Wood shear wall

A wood structural panel shear wall to AWC SDPWS 2021 Section 4.3, with the ASCE 7-22 load factors for wind and seismic. One calculation covers one story of a wall line: a segmented wall (one or more full-height segments) or a perforated wall, sheathed on one or both faces, with the overturning of the stories stacked above.

Source note. SDPWS 2021 (Chapter 4) was read against this module on 2026-11-08: every Table 4.3A value it holds, the design factors (4.1.4), the aspect ratio rules (4.3.3), Eq. 4.3-1 (4.3.4), two-sided walls (4.3.5.4), walls in a line (4.3.5.5), perforated walls (4.3.2.3, 4.3.5.6) and force transfer (4.3.2.2, 4.3.3.3). That reading corrected three Ga values and five rules; see Changes below.

Inputs of the wood shear wall #

• Sheathing: panel grade (Structural I or rated sheathing), thickness and nail (6d, 8d or 10d common), the edge nail spacing (6, 4, 3 or 2 in), one or both faces. The framing species sets G (NDS Table 12.3.3A); for species other than Douglas Fir-Larch and Southern Pine the capacities are multiplied by 1 − (0.5 − G), never more than 1.0. The panel type picks the OSB or plywood column of Ga (4-ply or more plywood and composite panels: Ga × 1.2), and framing wetter than 19 % at fabrication halves Ga. Entered replaces the table: vn and Ga of the whole wall (both faces), before the species factor. SDPWS 2021 prints one vn for wind and seismic: type it in the vn box. The second box takes a seismic vs from an SDPWS 2015 table or report only; seismic uses the smaller of vn and 1.4 vs, so with a 2021 value typed in both boxes nothing is raised.
• Two faces: both faces of wood structural panels combine as Kmin (Ga1 + Ga2), Kmin the smaller vn / Ga of the two faces, for wind and seismic (SDPWS 2021 4.3.5.4.1). Identical faces simply add.
• Hold-down on the inside face of the end post: with 10d nails, Table 4.3A footnote 10 multiplies vn by 0.92. Tick the box under Chords and hold-downs when it applies; a note reminds you on every wall with 10d nails.
• 3/8 and 7/16 in panels: SDPWS Table 4.3A footnote 2 permits the 15/32 in values when the studs are at 16 in o.c. or the panels run across the studs (used by the AWC and WoodWorks examples below). The module has no switch for it: pick the 15/32 in row of the same grade and nail in that case.
• Wall: the wall type, the height h and the length bs of each full-height segment. For a segmented wall you choose how the story shear is shared (4.3.5.5): in proportion to each segment's capacity, where a segment over 2:1 counts with 2bs/h (4.3.5.5.1 Exception 1, instead of 1.25 − 0.125 h/bs), or to its stiffness (equal top deflection by Eq. 4.3-1, with the anchorage slip; segments over 2:1 then take 1.25 − 0.125 h/bs). For a perforated wall enter the total length Ltot and the openings (width × clear height).
• Force transfer around openings: the piers left to right as the segments, and one opening between each pair: width, height and the wall above it. Each opening needs wall above and below it, so a door is refused: use a segmented or perforated wall there. One story at a time. Strap capacity is optional. The least depth above and below (1 ft) and the largest length to depth (6.5, advisory) are APA's limits as Malone quotes them, inputs because the code does not set them.
• Loads: the wind and seismic story forces at the top of this wall, and the forces of any stories stacked on it (same segments; each acts at the top of its story). ASCE 7-22 forces are strength level (W, QE); choose ASD level if you enter 0.6W and 0.7ρQE. The dead load on the wall resists overturning. ρ (ASCE 7-22 12.3.4) and SDS (vertical seismic Ev = 0.2SDS D, 12.4.2.2) are inputs.
• Chords and hold-downs: the chord centroid from each segment end (moment arm d = bs − 2 × offset), the chord E and area A, the anchorage slip Δa (hold-down, rod, shrinkage and crushing, from the manufacturer) and the hold-down capacity in the method's terms (0 reports the force only).
• Drift and deflection: Cd and Ie (ASCE 7-22 Tables 12.2-1 and 1.5-2), the allowable story drift ratio (Table 12.12-1, 0.020 prefilled), the serviceability wind factor and an optional wind deflection limit h / n.
• Code options: the aspect ratio factor for segments with h/bs > 2: SDPWS 2021 (1.25 − 0.125 h/bs, 4.3.3.2, with 2bs/h where 4.3.5.5.1 or 4.3.3.4 calls for it) or, for a project still under SDPWS 2015, 2bs/h for wind and seismic everywhere (as the AWC 2015/2018 design examples apply it).

Auto-design (editor toolbar) varies the sheathing and nail (Table 4.3A row), edge nail spacing and one or two faces. Objectives: lowest cost index (sheathing + nails). Every other input is kept; see Auto-design.

Checks performed #

Drawings #

The drawing sheet (Drawing sheet / DXF buttons, and the report appendix) shows the shear wall elevation of the story designed: the full-height segments (marked SW-1, SW-2 ... with the shear wall cross) or the perforated wall with its openings (O-1, O-2 ...), the stories above as a dashed outline, the story forces at each level, the hold-downs at the ends with net uplift labelled with the tension T, the sheathing and edge nailing callout, and the segment lengths and story heights. The unit shear of each segment, the opening sizes and the largest hold-down tension are in the design summary. The distance between segments, the opening locations, the hold-down device, end posts, sill anchorage and collectors are not part of the calculation; the sheet notes say so.

