How to Create Bar Bending Schedule Of Slab
TweetBar Bending Schedule is a list of reinforcement bars depicted in a tabular form giving the detailed information of Bars, the shape of the bending with sketches, length of each bar, total weight, and the total length of bars.
The Bar bending is a process of cutting and bending reinforcement steel bar into Desire shape as per structural drawing was given by structural engineer for various structural elements like footing, column, beam, slab, etc.
While working on reinforced cement concrete, a schedule of bars is usually maintained. With the help of the Bar Bending Schedule, the details and requirements of different sizes of bars and the lengths of bars may be known and may be arranged and bent up during the time of construction. Thus, by creating a bar bending schedule it keeps us informed about
- The shape of bending along with its sketch
- Number of sets or number of bars of each set
- Length of each and the total length of a running meter
- The total weight of bars
- Size and Type of Bars
In this article, we will majorly focus on the process of bar bending schedule, How to create it, and the major advantages of creating it.
Types of slabs used in Bar Bending schedule
Slabs can be classified into two types
- One way Slab
- Two-way slab
One way Slab
In one way slabs the main bars are provided in shorter direction whereas distribution bars are provided in the longer direction
Two-way Slab
In two-way slabs, the main bar are provided in both directions.
Estimating Bar bending schedule of one way slab
For a perfect bar bending schedule in one way slab, we should consider the following example
Length of the slab = 5000 mm
Width of slab = 2000 mm
Main Bar = 12mm @ 150 mm/cc
Ly/Lx = Longer span /Shorter span
=5000/2000
=2.5 > 2
Distribution Bar = 8mm @ 150 mm/cc
Clear Cover (Top and Bottom) = 25 mm
Thickness of slab =150 mm
Development Length = 40 d
Where d is the diameter of Bar
To calculate the bar bending schedule of the one-way slab.
Step 1 :
Calculate no of bars
Calculate no of bars required for main bars and distribution bars
No of bars = Length of Slab/ spacing + 1
No of main bars = Lx/spacing +1
=5000/150
= 34
Then we have to calculate no of distribution bars
= Ly/Spacing +1
=2000/150 +1
=14
Step 2:
Calculate cutting length of main bars and distribution bars
Cutting length of main bar
= clear span of slab + (2 x development length) + inclined length - (bend length)
Clear Span of Slab = 2000 mm
Development Length = 40 d
Inclined length = 0.42 d
1 d is for every 45º bend
Where d = diameter of Bar
Now let us calculate D
D = Thickness of slab - Both side clear cover (Top and Bottom) - diameter of bar
= 150 - (25 + 25) - 12
= 88 mm
Length of main bar
=Ly +2Ld + (1 x 0.42d) - (1d x 4)
= 2000 + (2 x 40 x 12) + (2 x 0.42 x 88) - (1 x 12 x 4)
=2838 mm
=2.838 m
Weight of main bars = d2 x L/162 X 34
=122 x 2.838/162
=86 kg
Length of Distribution Bar :
Clean span of slab + 2 x development length
= Lx + 2 Ld
= 5000 +2 x 40 x 8
=5640 mm
=5.64 m
Weight of distribution bars
= d2 x L/162 x14
=82 x 5.64/162 x 14
= 31 kg
Step 3:
Calculate the top bar which is provided at the top of critical length (L/4) area
No of Top Bars = {(Ly/4)/spacing+1}x 2
= {(2000/4)/150+1} x 2 = 9
Length of extra bar = Ly - 2x Ly/4 +2 x 100
{Here 2 x 100 is for both side Lapping of 100 mm for extra bar}
= 2000 - (2 x 2000/4) +200
=1200 mm
=1.2 m
Weight of Extra Bar = d2 x L/162 x 9
= 82 x 1.2/162 x 9
=4.266 kg
Bar Bending Schedule Of Two Way Slab
So we know, Longer span/Shorter span = Ly/Lx
=5000/3000
