Creating a Bar Bending Schedule (BBS) for a Reinforced Cement Concrete (RCC) sunshade is essential for accurate construction planning. This guide helps calculate the cutting length and weight of reinforcement bars used in a typical window projection.
Given Data for the Sunshade Design
- Sunshade Length: 1500 mm
- Sunshade Width: 900 mm
- Sunshade Thickness (Front): 75 mm
- Lintel Beam Width: 230 mm
- Lintel Beam Depth: 350 mm
- Main Bars: 10 mm Ø @ 150 mm c/c
- Distribution Bars: 8 mm Ø @ 150 mm c/c
- Sunshade Clear Cover: 20 mm
- Lintel Beam Cover: 25 mm
Cutting Length Calculations
Main Bar Cutting Length
The cutting length of the main bar includes straight lengths and bend allowances:
= [{sunshade thickness – (2nos. × cover)} + (sunshade width – cover) + {2nos.× (lintel width – cover)} + 100mm. + (100mm. – lintel cover) – (3nos. × 90° bend.) ]
= [{75 – (2 × 20)} + (900 – 20) + {2 × (230 – 20)} + 100 + (100 – 25) – (3 × 2 × 10)]
= [35 + 880 + 420 + 100 + 75 – 60]
= 1450 mm
= 1.45 meters
Distribution Bar Cutting Length
= 1500 – (2 × 20)
= 1500 – 40
= 1460 mm
= 1.46 meters
Number of Bars Required
Number of Main Bars
= [{1500 - (2 × 20)} ÷ 150] + 1
= [1460 ÷ 150] + 1
= 9.73 + 1 = 10.73 ≈ 11 bars
Number of Distribution Bars
= [{900 - 20 - 10} ÷ 150] + 1
= [870 ÷ 150] + 1
= 5.8 + 1 = 6.8 ≈ 7 bars
Weight of Steel Reinforcement
Main Bar Weight Calculation
Formula:
Weight (kg) = (D² × L × N) / 162
Where:
- D = Diameter of bar (mm)
- L = Length of bar (m)
- N = Number of bars
= (10² × 1.45 × 11) / 162
= (100 × 1.45 × 11) / 162
= 1595 / 162 ≈ 9.85 kg
Distribution Bar Weight Calculation
= (8² × 1.46 × 7) / 162
= (64 × 1.46 × 7) / 162
= 653.12 / 162 ≈ 4.03 kg
Summary Table
| Bar Type | Diameter (mm) | Length (m) | Quantity | Weight (kg) |
|---|---|---|---|---|
| Main Bars | 10 | 1.45 | 11 | 9.85 |
| Distribution Bars | 8 | 1.46 | 7 | 4.03 |
| Total Weight | 13.88 kg |
Click Here To See How To Calculate The Cutting Length Of Chair Bar In Footings (Step-by-Step Guide)
