Let us now calculate the cutting length of the lintel bar for the below-given drawing.
Length of lintel =1300mm.
Width of lintel = 230mm.
Depth of lintel = 200mm.
Top rebar = 2- T8.
Bottom rebar = 2- T10.
Stirrup = 8mm @ 175 c/c.
Clear cover = 25mm.
For your understanding, I have downloaded the drawing below, to show you the location of the lintel.
Calculation:
A. Cutting length:
1. Cutting length of the top rebar
= [Length of lintel - (2nos.× clear cover on both sides )]
= [1300mm -( 2nos. × 25mm )]
= 1250mm.=1.25m
2. Cutting length of the bottom rebar
= 1250mm ( same as top bar ) = 1.25m
3. Cutting length of the stirrup
= [( 2nos. × (a +b ) ) + ( hook length ) - ( 3nos ×90° bend + 2nos. × 135° bend )]
Here,
a = [ lintel width - ( 2 × clear cover ) - (1/2 ×dia. of stirrup bar)]
= [ 230mm - ( 2 × 25mm ) - (1/2 × 8mm )]
= [ 230mm - 50mm - 4mm ]
= 176mm
b = [ lintel depth - ( 2 × clear cover ) - (1/2 × dia. of stirrup bar )]
= [ 200mm - ( 2 × 25mm ) - (1/2 × 8mm )]
= [ 200mm - 50mm - 4mm ]
= 146mm
Cutting length of the stirrup
= [ {2 nos.× ( 176mm + 146mm ) } + (10d ) - (3 nos. × 2d ) - (2 nos. × 3d)]
Note:
1. 10d is taken for hook length.
2. We have deducted 2d for 90° bend -3nos., & 3d for 135° bend -2nos. as shown in the above drawing.
Cutting length of the stirrup
= [ { 2 nos.× 322mm } + (10 × 8mm) - ( 3 nos. × 2 × 8mm ) - ( 2 nos. × 3 × 8 mm.)]
= [ 644mm + 80 mm - 48mm - 48mm.]
=[ 724mm - 96 mm.]
= 628 mm i.e. 0.628m.
4. Number of stirrups
= [( length of the lintel ÷ stirrup spacing ) + 1]
= [(1300 mm. ÷ 175 mm) +1 ]
= [7.42 + 1]
= 8.42 nos.
By rounding off, the no. of stirrups required = 9 nos.
Go through the article👇
💁 ° What is a lintel? / FAQs related to lintel.
Now, let us prepare a BBS table for the lintel beam.
1. Top bar 8 2 1.250 2.50 0.395 0.9875
2. Bottom bar 10 2 1.250 2.50 0.617 1.54
3. Stirrups 8 9 0.628 5.652 0.395 2.232
Total weight of bars = 4.76 kgs.
Add 2% wastage = 0.095 kgs.
The grand total of rebars = 4.855 kgs.
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