Calculating the cutting length of rebar is essential for determining the amount of reinforcement required for various structural elements like beams, columns, slabs, and footings. Here are the steps to calculate the cutting length of rebar for different types of bends and shapes:
Basic Steps for Calculating Cutting Length
 Identify the Shape of the Rebar:


 Straight bar
 Bent bar (Lshape, Ushape, etc.)
 Stirrups or ties

 Gather the Required Measurements:


 Lengths of straight segments
 Angles and radii of bends

 Use Standard Formulas for Bends:

 For each bend, the additional length due to the bend (bend allowance) must be considered
1. Straight Bar:
The simplest case is a straight bar with no bends.
Cutting Length=Total Length of the Bar
Example:
 Length of the bar: 6 meters
Cutting Length=6 meters
2. LShape Bar (90degree bend):
For a bar with a single 90degree bend, we need to account for the bend allowance.
Given:
 Lengths:
A=500 mm, B=600 mm
 Diameter (D): 12 mm
Bend Allowance Calculation:
The bend allowance for a 90degree bend is calculated using the formula:
Bend Allowance=π×D/2
Bend Allowance=π×12/2=18.85 mm
Total Cutting Length:
Cutting Length=A+B+2×Bend Allowance
Cutting Length=500+600+2×18.85=500+600+37.7=1137.7 mm
3. UShape Bar:
For a bar with two 90degree bends (Ushape):
Given:
 Lengths: A=300 mm, B=400 mm, C=300 mm
 Diameter (D): 12 mm
Bend Allowance Calculation:
Same as above, for each 90degree bend:
Bend Allowance=18.85 mm
Total Cutting Length:
Cutting Length=A+B+C+2×Bend Allowance
Cutting Length=300+400+300+2×18.85=300+400+300+37.7=1037.7 mm
4. Stirrups:
Stirrups are closed loop bars with multiple bends. Typically, they have 4 corners (90degree bends).
Given:
 Lengths: A=200 mm, B=300 mm
 Diameter (D): 10 mm
Bend Allowance Calculation:
Same as above, for each 90degree bend:
Bend Allowance=π×102=15.7 mm
Total Cutting Length:
Cutting Length=2×(A+B)+4×Bend Allowance
Cutting Length=2×(200+300)+4×15.7
Cutting Length=2×500+62.8=1000+62.8=1062.8 mm
5. BentUp Bar:
For bars bent up at an angle (commonly 45 degrees in beams):
Given:
 Lengths: A=1000 mm, B=1000 mm
 Inclination Angle: 45 degrees
 Diameter (D): 16 mm
Bend Allowance Calculation:
The bend allowance for a 45degree bend is:
Bend Allowance=π×D/4
Bend Allowance=π×164=12.57 mm
Hypotenuse Calculation:
For the bent portion, calculate the hypotenuse of the right triangle:
Bent Length=Sqrt (Sq(A)+Sq(B))
Bent Length=1414.2 mm
Total Cutting Length:
Cutting Length=Bent Length+2×Bend Allowance
Cutting Length=1414.2+2×12.57=1414.2+25.14=1439.34 mm
Conclusion
These calculations ensure that you consider the additional length required due to bends, ensuring accurate cutting lengths for different shapes of rebar. Always refer to local codes and standards for specific requirements and modifications.