Floors - Multi-Storey Buildings.

These take the form of concrete slabs of various forms of construction spanning between steel floor beams (Fig. 2.23). The types generally found are:

• in situ concrete slab cast on to permanent profiled shallow or deep metal decking, acting compositely with the steel floor beams;
• precast concrete slabs acting non-compositely with the floor beams:
• in situ concrete slab, with conventional removable shuttering, acting compositely with the floor beams;
• in situ concrete slab cast on thin precast concrete slabs to form a composite slab, which in turn acts compositely with the floor beams.

The most widely used construction internationally is profiled shallow metal decking.

Composite action with the steel beam is normally provided by shear connectors welded through the metal decking on to the beam flange. Shallow floor systems using deep metal decking are gaining popularity in the UK although precast concrete systems are still used extensively. Composite action enables the floor slab to work with the beam, enhancing its strength and reducing deflection (Fig. 2.24).

Because composite action works by allowing the slab to act as the compression flange of the combined steel and concrete system, the advantage is greatest when the beam is sagging. Consequently composite floor systems are usually designed as simply supported.

Shallow metal deck floor construction   Experience has shown that the most efficient floor arrangements are those using shallow metal decking spanning about 3–4.5m between floor beams. For these spans the metal decking does not normally require propping...

Deep metal deck, shallow floor construction   Deep metal decks are normally used to create shallow floors e.g. Slimflor® and Slimdek® construction. The deep metal deck extends the span capability up to 9m; however, the deck and/or support beams may require propping during...

Precast floor systems   Universal beams supporting precast prestressed floor units (Fig. 2.28) have some advantages over other forms of construction. Although of heavier construction  than comparable composite metal deck floors, this system offers...

Floor construction

Metal deck floor slabs
Fig. 2.24 Metal deck floor slabs

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