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

The fire that the test beams were exposed to is based on the Eurocode Parametric
Fires. The temperatures were achieved by burning wood cribs with a fuel load of
20 kg wood/m 2 floor area, and having a ventilation factor of ¼ of the end wall.
The measurements recorded in Kirby, et al (1994), give the temperatures of the
lower flange throughout of the test, and of the atmosphere at 300 mm below the
roof, which is in line with the lower flange.
The calculations of the steel temperature by the spreadsheet method were made by
substituting the temperature of the fire at time steps, and then calculating the steel
temperature using this fire. The formula used is that used throughout this report,
equation 2.5. Although this protection is box protection, no allowance is made for
the radiation and convection between the inner surface of the insulation and the
steel surface in the spreadsheet method, Refer to Section 5.4 for more information
on boxed protection.
The simulation in SAFIR was made by entering the appropriate values for the
parametric fire to obtain a curve that fit as close as possible to the real fire curve as
seen above in Figure 6.5. The values for the fuel load density, ventilation factor
and wall linings properties were found in Kirby et al, (1994), and then modified to
obtain a curve that fit closely with the real fire curve.
Temperature ( o C)
1400
1200
1000
800
600
400
200
0
Real Fire
Real Steel Temp
0 50 100 150 200
Time (min)
Real steel temp
Eurofire
Spreadsheet
Euro fire
SAFIR
Spreadsheet
Fire Temp
SAFIR steel
Figure 6.5: Comparison between the temperature results measured from an experimental fire test
with the maximum temperatures found from a SAFIR simulation, and temperatures from the
spreadsheet method for protected steel.
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