How To Calculate Cutting Length of Stirrups for Beam and Column all Building

 

How To Calculate Cutting Length of Stirrups for Beam and Column 

Different shapes of rings/Links/stirrups have varying cutting lengths. Today here, we are going to learn “How to calculate the cutting length of Stirrups for various shapes”.

Remember, The transverse bars provided in the column are known as Ties, and the transverse bars provided in the beam are known as Stirrups. But on-site; generally, we use the same term stirrup for both mounts.

Stirrups are used in the beam to counteract shear failure and to hold the longitudinal bars in position.

Method for Calculating Cutting Length of Stirrups

Study the size of a beam or column on drawings

Check the diameter of the bar given for stirrups (Mostly 8mm diameter is used for stirrups)

Subtract the clear cover or concrete cover.

Calculate the total perimeter/outer length for stirrup by deducting the concrete cover.

Then add hook-length to the outer length of the stirrup

Now Subtract the Length of bends

Formula
Cutting Length of Stirrup = Perimeter of stirrup shape + Hook Length – Bend length

Important Formulas

Perimeter of Rectangle = 2( Length + Width )

Perimeter of Square = 4 × Side Length

Circumference/ perimeter of Circle = 2лr or лd ( Where R = radius, d = Diameter)

Standard Length of Hook and Bend

Hook length = 9d or 75 mm (for One hook)

Bend Length for 45° = 1d

Bend Length for 90° = 2d

Bend Length for 135° = 3d (Where d = Diameter of Bar)

Cutting Length of Square Stirrup

The square shape is also the most common and generally used for beam and column at several structures. This shape column and beam have square shape stirrups.

Considering 

Square Column of Size = 300 mm × 300 mm

The diameter of the bar used for stirrup = 8 mm

Concrete Cover = 25 mm

Deduct Concrete Cover

A = 300 – 25 – 25 = 250

B = 300 – 25 – 25 = 250

2. Perimeter of Square Stirrup = 4 × 200 = 1000

3. Total Hook Length = 9d + 9d = 18d

4. Bend Length

From the figure shown above, there are 3 bends at 90° and 2 bends at 135°

Total Bend Length = 3 × 2d + 2 × 3d = 6d + 6d = 12d

Cutting Length of Square stirrup = Perimeter + Hook Length – Bend length.

                                                    = 4 × 250 + 18 × 8 – 12 × 8

                                                    = 1048 mm say 1.048

Cutting Length of Helical Stirrup

A spiral stirrup is similar to a circular stirrup except for a hook.

Considering 

Circular Column of Diameter = 600 mm 

The diameter of the bar used for stirrup = 8 mm and pitch 150 mm

Concrete Cover = 50 mm

Deducting Concrete Cover = 600 – 25 – 25 = 550 mm

Perimeter of stirrup

Circumference of circle = πd = π × 550 = 1727.87 mm or 1.73

Numbers of spiral = Total Length/pitch + 1 = 9000/150 + 1 = 61 numbers

Length of Spiral Stirrup or Ring = Number of spiral × Length of one Spiral

                                                  = 60 × 1.73

                                                  =  103.8 say 104  meters.

We can also calculate the cutting length of spiral Stirrup by the formula given below.

Cutting Length of Helical Stirrup = n√(C2 + P2)

Where

n = Numbers of Spiral

C = Circumference of one spiral

P = Pitch

L = n√c2 + p2

N = H/p = 9/0.15 = 60

C = лD = л × 0.55 = 1.727 say 1.73 meter

P = 150 mm or 0.15 meter

L = n√c2 + p2

L = 150√1.732 + 1502

Cutting Length of Circular Stirrup

Considering 

Circular Column of Diameter = 300 mm 

The diameter of the bar used for Stirrup = 8 mm

Concrete Cover = 50 mm

1. Deduct Concrete Cove = 300 -50 = 250 mm

2. Circumference (perimeter) of stirrup = лd = л × 250 = 785.39 say 785 mm

3. Hook Length = 9d + 9d = 18d = 18 × 8 = 144 mm

4. Bend length 

There are two bends at 135°

So total bend length = 3d +3d = 6d = 6 × 8 = 48

Cutting Length of Circular stirrup = Perimeter/Circumference + Hook Length – Bend Length

                                                     = 785 + 144 – 48

                                                    = 881 mm or 0.88 meter

I hope now you have enough knowledge on how to calculate the cutting length of stirrup for different shapes, like this article, and share this information with your friends.