Axial Force and Biaxial Bending Interaction for I-Shaped Cross Section

Abstract

This paper presents new formulae for the determination of the plastic strengths of steel I-sections subjected to uniaxial bending about major or minor axis combined with an axial compression force. Moreover, new formulae are developed to describe the plastic yield surfaces of steel I-sections under biaxial bending moments combined with an axial force. The proposed formulae are obtained by performing large data regression analysis on the exact I-section strength results. In addition, the proposed formulae are simple and valid for any standard or general steel I-section, with conditions dependent on dimension ratios. These formulae are compared with the exact analytical solutions and with previous analysis methods and show very good correlations. New modified simple formulae are derived to predict the yield surface of I-sections. These formulae are more practical and easier for design purposes and lead to very good results compared to existing standards and exact solutions.