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

These methods may be used to provide a realistic analysis of structures exposed to
fire, and be based on fundamental physical behaviour in such a way as to lead to a
reliable approximation of the expected behaviour of the relevant structural
component under fire conditions.
These methods can be used to determine the temperature distribution within the
members and the mechanical behaviour of the structure or part of it.
Presently there are no thermal properties included in the New Zealand Steel Code.
For calculations for the temperature rise of steel by methods other than the
empirical equations currently included, however these values are required. From
the results seen in Sections 4 and 5, the variation of thermal properties affects the
time temperature curves of steel members so constant values or approximate
equations are adequate for the calculations likely to be performed by the users of
NZS 3404. The approximate values most often recommended to use are those
included in ENV 1993-1-2.
The limiting temperature of steel is a direct rearrangement of the formula to
calculate the variation of yield strength with temperature. Depending on the form
that the yield strength equation is will depend on the recommended limiting
temperature equation. If the mechanical properties as recommended by EC3 are
adopted by SNZ in the future, then it is subsequently recommended that the
limiting temperature is similarly changed to that in the Eurocode. If a modification
of the present formula, or a different equation modelling the variation of yield
strength with temperature is then the limiting temperature of steel members should
be changed accordingly.
7.2.6 External Steelwork:
Eurocode 3 has a large Annex that details the methods of heat transfer to external
steelwork. The compartment is assumed to be confined to one storey and external
openings are considered rectangular.
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