Building Construction Handbook, Eighth Edition

References: BS 4-1: Structural steel sections. Specification for

hot-rolled sections.

BS 449-2: Specification for the use of structural steel

in building. Metric units.

BS 5950-1: Structural use of steelwork in building. Code

of practice for design. Rolled and welded sections.

BS EN 1993-1: Eurocode 3. Design of steel structures.

Simple beam design (Bending)

Formula:

Z=Mf

where: Z = section or elastic modulus (BS 4-1)

M = moment of resistance > or = max. bending moment

f = fibre stress of the material, (normally 165 N/mm^2 for

rolled steel sections)

In simple situations the bending moment can be calculated:-

eg.

From structural design tables, e.g. BS 4-1, a Universal Beam

(^305) ¾ (^127) ¾ 48 kg/m with section modulus (Z) of 612„4 cm^3 about
the x-x axis, can be seen to satisfy the calculated 606 cm^3.
Note: Total load in kN can be established by summating the weight
of materials † see BS 648: Schedule of Weights of Building
Materials, and multiplying by gravity; i.e. kg ¾9„81 = Newtons.
This must be added to any imposed loading:-
People and furniture = 1„5 kN/m^2
Snow on roofs < 30°pitch = 1„5 kN/m^2
Snow on roofs > 30°pitch = 0„75 kN/m^2
Structural Steelwork---Beam Design (1)