Seismic Shear Wall Design: SDC D Residential per SDPWS 4.1.4.1

Example

In a residential building in Seismic Design Category D, a 9 ft × 10 ft wood-frame shear wall carries a lateral seismic force of 3,200 lb at the top. Dead load is 60 plf. Design the shear wall per SDPWS §4.3.5, §4.3.6. Seismic capacity uses Va = Vn/2.8 per SDPWS 4.1.4.1.

How StructSuite solves this

StructSuite's free shear wall design tool applies SDPWS §4.1.4.1 (seismic Va = Vn/2.8), Table 4.3A (nominal Vn), §4.3.3 (aspect ratio), Eq 4.3-7 (boundary forces T, C). Enter geometry in Step 1, lateral force in Step 3, gravity in Step 3; select sheathing in Step 2. In Step 4 Boundary Members & Hold-Downs, select a Simpson Strong-Tie hold-down model to satisfy overturning demand. Design Verification (Step 5) shows D/C check.

Steps

1. Step 1: Geometry & Configuration

   Design consideration: In SDC D, shear walls are primary lateral system. Aspect ratio h/b < 2 avoids SDPWS §4.3.3.2 reduction. Taller walls (larger h) increase overturning and drift; wider walls (larger b) increase capacity. For 9×10 ft residential (h/b=0.9), wall is relatively stiff. Plan dimensions must match actual framing—openings reduce effective b.

   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 9; in the Length, b (ft) input box enter 10.

2. Step 3: Load Definition

   Design consideration: Seismic force E is ASD; Va = Vn/2.8 (SDPWS §4.1.4.1) reflects higher uncertainty than wind (Vn/2.0). In SDC D, base shear distributed by Fx to diaphragms then to wall lines. E = 3,200 lb for 9×10 ft wall is typical for two-story residential in moderate-to-high seismicity. Higher E requires tighter nails or thicker panel.

   In StructSuite: Open Step 3: Load Definition. Under Lateral force at top of shear wall line, in the E — Earthquake (lb) input box enter 3200.

3. Step 3: Load Definition

   Design consideration: Seismic overturning uses 0.6D (ASCE 7) because D is the only reliable resisting force during shaking. L is not counted. For residential 60 plf, net uplift = V×h/b − 0.6×60×b/2. Lighter walls (lower D) need larger hold-downs. 60 plf typical for wall + tributary roof/floor in wood-frame residence.

   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 60.

4. Step 2: Sheathing & Fasteners

   Design consideration: Seismic Va = Vn/2.8 is stricter than wind Vn/2.0, so seismic often governs. In SDC D, 7/16 OSB with 8d at 6 in. or 4 in. edge is common. Tighter spacing (4 in.) adds capacity but labor cost. Blocked construction per Table 4.3A allows higher values.

   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: Seismic overturning T is often 1.5–2× wind for same shear because 0.6D reduces resisting moment. In SDC D, hold-downs are mandatory at chord ends. Simpson capacity: DF/SP > SPF/HF. Embedment depth for anchor bolt—per ACI 318 or ICC-ES—must exceed tabulated minimum; 5/8 in. bolt often needs 10–14 in. in concrete.

   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 confirms adequate capacity. Seismic detailing (full height blocking, proper nailing) often as important as capacity. Hold-down deflection affects story drift; stiffer models (e.g., HDUE vs DTT) reduce drift for tall walls.

   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.