Wind Tunnel Test Research On Extreme Wind Pressure Characteristic On Local Roof Of Low-rise Buildings

There are lots of low-rise buildings distributed widely in the coastal areas of China,and the influence of typhoon causes huge losses every year.Wind disaster statistics show that the damage of low-rise buildings is mainly the roof corners,edges and ridges which are easily damaged and cause the collapse of whole building.However,the key of researching local roof wind pressure and enhancing anti-wind ability is extreme wind pressure.Therefore,the study of extreme characteristics including PDF and non-Gaussian characteristics and extreme estimation method are performed by adopting wind tunnel test methods,and provides theoretical support for the wind design of low-rise building.First of all,adopting the rigid model of wind tunnel test at a scale of 1:20 and a body of 1.5:1:1,the wind pressure distribution of gable roof low-rise buildings were analyzed at different wind azimuth,slope pitch and landscape in the wind tunnel.And the accuracy of wind tunnel test data were verified.The distribu tion characteristics of PDF,Skewness and Kurtosis of wind pressure were discussed at different wind azimuth,slope pitch and landscape,as well as fitting the PDF.The test results show that roof pitch has a great influence on the distribution of roof Gaussian zone and non-Gaussian zone.Wind azimuth and landscape has an great influence on the Skewness and Kurtosis of roof flow separation area,however,the change low of roof Skewness and Kurtosis are consistent at different landscapes.The GEV distribution and Lognormal distribution fit PDF of roof wind pressure better than Gaussian distribution and Gamma distribution.Second,the estimated accuracy of extreme wind pressure by adopting Quan method,Wang method and Davenport method were analyzed based on win d tunnel test data.The peak factor affected by several methods commonly used were discussed at different wind azimuth,slope pitch and landscape.The test results show that Wang method is more suitable for estimating the roof extreme wind pressure of low-rise buildings.It is reasonable to use improved Davenport method for calculating peak factor.Finally,the roof local gust coefficients and extreme pressure change rule at B landscape were discussed by at different wind azimuths and slope pitches,and the analysis of gust coefficients were contrast with the specification value as well.The test results show that wind azimuth has great impact on the roof corners,edges and ridges gust coefficient at the slope angle roof of 45°.It is found that the specification value of gust coefficients and are extreme pressure lower than the wind tunnel test value,and may underestimate the design wind load of local roof,and is harmful to wind resistant of structure.