Interactive buckling regarding the axial extension mode of a thin-walled channel under uniform compression in the first nonlinear approximation

The present paper deals with an influence of the axial extension mode on interactive buckling of a thin-walled channel with imperfections subjected to uniform compression, when a shear lag phenomenon and distortional deformations are taken into account. A plate model is adopted for the channel. The structure is assumed to be simply supported at the ends. A method of the modal solution to the coupled buckling problem within the first order approximation of Koiter’s asymptotic theory, using the transition matrix method and Godunov’s orthogonalization (Kolakowski and Krolak, 2006), has been used. The calculations have been carried out for a thin-walled channel.