How to Calculate Slab Steel Quantity from Drawing | BBS of Slab

Steel Calculations

• Weight of bar in kg/meter should be calculated as (d² ÷ 162) where‘d’ is the diameter of bar in mm.
• ‘L‘ for column main steel in footing should be considered as minimum 30cm/as specified.
• For bent up bar add 0.42d in a straight length of the bar where’d’ is the clear depth of beam/slab.

Steel Quantity Calculation

1. (Calculation of bars no’s): first, calculate the number of bars required (main and distribution both). Formula = (total length – clear cover)/center to center spacing + 1 main bar, = (5000 – (25+25))/100 + 1, = 4950 divided by 100 + 1, = 51 bars., distribution bar = (2000 – (25+25))/125 + 1, = 1950 divided by 125 + 1, = 17 bars.
2. (Cutting length) main bar: formula = (l) + (2 x ld) + (1 x 0.42d) – (2 x 1d), where l = clear span of the slab, ld = development length which is 40 d (where d is diameter of bar), 0.42d = inclined length (bend length), 1d = 45° bends (d is diameter of bar) first calculate the length of “d“. D = (thickness) – 2 (clear cover at top, bottom) – diameter of the bar, = 150 – 2(25) -12, d = 88 mm ans, by putting values: cutting length = 2000 + (2 x 40 x 12) + (1 x 0.42 x 88) – (2 x 1 x 12), cutting length = 2000 + 960 + 36.96 – 24, =2972.96 mm ~ 2973 mm or 2.973 m.
3. (Cutting length) Distribution bar: formula = clear span + (2 x development length (ld)), = 5000 + (2 x 40 x 8),  = 5640 mm or 5.64 m
4. (Steel Quantity Calculation) Conclusion:
   1. Main bar nos = numbers 51, main bar length = length (51 x 2.973 m) = 151.623 m, main bar weight = weight (d^2/162) x length = 134.776 kg.
   2. Distribution bar nos = numbers 17, distribution bar  length= length (17 x 5.64 m) = 95.88 m, distribution bar  weight = weight (d^2/162) x length = 37.87 kg.

How to Calculate Steel Weight?

Weight of Steel = (l/1000) x (w/1000) x t x η

l = length in mm

w = width in mm

t = thickness in mm

η = Specific material density ( e.g.: steel = 7.85 kg / dm³)

Steel Quantity Calculation

(Cutting length) main bar: formula = (l) + (2 x ld) + (1 x 0.42d) – (2 x 1d), where l = clear span of the slab, ld = development length which is 40 d (where d is diameter of bar), 0.42d = inclined length (bend length), 1d = 45° bends (d is diameter of bar) first calculate the length of “d“.

Bar Bending Schedule Formulas

Example of Beam Reinflorcement Calculation:

• Length of B1 = clear distance between walls + 2 x width of walls – 2 x bar cover + 2 x bend length.
• Length of bar B2: A + B + C = 4000 + 2 x 230 – 2 x 40 + (1.414xH – H)
• B2 = 4000 + 2 x 230 – 2 x 40 + (1.414×334 – 334) = 4518.3 = 4520mm.

How to Calculate Steel Quantity for Slab?

The total steel quantity per slab must be equal to the total amount of main steel and stirrup steels. In simple terms, one can just multiply the length of the slab by its width and then divide the area by 12.5.

What Is Bar Bending Schedule?

Bar Bending Schedule (BBS) helps to determine the quantity of steel required in construction of your house. This helps to get the accurate estimation of steel. Once the calculation of cutting and bending is done it reduces the wastage of steel and it becomes economic.

How to Calculate Steel Quantity?

Steel quantity is calculated by multiplying the cross-section of steel with its total density which can be 7850 kg/m3. The total steel quantity per slab must be equal to the total amount of main steel and stirrup steels.

Slab Steel Calculation

The Thumb rule to calculate steel in slabs is 3.5 kg to 4 kg/sq. ft of built-up area. On the whole, approximately 3500 kg to 4000 kg of steel is required to build a 1000 square feet structure. This is one of the most basic important information that one must be aware of before building his/her own dream house.

Steel Quantity Calculation Formula

As per thumb rule steel quantity required in the formation of RCC beam should be 2% of total volume of concrete. To calculate the steel quantity in beam as 2% of volume of concrete = 0.02 x 7850 x 5.29 = 830 kg.

Steel Quantity Formula

In simple terms, one can just multiply the length of the slab by its width and then divide the area by 12.5. The above simple formula helps the builder to calculate the steel mesh that is required to make the slabs stronger and long-lasting.

Slab Reinforcement Calculation

Number of bars = (length ÷ spacing) + 1
Get the number of bars on the NORTH side. Say, 18 nos. Next, get the number of bars on the SOUTH side. As the clear length and spacing of bars are the same as the NORTH side.

Steel Quantity Calculation Excel Sheet

There are different ways to calculate steel quantity depending on the type of structure and the design requirements. However, a simple method to calculate the steel quantity for reinforced concrete structures is as follows:

• Determine the total length of steel bars required for the structure.
• Calculate the weight of steel required based on the length and the diameter of the bars.
• Multiply the weight of steel by the number of bars required.

Steel Calculator for Slab

To use this calculator, you’ll need to enter the following inputs:

• Length of the slab
• Width of the slab
• Depth of the slab
• Concrete grade (usually specified as a number followed by “MPa”, e.g. 25MPa)
• Spacing of the bars (center to center distance)
• Diameter of the bars
• Total number of bars in both directions (i.e. for top and bottom layers)

How to Calculate Steel Quantity Pdf?

Calculate Steel Quantity for Slab

• Compute number of steel bars. Main Steel Bars. No. of bars= (Slab length(L)/spacing)+1 Equation 1.
• Calculate cutting length:
• calculate the required number of bars for both directions. No. of bars = {(L or w – concrete cover for both sides) ÷ spacing} +1 Equation 8.

Number of Bars Formula

The formula to calculate the number of bars required for a structural element, such as a beam or column, is:

Number of Bars = (Area of Steel Required) / (Area of One Bar)

where:

• Area of Steel Required: The cross-sectional area of steel reinforcement required to meet the design specifications of the structural element, typically expressed in square millimeters (mm²) or square inches (in²).
• Area of One Bar: The cross-sectional area of a single bar of the specified diameter, typically expressed in square millimeters (mm²) or square inches (in²).

No of Bars Formula

Number of bars = (Total cross-sectional area of steel required) / (Cross-sectional area of one bar)

where:

• Total cross-sectional area of steel required: The total area of steel reinforcement required to meet the design specifications of the structural element, typically expressed in square millimeters (mm²) or square inches (in²).
• Cross-sectional area of one bar: The cross-sectional area of a single bar of the specified diameter, typically expressed in square millimeters (mm²) or square inches (in²).