Evaluation of Cold-Formed Steel Section Using Numerical Thermal Performance Under Fire Conditions

Abstract

In Algeria, especially in seismic regions such as Chlef, designers adopted light steel framing structures of cold-formed sections to decrease the overall weight of the building. In fire conditions, however, due to the small values of the section factor, the fire resistance of unprotected cold-formed steel sections is reduced leading to a rapid increase in the temperature within the slender sections. Consequently, the cold-formed steel (CFS) framing became vulnerable. This research work aims to analyze numerically the behaviour of cold-formed sections at normal and high temperatures under ISO 834 fire conditions, are to predict temperature profiles within the sections and time resistance. Finite element models for different sections are developed using ANSYS APD L software for thermal analysis. Both material and geometric nonlinearities are considered following the formulations and prescriptions from Eurocode 3 part1-2 for fire considerations and Eurocode 3 part1-3 for cold-formed steel sections. The obtained results show a uniform temperature distribution across the structural elements and no observed difference between the web and flange section. The thermal analysis represents that there is an initial period of relatively low temperatures followed by a linear phase in function of temperatures recorded.