All about civil construction knowledge- PARAM VISIONS

Bar bending schedule (BBS) of a pile cap.(Part-2) / Calculating the cutting length & weight of reinforcement in a pile cap.

  Part -1   👈 Back     


5. Side face or roundup bar:

Theoretically, the side face bars are the stirrups to hold the pile cap reinforcements as shown in the drawing.




But practically, if the size of the pile cap is large, the side face bars need lapping as the length exceeds 12m. So, in such cases, the side face bars are provided in two equal U-shape parts as shown below.



The cutting length of the side face bar

= [{2nos. × ( a +b )} +( 2nos. × hook length) - (3nos. × 90° bend) - (2nos. × 135° bend)]

Where,

a = [ pile width - ( 2 × cover) - (2nos. ×1/2 × dia. of bar)]

   = [ 2500mm. - ( 2 × 50mm. ) - ( 2nos. × 1/2 × 12mm.)]

 a  = 2388mm.


b= [ pile length - ( 2 × cover) - (2nos. ×1/2 × dia. of bar)]

   = [ 3200mm. - ( 2 × 50mm. ) - ( 2nos. × 1/2 × 12mm.)]

  b = 3088mm.


The cutting length of the side face bar

= [{2nos. × ( 2388mm. + 3088mm. )} +( 2nos. × 10d) - (3nos. × 2d) - (2nos. × 3d)]

= [{2nos. × ( 5476mm. )} + ( 2nos. × 10 × 12mm.) - (3nos. × 2 × 12mm.) - (2nos. × 3 × 12mm.)]

[{10958mm.} + ( 240mm.) - (72mm.) - (72mm.)]

= 11054mm.

= 11.054m. < 12m.

Hence no lapping is required.


B. No of rebars: 

1. No. of bottom bar layer -1 required

  = [{ length of pile cap - (2nos. × clear cover)} ÷ c/c distance ] + 1

 =  [{ 3200mm. - (2nos. × 50mm.)} ÷ 125mm. ] + 1

=   [{ 3100mm.} ÷ 125mm. ] + 1

= 24.8 +1

= 25.8.

By rounding off = 26 nos.


2. No. of Top bar layer -1 required

  = [{ length of pile cap - (2nos. × clear cover)} ÷ c/c distance ] + 1

 =  [{ 3200mm. - (2nos. × 50mm.)} ÷ 150mm. ] + 1

=   [{ 3100mm.} ÷ 150mm. ] + 1

= 20.66 +1

= 21.66

By rounding off = 22 nos.


3. No. of bottom bar layer -2 required

  = [{ width of pile cap - (2nos. × clear cover)} ÷ c/c distance ] + 1

 =  [{ 2500mm. - (2nos. × 50mm.)} ÷ 125mm. ] + 1

=   [{ 2400mm.} ÷ 125mm. ] + 1

= 19.2 +1

= 20.2

By rounding off = 21 nos.


4. No. of top bar layer -2 required

  = [{ width of pile cap - (2nos. × clear cover)} ÷ c/c distance ] + 1

 =  [{ 2500mm. - (2nos. × 50mm.)} ÷ 150mm. ] + 1

=   [{ 2400mm.} ÷ 150mm. ] + 1

= 16 +1

= 17 nos.



Now, let us prepare a BBS table for the pile cap.

Sl. No.

Type of Bar

Dia.

in mm.

Nos.

Length

in m.

Total length

in m.

Weight

in Kg/m.

Total

 bar wt.

in kg.

1.

Bottom bar

Layer-1

20

26

3.806

98.956

2.467

 244.12

2.

Bottom bar

Layer-2

20

21

4.466

93.786

2.467

 231.37  

3.

Top bar

Layer-1

12

22

4.004

88.089

0.887

   78.13

4.

Top bar

Layer-2

12

17

4.68

79.56

0.887

   70.57

5.

Side face bar

12

5

11.054

 55.27

0.887

   49.02

6.

       Total weight of steel bars =

  673.21

7.

         Add 3% wastage =

    20.20

8.

The grand total wt. of rebar's in pile cap =

 693.41

 

Thank you for going through these calculation steps. Have a good day 😄.

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