Analysis On Distortion Performance Of Bidirectional Flexural Members Made Of Thin-wall Cold-formed Stiffening Z-section Steel

Because the cold-formed thin-walled steel member have many advantages of high strength, light weight, quick speed of construction, the good mechanical properties and the superior economic performance, especially the Z steel member with the advantage of convenient connection, has been generally applied to industrial and civil constructions. Cold bending thin-wall Z steel section is broad and thin wall, After it is stiffened, the cross-section form is complicated, compared with the global buckling and local buckling of biaxial bending cold-formed thin-walled steel member, distortional buckling may have control function on the bearing capacity of the component. In this paper, the biaxial bending cold-formed thin-walled stiffened Z steel member’s distortional buckling performance is studied.Using ANSYS, the finite element software, the eigenvalue buckling analysis is made to the cold-formed thin-walled Z steel and stiffened Z steel under biaxial bending, and the members’ distortional buckling performance is studied in different edge width, component length, stiffener width and stiffener height, it is obtained that the distortional buckling critical moment reinforced of stiffened Z steel members is bigger than that of Z steel; at the same time, in the case of edge width and component length is unchangeable, considering the influence of stiffener width and stiffener height to the component’s distortional buckling critical moment to obtain a reasonable stiffener width and the range of stiffener height.Considering the effect of initial geometric defect, nonlinear buckling analysis is made to the selected Z steel and stiffened Z steel with different edge width, component length, stiffener width and stiffener height, and contrast with results of eigenvalue analysis, the nonlinear distortional buckling critical moment of component is less than that of linearity, which is consistent with the actual.With the effective width method in technical code of cold-formed thin-wall steel structures GB50018-2002, Z steel’s distortional buckling critical moment is calculated in different edge width and component length, and the higher degree of agreement is found in both when compare to the finite element nonlinear analysis’ result.