ComFlor
70 is designed for optimum performance
in span capacity, economy, composite performance
and concrete usage. The economy and spanning capacity
of a trapezoidal profile is combined with the
interlocking shear performance of a re-entrant
to give major performance advantages.
Standard shear studs
are fully effective with ComFlor 70
The profile is 70 mm deep, including the top re-entrant
section, but the height of the main trapezoidal
section at 55 mm defines the critical zone projecting
from the base of the shear connector to the web-to-flange
junction of the profile. This point was confirmed
in The Steel Construction Institute note AD147,
following tests. The shear connector should project
at least 35 mm above the main trapezoidal section,
meaning that a standard 95 mm stud is conservatively
adequate for use with ComFlor 70 profile.
Reduced slab depth
and concrete usage
The slab depth required for fire and structural
design is minimised by the profile design. The
concrete usage is further reduced by the profile
shape, which eliminates another effective 26 mm
from the slab depth. Reduced slab depth and concrete
usage results in lower overall floor height, lower
dead load structure and foundations, lower concrete
cost.
Optimum shear stud
placement
The arrangement of stiffeners in the ComFlor 70
trough allows shear studs to be positioned centre
trough, which makes them fully effective in both
directions, for composite beam design ie. no reductions
in stud capacity due to deck geometry.
Fire properties
of 55 mm deep profile
Not only can the top re-entrant section be disregarded
for stud design, tests have also confirmed that
it is too small to contribute to the transmission
of heat energy through the slab in a fire. Taking
the effective profile height as 55 mm results
in a reduced overall slab depth being required
for any particular fire rating.
Low cost and fast
service connection
Low cost connector devices can be used with the
small sized re-entrant, for the hanging of ceilings
and services direct to the profile.
Deck material
Zinc coated steel to BS EN 10147:1992, Fe E 350G,
Z275, with a guaranteed minimum yield stress of
350 N/mm2. Minimum zinc coating mass is 275 g/m2
total including both sides.
Anti-crack mesh
BS 5950: Part 4 currently recommends that anti-crack
mesh should comprise 0.1% of slab area. The Eurocode
4 recommendation is that anti-crack mesh should
comprise 0.2% of slab area for unpropped spans
and 0.4% of slab area for propped spans. Panels
and Profiles in conjunction with The Steel Construction
Institute, has agreed to modify the requirement
with regard to anti-crack mesh, to comply with
the Eurocode 4 recommendations. Accordingly, the
mesh shown in the quick reference tables complies
with EC4 and the design program defaults to these
values. Where EC4 mesh rules are used, the mesh
may be reduced midspan. The reduced British Standard
mesh values may still be used by overriding this
default in the design program. Mesh top cover
must be a minimum of 15 mm, and a maximum of 30
mm. Mesh laps are to be 300 mm for A142 mesh and
400 mm for A193, A252 & A393 mesh.
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