FIRE DESIGN OF STEEL MEMBERS - Civil and Natural Resources ...

From Figure 5.10 a-c, the ECCS equations give good results again with the
average steel temperatures found from the results of SAFIR simulations and
spreadsheet analyses. The upper temperature limitation again can be increased to
800 °C, and linear interpolation below 400 °C would give accurate results. The
time and beam size limitations do not appear to be relevant in this analyses which
supports the conclusions stated in Sections 5.2.3 and 5.3.2.
The average SAFIR temperature is always slightly cooler than the temperature
from the spreadsheet calculations as is also seen in Figure 5.9. The effect of the
thicker protection is to distribute the energy conducted to the steel more evenly and
at a slower rate. This means that conduction through the steel section more
actively reduces the variation of temperature across the cross section. In the
spreadsheet method conduction is not considered because the one dimensional heat
flow model that the formulas are based on give a uniform thickness and energy
flow to the steel.
5.6 RESULTS FOR THREE SIDED EXPOSURE WITH
HEAVY PROTECTION:
Protected beams with three sided exposure usually occurs when a concrete slab is
being supported by a steel beam, and the other three faces are protected with
insulation. In this section this is the only case considered, as the cases where
insulation is applied to the top face and three sided exposure still occurs is
unlikely. This approach gives lower temperatures than if insulation was applied to
the top face, but as seen in Section 4.3.1 and Figure 4.10, the maximum
temperature of the steel section is unaffected by the introduction of a concrete slab
rather than insulation to the top face. For this reason this simplification in
comparing methods has been taken.
The properties of the insulation applied to the steel section are those of Fendolite
by Firepro Safety Ltd, also used in Section 5.2, with constant values taken as
below:
Specific heat, c i = 1100 J/kg K
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