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

Gilvery and Dexter, (1997), prepared a report for and funded by NIST to determine the
possibility of using a computer programme to estimate or evaluate fire resistance times
and load capacity of structures subjective to fire, instead of conducting full scale
furnace tests. The purpose behind the project was to establish if a computer could
accurately model the behaviour of a member in a fire, and therefore save a lot of
money. A range of possible approaches were evaluated from simple calculations to
sophisticated numerical simulations. Simple calculations were found to be good for
members with a uniform temperature distribution, but for members with non uniform
temperature distributions, computer programmes were better. The paper reports that
one of the best computer programmes is SAFIR in terms of its ‘user friendliness’ and
accuracy. The use of SAFIR is shown by modelling complex structural elements, and
evaluating special situations such as partial fire exposure and exposure of a continuous
frame to fire in one bay. It is concluded that SAFIR is a very useful tool that could be
used as an alternative to furnace testing.
A University of Canterbury research report by Wong, (1999), on the reliability of
Structural Fire Design used the computer package @RISK to calculate the probability
of failure of structural steel elements designed for fire conditions. The @RISK
programme uses the standard deviation of the factors involved in the design of a steel
member and runs simulations to find the probability of failure of the member with all
factors considered. The results show the shortcomings in design and an option to
enhance the performance based design of structures.
1.3 SCOPE OF THIS REPORT:
This report is concerned with the design of single simply supported beams and
columns that will fail when the load capacity is reached and exceeded at one critical
point of the span, when a plastic hinge will develop and cause failure of the steel
member. The results found in this report do not apply to complex structural
arrangements such as frames and built in members as the effects from moment
distribution between individual members means that multiple plastic hinges must form
before failure occurs.
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