Influence Of Surface Roughness On Wind Load Effect Of Tall Buildings

As a symbol of the economic prosperity of a country’s cities,super high-rise buildings are also moving towards light materials,low impedance and high flexibility while constantly breaking through the height of the building.This has also led to an increase in the sensitivity of super-tall buildings to wind,and wind loads have become an important parameter for the study of super-tall buildings.The outer surface of modern high-rise buildings usually has decorative designs or structural parts with concave-convex shapes.The cross section of the building becomes a section with a certain rough nature,which changes the aerodynamic effect of the building surface.However,the high-rise buildings based on the assumptions of previous studies are not consistent with the current development of the building,and the conclusions of the study are not fully applicable to modern buildings.Therefore,it is necessary to systematically analyze and discuss modern high-rise buildings with rough surfaces.In this paper,a rigid model wind tunnel test is carried out on six different rough surfaces(including smooth models).The effects of different surface roughness on wind load characteristics are studied,including the following:(1)Based on the pressure test,the wind pressure characteristics of high-rise buildings with different roughness surfaces were studied.Firstly,the distribution of the average wind pressure coefficient and the pulsating wind pressure coefficient of each facade under the terrain category B and D is analyzed.The variation of the wind pressure coefficient of the typical measuring layer with the wind direction angle is also carried out.The results show that the surface roughness has little effect on the average wind pressure of high-rise buildings,and has a great influence on the pulsating wind pressure.The turbulent wind pressure of the horizontal rough model is the most obvious,and the characteristics of the wind field are rough.The wind pressure coefficient of the building is greatly affected.Secondly,the correlation and coherence of the pulsating wind pressure of each rough model are analyzed from the perspective of time domain and frequency domain respectively.The least squares of the square roots of horizontal and vertical coherence functions is performed by referring to the coherence function of the pulsating wind speed proposed by Davenport.The fitting is also studied for the characteristics of the pulsating wind pressure power spectrum.(2)The influence of surface roughness on the wind load of super high-rise buildings was studied.Among them,the variation of the base moment coefficient of each rough model with the wind direction angle is discussed,and the most unfavorable wind direction angle of each wind direction is obtained:the downwind direction is 0°,the cross wind direction is 15°,and the twist direction is 75°.Then the layer three-component force coefficients of each rough model are also analyzed.It is found that the layer three-component force coefficient of the vertical rough model has an increasing trend compared with the smooth model,while the horizontal roughness model is relatively reduced,and the sandpaper model does not change.obvious.Finally,the wind load power spectral density function under the most unfavorable wind direction angle of each rough model is analyzed.