We are going to learn how to crate a bar bending schedule bbs of a Foundation. We are going to use all the formulas we learned in How to create a bar bending schedule. I recommend you read the basic article first.
If you look at the image you can see that there are essentially four types of bars,Bottom Main Bar,Bottom Distribution Bar,Top Main Bar and Top Distribution Bar
Along with these four bars there is also bars of the column. Technically you have to create bbs for this column along with the foundation. But just for the sake of simplicity I am going to do that in a separate article BBS of a column.
Lets start with the Bottom Main Bar
Length
As we can see Length of the foundation = 1m
There is 50mm cover on both sides so total cover = 50mm+50mm= 0.1m
The bar has a 10d bent on both sides = 10d+10d= 20d= 0.20m (because d is 10mm)
Total Length of bottom main bar = Length of foundation – cover + Lbends
= 1 – 0.1 +0.20=1.1m
Deduction
We know that for every 45 degree bend we apply a deduction equal to d (Diameter of the bar)
Here we have 2 90 degree bends so total deduction = 2d+2d=4d=0.040m
Effective Length = Total Length – Deduction = 1.1-0.040 = 1.06m
Number of Bars
Number of bars = Distance/Spacing +1
Here Distance = Length of Foundation -2* cover (2* 50mm =100mm)
Spacing is 100mm
Number of bars = (1000-100)/100+1=9+1=10
Unit weight of 12mm bar = D2/162 = 10*10/162= 0.617
Hence Weight of Bottom Bar is = Length * Number *Unit Weight
= 1.06*10*0.617 = 6.54 kg
2: Bottom Distribution Bar
Length
Again in this case Length = 1m – 0.1m( cover )= 0.9m
The bar has a 10d bent on both sides = 10d+10d= 20d= 0.20m (d is 10mm)
Total Length of bottom main bar = Length of foundation – cover + Lbends
= 1 – 0.1 +0.20=1.1m
Deduction
We know that for every 45 degree bend we apply a deduction equal to d
Here we have 2 90 degree bends so total deduction = 2d+2d=4d=0.040m
Effective Length = Total Length – Deduction = 1.1-0.04 = 1.06m
Number of Bars
Number of bars = Distance/Spacing +1
Here Distance = Distance -2* cover – 2*diameter of main bar. ( Notice these bars are placed inside main bars)
Spacing is 100mm
Number of bars = (1000-100-24)/100=9+1=10 ( 8.76 round off to 9)
Unit weight of or 10mm bar = D2/162 = 10*10/162= 0.617
Hence Weight of Bottom Bar is = Length * Number *Unit Weight
= 1.06*10*0.617 = 6.54 kg
Because the top bars are nearly identical to the bottom bars we can simply copy our calculations for the top bars
Hence
Top Main Bar = 6.54Kg
Top Distribution Bar = 6.54Kg
When we combine all of the bars we get bbs of the entire foundation
In the next article we are going to learn how to make bar bending schedule of a column
If you want a free software to make bar bending schedule I highly recommend you download the official BBS app
BBS App Android Google Play Link: Click here to download
iPhone AppStore Line: Click here to download
If you are a fresher civil engineer and want to know how to get a job read this article: How to get a job as a fresher civil engineer.