N.Y.C. Admin. Code § BC 2305: Section BC 2305: General Design Requirements for Lateral Force-Resisting Systems

2305.1 General.

Structures using wood-frame shear walls or wood-frame diaphragms to resist wind, seismic or other lateral loads shall be designed and constructed in accordance with AWC SDPWS and the applicable provisions of Sections 2305, 2306 and 2307.

2305.1.1 Openings in shear panels.

Openings in shear panels that materially affect their strength shall be detailed on the plans and shall have their edges adequately reinforced to transfer all shearing stresses.

2305.2 Diaphragm deflection.

The deflection of wood-frame diaphragms shall be determined in accordance with AWC SDPWS. The deflection (D

dia

) 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.

(Equation 23-1)

where:

A

= Area of chord cross section, in square inches (mm

2

).

E

= Modulus of elasticity of diaphragm chords, in pounds per square inch (N/mm

2

).

e

n

= 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 of 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).

D

c

= Diaphragm chord splice slip at the induced unit shear, in inches (mm).

D

dia

= Maximum mid-span diaphragm deflection determined by elastic analysis, in inches (mm).

Table 2305.2(1)

e

n

Values (inches) for Use in Calculating Diaphragm and Shear Wall Deflection Due to Fastener Slip (Structural I)

a, c

Load Per Fastener

b

(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.

a. Increase e

n

values 20 percent for plywood grades other than Structural I.

b. Load per fastener = maximum shear per foot divided by the member of fasteners per foot at interior panel edges.

c. Decrease e

n

values 50 percent for seasoned lumber (moisture contest < 19 percents.

Table 2305.2(2) Values of Gt for Use in Calculating Deflection of Wood Structural Panel Shear Walls and Diaphragms

Panel Type

Span Rating

Values of Gt (lb/in. panel depth or width)

Structural Sheathing

Structural I

Plywood

Plywood

3-ply

4-ply

5-ply

a

OSB

3-ply

4-ply

5-ply

a

OSB

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

1 1/8

75,000

97,500

75,000

97,500

97,500

97,500

For SI: 1 inch = 25.4 mm, 1 pound/inch = 0.1751 N/mm.

a. 5-ply applies to plywood with five or more layers; for five-ply plywood with three layers, use values for four ply.

2305.3 Shear wall deflection.

The deflection of wood-frame shear walls shall be determined in accordance with AWC SDPWS. The deflection (D

sw

) of a blocked wood structural panel shear wall uniformly fastened throughout with staples is permitted to be calculated in accordance with Equation 23-2.

(Equation 23-2)

where:

A

= Area of end-post cross section in square inches (mm

2

).

b

Shear wall length, in feet (mm).

d

a

= Total vertical elongation of wall anchorage system (including fastener slip, device elongation, rod elongation) at the induced unit shear in the shear wall (v).

E

= Modulus of elasticity of end posts, in pounds per square inch (N/mm

2

).

e

n

= 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)).

h

= Shear wall height, in feet (mm).

v

= Induced unit shear, in pounds per linear foot (plf) (N/mm).

D

sw

= Maximum shear wall deflection determined by elastic analysis, in inches (mm).