Guideline, Basics and Formulas of Bar Bending Schedule [BBS]
Bar bending schedule is the ultimate list of reinforcement bars for any type of structural element. This schedule include shape, size, mark, length, location, and bending detail of reinforcement. BBS is the tabular view representation of every reinforcement bar used in different structural element.
Bar bending is the special process to bend, cut, and to fix the reinforcement bars according to the particular drawing.
Each and every RCC structural elements must have separate BBS. There is no need of grouping them. They must need to follow IS guideline for bending and length of hook.
It is very easy to memorize. Users must need to keep the shape codes of bar bending with themselves always. Users must use the thumb rule calculation of steel reinforcement to assure the estimation.
BBS Basics & Formulas to be remembered
1. Diameter of bars (in mm) – 6, 8, 10, 12, 16, 20, 25, 28, 32, 36, 40 mm
2. The standard length of reinforcement bar – 12 meter or 40 feet
3. Weight of bar (Kg) per meter formula – D2/162
Extension Length Formulas
Footing lap length formula – 40d
Column Lap length formula – 50d
Development length for dowel bars – 16d
Hook Length – 9d
Footing – 75 mm
Column & Beam – 25-50 mm
45° – 1d
90° – 2d
135° – 3d
Crank Length Formula
45° – 0.42d
30° – 0.27d
60° – 0.58d
Extra Bars Length – L/4 or L/5
Example of Bar Bending Schedule
Step 1 – Find Cutting Length of Bars
Cutting Length of Bottom Bar = Lclear – (2x concrete cover) + (2×500)
= 3000 – (2×40) + (2×500) = 3920 mm
Cutting Length of top bar = Lclear – (2x concrete cover) = 3000 – (2×40) = 2920 mm
Step 2 – Number of Stirrups
Number of Stirrups = (Length of Beam / Spacing) + 1 = (3000/200) + 1 = 16 numbers
Step 3 – Cutting Length of Stirrups
Cutting Length of stirrup = Perimeter of stirrup + (3 x 90° bend) + (2 x hook length)
= 2 (520+220) + (3 x 2d) + (2x1d) = 1480+(3x2x10) +(2×10) = 1560 mm
|Bar Bending Schedule Format|
|Bar Shape||Dia of Bar||Cutting Length||Number of Bar||Length of Bar (mm)|
|Total Length (m)||24.96||13.68||-||-||-|
|Weight Per Metre (Kg/m)||0.4||0.62||0.89||1.58||2.47|
|Total Weight in Kg||9.984||8.482||–||–||–|
1. At first this schedule suggests about the amount of steel to be procured.
2. Then This also instruct the contractor for planning of steel purchase in a week.
3. After that it also instruct the bar bender for fabrication the reinforcement into the desired shape according to the structural drawing.
4. To estimate the material, it can also instruct the quantity surveyor.
Making Process of Bar Bending Schedule
There are different type of bar bending schedule. These are mentioned below.
1. Bar bending schedule for slab
2. Bar bending schedule for beam
3. Bar bending schedule for column.
There are five steps of it. The steps are
(a) User has to find the amount of reinforcement bars for using
(b) User must find the length of cutting of each and every bar.
(c) Users have to find number of distribution bars’ calculation in one condition that is if the material is slab.
(d) Users must find the cutting length of stirrups.
(e) At last user just need to list down all the bars in the table and search the amount of steel.
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