced torsional response and complex dynamic interaction between wind load and buildings,the research on wind-induced torsional response of high-rise buildings and super high-rise buildings is of practical significance.In this paper,based on the data of wind field on the top of a high-rise building in Haikou and the data of pure torsional angular acceleration of four floors measured by RA013 type torsional angular accelerometer without translational component when typhoon "Sarika" was logged in,and taking the torsional wind-induced response of high-rise structure as the research center,the characteristics of typhoon wind field on the top of high-rise building at the source of wind-induced response were analyzed first,and then the torsional wind-induced response was analyzed The timedomain characteristics of the angular acceleration signal itself and the modal parameters obtained from the analysis are studied.Finally,the dynamic characteristics of torsional wind-induced vibration of high-rise buildings under the action of typhoon are obtained.(1)This paper introduces the background and significance of the research,and summarizes the current situation of wind field measurement and wind-induced torsional response of high-rise buildings.This paper introduces the general situation of the measurement research and the composition of the measurement system.(2)Using stationary wind model and non-stationary wind model to study the wind field characteristics on the top of high-rise buildings,Davenport power spectrum is more suitable than von Karman spectrum to describe the wind speed power spectrum of the calculation of non-stationary wind model,using the round test method to test the wind speed stability and divide the non-stationary model.The study of fluctuating wind speed power spectrum under different models broadens the application of wind speed power spectrum and lays a foundation for the study of load power spectrum.(3)Based on the time-domain statistical parameters of torsional angular acceleration,the characteristics of wind-induced torsional response of high-rise buildings are obtained.The statistical parameters and probability distribution characteristics of torsional signal at 10 min time interval are studied.The peak factor of the torsional angular acceleration is obtained by the target probability method,and a safer reference value of 3.5 is proposed.(4)This paper introduces the method and theory of torsional mode identification,and then identifies the modal parameters of high-rise buildings under wind-induced vibration.The first-order torsional mode damping ratio increases with the increase of signal amplitude,and the second-order and third-order damping ratio has no obvious trend of strong dispersion,which indicates that the wind-induced torsional response of high-rise buildings mainly depends on the first-order mode dissipation energy.