Dynamic critical load based on different stability criteria for coupled buckling of columns with stiffened open cross-sections

The dynamic coupled buckling loads were determined for the columns with intermediate stiffener subjected to in-plane pulse loading. The pulse loading of a rectangular shape was concerned. Columns made of isotropic material were assumed to be simply supported at loaded ends. A plate model was adopted in the analysis. The discussed problem of interactive buckling is solved by the analytical–numerical method (ANM) using Koiter’s perturbations method. The differential equations of motion were obtained from Hamilton’s Principle, taking into account all components of inertia forces. In this study, the interactions of two global modes with two local ones were presented. The results obtained by the analytical–numerical method (ANM) were compared with finite element method (FEM)—ANSYS. The dynamic critical loads using the most popular Budiansky–Hutchinson’s criterion, the Kleiber–Kotula–Saran’s criterion with Kubiak’s modifications and the phase plane criterion were determined. New versions of criteria: Kleiber–Kotula–Saran’s quasi-bifurcation dynamic criterion and the phase plane criterion were proposed.