Behaviour of high strength steel columns under fire conditions

With the scarcity of performance data on HSS columns at elevated temperature, a numerical model, which considered geometric imperfections and material non-linearity has been developed in ABAQUS (2014) and validated using experimental data on HSS at ambient temperature and mild steel grades at elevated temperature. After the model was validated, parametric studies incorporating material properties of two different steel grades: S690QL and S700MC were done, in order to determine the influence of the steel grades on the buckling behaviour and assess the suitability of the Eurocode fire resistance design rules for HSS columns. The results showed that the Eurocode generally provides conservative (i.e. safe) results with respect to the buckling coefficients and safely predicts the buckling resistance of columns made from S700MC, while a lower buckling curve may be needed for columns made from S690QL. In addition, because of the various alloying and production routes employed to produce HSS, variations in the stress-strain responses was also observed, in turn, this influenced the buckling response and highlighted possible unconservativisms (i.e. unsafe) in the Eurocode design approach as a result of generalising the material response.