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# Calculation formula of section area of round steel bar and its weight scale

Formula for calculating the section area of round steel bar

To find the sectional area of a plane circle from its radius, S=π r2 is 3.14×r×r = area 2

π is PI =3.14, and r is the radius of the circle

Examples:

The diameter of a steel bar is 35MM, seek its area?

A: 3.14 * 17.5 * 17.5

Area = 961.6252mm

## Rebar specification theory weight scale

Dimensions, external weight and allowable deviation of hot-rolled bar (Round bar); Theoretical weight scale of specifications (GB/T14981-94)

 The diameter of mm Allowable deviation, mm Roundness, mm Cross-sectional area mm2 Theoretical weight Kg/m A level precision Class B precision C level precision A level precision Class B precision C level precision 5.5 + / – 0.40 + / – 0.30 + / – 0.15 0.50 or less On-line calculator 0.40 or less 0.24 or less 23.8 0.187 6.0 28.3 0.222 6.5 33.2 0.260 7.0 38.5 0.302 7.5 44.2 0.347 8.0 50.3 0.395 8.5 56.7 0.445 9.0 63.6 0.499 9.5 70.9 0.556 10.0 78.5 0.617 10.5 + / – 0.45 + / – 0.35 + / – 0.20 0.60 or less 0.48 or less 0.32 or less 86.6 0.680 11.0 95.0 0.746 11.5 104 0.815 12.0 113 0.888 12.5 123 0.963 13.0 133 1.04 13.5 143 1.12 14.0 154 1.21 14.5 165 1.30 15.0 + / – 0.50 + / – 0.40 + / – 0.25 0.70 or less 0.56 or less + / – 0.40 177 1.39 15.5 189 1.48 16.0 201 1.58

Calculation formula: Radius x radius x 3.14 x per meter x 0.785

For example: the diameter of 6.0 steel bar, (0.03×0.03×3.14)×100×0.785=0.221841

In parentheses is the cross-sectional area, 3.14 is PI, 100 is centimeters (per meter), and 0.785 is specific gravity per square centimeter, so all values are converted to uniform units for calculation

## Round steel theoretical weight scale

General specific gravity of steel:

• Chromium steel 15CrA 20Cr, 7.74
• Ordinary carbon steel Q195, Q215, Q235, Q255, Q275 7.85
• 05F, 08F, 15F 10, 15, 20, 25, 30, 35, 40, 45, 50 7.85
• Carbon tool steels T7, T8, T9, T10, T12, T13, T7A, T8A, T9A, T10A, T11A, T12A, T13A, T8MnA 7.85
• Silicon manganese steel 60Si2nMnA 7.85

 Specifications of the diameter The weight per meterkg/m The diameter of The weight per meterkg/m 5.5 0.186 13 1.04 6 0.222 14 1.21 6.5 0.26 15 1.39 7 0.302 16 1.58 8 0.395 17 1.78 9 0.499 18 2.0 10 0.617 19 2.23 11 0.746 20 2.47 12 0.888 21 2.72 22 2.98 63 24.5 23 3.26 65 26 24 3.55 68 28.5 25 3.85 70 30.2 26 4.17 75 34.7 27 4.49 80 39.5 28 4.83 85 44.5 29 5.18 90 49.9 30 5.55 95 55.6 31 5.92 100 61.7 32 6.31 105 68 33 6.71 110 74.6 34 7.13 115 81.5 35 7.55 120 88.8 36 7.99 125 96.3 38 8.9 130 104 40 9.86 140 121 42 10.9 150 139 45 12.5 160 158 48 14.2 170 178 50 15.4 180 200 53 17.3 190 223 55 18.6 200 247 56 19.3 220 298 58 20.7 250 385 60 22.2 Formula: Radius x radius x 3.14 x per meter x 0.785 For example: the diameter of 6.0 steel bar, (0.03×0.03×3.14)×100×0.785=0.221841 In parentheses is the cross-sectional area, 3.14 is PI, 100 is centimeters (per meter), 0.785 is the specific gravity per square centimeter, so all values are converted into uniform units for calculation

## Rebar theoretical weight scale

 Thermal Gadolinium reinforcement (rebar) specification theory weight scale for reinforced concrete complete/per meter Type d0 (millimeter) Inside diameter d (millimeter) Outside diameter d1 (millimeter) Theoretical weight (kg/m) 6 5.75 6.75 0.222 7 6.75 7.75 0.302 8 7.5 9.0 0.395 9 8.5 10.0 0.499 10 9.3 11.3 0.617 12 11 13.0 0.888 14 13 15.5 1.21 16 15 17.5 1.58 18 17 20.0 2.00 20 19 22.0 2.47 22 21 24.0 2.98 25 24 27.0 3.85 28 26.5 30.5 4.83 32 30.5 34.5 6.31 36 34.5 39.5 7.99 40 38.5 43.5 9.87

Source: China Steel Bar Manufacturer – Yaang Pipe Industry Co., Limited (www.epowermetals.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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