CUTTING LENGTH OF STIRRUPS

HOW TO CALCULATE CUTTING LENGTH OF STIRRUPS IN BEAM AND COLUMB :- 

        To cater the stresses and loads in RCC, Bars are bent to different shapes in the bar bending schedule.

Steps involved in finding the cutting length of stirrups:-

                        

1. Look at the size of column or beam from drawings
2. Adopt Dia of the bar (generally 8mm Dia is used for stirrups)
   
   
   
3. Deduct the concrete cover or clear cover
4. Find the total outer length of stirrup after deducting concrete cover.
5. Add the length of the hook to the length of the stirrup
   
   
   
   
   
   
   
6. Deduct the length of bends
7. Use below formula to find the total cutting length of stirrups

Different Shapes of Stirrups :-

    

1.    Rectangular Stirrups

2.    Square Stirrups

3.   Circular Stirrups

4.    Triangular Stirrups

5.   Spiral Stirrups

6.    Diamond Stirrups

Types Of Stirrups Used In Beam And Columns :-

 1.    Single Legged Stirrups(Open stirrup)

2.    Two-legged or Double Legged Stirrups (Closed Stirrup)

3.    Four-legged Stirrups (Closed Stirrup)

4.    6-legged Stirrups (Closed Stirrup)

Formula To Find The Total Cutting Length Of Stirrups :-

     Cutting length of stirrups =perimeter of shape + total hook length - total bend length

  

   IMPORTANT BASIC FORMULA:-aaa

            Perimeter  of rectangle =2(length+breadth)

          

      Perimeter of square= 4× side length

        

          Perimeter of circle or circumference of circle = 2πr = πd (r= radius, d= Diameter of Circle)  

           =====hook length – To

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Typical Diagram of Stirrup:-

  Refer the below image of the typical diagram of stirrup for clear understanding about x & y length, bends, hooks and concrete cover.

 the above image, there are 5 bends at 4 corners, 2 hooks and concrete cover around the stirrup.

x = length of the stirrup in the x-direction after deducting concrete cover &
y = length of the stirrup in the y-direction after deducting concrete cover.

  

Important standards used in Bends & Hooks:

        The below standards are most important in calculating the hook length and bend lengths at corners while finding cutting length of stirrups.

• 1 Hook length = 9d or 75mm
• 45° Bend length = 1d
• 90° Bend length = 2d
• 135° Bend length = 3d                                                          Remember, d = Diameter of Bar

Cutting length for Rectangular Stirrups:-

      Rectangular column or rectangular beam is the most commonly used shape of the column in any construction. In this shape of beam or column, a rectangular stirrup is usually adopted.

     1.  Considering the below Rectangular column size 230mm x 450mm for calculation purpose

  2.Adopting Dia of Bar used for stirrups is 8m

3. Deducting the concrete cover 20mm from all sides x = 230 – 20-20 = 190m                                        y = 450-20-20 = 410mm

1.                               4. Total Length of the hooks:From fig, There are two hooks which means 9d+9d = 18d

    5.Total Length of BendsFrom above fig, There are 3 bends which are bent at an angle of 900 and two bends are bent at an angle of 1350Total bend length = 3 x 900 Bend length + 2 x 1350 Bend length = 3 x 2d + 2 x 3d = 12d = 12 x 8 = 96mm

                     Total Cutting length of Rectangular Stirrup = Perimeter of Rectangle + Total Hook length – Total Bend Length

                

              = 2 (x+y) +18d – 12d = 2(190 + 410) + 18 x 8 – 12 x 8 = 1248mm = 1.248m

 

Cutting length for Square Stirrups:-

     1.  Considered the column size as 450mm x 450mm

           

         2 .Adopting Dia of Bar used for stirrups is 8mm

      3.Deducting the concrete cover 25mm from all sides (in square all sides are equal)

         x = 450- 20-20 = 410mm

y = 450-20-20 = 410mm, Hence x = y (in square all sides are equal)

 

4. Total Length of the hook:There are two hooks which mean 9d+9d = 18d 

              

5 .Total length of Bends:

There are 3 bends which are bent at an angle of 900 and one is bent at an angle of 1350.
Total bend length = 3 x 900 Bend length + 2 x 1350 Bend length = 3 x 2d + 2 x 3d = 12d = 12 x 8 = 96mm

Total Cutting length of Square Stirrup = Perimeter of Square + Total Hook length – Total Bend Length

           B4 x 410 +18d – 12d = 1648mm = 1.64m