This construction video tutorial will teach you the method for working out the quantity of concrete in a trapezoidal footing.

With the help of a special formula, the calculation can be done easily for determining the volume.

The footing is divided in two parts as cuboid shape and trapezoidal shape. The cuboid shape is represented as 1 and trapezoidal shape is represented as 2.

Initially, it is required to find out the volume of cuboid as follow:-

• The dimension of lower base of footing is taken as 1800 x 1800 mm
• The dimension of upper base of footing is taken as 900 x 900 mm
• The height of cuboid shape is taken as 200 mm
• The height of trapezoidal shape is taken as 400 mm

The volume of cuboid 1 will be calculated as follow:-

Volume = Length x Breadth x Height

After putting all the values provided, we get the following output:-

1.8 x 1.8 x 0.2 meter (all the values are converted to meter)

= 0.648 m³

The volume of trapezoidal shape will be calculated as follow:-

Volume = h/3 (A₁ + A₂ + √(A₁ x A₂)

Here, h denotes height and A₁ denotes the area of lower base and A₂ denotes the area of upper base.

It is required to determine the volume of A₁ first.

So, A₁ = 1.8 x 1.8 = 3.24 m²

Now, it is necessary to find out the area of A₂

So, A₂ = 0.9 x 0.9 = 0.81 m²

After putting all the values in the above formula, the volume of trapezoidal area will be as follow:-

V₂ = 0.4/3 (3.24 + 0.81 + √(3.24 x 0.81) = 0.756m³

Therefore, total volume = volume of cuboid + volume of trapezoidal

After putting the value, we get the following results:-

= 0.756 + 0.648 = 1.404 m³

This method can be applied to determine the volume of any type of trapezoidal footing.

Video Courtesy : ENGINEERING TACTICS