Bar bending schedule (BBS) of a pile cap.(Part-1) / How to calculate the cutting length & weight of reinforcement in a pile cap?

  Let us make BBS of the pile cap as shown below.

The pile cap section is shown below mentioning different terms used while doing BBS calculations.

Given data:

Length of the pile cap = 3200mm.

Width of the pile cap = 2500mm.

Depth of the pile cap = 1500mm.

Clear cover = 50mm.

Pile cutoff length = 75mm.

Bottom bar layer-1 =20∅ @ 125 c/c.

Bottom bar layer-2 =20∅ @ 125 c/c.

Top bar layer-1 =12∅ @ 150 c/c.

Top bar layer-2 =12∅ @ 150 c/c.

Side face or roundup bar = 12∅-5 nos.

Calculation:

A. Cutting length:

1. Bottom bar layer-1:

Cutting length of the bottom bar layer-1

= [pile width + (2nos.× a ) - {(2nos. × clear cover ) + (2nos. × side face bar dia.) + (2nos. × 1/2 × bar dia.) + (2nos.× 90° bend)]

Where a 

    = [(1/2 × pile cap depth) + (1/2 × 300mm.) - pile cutoff - clear cover -  (1/2 × bar dia)]

   = [ (1/2 × 1500mm.) + ( 1/2 × 300mm.) - 75mm. - 50mm. - ( 1/2 × 20mm.)]

   = [ 750mm. + 150mm. - 75mm. - 50mm. - 10mm.]

  a = 765mm.

& 90° bend = 2d.

Cutting length of the bottom bar layer-1

= [2500mm. + (2nos.× 765mm. ) - {(2nos. × 50mm.) + (2nos. × 12mm.) + (2nos. × 1/2 × 20mm.) + (2nos.× 2 × 20mm.)]

= [ 2500mm. + 1530mm. - { 100mm. + 24mm. + 20mm. + 80mm.}]

= [ 4030mm. - 224mm.]

= 3806mm.

= 3.806m.

2. Top bar layer -1 :

Cutting length of the top bar layer-1

= [pile cap width + (2nos.× b ) - {(2nos. × clear cover ) + (2nos. × side face bar dia.) + (2nos. × 1/2 × bar dia.) + (2nos.× 90° bend)]

Where b

    = [(1/2 × pile cap depth) + (1/2 × 300mm.) - clear cover -  (1/2 × bar dia)]

   = [ (1/2 × 1500mm.) + ( 1/2 × 300mm.) - 50mm. - ( 1/2 × 12mm.)]

   = [ 750mm. + 150mm. - 50mm. - 6mm.]

  b = 844mm.

& 90° bend = 2d.

Cutting length of the top bar layer-1

= [2500mm. + (2nos.× 844mm. ) - {(2nos. × 50mm.) + (2nos. × 12mm.) + (2nos. × 1/2 × 12mm.) + (2nos.× 2 × 12mm.)]

= [ 2500mm. + 1688mm. - { 100mm. + 24mm. + 12mm. + 48mm.}]

= [ 4188mm. - 184mm.]

= 4004mm.

= 4.004m.

3. Bottom bar layer-2:

Cutting length of the bottom bar layer-2

= [pile cap length + (2nos.× c ) - {(2nos. × clear cover ) + (2nos. × side face bar dia.) + (2nos. × 1/2 × bar dia.) + (2nos.× 90° bend)]

Where c 

    = [(1/2 × pile cap depth) + (1/2 × 300mm.) - pile cutoff - clear cover - bottom bar layer-1 dia - (1/2 × bar dia)]

   = [ (1/2 × 1500mm.) + ( 1/2 × 300mm.) - 75mm. - 50mm. - 20mm. - ( 1/2 × 20mm.)]

   = [ 750mm. + 150mm. - 75mm. - 50mm. -20mm. - 10mm.]

   c = 745mm.

& 90° bend = 2d.

Cutting length of the bottom bar layer-2

= [3200mm. + (2nos.× 745mm. ) - {(2nos. × 50mm.) + (2nos. × 12mm.) + (2nos. × 1/2 × 20mm.) + (2nos.× 2 × 20mm.)]

= [ 3200mm. + 1490mm. - { 100mm. + 24mm. + 20mm. + 80mm.}]

= [ 4690mm. - 224mm.]

= 4466mm.

= 4.466m.

4. Top bar layer -2 :

Cutting length of the top bar layer-2

= [pile cap length + (2nos.× d ) - {(2nos. × clear cover ) + (2nos. × side face bar dia.) + (2nos. × 1/2 × bar dia.) + (2nos.× 90° bend)]

Where d

    = [(1/2 × pile cap depth) + (1/2 × 300mm.) - clear cover - top bar layer-1 dia. - (1/2 × bar dia)]

   = [ (1/2 × 1500mm.) + ( 1/2 × 300mm.) - 50mm. - 12mm. - ( 1/2 × 12mm.)]

   = [ 750mm. + 150mm. - 50mm.- 12mm. - 6mm.]

   d = 832mm.

& 90° bend = 2d.

Cutting length of the top bar layer-2

= [3200mm. + (2nos.× 832mm. ) - {(2nos. × 50mm.) + (2nos. × 12mm.) + (2nos. × 1/2 × 12mm.) + (2nos.× 2 × 12mm.)]

= [ 3200mm. + 1664mm. - { 100mm. + 24mm. + 12mm. + 48mm.}]

= [ 4864mm. - 184mm.]

= 4680mm.

= 4.68m.

Continued 👉 Part-2

Share: