HOW TO CALCULATE CUTTING LENGTH OF CIRCLE STIRRUPS IN BEAM AND COLUMN -lceted LCETED INSTITUTE FOR CIVIL ENGINEERS

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Aug 12, 2020

HOW TO CALCULATE CUTTING LENGTH OF CIRCLE STIRRUPS IN BEAM AND COLUMN


HOW TO CALCULATE CUTTING LENGTH OF CIRCLE STIRRUPS IN BEAM AND COLUMN

A stirrup is a closed loop of reinforcement bar that is used to hold the main reinforcement bars together in an RCC structure. In a column, the stirrups provide the lateral support to the main bars against buckling.

Different Shapes of Stirrups

1)     Rectangular Stirrups

2)     Square Stirrups

3)     Circular Stirrups - Also read: Calculator for circular 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)

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

Formula To Find The Total Cutting Length Of Stirrups

Cutting Length of Stirrups = Perimeter of Shape + Total hook length – Total Bend Length


PERIMETER OF SHAPE
Perimeter of Rectangle = 2 ( length + breadth)
Perimeter of Square = 4 x side length
Perimeter of circle or Circumference of Circle = 2πr = πd
(r= radius, d= Diameter of Circle)

TOTAL HOOK LENGTH
1 Hook length = 9d or 75mm

TOTAL BEND LENGTH
45° Bend length = 1d
90° Bend length = 2d
135° Bend length = 3d (Remember, d = Diameter of Bar)

Cutting Length of Circle Stirrups

Cutting Length of Stirrups = Perimeter of Shape + Total hook length – Total Bend Length

Cutting Length of Square Stirrup =  2πr or πd + 2 numbers of hooks – 3 numbers of 90° bends – 2 numbers of 135° bends

EXAMPLE CIRCLE STIRRUP CALCULATION

  
HOW TO CALCULATE CUTTING LENGTH
HOW TO CALCULATE CUTTING LENGTH



1. We can Consider the column size as

Radius = 600mm

 

2. Adopting Dia of Bar used for stirrups is 10mm (d=10mm)

(we usually use 10mm bar to the circle stirrups)

 

3. Deducting the concrete cover 25mm from all sides

R = 600 – 25 – 5 (half dia of bar) = 570mm

 

4. Total Length of the hook:

There are 2 hooks which mean 9d+9d = 18d

 

5. Total length of Bends:

There 2 bends at an angle of 1350. (3d)

 

Total Cutting Length of Square Stirrup = 2πr + 2 numbers of hooks  – 2 numbers of 135° bends

= 2 x π x r + (18d) – (2 x 3d)

(π = 3. 14)

(d=10mm as we mention step -2)

= (2 x 3.14 x 570) + (18 x 8) – (2 x 3 x 8)

= 3579.6 + (18 x 8) – (2 x 3 x 8)

= 3579.6 + (144) – (48)

= 3675.6mm = 3.67m

 

Total Cutting Length of Square Stirrup = 3.67m

 



    

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