STEEL CALCULATION FOR BEAM (BBS)

Steel Calculation for beam:

The quantity of the beam is very easy and simple. Just you need to know about the basics of Beam. Let solve this example to understand better.

Example:

Let us we have a simply supported beam having a cross section 300×500 mm and length of the beam is 4 m. The main bars used in this beam is 20 mm and the support bar diameter is 16 mm. The diameter of the stirrup is 12 mm and the spacing of stirrup is at an end is 100 mm and 150 mm at the mid support of the beams.



  1. Calculate the required quantity of steel for the beam?
  2. Cutting length of stirrups?
  3. 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 way 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 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 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 length of one stirrups 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 stirrups 5 bend is 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 total 38 stirrups

= 1.408 x 38

= 53.50 m

 

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:- http://www.civilclick.com/how-to-calculate-the-quantity-of-steel-in-two-way-slab-bbs/

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