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

292 Chapter Ten
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Depth
below
Top of
Form, ft
Maximum
Concrete
Pressure
(P m
= wh),
lb per sq ft
Single Span
(2 supports)
Maximum Spacing, in.
Two Spans
(3 supports)
Multiple Spans
(4 or more
supports)
Thickness, in. Thickness, in. Thickness, in.
5
⁄8 ¾ 1 5
⁄8 ¾ 1 5
⁄8 ¾ 1
4 600 9 11 14 10 11 14 11 13 16
5 750 9 10 13 9 10 12 10 11 14
6 900 8 9 12 8 9 12 9 10 13
7 1050 8 8 11 7 8 11 8 9 12
8 1200 7 8 10 7 8 10 8 9 11
9 1350 7 7 9 7 7 9 7 8 10
10 1500 6 7 9 6 7 9 7 8 10
11 1650 6 7 9 6 7 9 6 7 9
12 1800 6 7 8 6 7 8 6 7 9
13 1950 6 6 8 5 6 8 6 7 8
14 2100 5 6 7 5 6 7 5 6 7
15 2250 5 6 7 5 6 7 5 6 7
16 2400 5 6 7 5 6 7 5 6 7
17 2550 5 5 7 5 5 6 5 5 6
18 2700 5 5 7 4 5 6 4 5 6
19 2850 5 5 7 4 5 6 4 5 6
20 3000 5 5 7 4 5 6 4 5 6
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Notes:
1. For Plyform, values based on F b
= 1,930 psi, F s
= 72 psi, and E = 1,650,000 psi, with face
grain installed in the strong direction, physical properties for stress applied parallel to
face grain.
2. Concrete pressure based on concrete with 150 lb per cu ft unit weight. Spacings are
governed by bending, shear, or deflection. Maximum deflection limited to l/360, but
not more than 1 / 16 in.
TABLE 10-3 Maximum Spans of Plyform with Face Grain Across Supports
Maximum Spacing of Column Clamps Using Plyform with
Vertical Wood Battens
The maximum spacing of column clamps will be limited by the
strength of the sheathing that must transfer the concrete pressure
between clamps. As discussed in the preceding section, the sheathing
for square or rectangular columns usually consists of plywood with
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