Technical Buckling, Stress and Strain Simplified Analysis of Semi-Slender Thin-Walled Cylindrical Pinned Column

The stability of load-bearing members is a challenging issue for designers. The avoidance of possible stability troubles is a mandatory step of the overall design process. The paper presents and discusses two simplified methods based on the Technical Stability Theory (TSTh) of loss of stability of lateral buckling in elastic-plastic states of semi-slender columns axially compressed by force. It is assumed that in the critical elastic-plastic transverse cross-section there are the elastic and plastic parts of the area, keeping strength. To simplify the calculations, there are assumed the simplifications that the whole moment of inertia of a cross-section area is taken into account J_z = J_z^all, the plastic module equals compress module E_pl = E_c taken from experimental researches and as the next bigger simplification, the plastic module equals compressing module E_pl = 0. The graphs of functions of the curved axes, their slopes, deflections of the columns, stresses and strains in thin-walled columns and compressing critical stresses depending on the cross-section areas and slenderness ratios are presented as the theoretical examples of thin-walled cylindrical columns and compared to results obtained from experiments with columns made of steel St35.