Creep-based life prediction modelling of aluminium in fire

This paper presents a thermo-mechanical model based on creep mechanics to predict compression deformation and failure of aluminium alloys exposed to fire. The model is based on the analytical work by Maljaars et al. [1] for the compression deformation of aluminium due to primary and secondary creep processes when exposed to transient heating caused by fire. The model can predict the creep-induced buckling failure of aluminium plates exposed to fire. The model is validated by fire structural tests performed on a non-age-hardening aluminium alloy (5083 H116) exposed to constant heat flux levels between 25 and 50 kW/m2 (with the equivalent maximum surface temperature between 200 and 360 °C). The model predicts the failure time of the aluminium will increase when the applied compression stress and/or heat flux of the fire is reduced due to a slowing of the creep rate. This was confirmed with failure times measured in the fire structural tests, which showed close agreement with the theoretical failure times. The model predicts the aluminium alloy will not fail under low compression stress or low heat flux conditions because the creep process is too slow, and this was confirmed by fire structural testing. Parametric analysis presented in the paper shows the potential application of the model in predicting the deformation and failure of compression-loaded aluminium structures exposed to fires of high intensity.