Concrete · Special elements
Circular water tank wall calculator
Hydrostatic hoop tension, hoop reinforcement for a limiting steel stress and stored volume.
Standard: Hoop tension · AS 3735 steel stress limits
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 |
|---|---|---|
| Internal diameter | 10 | m |
| Water depth | 4 | m |
| Wall thickness | 250 | mm |
| Steel stress limit (crack control) | 150 | MPa |
| Hoop bar diameter | 16 | mm |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Max hoop tension (base, free-sliding) | 196.2 | kN/m |
| Hoop steel As = T/fs | 1,308 | mm²/m |
| Per face | 654 | mm²/m |
| N16 spacing per face | 300 | mm |
| Stored volume | 314 | m³ |
- ✓ Steel stress limit ≤ 150 MPa (typical for severe exposure)
- ✓ Wall ≥ 150 mm (practical minimum)
Method, formulas and assumptions
- T = γw·H·D/2 at the base for a free (sliding) base
- Fixed or pinned bases reduce hoop tension near the base and add vertical bending (not computed)
- Steel stress limit from AS 3735 crack-control provisions: choose by exposure classification
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.