Design of direct-formed square and rectangular hollow section beams. (January 2022)

• Record Type: Journal Article
• Authors: Tayyebi, Kamran; Sun, Min; Karimi, Kian; Daxon, Ray; Rossi, Brandon
• Is Part Of: Journal of constructional steel research. Volume 188(2022)
• Publication Date: 2022-01
• Subjects: Rectangular hollow section -- Flexural design -- Direct forming -- Galvanizing -- High-strength steel -- Cross-section classification; Steel, Structural -- Periodicals; Building, Iron and steel -- Periodicals; Acier de construction -- Périodiques; Construction métallique -- Périodiques; 624.1821
• DOI: 10.1016/j.jcsr.2021.107005
• Languages: English
• ISSNs: 0143-974X

Abstract

Abstract: A complementary experimental study showed that the flexural member design rules in the North American steel design standards (AISC 360–16 and CSA S16-19) can be excessively conservative for direct-formed regular- and high-strength steel square and rectangular hollow sections (hereinafter collectively referred to as RHS). It was also found that post-production hot-dip galvanizing can further improve member flexural behaviours through effective reduction of cold-forming-induced residual stresses. In this study, the experimental results of 22 full-scale beam tests from the complementary experimental study are used to validate non-linear finite element (FE) models. The FE models are developed using previously measured stress-strain relationships, residual stresses, and geometric imperfections. A subsequent parametric study including 788 beam models is performed to cover extended ranges of cross-sectional dimensions. The applicability of the existing slenderness limits and flexural design formulae are examined using the experimental and numerical data. The results justify the use of less stringent slenderness limits and higher design curves for direct-formed regular- and high-strength RHS beams (untreated and galvanized). Modifications to the existing design rules are proposed. Based on reliability analyses, the modified approaches are proven accurate and provide adequate safety margins. Graphical abstract: Unlabelled Image Highlights: Finite element analysis of 788 full-scale RHS beam members (regular- and high-strength steels). Comparison between direct-formed, indirect-formed and hot-finished RHS. Flexural design rules in current standards are conservative for direct-formed RHS. The effects of post-cold-forming hot-dip galvanizing are studied. Proposed slenderness limits and modified flexural design rules.