Numerical modelling of the behaviour of a stainless steel portal frame subjected to fire

It is known that stainless steel has a better fire performance than carbon steel, which can lead to a growing utilization of this kind of steel in structures. In fact, although more expensive than the carbon steel, structures in stainless steel can be competitive because of its smaller thermal protection need. With the purpose of modelling by Finite Element Method the behaviour of a stainless steel framed structure, without any protection, submitted to fire, has been introduced in the SAFIR program, the material properties of the stainless steel. SAFIR is a finite element program with geometrical and material non-linear analysis, specially developed in the University of Liège for studying structures subjected to fire. The thermal and mechanical properties of the stainless steel, introduced in the SAFIR program are temperature dependent, according to the Eurocode 3. The stress strain relationship, the thermal conductivity and the specific heat are the most important material properties for the structure analysis at high temperatures. These properties in stainless steel are considerable different from carbon steel. The behaviour of the structure will be compared in the two different materials: stainless steel 1.4301 (also known as 304) and carbon steel S235. The benefits of using stainless steel in the fire resistance of the structure, which is 3 times higher than the one obtained with carbon steel, avoiding any fire protection material needed to fulfil the necessary fire requirements will be shown.