Abstract
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 x 31 normally used for columns were considered for studying the characteristics of interaction curves. (C) 2012 Elsevier Ltd. All rights reserved.