Different types of stirrups are used in reinforcement according to the loads and stress induced on the structural members.

## Why are the Stirrups & Ties provided in reinforcement?

• It holds the rebars in position and prevents deformation.
• It positions the rods in the same alignment.
• To secure the beam and column from the buckling and shear failure.
• The stirrups are resisting the rods under compression or tensile force.

## Cutting Length of Stirrups Formula

The only formula that we need to remember is, Cutting Length of Stirrups = Perimeter of stirrup + Hook Length – Elongated Bend Length

Why subtracting the bend? – Because when we bend the steel bar, the bar’s length will slightly increase due to the stretch (elongation). The length depends on the angle of the elongation. That’s the reason we subtract it. ## Cutting Length of Rectangular Stirrups Let’s calculate the cutting length of the above rectangular stirrup

Cutting Length of Stirrup = Perimeter of Stirrup + 2 x Hook Length – 3 x 90° bends – 2 x 135° bends

= 2 (520+220) + (2 x 9d) – (3 x 2d) – (2x3d)

= 2(1480) + (2x9x8) – (3x2x8) – (2x3x8) = 3008 mm

## Cutting Length of Square Stirrups Let’s calculate the cutting length of the above square stirrup

Cutting Length of Stirrup = Perimeter of Stirrup + 2 x Hook Length – 3 x 90° bends – 2 x 135° bends

=  4a + (2 x 9d) – (3 x 2d) – (2x3d)

= (4×200) + (2x9x8) – (3x2x8) – (2x3x8) = 848 mm

## Cutting Length of Circular Stirrups Let’s calculate the cutting length of the above circular stirrup

Cutting Length of Stirrup = Perimeter of Stirrup + 2 x Hook Length – 2 x 135° bends

=  2πr + (2 x 9d) -(2x3d)

= (2×3.14×300) + (2x9x8) – (2x3x8) = 1980 mm

## Cutting Length of Triangular Stirrups Let’s calculate the cutting length of the above triangular stirrup

Cutting Length of Stirrup = Perimeter of Stirrup + 2 x Hook Length – 4 x 135° bends To find out the perimeter of the triangle stirrup, we need to calculate the Value of H

As from the diagram (pythagorean theorem), H = √(a2)+((b/2)2)

H = √(3502)+(1252) = 372 mm

Cutting Length of Stirrup = Perimeter of Stirrup + 2 x Hook Length – 4 x 135° bends

(Perimeter of stirrup = a + H + H = 250+372+372 = 994 mm

=  994 + (2 x 9d) – (4x3d) = (994) + (2x9x8) – (4x3x8) = 1042 mm

## Cutting Length of Diamond Stirrups Cutting Length of Diamond Stirrup = Perimeter of Stirrup + 2 x Hook Length – 3 x 90° bends – 2 x 135° bends

= (4 x y) + (2 x 9d) – (3x2d) – (2x3d) = (4*y) + 18d-6d-6d = 4y + 6d

In order to get perimeter of the diamond stirrup, we have find out the value of y (ref the diagram)

a = 400 – (2×25) = 350 mm

b = 450 – (2×25) = 400 mm

(pythagorean theorem), y2 = (a/2)2 + (b/2)2 = (350/2)2 + (400/2)2

Y = 266 mm

Therefore, cutting length of Diamond Stirrup = (4×266) + (6 x8) = 1112 mm

Happy Learning 🙂 Satheesh is a Civil Engineer who has more than 9+ Years of experience in residential construction. He is the author, editor of Civil Planets

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