Bar Bending Schedule (BBS)

Bar Bending Schedule :- 

                                         Is also known as `BBS' , BBS is basically means the representation of cut length and bend shapes of bars as per structure drawing.  bar are bended in various shapes and its depending on the shape of member 

         ex :- we consider 2 column and one resting beam  size 380 X 230 

              

  

2 Column and single beam 

                                                                         section   

hook = 10 d                                                                                   stirrups section

Ld     = 50 d              Ld = development length 

Lap   = 50 d

Cover =40mm

stirrups = 10mm , 100 c/c .

Top bar            

  

                                                                                           d = diameter of bar 

in this case we find Ld 

Step 1:- 50 d = 50x20 =1000 -190 =810                            

                      total (L =length =1000 so only for vertical distance we -ve the horizontal distance `190'

                            =  vertical distance get  810                    

step 2 :- length of beam + width of column + second column width

            = 12.8 + .23 + .23 = 13.26 -0.04-0.04                                      

                                     = 13.18                                                             cover distance = 0.04

                                                                                                              length of beam = 12.8           

                                                                                                              column width = .23

total length = 13.18   but in market we got maximum 12 M long steel

                         so in this case we will provide lap | and in top side reinforcement we provide 

                         lap at center because at center tension is minimum  

 Lap length = 50 x d = 50 x 20 = 1000 mm lap length we get 

 

                  Note : 1) In compression zone lap is provide at center

                             2) And in tension zone lap is provided at corner at L/3 distance

lap sample at top and bottom part : 

 

* The distance between 2 lap of top and bottom is 1.3XLd 

      so in this case lap distance is = 1.3 X 50 X20 =1300mm

Bottom bar :-

     

In this case lap is at any one of the corner distance is L/3

                                        = 13.18 / 3 = 4.4 m        and other distance is 8.75
Stirrups 

beam :- 380 X 230 

so for stirrup length first we want to reduce cover length              cover distance = 40

1st = 380 - 40 - 40 =300 mm                2nd = 230 -40 -40 = 150 mm

calculation :- (300 +150) X 2 +2 X 10d - 5 X 2d                      

                      =900 + 20 X10 - 10 X10                                     

                      =1000 mm                                                             5X2d = no. of bend 

                                                                                                    in this case no. of bend = 5

  .: length of single stirrup length is 1000mm

No. of Stirrups = length of beam / stirrups to stirrup distance c/c  

                         = 12800 / 100         = 128

       

               128 +1 = 129 no. of stirrups we required    ( +1 is for end stirrup addition )