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

From Figure 5.7 a-c, it appears that the ECCS equations give a good indication of
the average temperatures of the steel members when subjected to an ISO 834 fire.
The temperature range that these formulas are valid for is from 400 °C to 600 °C.
This upper limit could be extended to 800 °C based on the results of Figure 5.7 a-c,
and the section size limitations for protected steel members could also be extended,
although the current range is quite substantial and would cover most beams sizes
currently. The time period for which the formula is valid does not appear to be a
significant factor, because although the results here are sometimes out of the time
range suggested, the lines tend to fit to the SAFIR or spreadsheet curves regardless
of the time when these temperatures occur.
These results for light protection support the comments made in Section 5.2.3
about the ECCS equations for steel members with heavy insulation. The same
changes to the temperature limitations of the equations are made for both the heavy
and light protection forms of the equation and the other time and size limitations
appear unnecessary for both forms.
5.4 RESULTS FOR FOUR SIDED EXPOSURE WITH BOX
PROTECTION:
Four sided box protection is considered in this section. For box protection, the
section factor is calculated by a different procedure to that of protected beams with
spray on protection. The heated perimeter, H p , for four sided exposure is the
perimeter of the box, or twice the height and depth of the section, while the area,
A, is the cross sectional area of the steel section. This gives a smaller section
factor than with spray on protection and therefore a thicker effective width.
In this section the box protection is considered to be of GIB ©
properties of the insulate board are used as follows, Thomas, (1997):
Specific heat, c i = 1700 J/kg K
Thermal conductivity, k i = 0.25 W/m K
Density, ρ i = 600 kg/m 3
Thickness, d i = 0.02 m
Board. The
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