Beams link the frame together, and a house has dozens of them. Calculating one typical beam shows how the steel order builds up.
Inputs (from the drawing)
| Item | Example |
|---|---|
| Beam | 230 × 450 mm, clear span 4.0 m |
| Bottom bars | 3 nos, 12 mm |
| Top bars | 2 nos, 12 mm |
| Stirrups | 8 mm @ 150 mm c/c |
| Cover | 25 mm |
| Anchorage into columns | 50d = 0.6 m each end |
Main Bars
- Length per bar = 4.0 + 2 × 0.6 = 5.2 m
- Bars = 3 bottom + 2 top = 5
- Total = 5 × 5.2 = 26 m
- Weight = 26 × 0.888 = 23.1 kg
Stirrups
- Cutting length (from the bar bending schedule example) ≈ 1.224 m
- Number = 4,000 ÷ 150 + 1 = 27.7 → 28
- Weight = 28 × 1.224 × 0.395 = 13.5 kg
Total
| Part | Weight |
|---|---|
| Main bars | 23.1 kg |
| Stirrups | 13.5 kg |
| Per beam | ≈ 36.6 kg |
Add any extra top bars over supports, laps where bars are joined on long beams, and 2–5% cutting waste.
The Short Version
Main bars × (span + anchorage) × kg/m plus stirrups × cutting length × kg/m. A typical 4 m house beam carries about 35–40 kg of steel.
