Civil Engineering Reference
In-Depth Information
For steel to concrete connections, allow for tolerances and design
■
for the bounds of eccentricity (see
Figure 18.29
).
Control level and slopes of composite floor decking by beam
■
pre-cambers to address dead load deflection. Change the decking
to one with higher stiffness if deflections of 15-20 mm due to
ponding of wet concrete are a concern. Consider and control/spe-
cify concreting method/day joints, for example an exposed soffit.
Cracking over supports in composite slab construction is common
■
and accepted for offices with raised floors. In cases where brit-
tle finishes are applied directly to the slab use floating reinforced
screeds. In situations where vinyl flooring finishes are used ensure
the finish has the required crack bridging properties.
In tall, 12+ metre high single-storey frames where internal shelv-
■
ing/racking is close to columns, eaves sway, when combined
with construction tolerances can cause clashes. This is solved by
increasing the building size or stiffer columns.
Masonry clad single-storey buildings are less tolerant of eaves
■
■
Figure 18.28 Web holes predrilled for through bolting of timber
plates to fit timber joists at the same level as the steel
sway than metal clad buildings. Adjust column size to address
the limits allowed for masonry panel deformation. Refer to
Brick Cladding to Steel Framed Buildings: Commentary
(BDA,
1986).
Control/limit the imposed load deflection of perimeter floor
■
■
beams to span/500 for beams supporting masonry and brittle
cladding.
Base plates of internal column details adjacent to or supported on
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lift pit walls cause local substructure detailing problems and pits
may not be constructed early in the programme. Consider sup-
porting the column base plate on the base of pits with pit walls
concreted after steel erection.
Single-storey buildings often have ground floor slabs that are not
■
restrained. Top of foundations need adequate allowance for: depth
for slab, sand slip layer, sub-base, grout and plate thickness. HD
bolts need to be accommodated within the sub-base, possibly
resisting horizontal loads.
Base plates on perimeter columns should integrate with perim-
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eter walling/damproofing details. Consider the use of offset base
plates to facilitate walls detailed to run past columns.
Steel material is rolled within a range of rolling tolerances.
■
Fabrication and erection are achieved within certain tolerances.
Cladding zones need to be 'loose fit'. Structural interface toler-
ance summaries advised to the architect for incorporation in the
cladding specifications need to allow for all the tolerances likely
to occur.
18.6.7 Visually exposed steelwork
The designer would normally clarify aesthetic details require-
ments. In addition to special welding and plate profiling per-
manent deformation, due to dead load actions added to tol-
erance effects needs considering to avoid unsightly steelwork
(see
Figures 18.30
and
18.31
).
Web stiffeners in open sections cut back 10-15 mm from flange
■
toes preserve the visual effect of straight flanges and the fillet weld
can be kept back from the toe edges to avoid bulky weld groups
that are apparent in
Figure 18.34
and
Figure 18.35
.
Figure 18.29 Concrete drilled in fixing with slotted steel in, three
steel-to-steel connections with a single steel to concrete connection
to simplify tolerance design
