The finite element model involving geometric large deformation

materials and contact nonlinearity is established.Specimens of cold-formed steel quadruple-C built-up section members are simulated and the finite element models are proved to be valid.Then

numerical analysis on the behavior of specimens with different slenderness ratio and flange flakiness ratio are carried out

and then the axial bearing capacities of specimens are obtained.Based on effective width method and direct strength method (DSM) in related codes

two design methods of cold-formed steel quadruple-C built-up section members under axial compression are proposed:effective length method and correction factor method.It is shown that:the final failure characteristics of all specimens are local buckling and distortional buckling.In the case of not considering the reduction of effective length

the results calculated by each code are slightly lower than those of test and FEM when the slenderness ratio is less than 50

while the results are too conservative when the slenderness ratio is more than 50.