BBS Of Beam – Bar Bending Schedule For Beam [Steel Quantity]

Bar bending schedule or BBS plays an important role in construction. In this article, I will discuss how to prepare BBS for beam.

Bar Bending Schedule For Beam

This beam has more technical design implementation than the above simple beam. Let’s get started.

The beam has a clear span of 5 meters consisting of two bottom layers (2 no.s of 20 mm dia and 2 no.s of 16 mm dia) and one top layer (2 no.s of 12 mm dia).

It consists of 3 zones where zone 1 and zone 3 have 8 mm dia stirrups with a spacing of 150 mm & Zone 2 has 8 mm dia stirrups with a spacing of 200 mm.

Clear Span of Beam = 5000 mm

Development Length Ld = 50d (assumption)

Clear Cover on any ends = 25 mm

Bottom – 2 no.s 20Ø and 2 no.s of 16Ø

Top – 2 no.s of 12Ø

Stirrups

Zone 1,3 = 8Ø @ 150mm clear cover

Zone 2 = 8Ø @ 200mm clear cover

Step 1 – Calculate Cutting Length Of Top Bar

Cutting length of top bar = Clear Span of Beam + Development length – Bend

Where bend for 45deg=1d, 90deg=2d, 135deg=3d 

Cutting length = L + (2 x Ld) – (2 x 2d)

= 5000 + (2 x 50 x 12) – (2 x 2 x 12) 

= 5000 + (2 x 50 x 12) – 50

= 6152 mm

Step 2 – Calculate Cutting Length Of Bottom Bar

For First Layer (20Ø):

Cutting length of bottom bar = Clear Span of Beam + Development length – Bend

Where bend for 45deg=1d, 90deg=2d, 135deg=3d 

Cutting length = L + (2 x Ld) – (2 x 2d)

= 5000 + (2 x 50 x 20) – (2 x 2 x 20)

= 6920 mm

For Second Layer (16Φ):

Cutting length of bottom bar = Clear Span of Beam + Development length – Bend

Cutting length = L + (2 x Ld) – (2 x 2d)

= 5000 + (2 x 50 x 16) – (2 x 2 x 16)

= 6536 mm

Step 3 – Calculate Number of Stirrups

This beam has three zones where Zone 1 & 2 consist of 8 mm dia stirrups of 150 mm spacing and Zone 3 has 8 mm dia stirrups of 200 mm spacing.

First we need to calculate the length of each zone = L/3 = 5000/3 = 1666 mm

Number of stirrups required for Zone 1 = (Clear Span of beam/ Spacing  of stirrups) + 1

= (1666/150)+1 = 12.10 ♎ 12 no.s

Number of stirrups required for Zone 3 = Same as Zone 1 = 12 no.s

Number of stirrups required for Zone 2 = (Clear Span of beam/ spacing Stirrups) – 1 = (1666/200) – 1 = 7 no.s

The reason for the “minus 1 “ is already zone 1 has end stirrup so we don’t need to again start from the new one. we just continue the stirrups already existing with extra spacing.

Cutting length of stirrups:

Cross section of stirrups is

Width  = 300 mm

Height = 500 mm

a is horizontal length of stirrup

= 300 – (2 x clear cover) – (2 x half of bar dia )

= 300 – (2 x 25) – ( 2 x 4)

= 242 mm

b is vertical length of stirrup

= 500 – (2 x clear cover) – (2 x half of bar dia)

= 500 – (2 x 25) – (2 x 4)

=442

Now calculate cutting length of stirrup

Cutting length = 2 x (a+b) + hook – bend

= 2 x ( 242 + 442) + (9d x 2) – (3d x2) – (2d x 3) [For 2 no. 135 bend (3dx2) & for 3 no. 90 bend (2dx3)]

= 2 x 684 + (9 x 8 x2) – (3 x 8 x 2) – (2 x 8 x3)

= 926 + 144 – 48 – 48

= 974 mm = 0.97 m

Calculate Weight Of Stirrups:

Total no. of stirrups = 12 + 12 + 7 = 31

Total length of stirrups = 0.97 x 31 = 30.19 m

Total weight of stirrups = d2xL/162 = 8 x8 x 30.19/162 = 12 kg

BBS Of Beam:

	Diameter of Bar (mm)	Numbers	Cutting Length m	Total Length m	Total Weight kg
Top Bar	12	2	6.152	12.30	10.93
Bottom Bar	20	2	6.920	13.84	34.6
Bottom Bar	16	2	6.536	13.07	20.91
Stirrup	8	31	0.974	30.19	12

I hope you can now prepare bbs of beam easily. Happy learning.

Also Read

Bar Bending Schedule Of Slab

Bar Bending Schedule Of Lintel

Bar Bending Schedule Basics

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