Role of transient creep in fire induced progressive collapse of steel framed buildings

This paper examines the influence of temperature induced transient creep on the onset of instability in steel framed buildings under severe fire exposure. A numerical model is developed in ABAQUS to trace the temperature induced transient creep effects in steel framed structures subjected to fire exposure. The transient creep strain that develops under fire conditions is explicitly accounted for in the fire resistance analysis, in addition to temperature induced property degradation in steel. The developed model is applied to predict the overall response of the structure, as well as failure pattern of a 10-story braced steel framed building under fire exposure. Results from the fire resistance analysis indicate that transient creep strains become dominant when the steel temperature in the member increases beyond 600°C. Further, the results also show that neglecting an explicit treatment of transient creep in the model formulation can lead to unrealistic prediction of failure paths and thus, higher failure times in a steel framed building.