ADVANCED STEEL STRUCTURES
A real fire in a building grows and decays in accordance with the mass and energy balance within
the compartment in which it occurs. The energy released depends upon the quantity and type of fuel
available and upon the ventilation conditions. Figure 1.1 illustrates that the fire in a building can be
divided into three phases: the growth or pre-flashover period, the fully developed or post-flashover
fire and the decay period . The most rapid temperature rise occurs in the period following
flashover, a point at which all organic materials in a compartment spontaneously combust. Anyone
who has not escaped from a compartment before flashover is unlikely to survive
In the pre-flashover phase, the room temperature is low and the fire is local in the compartment.
This period is important for evacuation and fire fighting. Usually, it has not significant influence on
the structures. After flashover, the fire enters into the fully developed phase, in which the
temperature of the compartment increase rapidly and the overall compartment is engulfed in fire.
The highest temperature, the highest rate of heating and the largest flame occur during this phase,
which gives rise to the most structural damage and much of the fire spread in buildings. In the
decaying period, which is formally identified as a stage after the temperature falling to 80 percent of
its peak value, the temperature decreases graduallyStart Download