FAILURE OF STEEL COLUMNS IN FIRE

Results of an analytical study of the performance of geometrically perfect steel columns under fire conditions are presented. The analysis was based on the finite strip method and includes non-linear material characteristics as functions of temperature. Results obtained using different models of such functions are compared, demonstrating very significant variation in predicted behaviour. The influence of slenderness ratio was studied and shown to be a major factor controlling the failure temperature, whilst the effect of residual stress levels on column failure is little different from that at ambient temperature. Local buckling behaviour was also investigated. The results suggest that this mode of failure may be rather more critical for columns in fire than at ambient temperature. The effect of partial protection provided by blocking-in the column web was investigated. This shows that although there is relatively little improvement in failure temperature, significantly longer survival times are achieved using this form of construction. Although the study is not comprehensive, some useful indications are provided for future generation of practical design rules.