How to Calculate Unit Weight Of Steel Bar ?

How to calculate unit weight of steel bar ?

By Afroz Civil


Summary



Dia. of bar in mm                Weight of bar in Kg

6mm                                      0.222Kg
8mm                                      0.395 Kg
10mm                                    0.616 Kg
12mm                                    0.888 Kg
16mm                                    1.578 Kg
20mm                                    2.466 Kg
25mm                                    3.853 Kg
32mm                                    6.313 Kg
40mm                                    9.865 Kg

Formula for calculate Weight of steel bar per metre length.

*Weight =(Diameter of steel bar ) 2 /162 Kg/m *

Here , Explanation 

◆ What is Steel?

Steel is the most versatile commonly used structural material. The essential elements in steel are metallic iron and the element non-metallic carbon, with small quantities of other elements such as silicon, nickel, manganese, chromium and copper. It is thus an alloy. Though steel is usually more than 90% iron, with other elements present in small quantities, these other elements have a pronounced effect on the properties of steel.

◆ Types of Steel

Depending upon the chemical composition, different types of steels are classified as:

  1. Mild Steel
  2. Medium Carbon Steel
  3. High Carbon Steel.
  4. Low Alloy Steel
  5. High Alloy Steel

Out of these, the first three types of steels are known as structural steel, commonly used in steel structures. In Indian standard IS:800-1984(Code of practice for general construction in steel) is applicable to the types of structural steels covered by the following Indian Standard:

1. IS      :226-1975 Structural Steel (Standard Quality)

2. IS     :1977-1975 Structural Steel (Ordinary Quality)

3. IS     : 2062-1984 Weldable Structural Steel

4. IS     :961-1975   Structural Steel (High Tensile)

5. IS     :8500-1977 Weldable Structural Steel (medium and high strength qualities)

Steel conforming to IS: 226-1975 is suitable for all types of structures subjected to static, dynamic and cyclic loading, and is suitable for welding up to 20 mm thickness. The physical properties of mild steels are as under:

1. Density of Steel = 7850 kg/m3

2. Youngs’s modulus of elasticity 

                     (E)  =  2.04 x 105 Mpa (or N/mm2)

3. Modulus of Rigidity

                    (G)  =  0.785 x 105 Mpa (or N/mm2)

4. Poisson’s Ratio 

                    (µ)=0.3 (inelastic rang)

5. Coefficient of thermal expansion or contraction 

              = 12 x 10-6 per °C or 6.7 x 10-6 per °F.

◆ Derivation of Unit weight of steel bar  = d2/162 Kg /m.

As we know the density of steel  =  7850 kg/ m3

Weight of steel per metre  =  Volume × Density   (Volume = Area × Length)

=  π/4 x d2 × 1000 × 7850 kg/m  

                                             (length = 1000 mm)  

=  0.785 × d2 × 1000 × 7850 kg / (1000 × 1000  × 1000).                            (1 metre = 1000 mm)

=  785 x d2 × 0.00000785

=    d2/1  ×  0.00616225 /1

=    d2/1/0.00616225

=    d2/162.27 ≈

=     d2/162   kg/m     (say).




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