| The members
used in Light Gauge Steel Frame construction are manufactured by cold
forming: Sheet steel is fed from continuous coils through machines that
fold it at room temperature into long members whose shapes make them stiff
and strong. Thus, these members are often referred to as cold-formed
steel components, to differentiate them from the much heavier hot-rolled
shapes that are used in structural steel framing. The term light gauge
refers to the relative thinness (gauge of the steel sheet from which the
members are made. |
THE
CONCEPT
OF LIGHT GAUGE STEEL FRAMING CONSTRUCTION
Light Gauge Steel Frame construction is
the noncombustible equivalent of Wood Light Frame construction. The external
dimensions of the standard sizes of light gauge members correspond closely
to the dimensions of the standard sizes of 2-inch (38-mm) framing lumber.
These members are used in framing in much the same way as 2-inch wood members
are used: as closely |
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spaced studs, joists, and rafters. A Light
Gauge Steel Frame building may be sheathed, insulated, wired, and finished
inside and out in the same manner as a Wood Light Frame building.
The steel that is used in light gauge members
is manufactured to ASTM Standard A563, and the zinc coating that protects
the members from rust, to ASTM A924. For studs, joists, and rafters, the
steel is formed into C-shaped (cee) sections (Figure 12.1). For top
and bottom wall plates and for joist headers, runner channel sections
are used. The strength and |
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stiffness of a member depends on the shape
and depth of the section and the gauge (thickness) of the steel sheet
from which it is made. A standard range of depths and gauges is available
from each manufacturer. The webs of cee members are punched at the factory
to provide holes at 2 foot (600 mm) intervals; these are designed to allow
wiring, piping, and bracing to pass through studs and joists without the
necessity of drilling holes on the construction site.
For large projects, members may be manufactured
precisely to the required lengths. Otherwise, they are furnished in standard
lengths. Members may be cut to length on the construction job site with
power saws or special shears. A variety of sheet metal angles, straps, plates,
channels, and miscellaneous shapes are manufactured as accessories for light
gauge steel construction (Figure 12.2).
Light gauge steel members are usually joined
with self-drilling, self-tapping screws, which drill their own holes
and form helical threads in the holes as they are driven. Driven |
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