In-plane Stability Performance Research And Design Method Of Roll-forming Circular Steel Tube Arch

With the maturity and development of material processing technology,cold-formed steel is widely used in steel structure and large-span space structure at home and abroad due to its good mechanical performance and light weight.However,up to now,there are few studies on the mechanical properties of cold-formed steel arch structure at home and abroad.The same residual stress distribution mode of beam column components is still used in the design of stability bearing capacity of this kind of steel arch,which is different from the actual situation of engineering design.Therefore,based on the existing research results at home and abroad and the current structural codes and standards in China,the distribution of residual stress and strain in roll forming and the in-plane stability of the arc steel pipe arch are studied in detail:(1)Based on the existing research,the residual stress and strain distribution function of the tube section is obtained by using the analytical method in the springback stage of bending loading and unloading;According to the experimental data of the existing literature,the corresponding finite element model of roll forming is established,and the effectiveness and accuracy of the finite element simulation are verified by comparing the finite element results with the experimental data of the literature.Aiming at the three roll forming process,the influence of friction coefficient,upper roll displacement and double roll distance on roll forming radius was studied.Taking different upper roll displacement,diameter thickness ratio and steel yield strength as the research parameters,the relationship between the residual stress and strain of roll formed circular section steel pipe and the parameters is obtained,and finally the distribution mode of residual stress and strain of roll formed circular section steel pipe within a certain bending ratio and diameter thickness ratio is summarized.(2)According to the existing arch structure stability analysis theory,the solid element technology and discrete fiber element technology modeling based on the finite element simulation analysis have verified the rationality and reliability of the finite element simulation of the in-plane stability analysis of the steel arch in this paper.Based on the ABAQUS parametric modeling technology,script files for elastic buckling analysis and nonlinear buckling analysis are written,and finite element models of steel tube arches with different parameters are established in batches,which lays the foundation for the finite element analysis below.(3)Based on the definition of the regularized slenderness ratio of steel arches in the existing literature,under the conditions of three-hinged,two-hinged and non-hinged arch feet in roll forming,a more in-depth finite element analysis of the stability coefficient of steel tube arches under axial compression is done.Through the comparison of the finite element simulation results under different rise-span ratios with related specifications,the applicability of the related specifications is verified.Based on the relevant formulas,the calculation formulas for the stability coefficient of the roll forming three-hinged,two-hinged and non-hinged arc circular cross-section steel tube arch are proposed.(4)According to concentrated load,half span uniform load and full span uniform load,three hinged,two hinged and non hinged circular steel pipe arches with different parameters are established,and the elastic-plastic stability analysis is carried out.The influence of geometric slenderness ratio and rise span ratio parameters of steel pipe arch on the ultimate bearing capacity of steel pipe in plane is summarized.According to the comparison between the finite element results of this paper and the in-plane design methods of the relevant codes in China,the applicability of the existing codes to the in-plane stability bearing capacity of three hinged,two hinged and non hinged circular arc steel pipe arch under compression and bending is discussed,and the design formulas of the in-plane stability bearing capacity of three circular section circular arc steel pipe arch under compression and bending are proposed through data fitting,which can be used in practical engineering.