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Steel Designers' Manual - 6th Edition (2003)
68 Multi-storey buildings
concrete thicknesses are near the practical minimum for consideration of strength
and fire separation.
Steel studs are welded through the decking on the flange of the beams below to
form a connection between steel beam and concrete slab. Concrete, which may be
either lightweight or normal weight, is then poured on to the decking, usually by
pumping, to make up the composite system. Shallow metal decking acts both as permanent
formwork for the concrete and as tensile reinforcement for the slab. There
are many types of steel decking available (Fig. 2.25(a)) but perhaps the most commonly
used is the re-entrant profile type, which provides a flat soffit and facilitates
fixings for building services and ceilings.
Some of the advantages of composite shallow metal deck floor construction are:
• Steel decking acts as permanent shuttering, which can eliminate the need for slab
reinforcement and, due to its high stiffness and strength, propping of the construction
while the wet concrete develops strength.
• Composite action reduces the overall depth of structure.
• It provides up to 2 hours fire resistance without additional fire protection and 4
hours with added thickness or extra surface protection.
• It is a light, adaptable system that can be easily manhandled on site, cut to
awkward shapes and drilled or cut out for additional service requirements.
• Lightweight construction reduces frame loadings and foundation costs.
• It allows simple, rapid construction techniques.
Figure 2.26 illustrates alternative arrangements of primary and secondary beams for
a deck span of 3 m.
(a) (b)
Fig. 2.25 Metal deck profiles: (a) shallow deck (50–100 mm); (b) deep deck (150–250 mm)