CUTTING LENGTH OF BENT UP BARS IN SLAB AND BEAM
As a site engineer, you would like to calculate the cutting length of bars consistent with the slab or beam dimensions and searching for cutting length of steel.
For small area of structure, you'll be able to hand the reinforcement detailing to the bar benders for cutting and bending. They’re going to make sure of cutting length for no wastage or minimum wastage. But beware, that has to not be accurate. Because they are doing not give importance to the bends and cranks. They will give some extra inches to the bars for the bends which are totally wrong for wastage of fabric and money. So it's always recommended that as a site engineer calculate the cutting length yourself as accurate. During this article, we are going to discuss the way to the calculate length for reinforcement bars of slab. Let’s start with an example.
EXAMPLE:
Where,
Diameter of the bar = 12 mm
Clear Cover = 25 mm
Clear Span (L) = 8000
Slab Thickness = 200 mm
Development Length(Ld) = 40d
CALCULATION:
Cutting Length = Clear Span of Slab + (2 x Development Length) + (2 x inclined length) – (45° bend x 4) – (90° bend x 2)
Inclined length = D/(sin 45°) – dD/ (tan 45°) = (D/0.7071) – (D/1)= (1D – 0.7071D)/0.7071= 0.42 D
As you'll be able to see there are four 45°bends at the inner side (1,2,3 & 4) and two 90° bends ( a And b ).
45° = 1d ; 90° = 2d
Cutting Length = Clear Span of Slab + (2 X Ld) +(2 x 0.42D) – (1d x 4) – (2d x 2)
Where,
d = Diameter of the bar.
Ld = Development length of bar.
D = Height of the bend bar.
In the above formula, all values are known except ‘D’.
So we want to seek out out the worth of “D”.
D = Slab Thickness – (2 x clear cover) – (diameter of bar)
= 200 – (2 × 25) – 12
= 138 mm
Now, putting all values within the formula
Cutting Length = Clear Span of Slab + (2 x Ld) +(2 x 0.42D) – (1d x 4) – (2d x 2)
= 8000 + (2 x 40 x 12) +(2 x 0.42 x 138) – (1 x 12 x 4) – (2 x 12 x 2)
∴ Cutting Length = 8980 mm or 8.98 m.
So for the above dimension, you wish to chop the most bars 8.98 m long.
For small area of structure, you'll be able to hand the reinforcement detailing to the bar benders for cutting and bending. They’re going to make sure of cutting length for no wastage or minimum wastage. But beware, that has to not be accurate. Because they are doing not give importance to the bends and cranks. They will give some extra inches to the bars for the bends which are totally wrong for wastage of fabric and money. So it's always recommended that as a site engineer calculate the cutting length yourself as accurate. During this article, we are going to discuss the way to the calculate length for reinforcement bars of slab. Let’s start with an example.
EXAMPLE:
 |
| Example With Measurement |
Diameter of the bar = 12 mm
Clear Cover = 25 mm
Clear Span (L) = 8000
Slab Thickness = 200 mm
Development Length(Ld) = 40d
CALCULATION:
Cutting Length = Clear Span of Slab + (2 x Development Length) + (2 x inclined length) – (45° bend x 4) – (90° bend x 2)
Inclined length = D/(sin 45°) – dD/ (tan 45°) = (D/0.7071) – (D/1)= (1D – 0.7071D)/0.7071= 0.42 D
As you'll be able to see there are four 45°bends at the inner side (1,2,3 & 4) and two 90° bends ( a And b ).
45° = 1d ; 90° = 2d
Cutting Length = Clear Span of Slab + (2 X Ld) +(2 x 0.42D) – (1d x 4) – (2d x 2)
Where,
d = Diameter of the bar.
Ld = Development length of bar.
D = Height of the bend bar.
In the above formula, all values are known except ‘D’.
So we want to seek out out the worth of “D”.
D = Slab Thickness – (2 x clear cover) – (diameter of bar)
= 200 – (2 × 25) – 12
= 138 mm
Now, putting all values within the formula
Cutting Length = Clear Span of Slab + (2 x Ld) +(2 x 0.42D) – (1d x 4) – (2d x 2)
= 8000 + (2 x 40 x 12) +(2 x 0.42 x 138) – (1 x 12 x 4) – (2 x 12 x 2)
∴ Cutting Length = 8980 mm or 8.98 m.
So for the above dimension, you wish to chop the most bars 8.98 m long.
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