TABLE OF CONTENTS An engineering analysis to evaluate the response of a structure during a fire must consider both the heat transfer from the fire to the structural members and the structural response of these members under the defined threat. The focus of this guide is to define the heat flux boundary condition due to the fire used in the heat transfer analysis portion of this problem. Guidance is provided for two potential fire threats: fully developed enclosure fires and local fire plumes.
In fully developed enclosure fires, the conditions (gas temperatures, velocities, and smoke levels) are assumed to be uniform throughout the entire enclosure, and all combustible contents are generally considered to be contributing to the fire size and duration. Historically, conditions inside fully developed enclosure fires have been defined by the gas temperatures inside the enclosure, and the enclosure fire section includes a review of the most widely used methods for predicting gas temperatures.
Local fire plumes may be confined to a single fuel package in intimate contact with a structural member. The thermal exposure from local fires is spatially variable and is dependent on the geometry being considered. Though local fires may not expose as large an area as enclosure fires, the heat fluxes from local fires can be considerable and should not be neglected in an analysis. Heat fluxes from reasonable-size local fires can easily exceed 120 kW/m 2 and have been measured as high as 220 kW/m 2 in very large pool fires. Due to...
