Fire design proposal for members with cold‐formed lipped channel and sigma sections under compression

Abstract

AbstractSteel structural elements with cold‐formed thin‐walled sections are becoming increasingly common in buildings due to their lightness and ability to support large spans. In these members, local, distortional and global instabilities are important common failure modes. At high temperatures, these instability phenomena are intensified. This paper presents a numerical study on the behaviour of columns with lipped channel and sigma sections in case of fire when subjected to compression. A parametric study, considering different steel grades, temperatures and different cross‐sections with different slendernesses, is presented. Comparisons are also made between the numerical results and analytical design rules, such as the Part 1‐2 of Eurocode 3, using its Annex E or its French National Annex, where a different constitutive law is recommended for cold‐formed profiles. It is possible to conclude that the simple calculation rules are on the safe side but sometimes too conservative. Therefore, new proposals with adjustments to the current design rules are presented for these particular cases that are very common in cold‐formed steel constructions, in order to keep the results on the safe side becoming the design rules less conservative.