Civil Engineering Reference
In-Depth Information
either steel or concrete ribs or beams. Within a bay the usual
configuration is for the slab to span between secondary beams
which in turn span the longer direction of the rectangular bay
defined by four columns. This will tend to minimise the depth
of the primary beam that supports the secondaries and hence
minimise the overall depth of the structural zone.
However, this will not necessarily allow the shallowest
overall floor zone. If it is known that the largest service runs
are in one particular direction the directions of span can be
swapped so that the secondaries span the shorter dimension
and become shallower as a result. The large services running
parallel to the primary beams in this rectangular bay can move
upwards to the underside of secondaries, reducing the over-
all depth of the floor zone. This configuration of rectangular
bay can be useful in reducing floor to floor heights in, for
instance, airports, where the large baggage handling convey-
ors in ceilings might otherwise pump up the building's height
(see
Figure 7.8
).
One further integration of structure and services is through
the creation of beam-free zones (see
Figure 7.9
). By posi-
tioning columns on either side of the major service runs, the
secondary beams can span straight to them, with only slab in
between the lines of beams. Major duct runs can be hard up
against the slab with only smaller distribution ducts needing
to pass beneath the beams, dramatically reducing the multi-
disciplinary floor zone required.
7.6 Accommodating other components and issues
The structural engineer will often need to get involved in 'non-
structural' design issues of importance to the wider team: the
architect, building services engineer or contractor. It is import-
ant to plan ahead and agree the scope of the engineer's input to
these shared concerns to allow efficient progress for the team
as a whole.
These issues will not need to be fully described on the
engineer's drawings. The information may be passed to others
for use on their drawings or coordinated allowances made for
connections and loads from building systems.
Smooth design progress for the team as a whole is ensured
by agreeing the scope of 'who does what and by when' for
these issues across the disciplines as early as possible. The
multi-disciplinary team functions best when all team members
are looking out for each other's interests and anticipating prob-
lems, opportunities and needs. Generally, the more structural
Figure 7.8
A conceptual bay arrangement at an airport
