Symmetric modeling of the thermal actions in a structural fire experiment on a long-span composite floor beam in a compartment

Abstract

This paper presents symmetric modeling of the thermal actions in a structural fire experiment on a 12.8 m long composite floor beam in a compartment. A quarter of the fire compartment was modeled in FDS and a portion of about 1/160 of the composite beam was modeled in ANSYS. The FDS symmetry model gave consistent results with the FDS model of the entire compartment, the differences between the predicted upper layer gas temperatures were within 2 ∘C on average. The differences between the FDS symmetry model predicted upper layer gas temperatures and the experimental data were within 7% at the steady stage. Using the thermal boundaries predicted by the FDS symmetry model, the finite element symmetry model gave good prediction of the lower flange and mid web steel temperatures of the composite beam, the differences between predicted and measured maximum lower flange and maximum mid web temperatures were within 2%. The study indicates that symmetry model might be used to predict the thermal responses of structures in realistic fires.