Design of lean duplex stainless steel tubular sections subjected to concentrated end bearing loads at elevated temperatures

Design rules for web crippling of stainless steel tubular sections at elevated temperatures are currently unavailable. In this study, non-linear finite element models (FEMs) were developed for the web crippling of cold-formed lean duplex stainless steel (CFLDSS) square and rectangular hollow sections under the concentrated end bearing loads, namely the loading conditions of End-One-Flange (EOF), End-Two-Flange (ETF) and End Loading (EL). After successful validation of the FEMs, an extensive parametric study of 210 CFLDSS tubular sections at elevated temperatures (up to 950 °C) was performed. The appropriateness of the web crippling design rules in the current international specifications and literature was examined by comparing their ultimate strength predictions with those obtained from the parametric study. The material properties at room (ambient) temperature condition were substituted by those at elevated temperatures. It was found that the predictions by the current design specifications and the literature were generally unconservative and not reliable, while the European Code provided reliable but generally very conservative predictions. A new design method by using the Direct Strength Method was proposed for the web crippling of CFLDSS tubular sections at elevated temperatures under the loading conditions of EOF, ETF and EL. The assessments indicated that the predictions by using the new method were generally conservative and reliable.