round rods or light angles) on the top chord plane (fig.
3-23) and the bottom chord plane (fig. 3-24). After
these braces are installed, a sway frame is put into
place. (See fig. 3-25.)
PURLINS, GIRTS, AND EAVE STRUTS
Purlins are generally lightweight and
channel-shaped and are used to span roof trusses.
Purlins receive the steel or other type of decking, as
shown in figure 3-26, and are installed with the legs
of the channel facing outward or down the slope of the
roof. The purlins installed at the ridge of a gabled roof
are referred to as RIDGE STRUTS. The purlin units
are placed back to back at the ridge and tied together
with steel plates or threaded rods, as illustrated in
The sides of a structure are often framed with girts.
These members are attached to the columns
horizontally (fig. 3-28). The girts are also channels,
generally the same size and shape as roof purlins.
Figure 3-20.Installing bar Joists girder to girder.
Siding material is attached directly to the girts.
Figure 3-21.Steel truss fabricated from angle-shaped members.