The bar bending schedule (BBS) is essential in determining the quantity of reinforcement required for a lintel beam. This ensures proper planning and execution in construction. In this blog, we will break down the BBS for a lintel beam with step-by-step calculations.
Importance of BBS in Construction
- Accurate estimation of steel reinforcement.
- Minimises material wastage and optimises costs.
- Enhances construction efficiency and ensures structural integrity.
- Complies with IS 456:2000 and IS 2502:1963 for reinforcement detailing.
1. Calculation of Total Length of Main Bars
The length of each main bar is determined as follows:
Formula:
Length of 1 bar = Length of lintel – clear cover on both sides
Calculation:
3000 mm – (2 × 30 mm) = 2940 mm = 2.94 m
Since four bars are used:
Total length of main bars = 2.94 × 4 = 11.76 m
2. Weight of Steel for Main Bars
To determine the weight of steel required:
Formula:
Weight of steel = (D² × L) / 162
Calculation:
(16² × 11.76) / 162 = 18.53 kg
3. Determining the Number of Stirrups
Formula:
No. of stirrups = (Total length of lintel / Centre-to-centre distance) + 1
Calculation:
(3000 / 200) + 1 = 16
4. Calculation of Total Length of Stirrups
Inner dimensions:
Depth: 200 – 30 – 30 – 10 = 130 mm
Width: 200 – 30 – 30 – 10 = 130 mm
Cutting length of stirrups:
Cutting length = (2 × Depth) + (2 × Width) + Hooks – Bends
Hooks & Bends:
Hooks = 10d
Bends = 2d
No. of hooks = 2
No. of bends = 5
Calculation:
(2 × 130) + (2 × 130) + (2 × 10 × 10) – (5 × 2 × 10) = 620 mm = 0.62 m
Total length of stirrups:
0.62 × 16 = 9.92 m
5. Weight of Steel for Stirrups
Formula:
Weight of steel = (D² × L) / 162
Calculation:
(10² × 9.92) / 162 = 6.12 kg
6. Total Steel Requirement for Lintel Beam
Total weight of steel = 18.53 + 6.12 = 24.65 kg
IS Codes for Lintel Beam Reinforcement
- IS 456:2000 – General code for reinforced concrete design.
- IS 2502:1963 – Code for bending and detailing of reinforcement.
- IS 13920:2016 – Code for ductile detailing in seismic zones.
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Conclusion
A well-prepared bar bending schedule enhances construction accuracy and efficiency. By following these calculations, engineers can ensure proper reinforcement, minimising material waste while maintaining structural stability. Proper planning and execution of BBS contribute to a strong and durable lintel beam structure. Adhering to IS codes ensures standardised and safe construction practices.