Wood Shear Wall Design: Wind and Seismic Governing Load per SDPWS

Example

In a commercial building in SDC C, a 12 ft × 16 ft shear wall is subject to both wind and seismic. Wind lateral force = 4,000 lb, seismic = 3,500 lb. Dead load is 80 plf. Wind uses Va = Vn/2.0 (SDPWS 4.1.4.2); seismic uses Va = Vn/2.8 (4.1.4.1). Design the wall for the governing case—select sheathing that satisfies the larger demand.

How StructSuite solves this

StructSuite's free shear wall design calculator applies SDPWS 2021 Table 4.3A (nominal unit shear Vn), §4.1.4.1 (seismic Va = Vn/2.8), and §4.1.4.2 (wind Va = Vn/2.0). It checks aspect ratio per §4.3.3 and computes boundary forces T and C per Eq 4.3-7. Enter geometry, loads, and sheathing; select hold-down in Step 4. The software evaluates both wind and seismic and shows the governing check.

Steps

1. Step 1: Geometry & Configuration

   Design consideration: Low h/b = 0.75 (12×16 ft) gives stiff wall, no aspect-ratio reduction. Commercial buildings often have larger walls. Wider b increases shear capacity and reduces overturning; taller h increases both demand and overturning. For SDC C commercial, either wind or seismic can govern—depends on building location and height.

   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 12; in the Length, b (ft) input box enter 16.

2. Step 2: Sheathing & Fasteners

   Design consideration: Design sheathing for the governing demand. If wind governs, Vn/2.0 sufficient; if seismic governs, need higher Vn to meet Vn/2.8. Tighter nail spacing (4 in. vs 6 in. edge) or thicker panel (7/16 vs 15/32) increases capacity. Commercial often uses 7/16 or 15/32 OSB with 8d.

   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.

3. Step 3: Load Definition

   Design consideration: Wind uses Va = Vn/2.0; seismic uses Va = Vn/2.8. The governing case is whichever has higher demand/capacity ratio, not higher absolute force. In SDC C (moderate seismicity), coastal or tall buildings: wind may govern. Inland, shorter: seismic may govern. Check both—design for the critical one.

   In StructSuite: Open Step 3: Load Definition. Under Lateral force at top of shear wall line, in the W — Wind (lb) input box enter 4000; in the E — Earthquake (lb) input box enter 3500.

4. Step 3: Load Definition

   Design consideration: 80 plf commercial = heavier roof, possibly floor loads, taller walls. Higher D significantly reduces hold-down demand. Overturning resisting moment ∝ D×b²; doubling D can halve required hold-down capacity.

   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 80.

5. Step 4: Boundary Members & Hold-Downs

   Design consideration: Governing load (W=4,000 or E=3,500) drives T. Even with E < W, seismic T can exceed wind T because 0.6D reduces resisting moment. Select hold-down for max T from all combinations. Commercial footings often thicker—embedment usually adequate for Simpson bolt sizes.

   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: D/C < 1 for both wind and seismic (or governing case). Commercial permit review often requires both checks documented. Chord reinforcement and collector design use T and C at boundaries.

   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.