Calculating the amount of steel bar for reinforced concrete beams

For example, if we are going to make floor beams measuring 20 cm x 30 cm with a length of 3m, the main reinforcing steel we will use has a diameter of 10 mm, totaling 8 rods, while for shear stirrup we use steel bar of 8 – 200 (read: 8 mm diameter steel bar installed 20 cm apart).

Requirements for main reinforcing steel of D10

In the beam, there are 8 pieces of steel 10 mm in diameter, each 3 m long. So the total requirement is 8 pcs x 3 m = 24 m. If the length of steel bar on the market is 12 m per rod, then the steel bar requirement is 24 m : 12 m = 2 rods.

Requirements for shear stirrup of D8

For every 3 m of a beam, how many pieces of shear stirrups are there? We can calculate this by means of 3 m : 0.2 m = 15 pcs.
How long steel bar is required for one shear stirrup? We can calculate it by adding up the circumference of the shear stirrup, which is 0.15+0.25+0.15+0.15+0.05+0.05 = 0.9m.
So, the total requirement for shear stirrups is 15 pieces x 0.9 m = 13.5 m.
In the same way, when calculating the main reinforcing steel, we can find out the number of rods required to make the shear stirrups: 13.5 m : 12 m = 1.125 rods.

Meanwhile, we can calculate the concrete requirement using the m3 system, which is 0.2 m x 0.3 m x 3 m = 0.18 m3.

In conclusion, from the calculation above, we can know that the total amount of steel bar required is as follows:

Steel bar of D10 = 2 rods.
Steel bar of D8 = 1.125 rods.
Concrete = 0.18 m3.