Introduction - The Behaviour and Design of Steel Structures to EC3 - page 6

←
←
←
←
←

Knowledge
Experience
Imagination
Intuition
Creativity

Invention or modification
of structural system

- - -

Approximations
Loads
Behaviour

Preliminary analysis

← Design criteria

Design codes

Proportioning members
and joints

←

- -

Loads
Behaviour

Analysis

Design criteria
Design codes

←
←

Evaluation

Figure 1.5 The structural design process.

gatheredfromothers[9-12]; orthedesignermayusehisorherownimagination,
intuition, and creativity [13], or a combination of all of these.
Followingthesefirsttwostepsofdefinitionandinventioncomeaseriesofsteps
whichincludethestructuraldesign,evaluation,selection,andmodificationofthe
structural system. These may be repeated a number of times before the structural
requirements are met and the structural design is finalised. A typical structural
design process is summarised in Figure 1.5.
After the structural system has been invented, it must be analysed to obtain the
informationrequiredfordeterminingthemembersizes.First,theloadssupported
byandtheforcesactingonthestructuremustbedetermined.Forthispurpose,load-
ing codes [14, 15] are usually consulted, but sometimes the designer determines
theloadingconditionsorcommissionsexpertstodothis.Anumberofapproximate
assumptionsaremadeaboutthebehaviourofthestructure,whichisthenanalysed
and the forces and moments acting on the members and joints of the structure
are determined. These are used to proportion the structure so that it satisfies the
structural requirements, usually by referring to a design code, such as EC3 [8].
Atthisstageapreliminarydesignofthestructurewillhavebeencompleted,how-
ever,becauseoftheapproximateassumptionsmadeaboutthestructuralbehaviour,
itisnecessarytocheckthedesign.Thefirststepsaretorecalculatetheloadsandto