Research On Wind Load Characteristics Of Tapered Tall Buildings Based On Wind Tunnel Test And Numerical Simulation

With the development of construction technology,tall buildings are not limited to a single rectangular or cylindrical shape,and many tapered or semi-tapered tall buildings have emerged.However,after the vertical taper of high-rise buildings,the stiffness of the building structure decreases,the flexibility increases,and the impact of wind load on such buildings becomes greater.Therefore,how to reduce the wind load of such tall buildings is the key content of structural wind resistance design.In this paper,four tapered modification models(5%,10%,15% and 20%)are designed with the high-rise building standard model(CAARC)as the benchmark model.Based on wind tunnel test and numerical simulation,the wind load characteristics of the revised five models are studied.The main research contents are as follows:(1)The wind load characteristics of the standard high-rise building model after four tapered modifications are studied through the wind tunnel test.Included wind pressure distribution,local wind coefficients,base moment coefficients,power spectral density and vertical coherence function.The experimental results showed that tapered modifications could effectively reduce the wind pressure coefficients of the high-rise building surface;The tapered modifications significantly reduces the drag force coefficients and lift force coefficients of high-rise building model,among which the mean drag force coefficients and RSM drag force coefficients are reduced by about 13.1% and 26.7%,respectively,and the RSM lift force coefficients is reduced by about 38.4%;The power spectral density of the local wind coefficient and the power spectral densities of base moment coefficient are sensitive to the tapered modifications,and the peak of the power spectral densities of the across-wind force decreases with the increase of the taper ratio;The tapered modifications could reduce the base moment coefficients and vertical coherence function.(2)The LES research was carried out on five model,and the accuracy and effectiveness of the LES technology used in this paper were proved by comparing with the wind tunnel test results.Based on the advantages of numerical simulation flow field visualization,the effect of tapered modifications on the distribution characteristics of wind pressure is analyzed.The mechanism of vortex shedding around the five models is discussed,and it is concluded that the tapered modifications weaken the regularity of building vortex shedding.(3)In order to evaluate the effect of tapered modifications on the base moment coefficients,the empirical formula of base moment correction coefficients is obtained by fitting;The correlation factors of tapered modifications on the power spectral densities of base moment is defined,and the table for correlation factors of power spectral densities of base force moment is given;According to this table,the optimum taper ratio for power spectrum of along-wind base moment is 15% and 20%,and the optimum taper ratio for power spectrum of across-wind base moment is 5%;The regularization correlation factors of the base moment coefficients is defined,and the effect for the decrease of the windward area of the tapered model on the base moment coefficients is discussed.In this paper,the wind effects of the benchmark model and four tapered models are studied by means of numerical simulation combined with wind tunnel test.The research results can provide a reference for the wind resistance design of similar tapered high-rise buildings.