Derivation for d2/162

Hello every civil engineers. We know that d²/162  is the formula to find out the weight of circular steel bar per metre length . but some persons don’t know how  is arrived

So I will explain  how this formula is arrived.

Weight of circular shape steel bar per metre length = area x length x unit weight of steel

Unit weight of steel = 7850 kg/m³

Therefore,  weight = πD²/4 x 1000 x ( (7850/1000 x1000 x 1000 ) )

put all the values in ‘mm’

= 0.7854 x D² x ((7850/1000 x 1000 ))

= D² x ( ( 6162.25 / 1000 x 1000 ) )

= D² X 0.006162

= D² x 1 / (0.006162 )^-1

= D² /162.28

So we take

Weight of steel bar per metre length = D² /162

Note : why use this step 1 / (0.006162 )^-1  . because 0.006162   is equal to 1 / (0.006162 )^-1   but 0.006162  is six digit value It is not remember in our mind therefore this step is used for our remembrance. 

ALSO READ

HOW TO FIND UNIT WEIGHT OF STEEL BARS

HOW APPROXIMATELY CALCULATE STEEL BARS QUANTITY IN RCC ELEMENTS

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