Extreme Wind Pressure Study Of Super Tall Buildings With Large Aspect Ratios

Wind disaster is one of the disasters.For the wind-resistant designs of light-weight and high-flex supertall buildings,wind load is the main control loads.Peak wind pressure is the basis for the design wind load value of the envelope of supertall building,and it is also related to the accurate estimation of the wind response.The defined shape of the super high-rise building model in China’s building code is single.This paper conducts synchronous pressure tests on the series tapered and the set-back models with large aspect ratio(9:1)in the wind tunnel.The standard of Gaussian areas and non-Gaussian area of the building surface is proposed by the analysis of skewness coefficient and kurtosis coefficient of structural surfaces.Five estimation methods were used to estimate the extreme wind pressure in the Gaussian and non-Gaussian areas.The appropriate estimation method is proposed after comparing the advantages and disadvantages of above methods in different areas.The effects of three aerodynamic shape measures of section shrinkage,cutting and set-backing under different wind direction angles on the peak wind pressure were showed.The main contributions of the paper are as follows:(1)Comparing the five extreme wind pressure estimation methods,such as peak factor method,modified Hermite matrix method,single sample method,segmented multi-observation method and observation peak average method,it is found that when the sample time length is short time interval,the peak factor method is most accurate method in the Gaussian region.The modified Hermite matrix method is most accurate method in the non-Gaussian region.However,for samples with a medium-time course(120min),the observation peak averaging method is the most appropriate estimation method in all region and the error rate is within 10%.The above method is used for subsequent data analysis in this document.(2)With the increase of taper ratio,the positive pressures of the windward surface increase and the extreme wind pressure of the side surface and leeward surface decreased for models with section shrinking.The model with a taper ratio of 6.6% has the greatest decreasing trend.The section-shrinking has the same effect in other wind direction.(3)A large negative pressure generated at the cutting location of windward surface for cutting models and the value of negative pressure increase with the increase of height.However,compared with the results of square model,the extreme wind pressure of the leeward surface is effectively reduced.The square model with cutting has the best effect.The wind pressure on the side surface is reduced by 11.45% and the wind pressure on the leeward surface is reduced by about 35.62%.(4)The aerodynamic measures of set-backing increases the positive pressure of the windward surface.The increase value increases with the increase in the number of set-backing.The six-step model increase by about 19.64%.Set-backing can reduce the negative pressure.The reducing effect will be weakened with the increasing set-backing.The three-step model has the reduced effect by about 10.5%.The large negative pressure generates at the corner of set-backing location.The above results can be applied to the wind-resistant design of supertall buildings with large aspect ratios.