Buckling of steel columns in fire: non-linear behaviour and design proposal

In a fire the buckling strength of steel columns is heavily influenced by the distinctly non-linear material behaviour of steel at elevated temperatures. A general analytical model that explicitly includes the non-linear material behaviour is presented here and verified with full-scale tests at elevated temperature. Based on test results and this general model, a new model for flexural buckling is developed which can be used to design slender columns and allows non-linear stress-strain relationships, geometrical imperfections and load eccentricities to be considered. In addition, the model can be easily extended to include local cross-section instabilities describing the interaction between local and global buckling phenomena.