Columns are the steel-heaviest members per metre in a house frame. Working out one column precisely lets you check the bar bending schedule and the steel order.
Inputs (from the drawing)
| Item | Example |
|---|---|
| Column size | 230 × 300 mm |
| Main bars | 6 nos, 12 mm |
| Ties | 8 mm @ 150 mm c/c |
| Storey height | 3.0 m |
| Clear cover | 40 mm |
| Lap | 50d = 600 mm |
Main Bars
- Length per bar = 3.0 + 0.6 lap = 3.6 m
- Total = 6 × 3.6 = 21.6 m
- Weight = 21.6 × 0.888 = 19.2 kg
Ties
Cutting length of one tie:
- Inner width = 230 − 2 × 40 = 150 mm
- Inner depth = 300 − 2 × 40 = 220 mm
- Perimeter = 2 × (150 + 220) = 740 mm
- Two 135° hooks: 2 × 10 × 8 = +160 mm
- Bend deductions: three 90° (3 × 2 × 8 = 48) + two 135° (2 × 3 × 8 = 48) = −96 mm
- Cutting length ≈ 804 mm
Number of ties: 3,000 ÷ 150 + 1 = 21
Weight: 21 × 0.804 × 0.395 = 6.7 kg
Many designs close the tie spacing near beam junctions, which adds a few ties.
Total
| Part | Weight |
|---|---|
| Main bars | 19.2 kg |
| Ties | 6.7 kg |
| Per column per floor | ≈ 26 kg |
Multiply by the number of columns of this type on each floor, then add the footing starter bars and the length into the footing for the ground floor.
The Short Version
Bars × (height + lap) × kg/m, plus ties × cutting length × kg/m. A typical 230 × 300 mm house column carries about 26 kg of steel per floor.
