Let us calculate the **cutting length** of the top & bottom bar of a beam as shown below.

__Given data:__

Beam width = 300mm.

Beam depth = 550mm.

Column width = 400mm.

Effective length L1= 6m = 6000mm.

Effective length L2 = 5.5m. = 5500mm.

Top reinforcement = 20mm ∅ - 2nos.

Bottom reinforcement = 25mm ∅ - 2nos.

Clear cover = 30mm.

Development length Ld = 50d.

Lapping length = 50d.

**Calculation:**

**A. Cutting length:**

**1. Bottom bar:**

** Total length of the bottom bar**

= [L1 + L2+ (2nos. × development length) - (2nos. × 1/2 × column width) - ( 2nos. × 90° bend)]

= [6000mm. + 5500mm. + (2nos. × 50d) - (2nos. × 1/2 × 400mm.) - ( 2nos. × 2d)]

= [6000mm. + 5500mm. + (2nos. ×50 × 25mm.) - (2nos. × 1/2 × 400mm.)- ( 2nos. × 2× 25mm.)]

= [ 11500mm. + (2500mm.) - (400mm.)- ( 100mm.)]

= **13,500mm.**

**= 13.50m > 12m.**

**The total length (13.50m.) is greater than the available bar length(12m.). Hence there will be lapping in the bar.**

**Before proceeding further, ****Go through the article ðŸ‘‡**

**ðŸ‘€. Where to provide lapping in beam reinforcement?**

**S**o that you will understand the correct position of lapping in the beam & the basic rules of lapping.

**a. Cutting length of the part-1 of the bottom bar**

= [L1 + (development length) + (half of lap length ) - (1/2 × column width) - ( 1no × 90° bend)]

= [ 6000mm. + (50d) + ( 1/2 × 50d) - (1/2 × 400mm.) - ( 2d)]

= [ 6000mm. + (50 × 25mm ) + ( 1/2 × 50 × 25mm. ) - (1/2 × 400mm.) - ( 2 × 25mm.)]

= [ 6000mm. + (1250mm ) + ( 625mm. ) - ( 200mm.) - (50mm.)]

= 7625mm.

= **7.625m.**

**b. Cutting length of the part-2 of the bottom bar**

= [L2 + (development length) + (half of lap length ) - (1/2 × column width) - ( 1no × 90° bend)]

= [ 5500mm. + (50d) + ( 1/2 × 50d) - (1/2 × 400mm.) - ( 2d)]

= [ 5500mm. + (50 × 25mm ) + ( 1/2 × 50 × 25mm. ) - (1/2 × 400mm.) - ( 2 × 25mm.)]

= [ 5500mm. + (1250mm ) + ( 625mm. ) - ( 200mm.) - (50mm.)]

= 7125mm.

=** 7.125m.**

**Check:**

[Total length of bar + lap length ] = [cutting length of (part-1 + part-2)]

[13500mm + 50d] = [7625mm. +7125mm.]

[13500mm. + 50 × 25mm.] = 14750mm.

14750mm = 14750mm. **✓ **

**2. Top bar:**

** Total length of the top bar**

= [L1 + L2+ (2nos. × development length) - (2nos. × 1/2 × column width) - ( 2nos. × 90° bend)]

= [6000mm. + 5500mm. + (2nos. × 50d) - (2nos. × 1/2 × 400mm.) - ( 2nos. × 2d)]

= [6000mm. + 5500mm. + (2nos. ×50 × 20mm.) - (2nos. × 1/2 × 400mm.)- ( 2nos. × 2× 20mm.)]

= [ 11500mm. + (2000mm.) - (400mm.)- ( 80mm.)]

= **13,020mm.**

**= 13.02m > 12m**

**The total length (13.02m.) is greater than the available bar length(12m.). Hence there will be lapping in the bar.**

**a. Cutting length of the part-1 of the top bar **

= [L1 +( L2/2) + (development length) + (half of lap length ) - (1/2 × column width) - (90° bend)]

= [ 6000mm. + (5500mm.÷ 2) + (50d) + ( 1/2 × 50d) - (1/2 × 400mm.) - ( 2d)]

= [ 6000mm. + (2750mm.) + (50 × 20mm ) + ( 1/2 × 50 × 20mm. ) - (1/2 × 400mm.) - ( 2 × 20mm.)]

= [ 6000mm. + (2750mm.) + (1000mm ) + ( 500mm. ) - ( 200mm.) - (40mm.)]

= 10,010mm.

= **10.010m.**

**b. Cutting length of the part-2 of the top bar **

= [( L2/2) + (development length) + (half of lap length ) - (1/2 × column width) - (90° bend)]

= [ (5500mm.÷ 2) + (50d) + ( 1/2 × 50d) - (1/2 × 400mm.) - ( 2d)]

= [ (2750mm.) + (50 × 20mm ) + ( 1/2 × 50 × 20mm. ) - (1/2 × 400mm.) - ( 2 × 20mm.)]

= [(2750mm.) + (1000mm ) + ( 500mm. ) - ( 200mm.) - (40mm.)]

= 4,010mm.

=** 4.010m.**

**Check:**

[Total length of bar + lap length ] = [cutting length of (part-1 + part-2)]

[13020mm + 50d] = [10010mm. +4010mm.]

[13020mm. + 50 × 20mm.] = 14,020mm.

14,020mm = 14,020mm. **✓ **

**Thank you for going through these calculation steps❤. Have a good day ðŸ˜„.**

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