Bar Bending Schedule For R.C.C Slab
BBS for R.C.C Slab:
This article is about How to prepare bar bending schedule for Slab
To preparing bar bending schedule for a Slab. there are some criteria & assumptions that require to be met Let’s get started.
- 1 Forces on Slab:
- 2 Bar Bending Schedule (BBS) used by
- 3 BBS for Slab:
- 3.1 Details from the diagram:
- 4 Steps for BBS of Slab:
- 4.1 Number of Steels:
- 4.1.1 Numbers of steel in Main bar:
- 4.1.2 Numbers of steel in Distribution bar:
- 4.1.3 Numbers of Extra bar at x-axis:
- 4.1.4 Numbers of Extra bar at y-axis:
- 4.2 Cut length of steel:
- 4.2.1 Cut Length of Main Bar:
- 4.2.2 Cut Length of Distribution Bar:
- 4.2.3 Cut Length of Extra Bar at x-axis:
- 4.2.4 Cut Length of Extra Bar at y-axis:
- 4.3 Find out lapping:
- 4.3.1 Main Bar:
- 4.3.2 Distribution Bar:
- 4.4 Number of Steels:
- 4.4.1 Numbers of steel in Main bar:
- 4.4.2 Numbers of steel in Distribution bar:
- 4.4.3 Numbers of Extra bar at x-axis:
- 4.4.4 Numbers of Extra bar at y-axis:
- 4.5 Bar Bending Schedule:
- 4.1 Number of Steels:
Forces on Slab:
you should know the normal forces action on a Slab.
If you see the shear force and bending moment diagram, the slab has high moments at center and less at ends. The shear force is maximum at the ends while at the center shear force is zero or minimum.
- Use less cutting of steel and provide desirable lapping.
- Lap another steels at same time.
- Don’t Overlap at the same position/ place.
- Between the laps end to end spacing should be provided.
Bar Bending Schedule (BBS) used by
Bar bending schedule is used by different kind of peoples and officials on construction site which is given below:
- Quantity surveyor
- Steel fixer
- Contractor
- Project manager
- Inspectors
- Clerks of construction
In construction site all estimation and costing operation is the responsibilities of quantity surveyor. The bar bending schedule gives the details to quantity surveyor for finding out the number of steel its type, size and shape. Contractor are using bar bending schedule (BBS) for ordering the steel bar for proceeding the construction. Steel fixer using bar bending schedule (BBS) for doing their work or installing the bar in column, beam or slab according to the bar bending schedule (BBS) that how much cut length or bending of bar will be needed and which size of steel should be use. The inspector and clerks of construction refers to the BBS to make are that the reinforcement work in the field is in proper with the design reinforcement as per drawing.
BBS for Slab:
Details of Slab
Details from the diagram:
- Thickness of slab is150 mm
- Development Length is 50d
- Bottom bar of slab will be provided 12 mm dia of steel is at 200 mm center to center spacing
- Top bar of slab will be provided 12 mm dia of steel is at 200 mm center to center spacing
- Extra bar of slab at x- axis will be provided 12 mm dia of steel is at 125 mm center to center spacing
- Extra bar of slab at y- axis will be provided 12 mm dia of steel is at 125 mm center to center spacing
- Stirrup spacing is 8mm @ 150 mm C/C
- Concrete Cover of slab is 25 mm
Learn More
Calculation Method For Find Out The Overlapping Length Of Beam, Column And Slab
Steps for BBS of Slab:
Generally, there are five steps for preparing the bar bending schedule of column these five is given below:
- Number of steel
- Cut length of steel
- Find out lapping
- Bar Bending Schedule
Number of Steels:
Numbers of steel in Main bar:
Number of steels = (Total length of slab ÷ spacing of bar) +1
Number of stirrups = 5000 ÷ 200 + 1
Number of stirrups = 26 numbers
Numbers of steel in Distribution bar:
Number of steels = (Total length of slab ÷ spacing of bar) +1
Number of stirrups = 5000 ÷ 200 + 1
Number of stirrups = 26 numbers
Numbers of Extra bar at x-axis:
Number of steels = (Total length of slab ÷ spacing of bar) +1
Number of stirrups = 5000 ÷ 125 + 1
Number of stirrups = 41 numbers
Numbers of Extra bar at y-axis:
Number of steels = (Total length of slab ÷ spacing of bar) +1
Number of stirrups = 5000 ÷ 125 + 1
Number of stirrups = 41 numbers
Cut length of steel:
Cut Length of Main Bar:
Length of Main bar = slab length – 2(concrete cover) + Development length (Ld) + slab Length
= 5000 – 2(25) + (12×12) + (50×12)
= 5694 mm or 5.69 m
Now we find the length of bar.
