Calculating the cutting length of stirrups is a vital step in column reinforcement design. Accuracy ensures proper strength, safety, and economy of construction. Below is the step-by-step calculation for determining the cutting length of a 4-legged stirrup with all essential details.

Given Data for Calculation

• Column size: 600mm × 450mm
• Clear cover: 40mm
• Main rebar diameter: 20mm
• Number of rebars: 8
• Stirrup bar diameter: 8mm

Note: For 4-legged stirrups, the cutting length of stirrup-1 and stirrup-2 remains the same. Hence, we calculate for one stirrup only.

Formula for Cutting Length of 4-Legged Stirrup

The general formula is:

Cutting Length = { (2 × (a + b)) + Hook Length } – { (90° bend + 135° bend) }

Where:

• a = Shorter side adjustment
• b = Longer side adjustment

Step 1: Calculate X

X = [Column width – { (2 × Cover) + (2 × Stirrup dia.) + (2 × ½ × Main bar dia.) }] ÷ 3

= [450 – {(2 × 40) + (2 × 8) + (2 × 10)}] ÷ 3
= [450 – (80 + 16 + 20)] ÷ 3
= [450 – 116] ÷ 3
= 334 ÷ 3
= 111.33 mm

Step 2: Calculate “a”

a = [ (2 × X) + (2 × ½ × Main bar dia.) + (2 × ½ × Stirrup dia.) ]

= (2 × 111.33) + (20) + (8)
= 222.66 + 20 + 8
= 250.66 mm

Step 3: Calculate “b”

b = [Column depth – { (2 × Cover) + (2 × ½ × Stirrup dia.) }]

= 600 – {(2 × 40) + (8)}
= 600 – (80 + 8)
= 600 – 88
= 512 mm

Step 4: Apply the Formula

Cutting Length = { (2 × (a + b)) + Hook Length } – { (90° bend + 135° bend) }

Take hook length = 10d (where d = 8mm).
Deduct 2d for each 90° bend (3 nos.) and 3d for each 135° bend (2 nos.).

= { (2 × (250.66 + 512)) + (2 × 10 × 8) } – { (3 × 2 × 8) + (2 × 3 × 8) }
= { (2 × 762.66) + 160 } – { 48 + 48 }
= { 1525.32 + 160 } – 96
= 1685.32 – 96
= 1589.32 mm

Final Result

The cutting length of one 4-legged stirrup = 1589.32 mm

Since both stirrup-1 and stirrup-2 have equal cutting lengths:

Cutting length = 1589.32 mm each

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