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

The fire data entered into the SAFIR programme for this fire are:
Fuel load density, e t =320
Ventilation factor, F v =0.05
Thermal properties of the wall linings,
kρ c
p
=600
These values give an Eurocode fire with a heating time of 0.83 hours or 50 mins, a
peak temperature of 1163 °C and a decay rate of 404 °C/hour, or 6.7 °C/min.
Figure 6.5 shows the comparison of the temperatures in the lower flange for
protected steel as estimated by SAFIR and by the spreadsheet method with
temperature results from experimental tests. The difference between the SAFIR
results from the experimental results can be partly due to the difference in the fire
curve as it was not possible to get an exact match of fire data. The temperature of
the steel as predicted by SAFIR is higher than the experimental data, but the
temperature of the fire it is simulated from is higher than the experimental fire.
The maximum temperature reached in both curves is around the same but the peak
occurs from the SAFIR results much later than was found in the experiment.
The steel temperature as predicted by the spreadsheet was achieved by entering the
fire temperatures into the spreadsheet and adjusting the time step to fit the data
points available. The results from the spreadsheet are higher than those from
SAFIR and the experiment but as commented on in Sections 4.3 and 5.6, the
spreadsheet method does not take into account the cooling effects of a concrete
slab, and thus gives slightly higher temperatures than those found in SAFIR which
can account for these effects.
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