STEEL MEASUREMENT

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DO YOU KNOW STEEL IS MEASURED IN MM BUT ORDERED IN KG?

Steels or rebars for reinforced concrete are measured in mm from drawing and recorded in Bar Bending Schedule (BBS).

Example of B.B.S

Do you ever think how it is converted into kilograms or tonnes, as it is written or filled in Bill of Quantity (BOQ)?

Example of B.O.Q 

There is a simple formula that is used for steels or rebars conversion from mm into kg (D2/162), This is important as always we fill B.O.Q and ordering steel in terms of kilograms or tonne.
This formula used to find the weight of steels per length measured,
Therefore, Quantity in Kg/m = D2/162, where "D" is the diameter of steel in mm.

For example
If we have 106m of 12mm steel from structural drawing and BBS and we want to fill this quantity into B.O.Q we have to convert it into KG.

Soln
Quantity of steel per meter = D2/162
                                                                      = 122/162
                                                                      = 0.889 kg/m
                Then, for 106m we have 106 x 0.889 =94.234kg
                Therefore the quantity of cement is 94.234kg.

Do you know how  this formula D2/162 were obtained or formulated.
We have the density of steel which is 7850kg/m3, which means we have 7850kg for each 1m3 of steels or rebars.
From mass = density x volume
Mass per length = density x area
                             = 7850kg/m3 x πD2/4
After Conversion of units into mm then we have,
                                = πD2/4 x 1000 x 7850/ (1000 x 1000 x1000)
                                = 0.0061622D2
                                = D2/162.27 hence shown.

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Comments

  1. UnknownNovember 13, 2019 at 1:43 AM

    I think the idea is good just keep on updating

    ReplyDelete
    Replies
    1. BuilderzfocusNovember 13, 2019 at 8:20 AM

      We will always look for better materials and update our blog

      Delete

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