Bar Bending Schedule Basic Formulas | BBS Formula | What is BBS

Bar Bending Schedule Basic Formulas | BBS Formula | What is BBS | Hook Length | Cut Length of Straight Bar | Cut Length of Bend up Bar or Crank Bar | Length of Extra Bars | Hook’s Length Formula for Stirrups | Lap Length:

In this Article today we will talk about the Bar Bending Schedule Basic Formulas | BBS Formula | Hook Length | Cut Length of Straight Bar | Cut Length of Bend up Bar or Crank Bar | Length of Extra Bars | Hook’s Length Formula for Stirrups | Lap Length | Bar Bending Schedule format. These are the important Tips to make and find the steel cutting length and Prepare bar bending schedule, must watch the tutorial video about Basic BBS formulas in the bottom of this post.

What is  Bar Bending Schedule?

In Civil Engineering Bar Bending Schedule is the important part of Estimation chart. In the Bar Bending schedule provides the reinforcement (steel) calculation for reinforcement of concrete column , beam and slab cutting length and also use to find the types of bends of length which we provide in steel structures. Bar Bending Schedule format

BBS is used in finding cutting length of steel and total weight of steel per unit area. and we can make the bar bending schedule in Ms office Excel software.

It is important to learn the basics before dealing with BBS or Bar Bending Schedule format

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3. Bar Bending Schedule of RCC Beam in Excel | BBS of Beam in Excel

Bar Bending Schedule Basics Formula | Calculation of Reinforcement Shape, Cutting and Bending Lengths:

Bar Bending Schedule Formulas:

1. Commonly Used Diameter of Reinforcement Bars (in mm):

Diameter of Reinforcement Bars (in mm)

6mm, 8mm, 10mm, 12mm, 16mm, 20mm, 25mm, 28mm, 32mm, 36mm, 40mm

Diameter of Reinforcement Bars (in inches) 

#3 (3/8″) , #4 (1/2″), #5(5/8″) , #6(3/4″) , #7(7/8″) , #8(1″) , #9(9/8″) , #10(10/8″)

2. Standard Length of Reinforcement Bars:

The standard length of reinforcement bars is 12m or 40 ft Bar Bending Schedule format

3. Weight of Bar Per meter Length (in kg/m):

The weight per length of the reinforcement bars is expressed as,

Weight per meter = D²/ 162

For example; if the diameter of the reinforcement bar is 6mm, then,

Weight per meter = 6²/ 162

= 0.222 kg/m how to prepare bar bending schedule

(Note: you should keep the  value of D in mm and the answer comes in m.)

4. Weight of Reinforcement Bar per 12 m Length (kg/ bar)

The weight per bar can be expressed as,

Weight / bar = Weight of Bar per m x Standard Length of Bar

= 0.225 x 12

= 2.7 kg/bar how to prepare bar bending schedule

5. Weight of Bar Per feet Length (in kg/ft):

The weight per bar can be expressed as,

Weight per feet = D² / 533

For example; if the diameter of the reinforcement bar is #4 i.e. ½ in or 12.70mm, then,

Weight per feet = 12.70²/ 533 = 0.302 kg/ft (since, D must be in mm)

Also, how to prepare bar bending schedule

Weight per feet = D²/ 52.896 

For example; if the diameter of the reinforcement bar is #4, then,

Weight/ Length = 4²/ 52.896 = 0.302 kg/ ft (since, D must be in #No.)

6. Weight of Reinforcement Bar per 40 ft Length (kg/ bar)

The weight of reinforcement bar per bar can be expressed as,

 Weight / Bar = (D²/ 533 ) x standard length of bar

For example; if the diameter of the reinforcement bar is 12.70mm (#4), then,

Weight/ bar = (12.70²/ 533) * 40

= 12.10 kg/ bar

so the weight of 40ft bar is 12.10 kg/bar

7. Cutting Length of Main Reinforcement Bar with Hook:

Length of Hook = 9d, where d is the diameter

Length of Main Bar = L + 9d + 9d

8. Cutting Length of Main Bar with Bend:

Length of bend = 10d – 6d

Length of Main Bar = L + 12d + 12d

9. Concrete Cover:

Cover basically includes a clear cover and effective cover.

