Study On Wind Vibration Coefficient And Wind Induced Elastic-plastic Dynamic Failure Of Single-layer Reticulated Shell Structures

With the development of spatial structures, more and more lattice shell structures with more complex form are used. The greater span, the smaller depth and the use of light material make the lattice shell structures become more flexible in stiffness. The wind loads and the wind induced vibration become an important factor in the design of the structures. Especially the wind induced dynamic failure of the single-layer lattice shells has been interested by many researchers. Up to now, due to the complexity of the analysis for the spatial lattice shells and the wind load simulation, there are limited research results on this field. In this paper, the finite element method is used to analyze the wind vibration coefficient of the single layer lattice cylindrical shells, and the parametric analysis is also carried out to investigate the influence of different factors to the wind vibration coefficient. Furthermore, considering the geometric imperfection of the structures, the geometrical and material nonlinearity, the dynamic collapse analysis is carried out for the single layer lattice cylindrical and spherical shells. In the numerical analysis, the B-R criterion is employed to determine the dynamic collapse wind velocity of the structures. The detail research contents are as follows.(1).Using linear finite element method, the three dimension wind vibration analysis of the single-layer latticed cylindrical shell structures has been done. Based on the discussion of the formulas, the displacement and internal force wind vibration coefficients are calculated. For the displacement and internal force wind vibration coefficients, the parametric investigation of considering different rise to span ration, length to span ratio and different average wind velocity is carried out. The variation of the wind vibration coefficients with these parameters is discussed. For the single-layer cylindrical latticed shell structures, the regression formulas of the displacement wind vibration coefficient and the internal force wind vibration coefficient are obtained respectively based on the parametric analysis. Due to the consideration of both the economy and the safety of the structures, the displacement wind vibration coefficient and the internal force wind vibration coefficient are suggested as 3.7 and 3.6 respectively in the design of the single-layer cylindrical latticed shell structures.(2).The elastic-plastic dynamic response analysis of the single-layer cylindrical latticed shells under three dimensional wind loads is carried out. By the numerical analysis results, such as the time history curve of displacement of nodes, buckling mode, plastic development distribution, the influence of different parameters, such as the rise to span ratio and the length to span ratio, on the stability performance of the lattice shells have been presented in the paper. The numerical results show that the wind resistance capacity of the single-layer cylindrical latticed shell structures decrease with the increase of the rise to span ratio and length to span ratio. This indicates that the effective method to increase the wind resistance capacity of the single-layer cylindrical latticed shells is to decrease the rise to span ratio and length to span ratio of the structures. Through the comparison of the results considering and without considering the vibration effect of the wind loads, the paper shows that the wind induced collapse loads are much smaller than that when the wind loads are treated as static loads.(3).The elastic-plastic dynamic response analysis of the single-layer spherical latticed dome structures under three-dimensional wind loads is completed. By the numerical analysis results, such as the time history curve of displacement of nodes, buckling mode, plastic development distribution, the influences of different parameters ,such as the rise to span ratio, initial geometric imperfection, initial static loads and supporting form, on the stability performance of the single-layer spherical latticed dome structures have been presented in the paper. The numerical results show that the spatial correlation of wind load, supporting form and initial static loads has little influence on the wind resistance capacity of the single-layer spherical latticed dome structures. The dynamic buckling wind velocity slightly varies with the rise to span ratio, and when the rise to span ratio is 1/3, the structure has the greatest stiffness and also the greatest wind resistance capacity. Through the comparison of the results considering and without considering the vibration effect of the wind loads, the paper shows that the wind induced collapse loads are much smaller than that when the wind loads are treated as static loads. And this conclusion is very similar to that of the single-layer cylindrical latticed shell structures.