Resistance to moment-normal force interaction of I-shaped steel sections

Abstract This paper describes the assessment of the EN 1993-1-1 design rules for cross-section resistance to moment-normal force interaction ( M-N interaction). Besides the fact that the Eurocode design rules show unconservative predictions of the reduced plastic moment capacity for the presence of relatively low normal force, the recommended partial factor is γ M0  = 1.00 and relative large shear forces up to 50% of the shear resistance are allowed. This means that, neglecting a possible benefit from strain hardening, the EN 1993-1-1 design rules have no spare capacity available in the section. A few large scale experiments for M-N interaction were performed on HEA240 (S355JR) sections. In order to simulate the behaviour of a section to M-N interaction, a Finite Element Model was created in Abaqus/CAE. The model was validated against the experimental test results. Then, 1188 numerical test results were generated. A statistical evaluation to assess the design rule against these numerical test results showed that the recommended value γ M  = 1.00 of the partial factor used in the EN1993-1-1 design rules is statistically acceptable for I-shaped sections in steel grades S235 and S355. For S460 it is necessary to use γ M  = 1.10 based on the currently available statistical material data.