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

310 UB 40.4 beam
H p /A = 241 m -1 , A s = 5210 mm 2 , H p = 1256 mm
7850*600*5210 >2*300*1100*(1256*20)
2.45 x 10 10 > 1.66 x 10 10
180 UB 16.1 beam
H p /A = 334 m -1 , A s = 2040 mm 2 , H p = 681 mm
7850*600*2040 >2*300*1100*(681*20)
9.61 x 10 9 > 8.99 x 10 9
Clearly the heat capacity of the insulation described above is significantly less than
the steel heat capacity, and therefore can be neglected, when it is considered that
for the insulative term to be neglected it must be less than half that of the steel.
The results of the simulations in SAFIR and from the two spreadsheet calculations
are shown in Figure 5.5 a-c.
Figure 5.5 a-c shows that with light insulation there is a small difference between
the two spreadsheet formulas used. The temperatures from Spreadsheet 1, with the
heat capacity of the insulation included are slightly higher than the temperatures
from Spreadsheet 2 with the heat capacity neglected. This is as expected because
even if the effect of the insulation of the temperature rise of the steel is small, there
is still some effect from the heat capacity of the insulation.
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