Formwork for Concrete Structures by R.L.Peurifoy and G.D- By EasyEngineering.net

456 Chapter Seventeen
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Folding jack
20,000-lb capacity
Shoring heights:
6' 2" to 12' 6" standard
With extensions,
shoring heights
up to 16' plus
Adjustable jack
40,000 lb
capacity
(a) Folding jack
(b) Adjustable jack
FIGURE 17-6 Representative flying form trusses with cribbing jacks supporting
the trusses. (Source: Form-Eze Systems, Inc.)
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As illustrated in Figure 17-6, the lower chord of a truss is supported
at panel points by adjustable screw jacks, which rest on the
concrete floor slab. The folding jack legs in Figure 17-6(a) may be
rotated upward to a horizontal position to facilitate the moving of
forms. Folding jacks have a 20,000-lb load capacity for standard shoring
heights from 6 ft 2 in. to 12 ft 6 in. The adjustable jack in Figure
17-6(b) is available with a 40,000-lb load capacity and with extensions
for shoring heights of up to 16 ft. The concrete floor slab under the
jacks should be supported by reshores, which are located directly
below the jacks that support the trusses.
Versatility of Forms
It is possible to assemble form units suitable for use in casting almost
any concrete slab configuration by combining modules, components,
and accessories. Figures 17-7 through 17-12 illustrate the versatility of
the forms in casting a variety of slab configurations. Flying deck
forms may be used to form beam in slab, one-way joist, and upturned
or down-turned spandrel beam configurations. Pan waffles and oneway
pan joists are often attached to the top of the deck forms and
stripped and flown intact with the deck forms. The versatility of this
forming system provides flexibility for constructing many types of
concrete structures. Figure 17-7 illustrates the use of the deck forms to
cast various shapes of beam and slab designs.
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