All about civil construction knowledge- PARAM VISIONS

How to calculate the cutting length & make BBS of the Lintel bar./ Bar bending schedule & steel estimation of lintel beam.

 Let us now calculate the cutting length of the lintel bar for the below-given drawing.






Given data :

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.


sl.    bar                    dia.     no.     length    total      weight       total   
no.                        ( mm)                 (m.)     length     kg/m      weight

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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