ABSTRACT
Steel structural elements composed of cold-formed thin-walled sections are commonly applied in buildings due to their efficiency in terms of stiffness and strength. However, under fire conditions the thin walls of these profiles, along with the steel high thermal conductivity, induce fast increase on the steel temperature and corresponded significant loss of those referred stiffness and strength. This paper presents a numerical study on the members behaviour with cold-formed lipped channel sections at high temperatures, when subjected to bending plus compression. Comparisons between the finite element results and the analytical methodologies from EN1993-1-2 are presented, using its Annex E as well as its French National Annex, where different reduction factors for the steel constitutive law and different design formulae are recommended for cold-formed profiles. Both methodologies revealed to be safe but sometimes too conservative, which motivated the development of a new design proposal.
