Derivation of D^2/162

UNIT WEIGHT OF STEEL BARS

(Derivation of D²/162)

 Weight of Steel Bars per metre is calculated using the equation 

Weight of the steel bar W = D²/162

 Derivation 

We know, Weight of the steel bar W = Density x Volume

Volume = Area x Length

Area of a circular bar = (π x D ²) / 4

                                                = (3.142 x D ²) / 4

                                                = 0.785 x D ² mm ²

Length of the bar          = 1.0 m (Unit length)

                                                 = 1000 mm

 Density of Steel             = 7850 kg/m³

                                                 = 7850 / (1000 x 1000 x 1000) kg/mm³

                                                 = 7.85 x 10^-6 kg/mm³

 Weight of the steel bar

 W       = 0.785 x D ² mm ² x 1000 mm x 7.85 x 10^-6 kg/mm³

             = 0.00616 D ² kg

=D²/162.2 kg per m

 

This equation is applicable for circular shape steel with density 7850 kg/m³