Experimental Study Of Crosswind-induced Loads On Super High-rise Buildings With Different Depth-width Ratios

With the development of economy in our country,the demand for building functions and the rise of land prices,flat slab-type super high-rise residential buildings continue to derive,and have gradually become a very important part of the construction of high-rise residential buildings in the city.This type of slab-type residential building is characterized by the fact that the length of the building is obviously larger than the width,and shows excellent characteristics in the volume ratio,green rate and ventilation and lighting function of the high-rise building.However,in engineering practice,it is often found that the crosswind load（CWL）recommended by the load code is often too conservative and becomes a restrictive factor in the wind resistance design of the structure when the aspect ratio（D/B）of the slab-type super high-rise building is large.Aiming at the large aspect ratio（H/B=10）slab-type rectangular plane super high-rise building and the small aspect ratio（H/B=5）connected T-type plane super high-rise building with a height of about 200m,the high-frequency base force balance technology is adopted in this paper.The wind tunnel tests of 28 kinds of super high-rise building 3D printed models are carried out in B and C geomorphology.The crosswind base bending moment responses of rectangular plane buildings with different aspect ratio are investigated and compared with the results of"building structure load code"GB50009-2012.The effects of aspect ratio,turbulence and structural modal damping ratio on crosswind load are analyzed.Through the envelope analysis of different period ratio,the influence of aspect ratio is evaluated comprehensively,and finally the reduction effect of concave angle aerodynamic measures on crosswind load is evaluated.The main conclusions are as follows:（1）The CWL obtained by the wind tunnel test is in good agreement with the code results when D/B is in the range of 0.5 to 2,and the code results are higher than the wind tunnel test results to varying degrees when D/B≥2,and the maximum relative error can reach 38.9%.（2）The range of D/B which is the most sensitive to the influence of CWL on rectangular plane is 0.5～2.When D/B≥2.5,the CWL increases monotonously with the increase of D/B,and the CWL does not play a controlling role when D/B<0.5.The variation law of the CWL of the T-shaped plane with D/B is in good agreement with that of the rectangular plane.（3）In most cases,the CWL in terrain B is higher than that of in terrain C,and the difference between rectangular plane and T-type plane can reach 42.75%and 28.33%,respectively.The sensitivity of CWL to D/B of terrain C is significantly weaker than that of terrain B.The influence of turbulence on the CWL of T-type combination plane is greater than that of concave angle measures.（4）The structural modal damping ratiozhas a great influence on the CWL,and the CWL of rectangular plane and T-type plane calculated by using the 2%damping ratio is up to78.76%and 36.97%higher than the calculation result of the 5%damping ratio,respectively.When the resonance component σ_M,r plays a controlling role,the CWL is inversely proportional to the square root of ζ.（5）The best concave angle ratio of rectangular D/B=3,D/B=4 and T-type D/B=3 is 10%,15%and 25%respectively,which can reduce the CWL by 18.97%,7.69%and 9.10%,respectively.Compared with the load code,the reduction effect of concave angle measures on rectangular plane CWL is underestimated,and conventional concave angle measures only have a weak reduction effect on the CWL of T-type D/B=3 combination plane.