Investigation On Reynolds Number Effects Of Wind Loads On Tall Buildings Based On Wind Tunnel Tests

Based on the information of the surface wind load obtained by simultaneous press wind tunnel tests for the wind pressure on the surfaces of the rigid models, profound researches on Reynolds number effect of amplitude-frequency characteristics of rectangular high-rise building are conducted at Reynolds number ranging from26559to1912128in this dissertation. The main work and conclusions can be summarized as follows:(1)The wind tunnel tests were conducted in uniform flow field,20%homogeneous turbulent flow field, exposure category B and exposure category D flow fields respectively, with the model side ratios of1/3,1,3, and the geometric scales of1:600,1:300,1:100,1:50. The total number of the operating conditions was201among which149operating conditions were accomplished by the author and52operating conditions were accomplished by Doctor Chen Yin.(2)The Reynolds number effect of the wind loads on high-rise buildings was related to some certain factors such as mean wind speed, turbulence intensity, section type and geometric scale ratio.In this paper, Analysis on Reynolds number effect of wind loads on different positions of different surfaces under different azimuths was carried out in amplitude-frequency domain, the fitting formulae of related parameters were proposed in amplitude domain as the consequence. The Analysis suggests that Reynolds number effect caused by changing wind speed was weak while Reynolds number effect with the geometric scale changing was obvious in high turbulence.(3)In uniform flow and uniform turbulent flow fields, the Reynolds number effect on the mean wind coefficients and RMS wind coefficients on the windward side were not obvious. Meanwhile, the mean wind coefficients on the leeward side changed obviously and the Reynolds number effect caused by geometric scale ratio was significant. In high turbulent flow condition, the mean wind coefficients and RMS wind coefficients tended to decrease with the Reynolds number increasing. Meanwhile, in frequency domain the Reynolds number effect of wind load spectra was obviously at particular frequency band when the reduced frequency was evaluated by turbulence integral scale and the length of the windward surface respectively.(4) In uniform flow and uniform turbulent flow fields, RMS wind coefficient on the lateral sides tended to increase at the beginning then decrease with the Reynolds number increasing. In frequency domain, Wind load spectra of measure points, the Reynolds number effect of the wind load spectra of interlayers and torsional power spectra of interlayer tended to decrease while the Reynolds number increased. And the Reynolds number effect on the correlation coefficients of two lateral sides can be observed.(5) In exposure category B and exposure category D at the Reynolds number ranging from26559to317952, the mean resistance coefficients and the RMS resistance coefficients reduced by5%-10%with Reynolds number increased. In exposure category B, RMS lift coefficients changed within5%-10%with Reynolds number increasing. And in exposure category D, RMS lift coefficients increased by10%-20%when the geometric scale ratio of models with various side ratios changed from1:300to1:600, while the Reynolds number effect on torsional RMS coefficients was limited except that under the condition B/D=1/3.(6) In exposure category B and exposure category D, the Reynolds number effect of along-wind wind load spectra was limited. While the reduced frequency was in the range of nB/V=2·St-4·St, the wind load spectra tended to increase with the Reynolds number increasing. However, as spectrum energy relatively small in this frequency band, the influence of the Reynolds number effect on the evaluation of the wind-induced dynamitic response was limited.(7) Under different wind field conditions, Strouhal number of the models with the side ratio of1/3ranged from0.03to0.16, while Strouhal number of the ones with the side ratio of1and3were around0.1,the Reynolds number effect was insignificant.