Stability of steel structures in fire - State-of-the-art, recent studies in Switzerland and future trends

The stability behaviour of steel structures in fire is strongly affected by the decreasing stiffness during heating, the nonlinear elevated temperature stress-strain response and thermal creep effects. The paper gives an overview of studies on the fire behaviour of steel structures. A major focus of the paper is to summarize recent studies on the material, cross-sectional, member and global structure level performed in Switzerland in recent years. The results of the studies indicate that the use of force-based analytical models using uniform temperature-dependent effective yield strengths, as used for ambient temperature designs, are less suitable for fire design and distinct nonlinear material behaviour then deformation-based models which have been proposed for different stability phenomena. These models seem to accurately predict the fire behaviour of steel structures on all structural levels.