We can calculate the weight of this U – section in the same way as we calculated for L section

Here, we will have to know the outer and inner edge dimensions.

Volume of the U section = cross-sectional area × Length

V = A × L = (( X_{1} × Y_{1} ) – ( x_{2} × y_{2} )) × L

Where X_{1 }is outer edge width, Y_{1} is outer edge height and x_{2} is inner edge width, y_{2 }is inner edge height.

Let us consider a 1 m long U section of outer edge width 30mm = 0.030m, outer edge height = 20 mm = 0.020 m and inner edge width 20 mm = 0.020 m, inner edge height = 15 mm = 0.015 m.

So, Volume of the U section = [ ( 0.030 × 0.020 ) – ( 0.020 × 0.015 ) ] x 1 = 0.0003 m^{3}

Hence, mass of the U section = density × volume = 7900 × 0.0003 = 2.37 kg

By using this formula we can calculate the mass of u section beam of different dimensions.