// CODE SNIPPET
2305.2 Diaphragm Deflection
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The deflection of wood-frame diaphragms shall be determined in accordance with AWC SDPWS. The deflection (Δdia) of a blocked wood structural panel diaphragm uniformly fastened throughout with staples is permitted to be calculated in accordance with Equation 23-1. If not uniformly fastened, the constant 0.188 (For SI: 1/1627) in the third term shall be modified by an approved method.
For SI: Δdia = 0.052vL3/EAW + vL/4Gt + Len/1627 + Σ(xΔc)/2W
Δdia = 5vL3/8EAW + vL/4Gt + 0.188Len + Σ(xΔc)/2W
(Equation 23-1)
For SI: Δdia = 0.052vL3/EAW + vL/4Gt + Len/1627 + Σ(xΔc)/2W
where: | ||
A | = | Area of chord cross section, in square inches (mm2). |
E | = | Modulus of elasticity of diaphragm chords, in pounds per square inch (N/mm2). |
en | = | Staple slip, in inches (mm) [see Table 2305.2(1)]. |
Gt | = | Panel rigidity through the thickness, in pounds per inch (N/mm) of panel width or depth [see Table 2305.2(2)]. |
L | = | Diaphragm length (dimension perpendicular to the direction of the applied load), in feet (mm). |
v | = | Induced unit shear in pounds per linear foot (plf) (N/mm). |
W | = | Diaphragm width [in the direction of applied force, in feet (mm)]. |
x | = | Distance from chord splice to nearest support, in feet (mm). |
Δc | = | Diaphragm chord splice slip at the induced unit shear, in inches (mm). |
Δdia | = | Maximum mid-span diaphragm deflection determined by elastic analysis, in inches (mm). |
LOAD PER FASTENERb (pounds) | FASTENER DESIGNATIONS |
14-Ga staple × 2 inches long | |
60 | 0.011 |
80 | 0.018 |
100 | 0.028 |
120 | 0.04 |
140 | 0.053 |
160 | 0.068 |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound = 4.448 N.
PANEL TYPE | SPAN RATING | VALUES OF Gt (lb/in. panel depth or width) | |||||||
Structural Sheathing | Structural I | ||||||||
Plywood | OSB | Plywood | OSB | ||||||
3-ply | 4-ply | 5-plya | 3-ply | 4-ply | 5-plya | ||||
Sheathing | 24/0 | 25,000 | 32,500 | 37,500 | 77,500 | 32,500 | 42,500 | 41,500 | 77,500 |
24/16 | 27,000 | 35,000 | 40,500 | 83,500 | 35,000 | 45,500 | 44,500 | 83,500 | |
32/16 | 27,000 | 35,000 | 40,500 | 83,500 | 35,000 | 45,500 | 44,500 | 83,500 | |
40/20 | 28,500 | 37,000 | 43,000 | 88,500 | 37,000 | 48,000 | 47,500 | 88,500 | |
48/24 | 31,000 | 40,500 | 46,500 | 96,000 | 40,500 | 52,500 | 51,000 | 96,000 | |
Single Floor | 16 o.c. | 27,000 | 35,000 | 40,500 | 83,500 | 35,000 | 45,500 | 44,500 | 83,500 |
20 o.c. | 28,000 | 36,500 | 42,000 | 87,000 | 36,500 | 47,500 | 46,000 | 87,000 | |
24 o.c. | 30,000 | 39,000 | 45,000 | 93,000 | 39,000 | 50,500 | 49,500 | 93,000 | |
32 o.c. | 36,000 | 47,000 | 54,000 | 110,000 | 47,000 | 61,000 | 59,500 | 110,000 | |
48 o.c. | 50,500 | 65,500 | 76,000 | 155,000 | 65,500 | 85,000 | 83,500 | 155,000 |
Structural Sheathing | Structural I | ||||||
Thickness (in.) | A-A, A-C | Marine | All Other Grades | A-A, A-C | Marine | All Other Grades | |
Sanded Plywood | 1/4 | 24,000 | 31,000 | 24,000 | 31,000 | 31,000 | 31,000 |
11/32 | 25,500 | 33,000 | 25,500 | 33,000 | 33,000 | 33,000 | |
3/8 | 26,000 | 34,000 | 26,000 | 34,000 | 34,000 | 34,000 | |
15/32 | 38,000 | 49,500 | 38,000 | 49,500 | 49,500 | 49,500 | |
1/2 | 38,500 | 50,000 | 38,500 | 50,000 | 50,000 | 50,000 | |
19/32 | 49,000 | 63,500 | 49,000 | 63,500 | 63,500 | 63,500 | |
5/8 | 49,500 | 64,500 | 49,500 | 64,500 | 64,500 | 64,500 | |
23/32 | 50,500 | 65,500 | 50,500 | 65,500 | 65,500 | 65,500 | |
3/4 | 51,000 | 66,500 | 51,000 | 66,500 | 66,500 | 66,500 | |
7/8 | 52,500 | 68,500 | 52,500 | 68,500 | 68,500 | 68,500 | |
1 | 73,500 | 95,500 | 73,500 | 95,500 | 95,500 | 95,500 | |
11/8 | 75,000 | 97,500 | 75,000 | 97,500 | 97,500 | 97,500 |
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