Limitations #

• Blocked wood structural panel sheathing of Table 4.3A only. Unblocked walls (Cub), gypsum, fiberboard, particleboard and lumber sheathing (Tables 4.3B to 4.3D) are not offered; use Entered with your own values only for wood structural panels.
• Stories above stack on the same segments; a perforated wall is designed one story at a time.
• The anchorage slip Δa is a constant entered value (not computed from the hold-down force).
• Not checked: chord / end-post compression and bearing, sill plate anchor bolts and plate washers (4.3.6.4.3), collectors, the foundation.
• A perforated segment over 3.5:1 fails the aspect check here; SDPWS 4.3.3.4 lets it be left out of Σbi instead: leave it out of the segments.
• Read against SDPWS 2021 on 2026-11-08: every vn, Ga and nail bearing length of Table 4.3A held here, the footnotes used (2, 3, 4, 5, 6, 10), 4.1.4, 4.3.2.2, 4.3.2.3, 4.3.3, 4.3.4, 4.3.5.4, 4.3.5.5, 4.3.5.6, 4.3.6.1 and 4.3.7.1. The SDPWS 2015 option rests on the AWC 2015/2018 examples as Tekla quotes them; SDPWS 2015 is not on file.
• From NDS 2024 (on disk) the module takes only the framing specific gravity G (Table 12.3.3A; Redwood corrected to G = 0.37 at verification, which lowers its species factor from 0.94 to 0.87) and the common nail dimensions (Table L4); both are confirmed. NDS 2024 does not contain the SDPWS provisions.

Force transfer: the method rests on a rational analysis with assumptions the engineer accepts: full-length collectors, and the straps, blocking and their nails are for you to detail, at the head and sill, to develop the force. It cannot take a door or several stories here. Each pier's deflection is taken at the wall height by default, which is larger than APA T555C's method (about 0.48 in. against 0.352 in. by hand on its example); Deflection of the piers switches to the APA method: each pier pushed each way, h from the wall below an opening when pushed toward it, Δa in proportion to v h over the hold-down capacity, so enter Δa at that capacity. T555C permits piers down to 18 in. under conditions; this calculation keeps the code's 2 ft.

Verification examples #

Verification status: 186 values compared in 27 examples (16 published, 11 hand calculations from the cited equations): 184 within tolerance, 2 recorded deviations. Code basis: the provisions it uses were read in the target edition.

Published worked examples, all free from their publishers (research/sources/design_examples):

• WoodWorks, Five-Story Light-Frame Wood Structure over Podium, Design Example, 2nd Ed. (2025) (SDPWS 2021, ASCE 7-22): Tables 3.5, 3.13C, 3.18, 3.19 and 4.5.
• WoodWorks, Introduction to Wood: Structural Lateral Framing Design (January 2025 slides): two-story shear wall, slides 56-80.
• AWC Structural Wood Design Examples 2015/2018, E3.1, E3.2, E3.4 (SDPWS 2015), as quoted with inputs, wall figure and results on the free Trimble Tekla Tedds 2026 verification pages (the AWC book itself is not on file).

Two fixes came out of these examples (2026-11-01): the seismic capacity now follows SDPWS 2021 4.1.4 (φD = 0.50 on vn, was 0.80 on vs: the LRFD seismic capacity drops by about 12 %; ASD vn / 2.8 is within 1 plf of the former vs / 2.0), and the SDPWS 2015 aspect ratio rule 2bs/h now applies to wind as well as seismic and to ΣLi of a perforated wall (AWC E3.1, E3.4).

Changes from reading SDPWS 2021 (2026-11-08). Ga of three Table 4.3A rows (Structural I 7/16 in 8d plywood at 6 / 4 in, 13 / 16, were 14 / 17; Structural I 15/32 in 8d OSB at 4 in, 18, was 20; rated sheathing 15/32 in 8d plywood at 3 in, 15, was 16). Two faces combine as Kmin (Ga1 + Ga2), where wind used to add the faces and seismic took the larger of the stronger face and twice the weaker. Shear shared by capacity among several segments takes 2bs/h for segments over 2:1. Perforated walls: Co by Eq. 4.3-6 capped at 1.0, Σbi with 2bi/h, b = Σbi in the deflection, and the 2,435 plf limit on the wall's vn, one or two faces. Table 4.3A footnote 10 is an input. Entered values: seismic takes the smaller of vn and 1.4 vs.

Hand calculations of the remaining provisions, derived step by step in backend/tests/test_verify_wood_shearwall.py. 15/32 in Structural I, 8d at 4 in, OSB: vn = 1,205 plf, Ga = 18 kips/in (SDPWS 2021 Table 4.3A).

Force transfer around openings. Published: APA Technical Note T555C, Design for Force Transfer Around Openings (FTAO) (March 2024), and WoodWorks, FTAO Analysis for Complex Shear Wall Openings (Malone, May 2023).

The slide 20 labels read V = 4,500 lb and Fo = 2,076.9 lb, the values of Example 1; T555C confirms V = 3,750 lb and an 8 ft wall, which is what is entered. Closed-form equilibrium is tested too: the piers carry V, straps add to the vertical shear above and below the opening, and the overturning balances.