Strain hardening in M–P interaction for metallic beam of I-section

This paper derives bending moment–axial force (M–P) interaction relations for mild steel I-section by considering elastic–plastic and strain hardening idealisations with linear and parabolic strain hardening characteristics. The interaction curves have thus been developed. The interaction relations can predict strains, which is not possible in a rigid, perfectly plastic idealisation. The relations are obtained for different practically possible cases related to different locations of neutral axis. Two I-sections—one from DIN (German), IPE200 normally used for beams and another from AISC, W8×31 normally used for columns were considered for studying the characteristics of interaction curves.