The total length of Main bar = 5694 x number of steels in slab
The total length of bar = 5694 x 26
The total length of bar = 148044 mm or 148 meter
Cut Length of Distribution Bar:
Length of Distribution bar = slab length – 2(concrete cover) + Development length (Ld) + Overlap Length
= 5000 – 2(25) + (12×12) + (50×12)
= 5694 mm or 5.69 m
Now we find the length of bar.
The total length of Distribution bar = 5694 x number of steels in slab
The total length of Distribution bar = 5694 x 26
The total length of bar = 148044 mm or 148 meter
Learn More
Bar Bending Schedule For Slab And Estimation Of Steel Reinforcement In Slab
Cut Length of Extra Bar at x-axis:
Total Length of extra bar = Length of extra bar – concrete cover
= 1500 – 2(25)
= 1450 mm or 1.450 meter
Now we find the length of bar.
The total length of extra bar at x- axis = 1450 x number of extra bar in slab
The total length of bar = 1450 x 41
The total length of bar = 59450 mm or 59.45 meter
Cut Length of Extra Bar at y-axis:
Length of Extra Bar at y-axis = slab length – 2(concrete cover)
= 1500 – 2(25)
= 1450 mm or 1.40 m
Now we find the length of bar.
The total length of Extra bar = 1450 x number of extra bar in slab
The total length of bar = 1450 x 41
The total length of bar = 59450 mm or 59.45 meter
Find out lapping:
Main Bar:
length of lapping is 50d
Lapping length = 50 x Dia of steel
Length of lapping = 50×12 = 600 mm.
We know that the length of typical steel is 12.25 m or 40 feet length
Total Length of Main Bar = 148044 m that is more than 12.25 m or 40 feet so lapping should be provided.
Length of lapping is 600 mm the result will be 148044 + 600 = 148644 m
It is mentioned already in this article, consider the points while lapping the bar. There is no one right process we can use. Just remember the lines.
- Don’t tie a column at bottom and also at top
- Lap at another bars every time
- Overlap top bars with bottom bars always
Learn More
How To Work Out The Unit Weight Of Steel
Distribution Bar:
length of lapping is 50d
Lapping length = 50 x Dia of steel
Length of lapping = 50×12 = 600 mm.
We know that the length of typical steel is 12.25 m or 40 feet length
Total Length of Main Bar = 148044 m that is more than 12.25 m or 40 feet so lapping should be provided.
Length of lapping is 600 mm the result will be 148044 + 600 = 148644 m
It is mentioned already in this article, consider the points while lapping the bar. There is no one right process we can use. Just remember the lines.
- Don’t tie a column at bottom and also at top
- Lap at another bars every time
- Overlap top bars with bottom bars always
Number of Steels:
Numbers of steel in Main bar:
Number of steels = (Total length of slab ÷ spacing of bar) +1
Number of stirrups = 5000 ÷ 200 + 1
Number of stirrups = 26 numbers
Numbers of steel in Distribution bar:
Number of steels = (Total length of slab ÷ spacing of bar) +1
Number of stirrups = 5000 ÷ 200 + 1
Number of stirrups = 26 numbers
Numbers of Extra bar at x-axis:
Number of steels = (Total length of slab ÷ spacing of bar) +1
Number of stirrups = 5000 ÷ 125 + 1
Number of stirrups = 41 numbers
Numbers of Extra bar at y-axis:
Number of steels = (Total length of slab ÷ spacing of bar) +1
Number of stirrups = 5000 ÷ 125 + 1
Number of stirrups = 41 numbers
Bar Bending Schedule:
The bar bending schedule of column is shown below in table
| S. NO | Bar Mark | Bar dia | No of bars | Length (m) | unit weight(m/kg) | weight of steel (Kg) |
| 1 | Main Bar | 12 | 26 | 148 | 0.888 | 3417 |
| 2 | Distribution Bar | 12 | 26 | 148 | 0.888 | 3417 |
| 3 | Extra Bar x-axis | 12 | 41 | 59.45 | 0.888 | 2164.45 |
| 4 | Extra Bar y-axis | 12 | 41 | 59.45 | 0.888 | 2164.45 |
| Total Weight of Reinforced Concrete Slab | 11163 | |||||
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