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In the companion paper, test results were presented to explore the flexural performance of cold-formed ferritic stainless steel (FSS) closed built-up beams. Each specimen was fabricated by joining two lipped channels in a face-to-face configuration and securing them with spot welds at intermediate points along the beam span. Sectional aspect ratio, compression flange's sectional slenderness and moment gradient were the key parameters varied to explore their influence on the flexural response of such members through tests. The current paper establishes a simplified finite element (FE) model of cold-formed FSS closed built-up beams and verifies it against the test results. Further, an extensive parametric study is carried out using the validated FE model to generate a large pool of data points. A wider database comprising of test results, numerical results obtained from this study and numerical results available in the companion paper were used to critically examine the adequacy of the current Australian Specifications (AS/NZ), American Standard (SEI/ASCE-8), European Code (EN 1993-1-4), Modified Eurocode approach suggested by Gardner and Theofanous, and Direct Strength Method (DSM) in North American Specification (AISI-S100: 2016), Modified DSM approach proposed by the authors in the literature and Continuous Strength Method (CSM) for cold-formed steel (CFS) flexural members. This makes the current study the first to extensively assess the accuracy of the various design guidelines available in the codes and other relevant literature, which explicitly highlighted their grave limitations. Accordingly, through suitable modifications and recommendations, new design rules are proposed to reliably and safely predict the flexural capacity of cold-formed FSS closed built-up beams. [ABSTRACT FROM AUTHOR]

This paper reports an experimental and numerical investigation into the buckling behaviour and resistance of press-braked ferritic stainless steel slender channel section beam–columns under combined compression and minor-axis bending moment. An experimental programme was firstly performed, including material coupon tests, initial global and local geometric imperfection measurements and ten beam–column tests. The experimental programme was followed by a numerical modelling programme, where finite element models were developed and validated against the experimental results and then adopted to conduct parametric studies to generate additional numerical data. Based on the obtained test and numerical data, the existing design interaction curves, as set out in the European code, American specification and Australian/New Zealand standard, were evaluated and found to result in conservative and scattered resistance predictions. An improved design interaction curve, anchored to more accurate end points and featuring more appropriate shape, was then developed and shown to offer more accurate and consistent resistance predictions for press-braked ferritic stainless steel slender channel section beam–columns over the codified design interaction curves. Statistical analyses were also performed to confirm the reliability of the new proposal. • The behaviour of press-braked ferritic stainless steel slender channel section beam–columns was studied. • Ten beam–column tests were conducted. • FE models were developed to validate against the test results and then used to conduct parametric studies. • The codified design interaction curves were evaluated, revealing conservatism. • A new improved design interaction curve was developed. [ABSTRACT FROM AUTHOR]