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How to calculate the cutting length of reinforcement bars in circular R.C.C slab
Now, let us go through the procedure to find out the cutting length of the bars in a circular slab as shown below.
Given data :
Diameter of the circular slab = 1600mm = 1.6m.
Clear cover for the reinforcement = 25mm.
Rebar diameter = 10mm.
Rebar spacing = 150mm c/c.
The formula for finding the length of the bar
=2ār2 – d2
Where,
r = [diameter of the slab – (2nos.Ć clear cover )]Ā Ć· 2
d = c/c distance of the individual bars from the central bar of the circle.
As you can observe in the above-given drawing, I have drawn a red-colored circle by deducting the clear cover. Radius r in the above formula will be the radius of this red circle.
Ā Ā Ā Ā =Ā 775mm.
Note: All the rebars of the circular slab act as a chord of the red circle. To gain a basic understanding of this theory, you have to go through the article,
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1. Cutting length of bar cc1
= diameter of red circle = 1550mm.
2. Cutting length of bar DD1
=2ār2 – d2
Here, d = 150mm.
= 2 Ć ā7752 – 1502
= 2 ĆĀ ā 600625 – 22500
= 2 ĆĀ ā 578125
= 2 Ć 760.345
= 1520.69mm =Ā 1.521m.
3. Cutting length of the bar FF1
Here, d = 300mm.
=2ār2 – d2
= 2 ĆĀ ā 600625 – 90000
= 2 ĆĀ ā 510625
= 2 Ć 714.58
= 1429.16mm =Ā 1.429m.
4. Cutting length of the bar GG1
Here, d = 450mm.
=2ār2 – d2
= 2 ĆĀ ā 600625 – 202500
= 2 ĆĀ ā 398125
= 2 Ć 630.971
= 1261.94mm =Ā 1.261m.
5.Cutting length of the bar HH1
Here, d = 600mm.
=2ār2 – d2
= 2 ĆĀ ā 600625 – 360000
= 2 ĆĀ ā 240625
= 2 Ć 490.535
= 981.07mm =Ā 0.981m.
6. Cutting length of the bar JJ1
Here, d = 750mm.
=2ār2 – d2
= 2 ĆĀ ā 600625 – 562500
= 2 ĆĀ ā 38125
= 2 Ć 195.256
= 390.51mm =Ā 0.39 m
OTHER POSTS:
The calculation should be done until the cumulative value of d is less than r. So, we have calculated the cutting length ofĀ 5 barsĀ on the upper side of the central bar CC1.
No. of bars in a circular slabĀ
= [ (Ā 1600mm ) Ć·Ā 150mm] +1
Total no. of barsĀ
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Estimating Of Steel Bar Quantity for Construction
As the upper half part of the circle is identical to the bottom half part, you will have 2nos of central common bars and 4 nos of the chord bars having the same cutting length.
1. Cutting length of central bar CC1 = 1.55mĀ šĀ 2nos.
2. Cutting length of bar DD1Ā Ā Ā Ā Ā Ā = 1.521mĀ šĀ 4nos.
3. Cutting length of bar FF1Ā Ā Ā Ā Ā Ā = 1.429mĀ šĀ 4nos.
4. Cutting length of bar GG1Ā Ā Ā Ā Ā Ā = 1.261mĀ šĀ 4nos.
5. Cutting length of bar HH1Ā Ā Ā Ā Ā Ā = 0.981mĀ šĀ 4nos.
6. Cutting length of bar JJ1Ā Ā Ā Ā Ā Ā Ā = 0.390mĀ šĀ 4nos.
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