Study Of Wind Effects On Tall Buildings By Wind Tunnel Test

With the development of mechanical analysis, structure design and construction technology, the tall buildings has a rapid development around the world. Furthermore, the tall buildings tend to be lighter and more flexible, which makes the wind loads play a key role in the design of tall building. Therefore, it is necessary to investigate the characteristics of wind loads and the effects of aerodynamic coupling on tall buildings. Based on the wind tunnel tests, this th esis investigates the aerodynamic damping of the rounded square and rectangular tall building s, the characteristics of wind pressure and wind loads on the rounded square tall building s and equivalent static wind loads on those two type tall buildings. In addition, comparison between the results of the aero-elastic model tests and those of the rigid model tests are also made. The specific contents are as follows:A multi-DOF aero-elastic model with strong versatility was firstly designed and it can cover the basic natural frequency and modal coefficient of typical tall buildings. Then a series of aeroelastic experiments were conducted on the versatile model. The along-wind and across-wind aerodynamic damping of the rounded square and rectangular tall building were studied with the structural dynamic parameter identified from the measured acceleration time-history response through random decrement technology(RDT) and ARMA model time series analysis method. Based on the pressure test results, the characteristic s of wind pressure distributions and wind loads on the rounded square tall building were studied in detail. The variations of wind pressure coefficients with wind direction and the horizontal and vertical correlation of the fluctuati ng wind pressures are discussed. According to the variations of the three-component coefficients with wind direction and height, the mean and RMS of the drag and lift coefficient s under the most unfavorable wind direction were fitted with an appropriate mathematical model. The wind load power spectrum of the rounded square tall building under the most unfavorable wind direction was studied and fitted with the empirical formula, which indicated that the rounded corner modification eliminate the narrow ’peak’ phenomenon of power spectrum and essentially change the characteristics of across-wind load. The distributions of shape coefficients under typical wind direction were also investigated, which showed that the rounded corner modification is adverse to the wind resistance design of curtain wall.Both the Load-Response-Correlation(LRC) method and the Inertial-Wind Load(IWL) method were used to calculate the equivalent static wind loads(ESWL) of both rounded square and rectangular tall buildings. The along-wind and across-wind ESWL of those two types tall buildings were investigated. The ESWL acquired by LRC method and those by IWL method are compared, which revealed that the across-wind ESWLs on rectangular tall buildings were significantly changed with the calculation method. Furthermore, the effect of aerodynamic damping on ESWL and acceleration was studied, which testified the existence of aerodynamic damping and presented its obvious influence on the wind-induced responses.