HOW TO CALCULATE THE STEEL QUANTITY IN COLUMN FOOTING

The steel quantity in column footing can be calculated very easily. Before calculating the steel read carefully given footing drawing and note all the important points like.

1. Footing. (Length, Width, Thickness).
2. The diameter of Footing reinforcement.
3. A grade of reinforcement is going to use.
4. The spacing of the reinforcement (c/c).
5. Hook’s length (If needed).
6. Concrete Covers of the Footing. (Top and Bottom).

Let’s solve this example to understand well.

EXAMPLE:

Suppose we have a Column Footing having a Length 2 m, Width 2 m and having a Thickness 0.250 m. The main bars is 12 mm @ 150 c/c and Distribution bar is also 12 mm @ 150 c/c. The footing clear cover is 50 mm from the top and 75 mm from the bottom. Calculate the number of steel is going to use in this Column Footing.

Steel Quantity in Column Footing Formula

Given Data:

Length of the Footing = 2 m.

The width of the Footing = 2 m.

Thickness = 0.250 m

Main bar = 12 mm @ 150 c/c

Distribution bar = 12 mm @ 150 c/c

Clear cover = 50 mm from Top and Sides and 75 mm from Bottom.

Solution:

The first step is to calculate the number of bars which are going to use in the footing.

In the second step, we will calculate the cutting length of the bars and at the last, we calculate the weight of the reinforcement bars.

FOOTING MAIN BAR‘s:

No’s of Main bar = (Total distance – clear cover) / c/c + 1

No’s of Main bar = (2 m – (0.05+ 0.05) / 0.15 + 1

No’s of Main bar = 14 Bars.

Cutting Length of one Main Bar in Footing:

Length = {Total length – 2(Half diameter of the bar + Clear cover) + 2(Thickness of the slab –Bottom and Top clear cover – Half diameter of the bar)}.

Length = 2 m – 2 (0.006 + 0.05) + 2 (0.250 – 0.075 – 0.05 – 0.006).

Length = 1.676 m.

Total length = Length of one bar x No’s of bars.

Total length = 1.676 x 14.

Total length = 23.464 m.

Weight of main bar:

Weight =  D^2/ 162.2 x Length.

Total Weight = D^2  /162.2 x 23.464 m.

Total Weight = 20.84 kg.

FOOTING DISTRIBUTION BAR:

No’s of Distribution bar = (Total distance – clear cover) / c/c + 1

No’s of Distribution bar = (2 m – (0.05+ 0.05) / 0.15 + 1

No’s of Distribution bar = 14 Bars.

Cutting Length of one Footing Main Bar:

Length = {Total length – 2(Half diameter of the bar + Clear cover) + 2(Thickness of the slab –Bottom and Top clear cover – Diameter of the bar – Half diameter of the bar)}.

Length = 2 m – 2 (0.006 + 0.05) + 2 (0.250 – 0.075 – 0.05 – 0.012 – 0.006).

Length = 2.102 m.

Total length = Length of one bar x No’s of bars.

Total length = 2.102 m x 14.

Total length = 29.428 m.

Weight of main bar:

Weight =  D^2/ 162.2 x Length.

Total Weight = D^2  /162.2 x 29.428 m.

Total Weight = 26.13 kg.

CONCLUSION:

Footing Main Bar =12 mm @150 c/c = 14 No’s = 20.48 kg.

Footing Distribution Bar = 12 mm @150 c/c = 14 No’s = 26.13 kg.

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• 1: Quantity surveying,
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