Strain-hardening dependent cross-sectional slenderness limits for the plastic resistance of steel beams. (June 2023)

• Record Type: Journal Article
• Authors: Studer, Patrick; Taras, Andreas
• Is Part Of: Journal of constructional steel research. Volume 205(2023)
• Publication Date: 2023-06
• Subjects: Cross-sectional classification -- Numerical modelling -- Slenderness limits -- Strain-hardening; Steel, Structural -- Periodicals; Building, Iron and steel -- Periodicals; Acier de construction -- Périodiques; Construction métallique -- Périodiques; 624.1821
• DOI: 10.1016/j.jcsr.2023.107879
• Languages: English
• ISSNs: 0143-974X

Abstract

Abstract: Cross-sectional classification forms a relevant preliminary condition for the selection of the appropriate resistance models in the design of structural steel elements. It is thus important that cross-sections are correctly classified, as this determines their utilisation. The focus of this paper lies on the analysis of the transition point between cross-sectional classes 2 (compact) and 3 (elastic sections) for typical steel cross-section shapes. In particular, it studies how various degrees of strain hardening and ratios between ultimate and yield strength influence this transition point, which defines whether the plastic moment resistance of a section can be exploited. Based on numerical simulations on short beams, calibrated against full-scale tests, three independent cases were investigated i) outstand flanges and similar elements supported along one longitudinal edge loaded in pure compression, ii) webs and other internal elements supported along two edges, loaded in pure bending and iii) elements supported along two edges, loaded in pure compression. The first eigenform retrieved from the lateral buckling analysis (LBA) was used as initial imperfection for the geometric and material non-linear analysis (GMNIA). The results of the numerical simulations were analysed: in particular, the maximum achieved moment was compared with the theoretical plastic moment resistance. From these analyses, generalised observations could be made on whether the plastic moment resistance could be reached or not and consequently whether the cross-section should be assigned to class 2 or 3. Consequently, limit slenderness values could be determined and correlations to the hardening behaviour could be found and integrated into corresponding formulas. Graphical abstract: Unlabelled Image Highlights: Numerical simulations of short beam specimens with varying slenderness ratios. Investigations on the transition slenderness between cross-sectional classes 2 and 3. A refined definition of the transition between cross-sectional classes 2 and 3 is determined.