Unit Weight Of Different Dia Bar

Unit Weight Of Different Dia Bar

Reinforcement bars are measured, obtained & paid by unit of the weight i.e. in kilograms, pounds, tones etc. Unit weight of deformed rebars denotes it is weight per unit length. The common units applied for recording Unit Weight of Steel range from the kilogram per meter (kg/m) & pounds per feet ( lb/ft ).

In any construction project, if there are reinforcing bars, the contractor provides the ( BBS ) bar bending schedules to measure the Quantity of the rebar where details are given for the cut length of the bar, diameter & weight of the rebar.

The Site Engineer examines & approves these ( BBS ) bar bending schedules for addition in IPC of the Contractor which is then disbursed by the Employer.

Steel Weight Calculation Formula – The Unit weight of steel is calculated with the following formula

Unit weight of steel = d*d/162.28 (kg/m)

This formula is gives rough Estimation of the unit weight of the rebar, but it can’t provide you the proper value of the steel unit weight.

To get the exact result, it is required to follow the steel manufacturer’s manual where the unit weight of steel bars is cited.

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Derivation of the Rebar Unit Weight Formula D2/162.28

Unit weight of the steel = D2 / 162.28

This formula is originated from the density of the steel rebar that is 7850 Kg / m3.

D stands for the diameter of the rebar in mm.

The result of this formula will come as weight per length i.e. kg per meter.

By multiplying the density ( ρ ) with the Cross-Section area of rebar, the weight per length of the rebar will be produced.

Therefore

Ρ x A = (7850 kg/m3 ) x (π x D2)/4

= (7850 kg/m3 ) x (3.14 x D2)/4
=6162.25 x D2 kg/m (where D is in meters)

As φ diameter of the rebar is commonly provided in millimeters.

So, let’s assume Dm is diameter in mm & to change it into meters, it should be divided with 1000.

Thus;
1 meter = 1000 millimeters
=6162.25 x (Dm/1000)2 kg/m
=6162.25 x (Dm/1000)2 kg/m
=0.00616225 x Dm2

Or

= Dm2/(0.00616225)-1
= Dm2/162.2783 in kg/m

Where Dm stands for Dia of the rebar in mm.

Therefore, this formula is applicable for getting fairly accurate value of the unit weight of steel in MKS system.

Other Post

1. Checklist For R.C.C Slab & Beams

2. What is the difference Between PPC And OPC Cement

3. Bar Bending Schedule For Slab And Estimation Of Steel Reinforcement In Slab

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( Civil Engineering Technology )