Study On The Member Buckling Influence To The Stability Of Single-layer Reticulated Shell Structures

The stability of single-layer reticulated shell structure is a focus of research of spatialstructures. At present, the main emphasis for stability analysis of reticulated shell structureis the overall stability. In engineering, the reticulated shell structures are inevitable ofimperfection which includes mainly gemerical imperfection and member imperfection. Upto now, in the nonlinear analysis of the single layer reticulated shell, only the geometricalimperfections are considered and the member imperfection is neglected. In engineering,the member of the structures may buckle before the occurrence of the overall instability ofthe reticulated shell，therefore,considering the influence of the member buckling to thestructural overall stability is very necessary. This paper summarizes the type of instabilityof single-layer spherical reticulated shells,the factors affecting the stability of reticulatedshells, as well as the method of stability analysis of singer-layer spherical reticulated shells.The nonlinear analysis of the reticulated shell structures includes geometrical and materialnonlinearity. In this paper, besides the geometrical imperfection, the member imperfectionis also considered in the stability analysis of the reticulated shell structures.To simulate the imperfection of the members of the reticulated shell structures, asingle member model is analyzed using the different element divding unit. In the analysis,the imperfection of the member is simulated by the initial deformation of the members.The analysis results show that the buckling loads of the members are stable and accurateenough when the membsrs are devide into8elememts. Diferent amplitudes of the initialpeak deformation are investigated so that the buckling loads of members in the finiteelement analysis are in consistence with that calculated by the steel structure code inengineering.The stability behaviour of the reticulated shell can be presented by the whole processload-displacement curve obtained by the nonlinear finite element analysis. The influenceof the member imperfection and the member buckling to the stability of the reticulatedshells can also be shown by the whole process load-displacement curve of the structures.This paper investigates the influence of the member ipmerfection and the member bucklingto the stability behaviour of a K8single layer spherical reticulated shell. The results showthat if the members do not buckle before the stability limit loads of the structures, themember imperfection has little influence to the overall stability of the structure and can be neglected in the analysis. Otherwise, the member imperfection will reduce the stabilitycapacity of the structure and should be included in the analysis. To investigate theinfluence of member buckling to the stability behaviour of the reticulated shell structures,the smaller cross section members are used to replace the original members of differentlocations in the radial direction of the reticulated shell so that the smaller cross sectionmembers buckle before the structure reaching its stability limit loads. The analysis resultsshow that when the buckling members are close to the top of the reticulated shell, thestabliity limit loads of the structure reduce much more than that when the bucklingmembers are close to the supporting area of the structures. When the buckling members arein the second and third ring of the structures, the member buckling has the largest influenceto the stability behaviour of the structure, and will greatly reduce the stability limit loads ofthe structures. Furthermore, the reticulated shells with different supporting conditions arealso analyzed. The results show that the supporting conditions have no influence to thesensitivity of the sphericial reticulated shell to the member buckling.