Clear cover for

footing is taken as 75mm,

for column 25mm to 50mm,

for beam 25 to 50mm and

for slab 25mm

10. Hook Length for Stirrups:

The hook length is commonly provided for stirrups

Hook Length = 9D [D is Diameter of the Bar]

Hook Length | Bar Bending Schedule

Total Length of stirrup = Total length of Bar + 2 x Hook Length (Two hooks)

Total Length = L+2(9D)

Therefore Total length = L+18D (D is Diameter of bar)

But in some cases, we will consider 10D

IS code recommends hook length should not be less than; Minimum Hook Length = 75mm

11. Length of Straight Bar with Bends:

Total Length = Length of Straight Portion + 2(Hook Length)

Length of Straight Bar Formula | Bar Bending Schedule

12. Additional Length for Bent up or Crank Bar with Bends:

The additional length (la) that is introduced in the simple, straight end-to-end length of a reinforcement bar due to being bent up at (Theta) say 30o to 60o,

but it is generally 45o = l1 – l2 = la

Where,

Fig: Hooks and bends in Reinforcement

Giving different values to angle 30 degree, 45 degree and 60 degree

respectively), we get different values of la, as tabulated below:

Figure 2 presents the procedure to arrive at the length of hooks and the total length of a given steel reinforcement.

For 45 Deg | Crank length is provided in Slab  Shear stress is maximum at supports in Slab. So, to resist this stress we usually crank the bars at the ends of supports in slab.

Crank bar is bent up at an angle of 45 degree with the length of 0.42D

D = Depth of Slab-Top Cover-Bottom cover

13. Length for Extra Bars:

Now a days Extra bar is also provided under every crank bar. To keep crank bar in position. (Refer above image for clear idea).

14. Bend Hook Length Formula for Column:

Bend Length is usually provided in columns at ends to tie the columns to the footings.

Bend Length = 16D  [D is Diameter of the Bar]

15. Overlap Length / Lap Length in Reinforcement (Bar Bending Schedule):

Suppose the length of building is 20 m. The standard length of Rebar is 12m. We have to join two Re-bars for the total length of building. In order to Join the two bars (overlap). Overlap length is adopted.

Neck Column to Footing Overlapping = 40d – 50d

Column to Column or Beam Overlapping = 50d

Development Length for Dowel Bars = 16d

General overlapping on Completion of 12m bar = 50d

or we can say that,

Overlap Length for compression members = 40D

Overlap Length for tension members = 50D

[D is the Diameter of the bar]

16. Hook’s Length Formula for Stirrups:

Hook’s Length for Stirrups are mostly equal to 10d, Where d is dia of bar.

Rectangular Stirrups:

Rectangular Stirrups | Length of Stirrups = 2A + 2B + (2 x 10d)

Cutting Length of Rectangular Stirrups | Bar Bending Schedule

Triangular Stirrups:

Triangular Stirrups | Length of Stirrups = 3H + (2 x 10d)

Cutting Length of Triangular Stirrups | Bar Bending Schedule

Circular Stirrups:

Circular Stirrups | Length of Stirrups = (3.142 x Dia of Steel Ring) + (2 x 10d)

Cutting Length of Circular Stirrups | Bar Bending Schedule

Diamond Stirrups:

Diamond Stirrups | Length of Stirrups = 4H + (2 x 10d)

Cutting Length of Diamond Stirrups | Bar Bending Schedule

Spiral Stirrups:

Spiral Stirrups | Length of Stirrups = Length of Spiral or Helix Bar = n x (C2 + P2)^0.5

where,

• n = No. of Pitches = n = H/p + 1
• C = 3.142 x d
• P = Pitch or Spacing between spirals

17. Bend Deduction

As per Pakistan or some other countries, there is no need for bend deduction but as per Indian standards we should consider bend deduction as per the following procedure;

For 45 deg bend = 1d

For 90 deg bend = 2d

For 135 deg bend = 3d

For 180 deg bend = 4d

18. Rolling Margin of Reinforcement Steel Bar Formula:

Cut reinforcement bar into 3 pieces, each length 1 meter Weight Each piece differently i.e. 10 mm Día Bar, Reinforcement calculation excel

1st one weight 0.617,

2nd one weight 0.62,

3rd one weight 0.625

Now Calculate the rolling margin of Reinforcement bar

19. Development Length for Reinforcement Bars:

20. Bar Bending Schedule Basic Formulas | Video Tutorial

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2. How to Calculate Cutting Length of Stirrups

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5. Bar Bending Schedule for footings | Steel Estimation for footings

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7. Design Example of Dog Legged Staircase

FAQs:

Conclusion:

Full article on Bar Bending Schedule Basic Formulas | BBS Formula| Hook Length | Cut Length of Straight Bar | Cut Length of Bend up Bar or Crank Bar | Length of Extra Bars | Hook’s Length Formula for Stirrups | Lap Length. Thank you for the full reading of this article in “The Civil Engineering” platform in English. If you find this post helpful, then help others by sharing it on social media. If you have any question regarding article please tell me in comments.