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Steel Designers' Manual - 6th Edition (2003)
1028 Fire protection and fire engineering
Since a great deal of data have been gathered over the years on the performance
of materials in the standard fire test, methods have been sought to
relate real fire conditions to standard fire performance in order that the existing
data can be used in fire engineering. The time equivalent or equivalent
required fire resistance is given by:
Teq = CWQf
where Qf = fire load density in MJ/m, i.e. the amount of combustible material
per unit area of compartment floor,
W = ventilation factor relating to the area and height of door and
window openings,
C = a constant relating to the thermal properties of the walls, floor
and ceiling.
Detailed methods for calculation of temperatures in natural fires are given in
Eurocode 1 (prEN1991-1-2 13 ).
Fire engineering is not a concept that can be recommended for buildings that are
subject to frequent change of use, such as advance factory units, but many buildings
are ‘fixed’ in terms of their occupancy (car parks, hospitals, swimming pools, etc.)
and in such cases fire engineering is a valid approach. It is most appropriate for
buildings of large volume with low fire load.
In the UK a number of buildings have been built using unprotected steel on fire
engineering principles, one example being the north stand at Ibrox football ground
in Glasgow.
Other examples of the use of calculation methods in determining structural
response in fire are external steel in framed buildings, 14 and portal frames with fireresistant
boundary wall. 15
References to Chapter 34
1. The Building Regulations (a) Approved document B (1991), Fire safety, Department
of the Environment and the Welsh Office. HMSO.
(b) Technical standards for compliance with the Building Standards (Scotland)
Regulations (1990) HMSO
(c) The Building Regulations (Northern Ireland) (1990) Department of the
Environment, HMSO.
2. British Standards Institution (1990) Structural use of steelwork in building. Part
8: Code of practice for fire resistant design. BS 5950, BSI, London.
3. The Steel Construction Institute/Association of Structural Fire Protection
Contractors and Manufacturers (1989) Fire Protection of Structural Steel in
Buildings, 2nd edn. SCI/ASFPCM.
4. Bailey C.G., Newman G.M. & Simms W.I. (1999) Design of Steel Framed Build-