Mutual influence of cross-sectional and member classifications on stability of I-beams

In evaluating the flexural strength of a structural member, its structural classification based on cross-sectional and member classifications should be considered. The cross-sectional classification of I-beam is usually specified by the width-thickness ratios of web and flange plates. However, the cross-sectional classification that includes the interaction of these two parameters is not satisfactorily clarified yet. Therefore, this paper presents the interaction classification based on the results obtained by ultimate strength analysis and parametric study of plates under various compressive loadings. This paper also proposes the structural classification of I-beams by estimating the mutual influence of the proposed cross-sectional classification and member classification on the lateral-torsional stability strength of steel I-beams. Furthermore, based on the classified results, an ultimate stability strength design criterion for the overall inelastic buckling of the beams is presented.