Designing fire resistance on a performance basis requires three steps:

1. Estimating the fire boundary conditions

2. Determining the thermal response of the structure

3. Determining the structural response

This guide provides information relevant to estimating the fire boundary conditions resulting from a fully developed fire. Methods are provided for fully developed enclosure fires and for fire plumes. Fully developed enclosure fires can be expected in compartments with fuel uniformly distributed over their interiors. For situations where a fire would not be enclosed or for enclosures with sparse distributions or concentrated fuel packets, the methods identified in the fire plumes section should be used.

Several methods are evaluated for fully developed enclosure fires. Law's method is recommended for all roughly cubic compartments and in long, narrow compartments where does not exceed ? 18 m ^? . To ensure that predictions are sufficiently conservative in design situations, the predicted burning rate should be reduced by a factor of 1.4 and the temperature adjustment should not be reduced by Law's ? factor.

Law's method does not predict temperatures during the decay stage. For cases where a prediction of temperatures during the decay stage is desired, a decay rate of 7 C/min can be used for fires with a predicted duration of 60 minutes or more, and a decay rate of 10 C/min can be used for fires with a predicted duration of less than 60 minutes.

For long, narrow spaces in which is in the range of 45 to 85 m ^? , Magnusson...