Research On The Snow Loads On Several Typical Roof Structures

Large-span roof structures usually have the characteristics of light in weight,small damping,and flexible stiffness,ect.In recent years,there were lots of collapse accidents of large-span roof structures casued by the uneven distribution of snow.Therefore,it is siginificant to predict the snow distribution on the large-span roof accurately.However,the recent research about preventing the damages of building structures casued by wind and snow loads remains to be perfect,and this include the two aspects as followings: 1)The load standard used recently cannot reflect the real situation of snow load,and do not consider the influence of other factors,such as 3-D distribution and wind directions,ect.2)In the design of larg-span roof structures,the researches of reasonable determination of the snow distribution coefficient,which is a key parameter for the design,still need to be improved.ITherefore,it is very necessary to simulate and study the wind induced snow drift of typical long-span roof structures.The main contents of this paper are listed below:(1)Based on the domestic and foreign studies,this paper introduced the basic theory of wind induced snow drift,and the calculating principle of FAE(Finite Area Element)method.Besides,the calculation process of FAE method is given.(2)In this paper,the basic theory of CFD(Computational Fluid Dynamic)numerical simulation,the concept of air phase and snow phase,turbulence models and boundary conditions are described in detail.The velocity vector distribution and snow distribution coefficients on roof parapets with different forms under different wind directions were studied by the CFD software ANSYS FLUENT.(3)Based on the combination of wind tunnel test and FAE method,the uneven snow loads on 6 typical large span roof structures with different forms were studied in detail.There are mainly two steps included in the method: 1)Through wind tunnel test,the values of average wind speeds near the surface of the roof of model were obtained,and combined with CFD simulation,the data was then used to determinte the wind direction of average wind speeds.2)The wind-Snow flux empirical formula was then used to calculate the snow distribution coefficient of the roof.Based on the computational results,this paper had studied the influence of different wind speeds and wind directions on the snow distribution coefficients and unbalanced snow loads on the roof surface.Finally,according to the analysis results,some suggestions were proposed for the design of snow loads on large-apan roof sturcutures.The research of this paper can provides a valuable reference for the analysis and evaluation of large-span roof structures,and has certain significance to improve the structural design of buildings.