APPROXIMATE EXPRESSION FOR ELASTO-PLASTIC CURVE OF AXIAL FORCE AND AXIAL DISPLACEMENT OF COMPRESSED BAR
This paper investigates the deformation of compressed bars with I-section.A finite-element program of 3D-Steel-Struct developed by authors is used in the analysis.Initial geometric crookedness,residual stress and material inelasticity are considered in the investigation.Second order elastic and second order rigid-plastic analysis are carried out for imperfect members,and relations between axially compressive force and deformation are deduced.Analytical expression for axially compressive force and deflection at mid-span are presented,as well as that for axially compressive force and axial shortening.A comparison shows the excellent agreement between the proposed explicit expressions and the numerical results.The axial ductility of compressed member is also studied in the paper.A formula relating the ductility to the slenderness is proposed.