Study On The Stability Of Cutting Single Layer Spherical Reticulated Shell And Vertical Single Layer Cylindrical Shell

Stability is often a controlling factor in the design of single-layer reticulated shell structures.The technical code for spatial grid structures JGJ7-2010(hereinafter referred to as the "code")requires that the design of single-layer reticulated shell structures must be based on stability analysis and meet the specified safety factor requirements.The value of safety factor in "regulation" is determined based on the stability analysis of regular single-layer spherical reticulated shell and flat shell structure,whether it is suitable for non-regular single-layer reticulated shell structure remains to be studied.In this paper,cutting single-layer spherical reticulated shell and vertical single-layer cylindrical shell are taken as the research objects,and a large number of stability parameters are analyzed to suggest the value of stability "safety factor".The main contents are as follows:(1)study on the stability of single-layer spherical reticulated shell.Based on the Rhinoceros software platform,a parametric modeling program for cutting single-layer spherical reticulated shell structure was written.Considering the influence of geometric initial defects,uneven load distribution,bearing arrangement and lateral stiffness of supports,96? The stability ultimate bearing capacity of the spherical reticulated shell model is analyzed.It is suggested to use the elastic analysis method to calculate the stable allowable bearing capacity of the spherical reticulated shell.(2)study on stability performance of vertical single-layer shell structure.Based on Rhinoceros software platform,the parametric modeling program of vertical single-layer shell structure was written.Considering the influence of geometric initial defect and material nonlinearity,the stability ultimate bearing capacity of 18 vertical single-layer shell models was analyzed.The results show that the vertical single-layer shell structure is not sensitive to defects.It is suggested to use the elastic analysis method to calculate the stable allowable bearing capacity of vertical single-layer shell.The safety factor is5.50 when the height of shell is 0～30m,9.50 when the height is 30～60m,and 13.50 when the height is 60～90m.The stability of vertical single-layer spiral shell structure is poor.(3)Suggestions for improving the stability of single-layer spherical reticulated shell and vertical single-layer cylindrical shell.It is suggested that two types of reticulated shell structures should set stiffeners at appropriate locations to improve their stability performance.The analysis of examples shows that after adding stiffeners at appropriate locations,the stability ultimate bearing capacity of the cut single-layer spherical reticulated shell increases by more than 20%,and that of the vertical singlelayer cylindrical shell increases by more than 65%.For a vertical monolayer spiral shell project,the method of adding circumferential stiffener was adopted to improve the stability of the reticulated shell structure and make it meet the requirements of the code.