Bar Bending Schedule Formulas & Preparation
Bar Bending Schedule stands for a thorough list of bent reinforcement bars provided in any structural concrete component. Bar Bending Schedule comprises of bar mark, diameter, length, shape, and weight.
The Bar bending refers to a method for cutting and bending reinforcement steel bar into required shape according to structural drawing supplied by structural engineer for several structural components ranging from footing, column, beam, slab, etc.
A Bar Bending Schedule facilitates the site engineer to work out the necessary quantities of different diameter of bars employed in construction. The engineer will be able to examine the reinforcement work accomplished by the contractor.
Preparation of Bar Bending Schedule
Recognition of Members (Steel Bars
Every diverse type of steel bar or member is normally tagged with a number or bar mark in the structural drawing. Just open a structural drawing and record all the shapes of bars provided in the structural drawing. Now prepare a table and label the diameter of member in the table.
As for example, the numbers of bars may come as #5, #6, #9, etc, together with día of the bar (e.g. #5@12”)
Calculate the Number of bars
Now, calculate the number of each diverse shapes of the bar and record in bar bending schedule.
To work out a number of bars in large slab structure, it is required to verify the exact distance among bars (center to center or c/c) and the length of the concrete slab in which the bars should be allocated.
Number of Bars = (Concrete slab length in which bar is allocated – 2 X Cover) / (c/c spacing among bars)
As for instance:
Assume, 10 MM bars are allocatede in the 10-meter-long slab at 150 mm c/c spacing, choosing the side cover as 50 mm. Then work out the number of bars
Number of Bars = (10000 – 2 X 50) / (150) = 66 Bars of 10 mm Día
Measure the length of Reinforcement bars
The following formula is used for computing the length of those bars.
Compute the unit weight of Reinforcement Bar
It is computed with the following formula :-
Unit weight of Bar = Volume of Bar X Density of Bar (7850 kg/m3)
Unit Weight of Reinforcement Bar with Día (D) = D2 / 162
As for instance, 10 mm Día reinforcement bar Weight = 102 /162 = 0.617 kg/m.
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Workout the weight of particular shape of bar
Weight of Reinforcement Bar (Shape of Bar) = No of Bars X Length of Bars X Unit weight of Bar
With this formula, the total weight of specific shape bar is obtained in kilogram.
Guidelines for creating Bar Bending Schedule
- Create several Bar Bending Schedules for various RCC components (i.e. break up the table into various parts like Footing, pedestal, Beam, Column, Slab, etc) so that no errors occur.
- Always retain the unit weight of bars available for creating Bar Bending Schedule easily.
- Remember thumb rules which can be used for cross-checking your calculation. As for example a) rough quantity of reinforcement steel for small structure differs from 3 to 4 Kg/Sqft of Built-up area. b) total volume of Reinforcement steel for the slab is approximately 1.5% to 2% of the volume of Concrete. (Volume of Steel Reinforcement is measured by dividing the weight by density of steel, that is 7850 Kg/M3)
Tips to work out Rolling Margin of Reinforcement Steel Bar
Rolling Margin = Weight remains higher as compared to standard weight
Cut reinforcement bar into 3 pieces, each with 1 meter length
Weight every piece separately
i.e. 10 mm Día Bar, 1st one weigh 0.617, 2nd one weighs 0.62, 3rd one weigh 0.625
Now Calculate the rolling margin of Reinforcement bar
Rolling Margin = Weight of Bar 1+Weight of bar 2+weight of bar 3 / 3
Rolling margin = 0.617+0.62+0.625 / 3
Rolling margin = 1.682/3 = 0.620