STEEL CALCULATION FOR BEAM (BBS)
The quantity of the beam is very easy and simple. Just you need to know about the basics of Beam. Let’s solve this example to understand it better.
Example:
Let us have a simply supported beam having a cross-section of 300×500 mm and the length of the beam is 4 m. The main bars used in this beam are 20 mm and the support bar diameter is 16 mm. The diameter of the stirrup is 12 mm and the spacing of the stirrup at an end is 100 mm and 150 mm at the mid-support of the beams.
- Calculate the required quantity of steel for the beam.
- Cutting length of stirrups?
- Calculate the weight of steel.
Given data:
Length = 4 m
Height = 500 mm
Width = 300 mm
Solution:
Main bars (20 mm):
length = length of beam + development length – bend
#Where
<bend 45deg=1d 90deg=2d 135deg=3d >
<development length is the grip between steel and concrete >
Length:
Main = 4000 + (50d×2) – (2d×2)
= 4000 + (50×20×2) – (2×20×2)
= 4000 + 2000 – 80
=5920 mm or 5.92 m Ans.
For 2 nos
= 5.92×2
=11.84 m
Weight
= d2/162 × length
=20 × 20/162 × 11.84
=29.2 kg
Supports bars (16 mm):
Length = length of beam + Ld – bend
#where
<for 90 deg bend=2d>
Support = 4000 + (50d×2) – (2d×2)
= 4000 + (50×16×2) – (2×16×2)
= 4000 +1600 – 64
=5536 or 5.536 m Ans…
For 2 nos
= 5.536 × 2
=11.072 m
Weight= d2/162 × length= 16 × 16/162 × 11.072= 16.47 kg
Stirrups:
Length is divided into 2 ways 1st is at support and 2nd is at mid-support.
For end supports: (spacing 100 mm)
Length / 3:
= 4000/3
= 1333.3 m
No of stirrups
= Length/spacing + 1
= 1333.3/100+1
=14.33 use 15 No’s
Total no of stirrups for end supports
= 15×2
= 30 No’s
For mid supports: (spacing 150 mm)
Length = 1333.3 m
No of stirrups
= length /spacing + 1
= 133.3/150+1
= 7.88 use 8 nos
Cutting length of stirrups:
Cross section of stirrups is
Width = 300 mm
Height = 500 mm
A is the horizontal length of stirrup
= 300 – (2 x clear cover) – (2 x half of bar dia )
= 300 – (2 x 30) – (2 x 6)
= 228 mm
B is the vertical length of stirrup
= 500 – (2 x clear cover) – (2 x half of bar dia )
= 500 – (2 x 30) – (2 x 6)
= 428 mm
Cutting the length of one stirrup is
Cutting length
= (2 x A)+(2 x B)+(2 x 10D)-(3d x 2)-(2d x 3)
#where
<10d is hook and 3d is bend 135 for deg and 2d is bend for 90 deg>
<In one stirrup 5 bends are required>
Cutting Length:
= (2 x 228)+(2 x 428)+(2 x 10 x 12)-(3 x 12 x 2)-(2 x 12 x 3)
= 456 + 856 + 240 – 72 – 72
= 1408 mm or 1.408 m
For a total of 38 stirrups
= 1.408 x 38
= 53.50 m
The weight of stirrups is
= d2/162 x length
= 122/162 x 53.50
= 47.55 kg
Total weight of steel
= Main bars + Supports bars + Stirrups
= 29.2 + 16.47 + 47.55
= 93.22 kg
Read also:- https://www.civilclick.com/how-to-calculate-the-quantity-of-steel-in-two-way-slab-bbs/
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