New web crippling design rules for cold-formed steel beams

Lipped channel beams (LCBs) and SupaCee sections are commonly used as floor joists and bearers in the construction industry. SupaCee section is one of the cold-formed steel members, which is increasingly used in the building construction sector. It is characterized by unique ribbed web and curved lip elements, and is claimed to be more economical with extra strength than the traditional channel sections. These thin-walled LCBs and SupaCee sections are subjected to specific local and global failures, one of them being web crippling. Several experimental and numerical studies have been conducted in the past to study the web crippling behaviour and capacities of different cold-formed steel sections under different concentrated load cases. However, due to the nature of the web crippling phenomenon and many factors influencing the web crippling capacities, capacity predictions given by most of the cold-formed steel design standards are either unconservative or conservative. Hence both experimental and finite element studies were conducted to assess the web crippling behaviour and strengths of LCBs and SupaCee sections under ETF, ITF, EOF and IOF load cases. New equations were proposed to determine the web crippling capacities of LCBs and SupaCee sections based on the results from experiments and finite element analyses. Suitable DSM based web crippling design equations were also developed.