Cold-formed Thin-walled Channel Steel Column Curling Study

The cold-formed of thin-wall channel steel columns which have large width to thickness ratio, trend to local buckling under the compression state, reducing the overall stability of components. Bending the free edges of the flange can enhance the local stability, In order to improve the edge rigidity and prevent edge to occur local buckling, which makes component stability performance becoming poor, can bend simple edge repeatedly to form complex edge so as to effectively improve the stability of the component performance.The emergence of the edge introduces a new mode of buckling-distortional buckling. The domestic and foreign scholars have launched thorough research and analysis for the simple edge components, but the study of distortional buckling is still needed to be further discussed. In the domestic, the complex edge of the component research is at the beginning stage, the main research direction focuses on the elastic stage of the components, while the research about the component during the elastic-plastic stage is relatively less.In order to research the influence of the edge about cold-formed steel axially compressed columns, this article simulates the channel steel column with the simple edge, inside complex edge and outside complex edge by using the finite element method, establishing the elastic buckling models which based on small deformation theory, and the elastic-plastic model considering initial geometric imperfections geometrical nonlinearity and material nonlinearity. Found that when the component occurs local buckling, the edge stiffening effect from high to low in turn is the outward complex edge, the inward complex edge and the simple edge; when the component occurs distortional buckling, the edge stiffening effect from high to low in turn is the simple edge, the inward complex edge and the outward complex edge. Meanwhile, this paper analyses the influence of the parameters of component such as the flange width, web height and thickness about the stability of the components with different edges, in which the thickness of component is the most important parameter, thickness changed can significantly change the buckling stress, and make the buckling mode changed. When the other dimension of the component cross section is constant, increasing thickness can improve the stability of the component performance; increasing the flange width or web height can make the stability of the component become poor.Finally, this article discusses the stability of the plate on the buckling half-wavelength by the finite strip method. Finding when the component occurs distortional buckling, the change rule of buckling stress and buckling half-wavelength with different edge form is similar; While the component occurs local buckling, the change rule of buckling stress and buckling half-wavelength with different edge form is opposite.