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

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. Keep learning.

Also Read –

Bar Bending Schedule Of Slab

Bar Bending Schedule Of Lintel

Bar Bending Schedule Basics

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