The Research Of Snow Loads On Long-Span Space Structure

The long-span space structure is quite sensitive to snow loads, many cases of collapse have occurred over the last few years which bring great threats to safety and property of the public. The snow on roof subjected to wind loads will erode and deposit which leads to uneven snow distribution, along with the large snow pressure during bad weather, they prove to be the major causes of long-span space structure collapse. The snow loads set by current load code are quite simple, so it’s necessary to deeply research the snow loads on typical long-span space structure.Firstly, this paper introduced the numerical simulation theory of snowdrift, expounded the wind flow mixed with snow, then provided the model equations and boundary conditions of numerical simulation about wind and snowdrift. The erosion and deposition model of snow was also introduced.The snowdrift on long-span spherical shell roofs and shed roofs under different spans, wind velocities and rise-span ratios or dip angles were simulated by the one-way coupled and single-equation model method in CFD software FLUENT, and a formula which showed the relations between the erosion or deposition amount of snow and wind velocity, rise-span ratio or dip angle was fitted. For convenience of engineering application, the uneven distribution coefficient of snow on spherical shell roof and shed roof was then derived and compared with those provided by different codes.The method for determining the basic snow pressure was expounded, as well as the current research of the basic snow pressure and the phenomena of refreezing after snow melting. The coefficient of disastrous snow load and refreezing after snow melting was then suggested in this paper.Finally, a shed roof model was analyzed in MST, an analysis software for long-span space structure. The stresses and slenderness ratios of the bars in shed roof model subjected to the snow loads advised in code were compared with the results of the roof model subjected to the disastrous snow loads obtained in this paper, so as to prove the adverse effect of the disastrous snow loads.