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Steel Designers' Manual - 6th Edition (2003)
66 Multi-storey buildings
Fig. 2.22 Stub girder
2.3.3 Floors
3000 3000 • 3000 3000
bottom stub
chord
: slob
stub
bottom chord
_______ (universal column)
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.