In-plane bending of beams - The Behaviour and Design of Steel Structures to EC3 - page 183

5.6 Strength design of beams

5.6.1 Elastic design of beams

5.6.1.1 General

Fortheelasticmethodofdesigningabeamforthestrengthlimitstate,thestrength
design loads are first obtained by multiplying the nominal loads (dead, imposed,
orwind)bytheappropriateloadcombinationfactors(seeSection1.5.6).Thedis-
tributions of the design bending moments and shear forces in the beam under the
strength design load combinations are determined by an elastic bending analysis
(when the structure is statically indeterminate), or by statics (when it is statically
determinate). EC3 also permits a moment redistribution to be made in each ade-
quately braced Class 1 or Class 2 span of a continuous beam of up to 15% of the
span's peak elastic moment, provided equilibrium is maintained. The beam must
be designed to be able to resist the design moments and shears, as well as any
concentrated forces arising from the factored loads and their reactions.
The processes of checking a specified member or of designing an unknown
member for the design actions are summarised in Figure 5.32. When a specified

Checking Designing

Length and loading

Section

Analysis for M Ed , V Ed , R Ed

Find f y
Classify section

Guess f y and section
classification

Check moment Select trial section

(usually for moment)

Check f y and
classification

Check bracing
Check shear
Check shear and bending
Check bearing

Check serviceability

Figure 5.32 Flow chart for the elastic design of beams.