Let us prepare the bar bending schedule of the footing for the below-given drawing.
footing length = 2000 mm., width = 1500 mm. , depth = 300 mm.
rebar diameter = 12 mm. spacing =150 mm, cover = 50 mm on all the sides.
No. of bars along x-direction
= [ {( footing length ) - ( 2 × cover )} ÷ spacing ] + 1
= [ {( 2000 mm.) - ( 2 × 50 mm.)} ÷ 150 mm.] +1
= [ { 1900 mm } ÷ 150 mm. ] +1
= 12.67 +1
= 14 nos.
( by rounding off )
No. of bars along y-direction
= [ {( footing width ) - ( 2 × cover )} ÷ spacing ] + 1
= [ {( 1500 mm.) - ( 2 × 50 mm.)} ÷ 150 mm.] +1
= [ { 1400 mm } ÷ 150 mm. ] +1
= 9.33 +1
= 10 nos.
Cutting length of the bar along the x-direction
= [ {bar length in x - axis } +{ 2 nos. ×( L- bend length)}] - 2nos.× ( 2 times bar dia. for 90° bend.)
=[ { footing length - 2 × cover } + 2nos.×{ footing height - 2 × cover}] - 2× ( 2 × bar dia. )
= [ { 2000 mm. - 2 × 50 mm. } + 2 × { 300 mm. - 2 × 50 mm. } ] - 2 × ( 2 × 12 mm.)
= [ 1900 mm. + 400 mm ] - 48 mm.
= 2300 mm - 48 mm
= 2252 mm. i.e. 2.252 m.
Cutting length of the bar along the y -direction
= [ {bar length in y - axis } +{ 2 nos. ×( L- bend length)}] - 2nos.× ( 2 times bar dia. for 90° bend.)
=[ { footing width - 2 × cover } + 2nos.×{ footing height - 2 × cover}] - 2× ( 2 × bar dia. )
= [ { 1500 mm. - 2 × 50 mm. } + 2 × { 300 mm. - 2 × 50 mm. } ] - 2 × ( 2 × 12 mm.)
= [ 1400 mm. + 400 mm ] - 48 mm.
= 1800 mm - 48 mm
= 1752 mm. i.e. 1.752 m.
Now, we will prepare BBS of the footing, from calculated data.
1. x- axis 12 10 2.252 22.52 0.89 20.043
2. y - axis 12 14 1.752 24.528 0.89 21.829
Total weight of the bars = 41.872kgs
Add 2 % wastage = 0.837kgs
The grand total of rebar for footing = 42.709 kgs.
Note : Weight of 12mm dia bar /meter is 0.89 kg.
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