Shear Wall Aspect Ratio Check: Tall Wall Design per SDPWS 4.3.3

Example

A narrow 10 ft tall × 4 ft wide shear wall in a residential building carries 1,800 lb wind load at the top. Aspect ratio h/b = 2.5 exceeds the 2:1 limit for unblocked wood structural panels (SDPWS Table 4.3.3). Apply the 4.3.3.2 adjustment factor. Dead load is 40 plf. Select sheathing, verify capacity, and size hold-down.

How StructSuite solves this

StructSuite's free shear wall design calculator applies SDPWS §4.3.3 (aspect ratio limits), §4.3.3.2 (adjustment factor 1.25 - 0.125(h/b) when h/b > 2), Table 4.3A (Vn), and §4.1.4.2 (Va = Vn/2.0 for wind). Design verification shows 4.3.5.5.1 Exception 1 and 4.3.3.2 checks. Step 4: select hold-down model.

Steps

1. Step 1: Geometry & Configuration

   Design consideration: h/b = 2.5 exceeds SDPWS Table 4.3.3 limit of 2:1 for unblocked panels. Tall narrow walls are flexible—more drift, less effective as cantilever. Factor 1.25 − 0.125(h/b) = 0.9375 reduces capacity. Adding width (b) or using blocked construction avoids reduction. Common where openings (window, door) limit wall width.

   In StructSuite: Open Step 1: Geometry & Configuration. In the Shear wall line — segments and spacing area, for Shear Wall 1: in the Height, h (ft) input box enter 10; in the Length, b (ft) input box enter 4.

2. Step 3: Load Definition

   Design consideration: 1,800 lb for 10×4 ft wall = 450 plf unit shear. Moderate wind zones (Risk Cat II) often govern over seismic for single-story. In SDC D+, seismic may control—check both when both apply.

   In StructSuite: Open Step 3: Load Definition. Under Lateral force at top of shear wall line, in the W — Wind (lb) input box enter 1800.

3. Step 3: Load Definition

   Design consideration: 40 plf is light—typical for narrow wall with minimal tributary. Lower D increases hold-down demand: T ∝ V×h − 0.6D×b²/2. Narrow wall + light D = large T; may need HDUE-size hold-down instead of DTT.

   In StructSuite: Open Step 3: Load Definition. Under Gravity loads on walls, click the + Add gravity load button. In the new row, set Type = D in the dropdown; set Distribution = Uniform (lb/ft); in the Value (plf) input box enter 40.

4. Step 2: Sheathing & Fasteners

   Design consideration: 4.3.3.2 reduces Va; need higher base Vn to compensate. Tighter nail spacing (4 in. or 3 in. edge) or blocked construction increases capacity. 7/16 OSB with 8d at 4 in. common for tall narrow walls.

   In StructSuite: Open Step 2: Sheathing & Fasteners. In the SDPWS 2021 Table 4.3A grid, locate the row for your panel type (e.g., Wood Structural Panels - Sheathing, 15/32 in., 8d common) and click the cell in the column for the desired nail spacing (e.g., 6 in. edge). The nominal unit shear will populate. Open Step 5: Design Verification to confirm wind and seismic capacity checks pass.

5. Step 4: Boundary Members & Hold-Downs

   Design consideration: h/b=2.5 produces high T: overturning moment V×h is large, resisting arm b is small. Hold-down stiffness affects drift—flexible DTT may add 0.1–0.2 in. deflection. For drift-sensitive designs, HDUE preferred.

   In StructSuite: Open Step 4: Boundary Members & Hold-Downs. Under Hold-down model, select DF/SP or SPF/HF for species. In the Simpson Strong-Tie table, click the row for a hold-down model (e.g., DTT2Z® for 1825 lb DF/SP, 1/2 in. anchor bolt) whose capacity exceeds the max tension (T) from overturning. The anchor bolt diameter column shows required bolt size. Open Step 5: Design Verification to confirm D/C ≤ 1.

6. Step 5: Design Verification

   Design consideration: 4.3.3.2 factor must be applied to Va. Both shear (unit demand ≤ Va) and overturning (T ≤ hold-down capacity) must pass. Tall narrow walls often hold-down critical.

   In StructSuite: Open Step 5: Design Verification. Scroll to verify capacity checks pass for each wall. Open Step 6: Summary & Visualization. Use the boundary forces T and C shown for hold-down specification at chord locations. Note: Hold-down sizing UI is under construction.

Live design (pre-filled)

The form below is the real StructSuite module with example data loaded. Display only—values cannot be changed.