Fig. 3.45 Typical floor-slab systems for steel frameworks.
(a) In situ reinforced concrete flat slab.
(b) Precast concrete floor units.
(c) In situ concrete on profiled steel permanent formwork.
(d) Composite precast and in situ concrete.
All of these systems are normally one-way-spanning and
require to be supported on a parallel arrangement of steel
beams. System (a) can be two-way-spanning.
arrangement is one in which the columns are
positioned at every third or fourth beam and
intermediate beams are carried on a second
system of beams which run at right angles to
the direction of the main beams (Fig. 3.47).
This produces a column grid which is rectangu-
lar. A variation of this is the grid in which
columns are provided at every main beam
where these meet the perimeter of the build-
ing, and at every third or fourth beam in the
building's interior (Fig. 3.48). This eliminates
Fig. 3.46 Shear studs welded to the top flanges of steel
floor beams allow composite action to be developed
between the beams and the floor slabs. This reduces the
size required for the beam. As is shown, such action is
possible with both in situ and precast floor systems. 89Steel structures