Out‐of‐plane stability design of stainless steel beams by GMNIA with strain limits

Abstract

Design by geometrically and materially nonlinear analysis with imperfections (GMNIA) using beam finite elements and strain limits has emerged as an accurate and efficient design approach, capturing the key structural behaviour while reducing the need for separate cross‐section classification and member design checks. However, to date, the majority of studies have focused on in‐plane buckling behaviour, with the extension and comprehensive verification of out‐of‐plane design so far limited to carbon steel. Thus, this paper extends the GMNIA‐based design approach to the out‐of‐plane stability design of stainless steel beams, with a focus on lateraltorsional buckling (LTB). A shell finite element (FE) model was validated against the results from 38 LTB experiments from literature and was then employed to generate the benchmark results. A comprehensive parametric study was then carried out using beam FE models with strain limits determined from the Continuous Strength Methods (CSM) to investigate the LTB behaviour of stainless steel beams. Austenitic, duplex and ferritic stainless steel beams were considered, covering a wide range of cross‐section and member slendernesses. The ultimate member resistance predictions obtained from the proposed GMNIA‐based design approach as well as EN 1993‐1‐4 provisions were compared against the benchmark shell FE results. The findings demonstrate that the proposed approach delivers consistently higher accuracy and safety than the EN 1993‐1‐4 provisions in predicting the member resistance of stainless steel beams.