How to measure the concrete work of the bridge girder

This another useful presentation by renowned engineer S.L. Khan. In this video, Mr. Khan teaches you how to determine the concrete work (volume) for the I shaped girder of a bridge.

By applying the following formula, the volume of girder is calculated :-

Volume of girder = cross section area x length of the girder

Calculation is made on the basis of the following steps :-

1) Transform the section into simple geometry.
2) Work out section area of each segment.
3) Add sectional areas of segments= total sectional area.
4) Multiply total section area with the length of girder = volume or concrete work

To make the calculation, the solution is given to the following problem :-

Problem : Determine the volume of concrete work for the specified girder. Consider the length of the girder as 20 feet. If there is any steel, just omit it.

Area of figure 1 = 24” x 6” = 144 in²
Area of figure 2 = 36” x 6” = 216 in²
Area of figue 3 = 24” x 6” = 144 in²
So, entire sectional area = 504 in²

Now convert it to square inches to square feet by dividing it with 12 x 12

So, total sectional area = 3.5 ft²

Volume of the girder = sectional area x length

After putting the all the values we get :-
Volume of the girder = 3.5 x 20 = 70 ft³

To learn how the calculation is made by applying other examples, go through the following video tutorial.

Video Source: SL Khan