MB 125 (ISMB 125)

I-beam — 13.35 kg per metre, 17 cm² cross-sectional area. IS 808 Table 1 - Medium & Wide Flange Beams.

zyB 70D 125T 8R2 4.5R1 9t 5
Mass per metre
13.35kg/m
Sectional area
17cm²
Depth
125mm
Width
70mm

Medium & Wide Flange Beams (MB, WB). Reproduced as printed in IS 808 Table 1 - Medium & Wide Flange Beams.

MB 125 section properties

As printed in IS 808 Table 1 - Medium & Wide Flange Beams. 125 mm deep, 70 mm wide. Units are shown on every row, because the two standards on this site use different ones for the radius of gyration.

Dimensions

Depth of section D 125 mm
Width of flange B 70 mm
Thickness of web t 5 mm
Thickness of flange T 8 mm
Flange slope 98 °
Root radius R1 9 mm
Toe radius R2 4.5 mm

Mass and area

Mass per metre M 13.35 kg/m
Sectional area A 17 cm²

Major axis (z-z)

Second moment of area Izz 445 cm⁴
Radius of gyration rzz 51.1 mm
Elastic section modulus Zzz 71.3 cm³
Plastic section modulus Zpz 82.1 cm³

Minor axis (y-y)

Second moment of area Iyy 38.4 cm⁴
Radius of gyration ryy 15 mm
Elastic section modulus Zyy 10.9 cm³
Plastic section modulus Zpy 18.4 cm³

Torsion and warping

Torsion constant (St Venant) It 3.99 cm⁴
Warping constant Iw 1,560 cm⁶

What a length of MB 125 weighs

Total weight is the mass per metre multiplied by the length and the number of pieces. Ten pieces of MB 125 at six metres each is 13.35 × 6 × 10 = 801 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: 17 cm² of steel at 7 850 kg/m³ is 13.35 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 →

Common questions about MB 125

What is the weight of MB 125 per metre?

IS 808 : 2021 gives MB 125 a mass of 13.35 kg per metre. Its printed cross-sectional area of 17 cm² agrees: 17 cm² of steel at 7 850 kg/m³ works out at 13.35 kg per metre.

How much does a 6 m length of MB 125 weigh?

80.10 kg. Mass per metre times length: 13.35 × 6. Ten such pieces come to 801 kg.

Is MB 125 the same as ISMB 125?

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 ISMB 125 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.

What are the dimensions of MB 125?

125 mm deep and 70 mm wide, with a 5 mm web and 8 mm flanges.

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Where these figures come from. IS 808 Table 1 - Medium & Wide Flange Beams 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.

What is ours. The selection and arrangement of these tables, the checks run against them, and the findings those checks produced — which rows disagree with themselves, which figures were superseded by amendment, and which could not be read — are QuickBOQ’s work, and so is this wording. Quote the numbers freely; they belong to everyone. Copying the compilation and the commentary is a different thing, and we would rather you linked to it.