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

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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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