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

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Patented Forms for Concrete Floor Systems 375
FIGURE 12-12 Installation of cellular units for an elevated fl oor system. (Source:
H. H. Robertson Company)
on the panels known, and the permissible deflection specified, it is
necessary to select a panel unit having the required moment of inertia
or section modulus, considering the resistance to bending moment
and deflection. The panel unit should be selected for a simple span or
a continuous beam, whichever is applicable.
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Horizontal Shoring
This is a system of supporting decking, or wood joists and decking
for concrete slabs, using telescoping horizontal beams whose lengths
can be adjusted over a wide range. The ends of these shores may be
supported on permanent steel beams, concrete beams, walls, or temporary
stringers and vertical shores. They are available for clear spans
in excess of 25 ft, which require no intermediate supports.
Figure 12-13 illustrates a shore consisting of two parts, a latticetrussed
triangular section and a plate section that telescopes into the
lattice section to produce the designed length. Horizontal prongs that
project from the ends of the shores rest on the supporting members.
The shores are made with built-in wedges or other devices that permit
them to be set with a camber, if one is desired.
The shores are installed at the desired spacing, the end prongs
resting on the supporting members as illustrated in Figure 12-14. The
wood joists and decking are installed, and the concrete slab is placed.
After the concrete has gained the desired strength, the camber is eliminated
and the ends of the shores are pried far enough away from the
supporting members to permit them to be lowered. Figure 12-15
illustrates decking installed directly on top of horizontal shoring.
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