283757893275

Cladding and Curtain Wall Construction 455
Restraint
angle
Bolt in oversize
hole bolted to
socket
Neoprene bush
and shims
Flexible
rod bolted
to panel
and angle
Angle
bolted
to floor
Resilient bush restraint
Figure 7.35 Restraint fixings.
Flexible rod restraint
the cement-rich material and the considerable wind forces acing on a wall. To provide
support for large single skin panels and at the same time make allowance for moisture
movement, a system of stud frames was developed and has been extensively used. A frame
of hollow and channel steel section is prefabricated with welded joints to the top, bottom
and side members, and intermediate vertical sections spaced at about 600 mm, as illustrated
in Figure 7.36. L-section, 9.5 mm round steel section anchors are welded to the hollow
section studs at about 600 mm centres to serve as flex anchors to the GRC panel. Near the
base of the frame, T-sections are welded to the sides of the edge studs to serve as gravity
anchors. Angles are also welded to the back face of the studs as seating angles to support
the stud frame.
The fabricated stud frame is galvanised or powder coated to inhibit rusting. As the GRC
panel is being manufactured, and the skin and flanges and ribs are formed, the stud frame
is placed on the back of the compacted and still moist GRC, with the flex anchors and T
bearing on the back of the panel. Moist strips of GRC are then rolled on to the back of the
panel over the flex anchors and T anchors to secure them to the panel, as illustrated in
Figure 7.36. The GRC strips, which are rolled over the flex anchors on to the back of the
panel, provide a firm attachment to maintain the thin skin as a flat panel yet allow sufficient
rotational and lateral movement of the panel to prevent failure.
Figure 7.37 is an illustration of the fixing of storey height stud frame panels of GRC to
the beams of a structural steel frame. T-section, steel beam brackets are welded to plates
that are welded to the web of beams. These brackets support T-sections welded to cleats.
One beam bracket is welded to beams centrally on the junction of vertical and horizontal
joints between GRC panels.
The weight of the stud frame is supported by the bearing of the bottom flange of the
frame on the lower flange of the beam. Top and bottom restraint fixings, cast in the side ribs
of the GRC panel, are bolted to the angles of the beam brackets. Open drained or mastic
or gasket joints are made to joints between panels. Stud frames are best suited to flat storey
height panels which are supported at floor levels. Curved and profiled panels may have
sufficient stiffness in their shape and not justify the additional cost of a stud frame. Similarly,
small under window and spandrel panels of GRC do not generally require a stud frame.