Dynamic Collapse Analysis Of Single-Layer Reticulated Shell Structures Under The Combination Of Wind And Snow Loads

As the span of space structure is increasing and the thickness is decreasing, the dynamic load distribution on the surface of the structure becomes more sensitive, which becomes a controlling factor in structural design. Therefore, the stability of reticulated shell structure is a focus in the study of space structure. Scholars at home and abroad have made a lot of researches on the dynamic stability of large span space structure and the seismic collapse analysis. However, the study of dynamic collapse under different wind and snow load is still very limited.In recent years, a wide range of snow disaster happens constantly which results in huge economic losses and serious casualties. Analysis of the accidents of structural damage resulting from snowstorm finds that the non-uniform distribution of snow pressure caused by strong winds blow and sunshine makes the snow load exceeds the design load, which is the main reason for structural collapse. Therefore, this paper, based on the nonlinear finite element theory, a finite element model was established for three way single-layer cylindrical Reticulated shells. Considering the material non-linearity, geometrical non-linearity and initial geometric imperfection, the paper systematically analyzes the whole process of dynamic failure and destruction of the structure under different wind and snow load combinations. By the load- displacement curve and using B-R criterion, the critical wind speeds of the dynamic collapse of the structure are determined. The main research contents and achievements of this paper are as follows:(1) Nonlinear finite element method is used to analyze the dynamic collapse of the three-way grid single-layer cylindrical reticulated shell in nine situations of wind and snow load combinations. Through comparing the critical wind speeds of the dynamic collapse of the structure in different situations, it is found that the combination of non-uniformly distributed snow load(a heavy snow accumulated on the windward side) on the windward side and wind load combination is the most disadvantageous combination for single-layer cylindrical reticulated shell; in addition, no matter uniform distribution or non-uniform distribution of snow load, when snow load on the windward side is combined with wind load, the critical wind speed of the dynamic collapse is minimum; when snow load on the leeward side is combined with wind load, the critical wind speed reaches maximum; when snow load on the full span of the reticulated shell structure is combined with wind load, the critical wind speed value is between those of the former two combinations.(2) The influence of different snow pressures on the dynamic collapse analysis of single-layer cylindrical reticulated shell structure under different wind and snow load combinations is analyzed, and the numerical results indicate: the increase(decrease) ratio of the critical wind speed under the action of a full span of non-uniformly distributed snow load, compared with that under the action of a full span of uniformly distributed snow load, decreases(increases) with the increase of the basic snow pressure; the decrease ratio of the critical wind speed under the action of non-uniformly distributed snow load on the windward side, compared with that under the action of uniformly distributed snow load on the windward side, increases with the increase of the basic snow pressure; the increase(decrease) ratio of the critical wind speed under the action of non-uniformly distributed snow load on the leeward side compared with that under the action of uniformly distributed snow load on the leeward side, increases with the increase of the basic snow pressure.