Reduction factor for buckling of central-compressed steel elements considering initial geometrical imperfections and residual stresses

The main goal of work is to synthesize a theoretical approach to obtain reduction factor for buckling for the centralcompressed elements considering an initial imperfections and residual stresses. Methodology. The buckling of central-compressed steel element is investigated using a model of buckling of non-central-compressed element with small eccentricity. The maximum of deformations depends on the initial residual strains, on the initial strains due to bending and depends on the compressive deformations. This type of buckling usually occurs within the nonelastic work of the material. The impact of elastic-plastic deformations in the cross section of the column was taken into account by the elastic modulus reducing. The main buckling solution for of column was received. The equation for buckling of column takes in to account the initial imperfections and development of plastic deformation in cross section. Findings. Received solution give a possibility to determine the reduction factor for the relevant buckling mode according to the Eurocode 3 and to the national DBN В.2.6-198:2014 is usable for a different experimental data. Also it usable for a buckling checking for an elements with different imperfections: initial bow, initial eccentricity between the axis of the longitudinal force and the axis of the element, reducing of elastic modulus, the plastic properties of a cross-section, initial residual stresses etc. Scientific innovation. The generalized analytical solution of stability based on theoretical studies for buckling of the central compressed elements was received. Ths solution gives a possibility to determine a reduction factor for buckling according to the Eurocode 3 and the national DBN. Practical value. Obtained analytical equation allows determining the theoretical value of the critical load for a steel elements in compression and this equation is usable for the analysis of experimental data.