Study On The Wind Induced Viberation Of Tall Buildings In Hilly Terrain Wind Field

Because of the interference of hills, characteristics of hilly terrain wind field are distinct from that of flat terrain wind field. It will cause severe errors to utilize algorithm in flat terrain wind field to calculate wind induced response of tall buildings in hilly terrain. In that condition, only combination of profile of hilly terrain wind field and wind load of tall buildings in complex wind field can get the characteristics of peak value of vibration. By means of wind tunnel tests, profiles of wind field in typical hilly terrain and wind load of tall buildings are systematically investigated. Solution of wind induced vibration and equivalent wind load is put forward. In this paper, some works are studied as follows:â‘ By means of wind tunnel tests of rigid hill models, mathematical models of speed-up ratio of mean and fluctuating wind in hilly terrain wind field are established. When single hill exists,profiles of mean and fluctuating wind speed under different slope and height of hills, mean speed of wind are investigated. When it comes to the multiple hills, profiles of mean and fluctuating wind speed under different distance, slope, height and number of occluding hills are discussed. According to the results of tests, mathematicl models of hilly terrain wind field are established. Given slope and height of single hill, distance, slope, height and number of occluding hills, mean and fluctuating wind speed at every location and elevation can be acquired. Some examples are presented to demonstrate the model and tests are consistent.â‘¡Mathematical models of amplitude and frequency characteristics of wind load of tall buildings in hilly terrain wind field are established according to rigid model wind tunnel tests of tall buildings. Different levels of turbulence are produced to simulate the complex change of turbulence in hilly terrain wind field. Tests of rigid model of tall buildings, including rectangular and round section, several aspect ratio and width-thickness ratio, are achieved. Changing the mean speed of wind and turbulent intensity of inflow, characteristics of mean value, root-mean-square value and power spectrum density of wind load on along-wind, across-wind and torsion direction and coherence function between across-wind and torsion direction. Mathematical models of mean value, root-mean-square value and power spectrum density of wind load on along-wind, across-wind and torsion direction and coherence function between across-wind and torsion direction are established. Some examples are presented to demonstrate the model and tests are consistent. The models can be used to calculate wind loads of tall buildings on complex hilly terrain.â‘¢Effects of hill parameters on wind induced response are analyzed. According to mean and fluctuating wind speed models and amplitude and frequency models of tall buildings, wind load spectrum of tall buildings in hilly terrain wind field is calculated. Coherence function of fluctuating wind speed is adopted on along-wind direction while coherence function of vortex-shedding is adopted on across-wind direction to get generalized wind load spectrum. Spectrum of wind induced response of tall buildings is attained according to theory of random vibration. Examples of different slope and height of single hill, distance of occluding hills are analyzed, and the effects of parameters on wind induced response of tall buildings are discussed.â‘£Equivalent wind loads of tall buildings in hilly terrain wind field are studied and effects of hill parameters on equivalent wind loads are analyzed. According to the particular profile of mean and fluctuating wind speed in hilly terrain wind field, mean, background and resonant wind loads of tall buildings are investigated. Some examples are calculated, and effects of location and slope of wind on equivalent wind load of tall buildings are compared.