I-beam — 79.18 kg per metre, 100 cm² cross-sectional area. IS 808 Table 3 - Narrow Parallel Flange Beams.
Narrow Parallel Flange Beams (NPB). Reproduced as printed in IS 808 Table 3 - Narrow Parallel Flange Beams.
As printed in IS 808 Table 3 - Narrow Parallel Flange Beams. 340 mm deep, 250 mm wide. Units are shown on every row, because the two standards on this site use different ones for the radius of gyration.
| Depth of section D | 340 | mm |
|---|---|---|
| Width of flange B | 250 | mm |
| Thickness of web t | 9 | mm |
| Thickness of flange T | 14 | mm |
| Flange slope | 90 | ° |
| Root radius R1 | 18 | mm |
| Toe radius R2 | 0 | mm |
| Mass per metre M | 79.18 | kg/m |
|---|---|---|
| Sectional area A | 100 | cm² |
| Second moment of area Izz | 21,500 | cm⁴ |
|---|---|---|
| Radius of gyration rzz | 146 | mm |
| Elastic section modulus Zzz | 1,260 | cm³ |
| Plastic section modulus Zpz | 1,400 | cm³ |
| Second moment of area Iyy | 3,650 | cm⁴ |
|---|---|---|
| Radius of gyration ryy | 60.1 | mm |
| Elastic section modulus Zyy | 292 | cm³ |
| Plastic section modulus Zpy | 446 | cm³ |
| Torsion constant (St Venant) It | 63.4 | cm⁴ |
|---|---|---|
| Warping constant Iw | 9,68,000 | cm⁶ |
Total weight is the mass per metre multiplied by the length and the number of pieces. Ten pieces of NPB 350 × 250 at six metres each is 79.18 × 6 × 10 = 4,751 kg. There is nothing else to it — the standard publishes the mass, so no one needs to compute it from the area.
You can check that mass against the area on this page: 100 cm² of steel at 7 850 kg/m³ is 78.5 kg/m. Every row in this dataset was checked that way, which is how the contradictions flagged on some of these pages were found.
Work it out for your own lengths and quantities →
IS 808 : 2021 gives NPB 350 × 250 a mass of 79.18 kg per metre. Its printed cross-sectional area of 100 cm² agrees: 100 cm² of steel at 7 850 kg/m³ works out at 78.50 kg per metre.
475.08 kg. Mass per metre times length: 79.18 × 6. Ten such pieces come to 4751 kg.
340 mm deep and 250 mm wide, with a 9 mm web and 14 mm flanges.
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