Principles of limit state design

The Structural Eurocodes are based on limit state principles, in which a distinction is made between ultimate and serviceability limit states.

Ultimate limit states are concerned with the safety of people and the structure. Examples of ultimate limit states include loss of equilibrium, excessive deformation, rupture, loss of stability, transformation of the structure into a mechanism, and fatigue.

Serviceability limit states are concerned with the functioning of the structure under normal use, the comfort of people, and the appearance of the construction works. Serviceability limit states may be reversible (e.g. deflection) or irreversible (e.g. yield).

Limit state design involves verifying that relevant limit states are not exceeded in any specified design situation (see Section 2.6). Verifications are performed using structural and load models, the details of which are established from three basic variables: actions, material properties, and geometrical data. