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486 Barry’s Advanced Construction of Buildings
As an alternative, a system of primary lattice steel frames and secondary tension cable
rigging may be used in alternate vertical supports to suspended glass, as illustrated in
Figure 7.61. In this secondary rigging, the cable is tensioned between floor and roof across
the solid props that are bolted to the glass at the junction of four panes of glass, which act
with the rigging as a tensioned truss. This tensioned rigging is used as a less obvious and
unobtrusive means of support, which provides some support for the glass and more particularly
as resistance to wind pressure acting on the glass screen. Lattice frame and secondary
rigging systems depend on anchorages to the floor and a structural roof for support,
with the top panes of glass being supported by the roof and the bottom edge of lower panes
by restraint from the floor.
Where suspended glass is used as an enclosure to walls and roof, a structural steel frame
is used to support the whole of the weight of glass and wind loads. Various systems of light
section – vertical, horizontal and sloping lattice frames – are used together with tensioned
cable rigging systems for stability and effect. A variety of plates are used for bolting glass,
the most straightforward of which is one plate shaped to take the bolts at the junction of
four panes of glass. Figure 7.62 is an illustration of a comparatively simple system of suspended
glass supported by horizontal lattice steel frames fixed between steel portal side
frames to give support to the glass. The horizontal lattice frames are braced with tension
cables and braced up the face of the glass with cables. Photograph 7.5 shows a suspended
glazing system.
Cable stays
between supports
Tubular
frames
Star plate
fixing for
bolts to
four glass
panes
Flank
wall
Horizontal lattice girder
with cable stay
Figure 7.62 Horizontal lattice girder and cable stay supports.