ABSTRACT
This paper addresses the selected issues of designing the cold-formed steel structures in the form of shells and bars such as facades, purlins, wall rails and main bearing capacity members. In first part of the study particular consideration is paid on stability of steel structures with a reference to the theoretical background of global, local and distortional buckling. To study the most typical stability response of structures with imperfections using nonlinear algebraic equilibrium equations which strictly describe pre- and post-buckling behaviour of structures a basic bar model is analysed. The second part of the article presents the transition from the von Kàrmàn scientific theory to the first semi-empirical approach known as “Winter formulas” and the formulas adopted in EN 1993-1-3 and EN 1993-1-5, to be currently used in structural engineer practice. Then, the particularities in the verification of the resistance and different modes of buckling of the cold formed profiles with stiffened or unstiffened walls are discussed, through theoretical calculations and test-assisted calculations. Finally, the typical applications of cold formed products are presented.
