Cutting length of different shapes of stirrup

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Stirrups: Stirrups are lateral ties provided in column to resist shear force and to hold longitudinal bars (main bars) of column in position.

1. Cutting length of Rectangular/Square stirrup:

Procedure to be followed for calculating cutting length of rectangular/square stirrup:

Step 1: Mark c/c distance of stirrup along length as ‘a’ as per the given structural drawing of stirrup.
Step 2: Mark c/c distance of stirrup along breadth as ‘b’ as per the given structural drawing of stirrup.
Step 3: Calculate a & b separately from structural drawing of stirrup.
Step 4: Now, calculate the cutting length of rectangular/square stirrup.

Calculation part:
General Notes:
For hook part, consider as 10*d.
For 45˚ bend, consider as d.
For 90˚ bend, consider as 2*d.
For 135˚ bend, consider as 3*d.

Size of column = 300*600 mm
From the above given structural drawing of stirrup:
Consider diameter of stirrup bar, Ø = 8mm.
No. of 90˚ bend = 3 & No. of 135˚ bend = 2
Clear cover as 30mm.
a = L – 2*clear cover – 2*half of diameter of bar = 300 – 2*30 – 2 *(8/2) = 232mm.
b = B – 2*clear cover – 2*half of diameter of bar = 600 – 2*30 – 2*(8/2) = 532mm.
Cutting of length of stirrup = 2*a + 2*b + hook – bend (90˚ & 135˚)
                                                 = 2*a + 2*b + 2*10*d – 3*2*d – 2*3*d
                                                 = 2*232 + 2*532 + 2*10*8 – 3*2*8 – 2*3*8 = 1592mm = 1.592m

2. Cutting length of Triangular stirrup:

Procedure to be followed for calculating cutting length of rectangular/square stirrup:

Step 1: Mark c/c distance of stirrup along base as ‘a’ as per the given structural drawing of stirrup.
Step 2: Mark c/c distance of stirrup along side of triangular stirrup as ‘b’ as per the given structural drawing of stirrup.
Step 3: Calculate a & b separately from the given structural drawing of stirrup.
Step 4: To calculate H from the given stirrup drawing, draw a perpendicular from apex of triangular stirrup to base of stirrup which is equal to ‘b’. (Refer Figure - 2)
Step 5: Now, calculate the cutting length of stirrup. 

Calculation part:
General Notes:
For hook part, consider as 10*d.
For 45˚ bend, consider as d.
For 90˚ bend, consider as 2*d.
For 135˚ bend, consider as 3*d.
                                                                                    Figure - 1
Refer figure -1                                              
Size of column = 600*500 mm
Diameter of stirrup bar, Ø = 8mm
No. of 135˚ bend = 4
Take clear cover as 40mm
a = 600 – 2*clear cover – 2*half of dia of bar = 600 – 2*40 – 2*(8/2) = 512 mm.
b = 500 – 2*clear cover – 2*half of dia of bar = 500 -2*40 – 2*(8/2) = 412 mm.
To calculate H, refer Figure - 2
                                                          
                                                                                             Figure - 2
By using Hypotenuse Formula, 
H = [(a/2)2 + b2]1/2 = [(512/2)2 + 4122]1/2 = 485mm.
Now, Cutting length of stirrup = 2*H + a + hook – bend (135˚) = 2*H + a + 2*10*d – 4*3*d
                                                 = 2*485 + 512 +2*10*8 – 4*3*8 = 1546mm = 1.546m.

3. Cutting length of circular stirrup:

Procedure to be followed for calculating cutting length of circular stirrup

Step 1: Calculate the radius (r) up to center of circular stirrup as per given structural drawing of stirrup.
Step 2:  Now, calculate the cutting length of circular stirrup.

Calculation part:
General Notes:
For hook part, consider as 10*d.
For 45˚ bend, consider as d.
For 90˚ bend, consider as 2*d.
For 135˚ bend, consider as 3*d.
Diameter of column = 1000mm.
Diameter of stirrup bar, Ø = 8mm
Clear cover = 40mm
No. of 135˚ bend = 2
r = diameter of column/2 – clear cover – half of diameter of bar = 1000/2 – 40 – 8/2 = 456mm
Cutting length = 2πr + 2*10*d (hook) – bend (135˚) = 2π*456 + 2*10*8 – 2*3*8 = 2975.68mm = 2.975m

4. Cutting length of Rhombus (Diamond) stirrup:

Procedure to be followed for calculating cutting length of Rhombus (Diamond) stirrup:

Step 1: Mark ‘a’& ‘b’ in given structural drawing of stirrup.
Step 2: Calculate any one side of rhombus, H using hypotenuse formula. (refer Figure - 2)
Step 3: Calculate the cutting length of rhombus stirrup.

Calculation part:
General Notes:
For hook part, consider as 10*d.
For 45˚ bend, consider as d.
For 90˚ bend, consider as 2*d.
For 135˚ bend, consider as 3*d.
                                                                                 Figure -1
From Figure - 1
Size of column = 600*500mm
Diameter of stirrup bar = 8mm 
Clear cover = 40mm
No. of 90˚ = 3 & No. of 135˚ = 2
a = 600 – 2*clear cover = 600- 2*40 = 520mm
b = 500 – 2*clear cover = 500-2*40 = 420mm 
                                                                              Figure -2
From Figure -2
H = [(520/2)2 + (420/2)2]1/2 = 334.21mm

Cutting length of stirrup = 4*H + 2*10*d (hook) – 3*2*d (90˚ bend) – 2*3*d (135˚ bend)
                                        = 4*334.21 + 2*10*8 – 3*2*8 – 2*3*8 = 1400.84mm = 1.4m

 

 



  

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