CALCULATING BAR BENDING SCHEDULE FOR RCC BEAM

CALCULATING BAR BENDING         SCHEDULE FOR RCC BEAM

      Bar Bending Schedule commonly referred to as “BBS” provides details of reinforcement cutting length, type of bends, and bend length.

For example, we will take the following beam calculation!!!!!

Consider a beam of the clear length of 5000mm, 300mm wide by 450mm depth. It consists of 2-12 diameter bars at the top, and 2-16 diameter and 1 – 12 diameter bars at the bottom. The diameter of the stirrup is 8mm spaced at 180mm center to center. Clear cover to reinforcement provided is 40mm.

Now calculate the length of reinforcement based on shapes of reinforcement required for reinforced concrete beam in the above example.

We will start with bottom reinforcement, B1.

Bar shape of B1 is as shown below:

Length of B1 = clear distance between walls + 2 x width of walls – 2 x bar cover + 2 x bend length

Bend length = 6 x 16 = 96 consider as 100mm

Bend length is calculated as 6 x diameter of bar for reinforcement conforming to IS: 1786-1961

Length of B1 = 5000 + 2 x 230 – 2 x 40 + 2 x100 = 5580mm

Length of bar B2 is calculated based on shape of this bar. This bar bends up near the support as shown below:

Length of bar B2: A + B + C = 5000 + 2 x 230 – 2 x 40 + (1.414xH – H)

H = 450 – 2 x 40 – 2 x 12 – 2 x 12/2 = 334mm

B2 = 4000 + 2 x 230 – 2 x 40 + (1.414×334 – 334) = 5518.3 = 5520mm

Length of Bar T1 = 5000 + 2 x 230 -2 x 40 = 5380 mm

Length of Stirrups S1:

Stirrups are spaced at 180mm centre to centre. Stirrups are provided between walls or support for a beam.

No. of stirrups required for given beam = (5000/180)+1=29         

Length a = 450 – 2 x40 – 8 = 362mm

Length b = 300 – 2 x 40 – 8 = 212mm

Therefore length of 1 stirrup S1 = 2 x (212 + 362 + 90) = 1328 mm

Where 90mm is the minimum hook length as per IS 2502 – Table – II

Finally, We got BBS,

No.	Bar Mark	Bar dia (mm)	No. of bars	Length (mm)		Weight of bars (kg)
1	B1	16	2	5580		14.5
2	B2	12	1	5520		4.02
3	T1	12	2	5380		7.80
4	S1	8	24	1330		12.6