Steel is a very important building material and it is widely used in construction. Some structural members can not be built without steel like Slab, beams, columns, etc. Therefore today we are going to discuss how to calculate the quantity of steel in Slab, Beam, and Column. Because it is very important, for the estimation of steel cost in slab, beam, and column.
Steel is used in construction in the form of steel bars, and steel bars come in different sizes like 8mm, 10mm, 12mm, 16mm, etc. Every different size steel bars weight is different. If you want to know more about the weight of steel bars. And how to calculate steel bar weight then you can read our previous article.
Quantity of steel in Slab, Beam, and Column
As I already tell you steel bars come in different sizes. And in every RCC structure different size of steel bars is to be used. In some circumstances, it is decided by the thumb rule and in some circumstances, it decides by many factors. Like What load coming on the structure, types of buildings, the purpose of the building, etc. Therefore I will tell you the required steel quantity in slab, beam, and column.
Quantity of steel in Slab
In the slab two types of steel bars use. One is the main bar and the second is the distribution bar. The main bar is always used in the width of the slab, and its diameter should not be less than 10mm.
Distribution bars always use in the length of the slab, and it is generally used in 8mm size. But the size of the distribution bar should not be less than 8mm also. If the width and length of the slab are equal then you can use the main bar and distribution bar according to your convenience.
How to calculate steel quantity in the slab
Assume the length of the slab is 15 meters, and the width of the slab is 8 meters.
Steel bars are placed in the slab at a 150-mm distance.
Now, convert 150mm into the meter
1000mm = 1 meter
So, 150mm = 150 /1000 = 0.150 m.
Total number of the main bars (10mm) = Length of the slab/distance between two bars
= 15/0.150 = 100, you should always add 1 piece extra so 100+1 = 101.
Weight of steel bars = D2L/162
= (102) 15/162
= 1500/162 = 9.259 kg. (This is the weight of 1 piece of steel bar).
total main bar weight = 9.259 × 101 = 935 kg.
Total number of distribution bars (8mm) = Width of the slab/distance between two bars
= 8/0.150 = 53, you should always add 1 piece extra so 53+1 = 54.
Weight of steel bars = D2L/162
= (82) 8/162
= 512/162 = 3.16 kg. (This is the weight of 1 piece of steel bar).
total distribution bar weight = 3.16 × 54 = 170 kg.
Total weight of steel bar = Main bar weight + distribution bar weight
= 935 + 170 = 1105 kg.
Quantity of steel in Beam
The quantity of steel required for the beam is about 2% of the total volume of the concrete, and in the beam minimum, 12mm size of steel bar should be used with the 8mm stirrups. Because the beam is a load-bearing structure so M20-grade concrete should be used for the construction of the beam.
How to calculate steel quantity in beam
We know the steel required for beam is 2% of the concrete volume.
let’s assume the beam size is 3 meters long, 0.304 meters wide, and 0.457 meters depth.
So, the volume of the beam = Length × width × depth
= 3 × 0.304 × 0.457
= 0.416 cubic meters.
Now, we will calculate 2% of the total concrete volume
2% of the concrete volume = (2/100) × 0.416
= 0.00832 cubic meters.
We know the density of the steel bar = 7860 kg/m3.
So the steel quantity = density of steel × volume of steel
= 7860 × 0.00832
= 65.395 = 65 kg.
You can also calculate required steel quantity for the beam using this method.
Quantity of steel in column
The quantity of steel required for the column is about 6% of the total volume of concrete, and in the column minimum 12mm of steel bar should be used with the 8mm stirrups. The size of the steel bar in the column can increase according to the load and floors of the building. The column is also a load-bearing structure so the M20 grade of concrete should be used in the construction of the column.
How to calculate steel quantity in column
We know the steel required for column is 6% of the concrete volume.
let’s assume the column size is 5 meters long, 0.304 meters wide, and 0.457 meters depth.
So, the volume of the column = Length × width × depth
= 5 × 0.304 × 0.457
= 0.694 cubic meters.
Now, we will calculate 6% of the total concrete volume
6% of the concrete volume = (6/100) × 0.694
= 0.0416 cubic meters.
We know the density of the steel bar = 7860 kg/m3.
So the steel quantity = density of steel × volume of steel
= 7860 × 0.0416
= 327.29 = 327 kg.
You can also calculate required steel quantity for the column using this method.
Conclusion
In this article, we have discussed how to calculate steel quantity in slab, how to calculate steel quantity in beam, and how to calculate steel quantity in the column. You can calculate steel quantity in slab, beam, and column using the above method, which I told you about.