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

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Forms for Beams and Floor Slabs 321
For example, for a 6-in.-thick slab of 150 lb per cu ft concrete, the
vertical dead load of the concrete on the floor decking will be:
p = w c
(h)
= 150 lb per cu ft (6/12 ft)
= 75 lb per sq ft
The live load will include workers and buggies used to place the
concrete, plus materials that may be stored on the slab. It is common
practice to assume a live load varying from 50 to 75 lb per sq ft of
floor or more, depending on the anticipated conditions. The live loads
on formwork are discussed in Chapter 3.
The following is an illustration of the loads of formwork on a 6-in.
slab with a 5.0 lb per sq ft dead load of formwork materials and a live
load of 50 lb per sq ft:
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Dead load of freshly placed concrete = 75 lb per sq ft
Dead load of formwork materials = 5 lb per sq ft
Live load of workers and tools = 50 lb per sq ft
Total load = 130 lb per sq ft
Definition of Terms
Sometimes there are variations in the terminology used in the construction
industry. Figure 11-1 illustrates the components of a jobbuilt
slab-forming system for a beam and slab concrete structure. The
following terms are used in this book:
1. Decking is the solid plywood panels that form the floor of the
formwork against which the fresh concrete is placed. Sheets
of Plyform, the plywood manufactured especially for concrete
formwork, are commonly used. The decking may also be patented
fiberglass domes or steel panel forms. It provides resistance
to the vertical pressure of the freshly placed concrete.
2. Joists are the members under the decking that provide support
for the floor decking. Joists are usually single members
FIGURE 11-1 Forms for concrete beams and slab with intermediate stringers.
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