Localized Fire for Structural Safety

Abstract

Fires in the open or in large enclosures are characterized as localized fires, e.g., vehicle fires in transportation infrastructures, small shop fires in transport terminal halls, and workstation fires in open plan office buildings. Compartment fires start from localized burning. The current structural fire design approaches are developed for fully-developed compartment fires, the gas temperatures of which can be approximated as uniformly distributed in the compartment. In localized fires, the gas temperature distributions are spatially non-uniform. There is lack of knowledge about the behavior of structures subjected to localized fires. Design guides and engineering approaches are needed for structural safety design in localized fires. This paper discusses the application of localized fires for structural safety design. Some recent studies on the thermal calculation and structural analysis of steel members subjected to localized fires were presented. Simple fire models were provided to calculate the temperature of exposed steel members in a localized fire. Thermo-mechanical simulations were performed to investigate the failure mode of bare steel members in a localized fire. The studies found that due to thermal gradient, a bare steel member may fail in a totally different way in a localized fire than in a standard fire; and the failure temperature for a bare steel member in a localized fire might be hundreds of degree lower than that in a standard fire. Using the proposed simple models, an engineering approach was also provided to determine the safety distance from a bare steel column to a fire source, which could be used in a performance-based fire safety design