Lumber Sheathing

Shearwalls

SDPWS / ASCE 7

Major References

-

SDPWS Table 4.3D, SDPWS 4.3.7.6-.9

Wall Construction

(for more details, see table for Wall Construction)

Sheathing Thickness

¾”

1” nominal

Orientation

Horizontal, Vertical, Diagonal, or Dbl. Diag.

Horizontal, Vertical, Diagonal, or Double diagonal

Sheathing surface

Either, Both

Either or both

Plies

Via Orientation input

1 or 2 (Double Diagonal)

Blocking (vertical)

Blocked

"Applied to studs and blocking"

All others

Unblocked

Doesn't say (not needed)

Stud Spacing

12,16,24

Doesn’t say

Fastener Spacing

depends on fastener type (for more details, see table for Fastener spacing )

Edge spacing

2”-7”

3-6 per board

Int Spacing

2”-7”

2-4 per board

Fastener Types and Sizes

(for more details, see table for Fastener type and lengths (see Fastener topic))

Common nails, single ply

8d,10d,16d

8d

Common nails, double diagonal

8d,10d,16d

8d

Box nails

Not included

8d

Sheathing Shear Capacities

Reference

-

SDPWS Table 4.3D*

Diagonal

300

300

Single

50

50

Double Diagonal

600

600

Vertical

45

45

The shear capacities shown here are the seismic values in table 4.3A divided by 2.0 for ASD design as per 4.3.3 . For wind design, multiply by the 1.4 wind increase factor (see Shear Capacity Adjustments, below)

Shear Capacity Adjustments

Reference

SDPWS Table 4.3D

ASD Reduction Factor

Values in Table 4.3D divided by 2.0.

2.0 ( Note 1 referring to 4.3.3)

Wind Increase Factor**

1.4

Incorporated in Table 4.3D

Specific gravity factor

None

None

Aspect Ratio Factor

None

None

*The shear capacities shown below are the seismic values in table 4.3A divided by 2.0 for ASD design.

**Shearwalls multiplies seismic resistances from Section A the table by 1.4 for wind design. The values may be slightly different than those in Section B of the table due to rounding.

Seismic Information

Allowable Design Categories

ASCE-7 Table 12.2-1, SDPWS 4.3.7.5

Diagonal or Double DIagonal

35 feet or less

Sets capacity to 0 for E, F

Allows A, B, C, D

35 Feet or less

Sets capacity to 0 for E, F

Allows A, B, C, D

Vertical or horizontal

Sets capacity to 0 for D, E, F

Allows A, B, C

Response modification factor R

Input in Site Dialog, Prompts to change upon load generation

ASCE-7 Table 12.2-1, 12.8.1.1

R -bearing walls

Default 2.0

2.0

R -building frames

Default 2.5

2.5

Deflection amplification factor C_d

Input in Site Dialog, Prompts to change upon load generation

ASCE-7 Table 12.2-1,

12.8.6

C_d - bearing walls

Default 2.0

2.0

C_d - building frames

Default 2.5

2.5

Overstrength Factor W₀*

Cannot be overriden

ASCE-7 Table 12.2-1, inc. note b; 12.10.1.1.

W₀ - bearing walls, rigid diaphragms

2.5

2.5

W₀ - building frames, rigid diaphragms

2.5

2.5

W₀ - bearing walls, flexible diaphragms

2.0

2.0 or 2.5

W₀ - building frames, flexible diaphragms

2.0

2.0 or 2.5

*for drag strut force from discontinuous shear lines above, only

Use "shear panels with all other materials category" for R, , C_d , and W₀*

Permissible Force Distribution Method

Refer to Shear Force Distribution Methods for more a description of these methods and how they are selected.

Reference

SDPWS 4.3.3.4.1

Deflection-based distribution

Allowed

Allowed

Capacity-based distribution

Contribution of lumber sheathing ignored for seismic design

Not allowed

Aspect Ratio

= h/b, b_s = segment length, h = height, applies to wall segments or force-transfer piers. For more details see Aspect Ratio Limits and Factors.

Maximum aspect ratio

4.3.4, Table 4.3.4, Table 4.3.4 Note 2

Vertical, Horizontal

2:1*

Doesn't say

Diagonal

2:1

2:1 ( (Refers to Diagonal, conventional)

Double diagonal

3.5:1**

Refers to "regular" diagonal for 2:1 ratio.

*Use value for single diagonal in absence of guidance for horizontal and vertical lumber sheathing

**Use value for wood structural panels, on the assumption that "conventional" refers to single diagonal only.

Combination of Sheathing Capacities

For more details, refer to Combination of Sheathing Capacities,

Reference

SDPWS 4.3.3.3

Same orientation of lumber sheathing on both sides, seismic or wind

Add capacities

Add capacities

With different orientation of lumber sheathing on other side, wind

V_wc =K_min G_ac

No guidance

With different orientation of lumber sheathing on other side, seismic

V_sc =K_min G_ac

V_sc =K_min G_ac

With wood structural panels, gypsum or fiberboard on other side, seismic or wind

twice weakest or strongest

twice weakest or strongest

With wood structural panels on other side, wind

Add capacities

Add capacities

Sheathing Bending Capacities

Reference

All types – 3/4"

From WFCM Table 3A

Not included in SPDWS Table 3.2.1,

included in WFCM Table 3A