Directionality Of Wind Load On The Claddings And Components Of Low-rise Buildings

For a specific building structure,the wind load generated by the incoming wind from different directions on the structure are different.If the data of the extreme value of wind speed or the extreme value of wind pressure coefficient is used when calculating the wind load,the result will obviously be larger than the actual situation,that is,when the influence of directionality is not considered,the calculation result of wind load is conservative.In our country’s Building Structural Load Code GB50009-2012,it is stipulated that the design value of wind load shall be calculated by the extreme wind speed and extreme wind pressure coefficient of the full wind directions,and the influence of wind direction is not considered,which will make the calculation result too large.Therefore,the rationality of the wind-resistant design of the building structure cannot be satisfied.For common low-rise houses,considering the influence of different wind directions on the structure can not only optimize the design scheme,but also reduce the construction cost and save the economy.Based on the wind tunnel experiment of low buildings,this paper studies and analyzes the direction of wind load.The main contents are as follows:（1）This paper mainly introduces the up-crossings method and the up-crossings method considering the directionality of the wind pressure coefficient based on the parents distribution of wind speed,as well as the derivation process of the formula.At the same time,the advantages and disadvantages of different wind load research methods are briefly described.The different calculation methods of wind speed threshold and Generalized Pareto Distribution parameters are introduced in detail.The research methods selected in this paper are as follows: for the estimation value of wind speed threshold,the method combining Mc Neil and Frey heavy-tailed distribution and normal distribution intersection method and mean exceedance function graph method are used to estimate the wind threshold;the maximum likelihood estimation method is used to select for the parameters of Generalized Pareto Distribution.（2）Based on the wind speed data of China Meteorological Data Network,it calculates the wind speed threshold and the parameters of the Generalized Pareto Distribution for different wind directions.According to the parameters,the Generalized Pareto Distribution,Weibull distribution and the empirical distribution fitting diagram of wind speed samples are analyzed.At the same time,the directionality of the wind pressure coefficient is studied through the extreme value of the wind pressure coefficient.The results show that the Generalized Pareto Distribution has a good fitting effect on wind speed,but the tail of Weibull distribution deviates significantly from the original wind speed data;for the direction of the wind pressure coefficient,it is found that the extreme value of the wind pressure coefficient at the same measuring point of the building structure is different under different wind direction angle,and the extreme value of the wind pressure at the corner of the structure is the largest.（3）The low-rise building model is used for experiments,and by selecting representative measurement points on the roof surface of the building structure,the Gumbel distribution,Weibull distribution and Generalized Pareto Distribution are studied and analyzed for the wind load and wind direction reduction coefficient of the low-rise building envelope.The results show that the Generalized Pareto Distribution is the best fitting for wind load;for the wind direction reduction coefficient,the results obtained by the three methods are not much different,and the results obtained by the Gumbel distribution and the Generalized Pareto Distribution are similar.When considering the wind direction reduction coefficient of the whole structure,it is suggested that the corner and the other positions of the building structure are divided into two parts,and the mean value of the wind direction reduction coefficient is taken to reduce the design wind load.