Example
A 8 in. diameter round post, 10 ft tall, pinned both ends. Load 5000 lb D+L. Southern Pine. NDS 2024 §3.7.3: round columns designed as equivalent square (same area). Common for timber frame, poles.
How StructSuite solves this
StructSuite: select Sawn Lumber (or appropriate product), round cross-section. Enter diameter 8 in. Equivalent square b=d=√(π×8²/4)≈7.09 in. NDS 2024 §3.7.3. Axial capacity per Eq 3.7-1. 8 in. round ≈ 7×7 equivalent; capacity similar to 6×6 sawn at same height.
Steps
- Step 1: Geometry & End Conditions
Design consideration: NDS §3.7.3: equivalent square b=d=√(πD²/4). 8 in. round → 7.09 in. square. Le/d uses equivalent d. Round has same area as square; buckling uses √A. Tapered poles: use avg or conservative D. 6–12 in. dia common.
In StructSuite: Open the Geometry section. In the Unbraced length (ft) input box enter the column height. Use the End condition dropdown to select the end fixity (Fixed-Fixed Ke=0.65; Pinned-Pinned Ke=1.2; Fixed-Free Ke=2.4 per NDS 2024 Table G1). Select the column size (e.g., 4×4, 6×6) from the dropdown or size table.
- Step 3: Material & Section
Design consideration: Round posts: Southern Pine, DF peeler. Design values from NDS. PT for ground contact. Poles (utility, lighting): ASTM D3200, D2899. Round timber vs sawn: different grading; verify product.
In StructSuite: Open the Materials section. Use the Product dropdown to select Sawn Lumber, LVL, or Glulam. In the Species dropdown select Douglas Fir-Larch, Hem-Fir, Southern Pine, Spruce-Pine-Fir, etc. In the Grade dropdown select #2, #1, Select Structural, etc. NDS 2024 Supplement Tables 4A–4D provide Fc and Emin.
- Step 2: Load Definition (ASCE 7-22 / NDS 2024)
Design consideration: 5 kip concentric. Eccentric (cantilever post, lateral): beam-column. Wind on sign, canopy: adds moment. CD=1.6 for W, E. Self-weight for 10+ ft poles.
In StructSuite: Open the Loads section. Click Add load case. In the Type dropdown select D, L, Lr, S, W, or E. In the Axial load (lb or kip) input box enter the load. CD = 1.6 for wind/earthquake per NDS Table 2.3.2. Add all applicable load cases. Include self-weight if significant.
- Step 5: Design Verification
Design consideration: 8 in. round ≈ 7×7 square capacity. At 10 ft, ~6–8 kip typical. Bearing uses full area πD²/4. Pitfall: Le/d with D instead of √(πD²/4) overestimates capacity. Round often used for appearance (timber frame, rustic).
In StructSuite: Open the Design Verification section. StructSuite checks axial capacity per NDS 2024 Eq 3.7-1 (buckling) and Fc⊥ bearing. Review the D/C ratios. If overstressed, increase size in the Geometry section or reduce unbraced length. Slenderness ratio Le/d ≤ 50 for sawn lumber per NDS.
Live design (pre-filled)
The form below is the real StructSuite module with example data loaded. Display only—values cannot be changed.
Wood Column — Design per 2024 NDS
NDS 2024 Ch. 3 — Solid columns (3.6.2.1) per Section 3.7
Column unbraced length and end conditions per NDS 3.7. Ke affects buckling capacity.
Buckling modes |  |  |  |  |  |  |
| Select mode | ||||||
| Theoretical Ke value | 0.5 | 0.7 | 1.0 | 1.0 | 2.0 | 2.0 |
| Recommended design Ke when ideal conditions approximated | 0.65 | 0.80 | 1.2 | 1.0 | 2.10 | 2.4 |
| End condition code |  | Rotation fixed, translation fixed | ||||
 | Rotation free, translation fixed | |||||
 | Rotation fixed, translation free | |||||
 | Rotation free, translation free | |||||
Le = Ke × L. Use different Le for strong/weak axes if bracing differs.
L1: total unbraced height. L2: unbraced length above intermediate brace. Le = Ke × L.