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

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Forms for Walls 233
Plywood
Thickness,
in.
¹ 5 ⁄32 3,560
(3,560)
½ 3,925
(3,925)
¹ 9 ⁄32 4,110
(4,110)
5
⁄8 4,305
(4,305)
23
⁄32 5,005
(5,005)
¾ 5,070
(5,070)
1 1 ⁄8 7,240
(7,240)
Support Spacing, in.
4 8 12 16 20 24 32
890
(890)
980
(980)
1,225
(1,225)
1,310
(1,310)
1,590
(1,590)
1,680
(1,680)
2,785
(2,785)
360
(395)
410
(435)
545
(545)
580
(580)
705
(705)
745
(745)
1,540
(1,540)
155
(205)
175
(235)
245
(305)
270
(330)
350
(400)
375
(420)
835
(865)
115
115
100
(135)
145
(190)
160
(215)
210
(275)
230
(290)
545
(600)
—
—
—
—
—
(100)
—
100
110
(150)
120
(160)
310
(385)
—
—
—
—
—
—
—
—
—
—
—
—
145
(190)
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Notes:
1. Courtesy APA—The Engineered Wood Association, “Concrete Forming,” 2004.
2. Deflection limited to l/360th of the span, l/270th for values in parentheses.
3. Plywood continuous across two or more spans.
TABLE 9-9 Recommended Maximum Pressures on Structural I Plyform—Values in
Pounds per Square Foot with Face Grain Across Supports
Equations (9-1) through (9-7) were used in determining the recommended
maximum pressures of concrete on plywood used for
decking or sheathing, as given in Tables 9-7 through 9-10.
Allowable Pressure Based on Fiber Stress in Bending
For pressure controlled by bending stress, use Eqs. (9-1) and (9-2),
w b
= 96F b
S e
/(l b
) 2 for two spans (9-1)
w b
= 120F b
S e
/(l b
) 2 for three spans (9-2)
where w b
= uniform pressure of concrete, lb per sq ft
F b
= allowable bending stress in plywood, lb per sq in.
S e
= effective section modulus of a plywood strip 12 in. wide,
in. 3 /ft
l b
= length of span, center-to-center of supports, in.
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