=1.66 < 2
It is a two-way slab
Given,
Length of Longer Span = 5000 mm
Length of Shorter Span = 3000 mm
Main Bar = 12 mm @150 mm/cc
Clear Cover (Top and Bottom) = 25 mm
Thickness of slab = 20 mm
Development Length = 40 d
Where d is the diameter of the bar
Step By Step Method To calculate the bar bending schedule of the two way slab
Step 1: For section A-A
Calculate number of bars required for main bars and distribution bar
No of Bars = Length of slab/spacing +1
Total no of bars = Ly/150 +1
=4000/150+1
=27
No of main bars =14
No of distribution bars =13
Step 2:
Calculate cutting length of main bars and distribution bars
Cutting length of Main Bar = Clear span of slab +(2 x development length) + (inclined length) - (Bend length)
Clear Span of slab= 5000 mm
Development Length = Ld°°
Ld = 40d
Inclined length = 0.42d
1d is for every 45° bend
Where d is the diameter of the bar
Now Calculate D
D = Thickness of the slab - both side clear cover (top and bottom) - diameter of bar
200 - (25 +25) - 12 = 138 mm
Length of Main bar = Lx +(2 x Ld) + (2 x 0.42d) - (1d x 4)
= 5000 +(2 x 40 x 12) + (2 x 0.42 x 138) - (1 x 12 x4)
=2838 mm
=6.02 m
For 14 bars total length
=6.02 x 14
= 84.28 m
Weight of main bars= d2 x L/162
= 122 x 84.28/162
=75 kg
Cutting Length of Distribution Bar
= clear span of slab + 2 x development length
= Lx +2 Ld
= 5000 +2 x 40 x 8
=5640 mm
=5.64 m
Total Length of Distribution Bar
=5.64 x 13
= 73.32
Weight of Distribution Bars
=d2 x L/162
= 82 x 73.32/162
=29 kgs
Step 3:
Calculate Top Bar which is provided at the top of critical length(L/4) Area
No. Of Extra Bars ={(Ly/4)/spacing +1}x 2
={(4000/4)/150 +1} x 2 =16
Length of Extra Bar = Lx - 2 x Lx/4+2 x100 [ here 2 x100 is for both side lapping of 100 mm of extra bar]
=5000 - (2x 5000/4) + 200
=2800 mm
=2.7 mm
Total Length Of Extra Bar
= 2.7 x 16
= 43.8
Weight of Extra Bar = d2 x L/162
= 82 x 43.2/162
=17 Kg
Step 1 For Section B-B
Calculate number of bars required for main bars and distribution bar
Total No.of Bars = Length of Slab/Spacing +1
Total No.of Bars = Lx/150 +1
=5000/150 +1
=35
No.Of Main Bars = 18
No. Of Distribution Bars = 17
Calculate The Cutting Length of Main Bars
Cutting length of Main Bar = Clear span of slab +(2 x development length) + (inclined length) - (Bend length)
Clear Span of Slab = 4000mm
Development length = Ld = 40d
Inclined Length = 0.42d
1d is for every 45° bend
Where d = Diameter of The bar
Now let us claculate d
d = Thickness of Slab - Both Side Clear Cover - Diameter of Bar
= 200 - (25+25) - 12
=138 mm
Cutting Length Of Main Bar
= Ly + 2 x Ld
= 4000 + 2 x 40 x 8
=4640 mm
= 4.64 m
Total Length Of Distribution Bar
=4.64 x 17
= 78.88
Weight of Distribution Bars
= d2 x L/162
= 82 x 78.88/162
=31 kg
Step 3 :
Calculate No of Extra Bars
No.Of Extra Bars = {( Lx /4)/spacing +1 } x 2
={(5000/4)150 + 1} x 2 = 9
Length of Extra Bar = Ly -(2 x -Ly/4) + (2 x 100) [here 2 x 100 is for both side lapping of 100 mm for extra bar]
= 4000 - (2 x 4000/4) + 200
=2200 mm
=2.2 m
Total Length of Extra Bar
=2.2 x 9
=19.8 m
Weight of Extra Bar
= d2 x L/162
=82 x 19.8/162
=8kg
Thus in these easy step-by-step methods, one can create bar bending schedule.
Advantages of Bar Bending Schedule
The following are the main advantages of Bar Bending schedule
- It helps in stock management at site
- It helps in auditing of reinforcement and provides a check on theft.
3) One can estimate the steel quantity through Bar Bending Schedule
Conclusion:
Hope this article was useful and now one can easily estimate the Bar Bending Schedule if they follow these easy steps.