Timber · Columns & studs
Timber wall stud: axial load and wind calculator
Load-bearing stud carrying the roof or floor load and face wind pressure. Slenderness about the major axis uses the full stud height and about the minor axis the nogging spacing; k12 follows from ρc·S. Combined actions are checked with AS 1720.1 Eq 3.5(1) about the major axis and pure compression about the minor axis.
Standard: AS 1720.1-2010 Cl 3.3 (compression, k12 from ρc·S), Cl 3.2 (bending), Cl 3.5 combined (N*/Ncx)² + M*/Mdx ≤ 1 · AS 1684 practice for nogging restraint
Inputs in the worked example
The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.
| Input | Value | Unit |
|---|---|---|
| Grade | MGP10 | |
| Stud breadth (minor axis) | 45 | mm |
| Stud depth (major axis) | 90 | mm |
| Stud spacing | 600 | mm |
| Stud height | 2.7 | m |
| Nogging spacing (minor-axis restraint) | 1.35 | m |
| Axial line load on the wall (design) | 8 | kN/m |
| Wind pressure on the wall (design) | 1 | kPa |
| k1 (wind combination) | 1 | |
| Temporary/total load ratio r | 0.25 | |
| φ | 0.85 |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| N* per stud | 4.80 | kN |
| M* per stud (wind) | 0.547 | kNm |
| ρc | 0.958 | |
| Major axis S3 = H/d → k12 | 30.0 → 0.242 | |
| Minor axis S4 = Lay/b → k12 | 30.0 → 0.242 | |
| φNcx / φNcy | 15.01 / 15.01 | kN |
| φMdx | 0.878 | kNm |
| Combined (N*/φNcx)² + M*/φMdx | 0.725 |
- ✓ Combined actions (major axis) — 73 %
- ✓ Minor-axis compression
- ✓ Bending alone
Method, formulas and assumptions
- ρc = 11.39(E/f′c)^−0.408·r^−0.074; k12 = 1 (ρcS ≤ 10), 1.5 − 0.05ρcS (≤ 20), 200/(ρcS)².
- Major axis S3 = Lax/d over the full height; minor axis S4 = Lay/b between noggings (sheathing ignored).
- AS 1720.1 Eq 3.5(1): (N*/φNcx)² + M*x/φMbx ≤ 1 and N*/φNcy ≤ 1; k12 = 1 in bending (compression edge restrained by lining). Grade properties are typical: confirm against AS 1720.1 / supplier.
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.