Study On The Influence Of Eccentricity Of Members On The Stability Bearing Capacity Of Typical Single-layer Reticulated Spherical Shells

Reticulated shell structure is a long-span space structure.Because of its large span,abundant modelling ability and simple construction,it is widely used in various large-scale building structures.However,reticulated shells are defect-sensitive structures.The collapse of reticulated shells due to instability occurs frequently all over the world.Therefore,considering the influence of defect factors on reticulated shell structure is the main problem of current research.Although the research on the influence of imperfections on reticulated shells is extensive at home and abroad,the consideration of initial eccentricity of members to joints is hardly involved.Therefore,this paper focuses on the influence of eccentricity of random members on the stability of single-layer reticulated shells.Firstly,this paper takes ribbed ring and K8 single-layer spherical reticulated shells as research objects,establishes a simplified mechanical model of reticulated shells which can take into account the eccentricity of random members by using ANSYS finite element software,and expounds the realization method of eccentricity of random members in numerical calculation.Secondly,the whole process of the ideal structure of two kinds of reticulated shells is analyzed,and the ultimate load is obtained.At present,the purpose is to compare and analyze the ultimate load of reticulated shells with defects.Then,the eccentricity is divided into five groups:2mm,3mm,4mm,6mm and 10 mm.Each group of eccentricity corresponds to 50 random models.By means of double non-linear analysis,the ultimate loads of five groups of ribbed ring single-layer reticulated shells and K8single-layer reticulated shells with different eccentricities are obtained.The ultimate loads obtained are compared with the ultimate loads of two types of ideal latticed shells.Through statistics and analysis of the data obtained,the influence of different eccentricities on the bearing capacity of the two types of reticulated shells,as well as their failure mechanism and failure process are clarified.The results show that with the increase of eccentricity,the bearing capacity of the two types of reticulated shells gradually decreases,and the ribbed ring reticulated shells are more sensitive to defects,and the reduction of bearing capacity is very obvious.The maximum average reduction percentage is 36.2%.In addition,with the increase of eccentricity,the discrete degree of bearing capacity of rib-ring reticulated shells decreases from large to small,but it decreases obviously.The discrete degree of bearing capacity of K8 reticulated shells increases with the increase of eccentricity,which also shows that ribbed ring reticulated shells are sensitive to defects.Finally,by comparing the load-displacement curve of reticulated shell structure with the axial force-axial displacement diagram of the maximum displacement key bar in the reticulated shell,it is shown that the instability process of any reticulated shell structure is caused by the first instability of some bar.