Scheme Comparison And Optimization Design Analysis Of Bidirectional Cylindrical Combined Shell Structure

The space structure provides a large range of unlimited using space,while the internal support member has little interference.As one of the most common spatial structural forms,shell structure is widely used in various public buildings.Compared with the general planar structure,the possibility of structural instability and damage is increased,which has caused scholars and engineers to pay attention to the study of the stability of the shell structure.The bidirectional combined shell structure is one of the future development directions.At present,there is little research on the stability of the bidirectional combined cylindrical shell structure.This project is tentatively adopted with the bidirectional cylindrical composite steel mesh shell or reinforced concrete shell structure as the actual engineering background of the swimming pool roof of Jiulong Lake campus of Southeast University in Jiangning District.According to the requirements of current national regulations,SAP2000 and Midas/Gen were used to design and check the steel reticulated shell(mesh shell and concrete shell respectively,and the ABAQUS finite element model was established for parameterized stability analysis.The eigenvalue buckling analysis and nonlinear stability analysis were carried out.On the basis of the single variable,the effects of nonlinearity,initial defects,shell thickness and other factors on the stability of the critical load factor are discussed.Main conclusions are drawn as follows:(1)In the cylindrical latticed shell structure,the cross-section of the canopy of the end of the large cylindrical shell should be appropriately increased from the top of the shell to the top of the shell to the section of the floor;the stability critical load factor of the bidirectional cylindrical composite steel reticulated shell The nonlinear effect is obvious and the initial defect amplitude sensitivity is low.At the same time,the introduction of initial defects and the increase of amplitude have great influence on the deformation and stress distribution of the structure.In the stability analysis,the influence of initial defects should be considered according to the research objectives..Comparing the stability critical load scale factor under the combination of the most unfavorable load combination condition and the vertical constant load standard,the stability analysis of the bidirectional steel reticulated shell structure according to the vertical constant load standard recommended by the current code is safe.(2)The concrete shell has less stress under the action of temperature,and the temperature stress can be alleviated by constructing measures such as post-casting belt.The nonlinear effect of the stability critical load factor of the two-way cylindrical composite reinforced concrete shell is obvious,the initial defect mode and the amplitude sensitivity are low.In the stability analysis,the influence of the initial defect could be ignored within the engineering tolerance.By comparing the results of the elastoplastic full-process stability analysis under the combination of the most unfavorable load combination and the vertical constant load,the bidirectional steel shell can be obtained by analyzing the combined working conditions of the vertical constant load recommended by the specification.The effects of horizontal loads such as horizontal seismic loads should also be considered.(3)The concrete shell can be lightly designed by reducing the X-direction small arch,the Y-direction large arch,the XY oblique arch into the variable-section arch form,and reducing the thickness of the shell.At the same time,the structural stability critical load coefficient meet current regulatory requirements...