Web crippling design of lean duplex stainless steel tubular members at ambient and elevated temperatures

• Published in: Advances in structural engineering Vol. 28; no. 10; pp. 1858 - 1876
• Main Author: Cai, Yancheng
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.07.2025
• Subjects: elevated temperatures; web crippling strength; cold-formed stainless steel; direct strength method; lean duplex
• ISSN: 1369-4332; 2048-4011
• DOI: 10.1177/13694332251319100

Lean duplex stainless steel is a relatively new material to the stainless steel family. In recent years, significant progress has been made in developing design rules for lean duplex stainless steel tubular members, while the investigation on web crippling behavior is relatively limited at ambient and elevated temperatures. In this paper, experimental and numerical investigations as well as design rules on cold-formed lean duplex stainless steel (CFLDSS) performed by the author are summarized. Firstly, experimental investigation that focused on CFLDSS tubular members subjected to concentrated transverse bearing loads at ambient temperature were presented. A total of 108 CFLDSS tubular members subjected to six different concentrated transverse bearing loads were tested. The tubular members had square and rectangular hollow sections. The six loading conditions were loadings of End-One-Flange (EOF), End-Two-Flange (ETF), end loading (EL), Interior-One-Flange (IOF), Interior-Two-Flange (ITF) and interior loading (IL). Secondly, modified equations, i.e., the unified design equation and the direct strength method (DSM) for web crippling design of CFLDSS tubular members at ambient temperature were summarized. The modified design equations were calibrated by the test results and the newly generated numerical results. It is shown that the modified design equations are generally more accurate and reliable than the codified design rules and those design rules in literature in predicting the web crippling strengths of CFLDSS. Lastly, numerical investigation on web crippling of CFLDSS tubular members at elevated temperatures and the subsequently proposed DSM were presented. The proposed design method was calibrated by over 400 numerical results at elevated temperatures ranging from 22 to 950°C. The assessments indicate that the strength predictions by the proposed DSM method were generally conservative and reliable. The newly proposed design rules can be used by practical engineers and code writers for the web crippling of CFLDSS tubular members at ambient and elevated temperatures.