Steel · Columns & beam-columns
Rod bracing (tension-only) calculator
Brace force from the bay shear and geometry with a prestress allowance, threaded rod capacity on the tensile stress area.
Standard: AS 4100 Cl 7
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 |
|---|---|---|
| Bay design shear | 60 | kN |
| Bay width | 6 | m |
| Bay height | 4.5 | m |
| Rod diameter | 24 | mm |
| Rod fu | 400 | MPa |
| Rod fy | 250 | MPa |
| Prestress allowance | 10 | % |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Brace angle | 36.87 | ° |
| Brace force V/cos θ (+ prestress) | 82.50 | kN |
| Gross area | 452.4 | mm² |
| Threaded stress area ≈ 0.78 Ag | 352.9 | mm² |
| φNt = 0.9 min(Ag fy, 0.85 As fu) | 101.8 | kN |
- ✓ Rod capacity
Method, formulas and assumptions
- Brace angle = DEGREES(ATAN(4.5/6)) = 36.87 °
- Brace force V/cos θ (+ prestress) = 60/COS(RADIANS(36.87))*(1+10/100) = 82.5 kN
- Gross area = PI()*24^2/4 = 452.39 mm²
- Threaded stress area ≈ 0.78 Ag = 0.78*452.39 = 352.86 mm²
- φNt = 0.9 min(Ag fy, 0.85 As fu) = 0.9*MIN(452.39*250,0.85*352.86*400)/1000 = 101.79 kN
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.