angle — 53.85 kg per metre, 68.6 cm² cross-sectional area. IS 808 Table 10 - Unequal Leg Angles.
Unequal Leg Angles. Reproduced as printed in IS 808 Table 10 - Unequal Leg Angles.
As printed in IS 808 Table 10 - Unequal Leg Angles. legs 180 × 180 mm, 20 mm thick. Units are shown on every row, because the two standards on this site use different ones for the radius of gyration.
| Length of leg A A | 180 | mm |
|---|---|---|
| Length of leg B B | 180 | mm |
| Thickness of leg t | 20 | mm |
| Root radius R1 | 18 | mm |
| Toe radius R2 | 4.8 | mm |
| Mass per metre M | 53.85 | kg/m |
|---|---|---|
| Sectional area A | 68.6 | cm² |
| Centroid from the back of leg A Cx | 52 | mm |
|---|---|---|
| Centroid from the back of leg B Cy | 52 | mm |
| Second moment of area Ixx | 2,060 | cm⁴ |
|---|---|---|
| Radius of gyration rxx | 54.9 | mm |
| Elastic section modulus Zxx | 161 | cm³ |
| Plastic section modulus Zpx | 290 | cm³ |
| Second moment of area Iyy | 2,060 | cm⁴ |
|---|---|---|
| Radius of gyration ryy | 54.9 | mm |
| Elastic section modulus Zyy | 161 | cm³ |
| Plastic section modulus Zpy | 291 | cm³ |
| Second moment of area Iuu | 3,270 | cm⁴ |
|---|---|---|
| Second moment of area Ivv | 853 | cm⁴ |
| Radius of gyration ruu | 69.1 | mm |
| Radius of gyration rvv | 35.3 | mm |
| Tangent of the principal axis angle tan α | 0.79 |
| Torsion constant (St Venant) It | 90.6 | cm⁴ |
|---|
Total weight is the mass per metre multiplied by the length and the number of pieces. Ten pieces of ∠ 180 × 180 × 20 at six metres each is 53.85 × 6 × 10 = 3,231 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: 68.6 cm² of steel at 7 850 kg/m³ is 53.85 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 ∠ 180 × 180 × 20 a mass of 53.85 kg per metre. Its printed cross-sectional area of 68.6 cm² agrees: 68.6 cm² of steel at 7 850 kg/m³ works out at 53.85 kg per metre.
323.10 kg. Mass per metre times length: 53.85 × 6. Ten such pieces come to 3231 kg.
It is the same section under the name IS 808 : 2021 gives it — the 2021 revision of IS 808 dropped the "IS" prefix, so a drawing saying ISA 180x180x20 means this section. Check the edition before assuming the figures match, though: this page publishes the current tables, and a great many tables in circulation were copied from the 1989 edition.
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Log in to QuickBOQ →Where these figures come from. IS 808 Table 10 - Unequal Leg Angles Section properties are facts published in the standards, and they are reproduced here as printed. Where a standard contradicts itself, both of its figures are shown and neither is corrected.
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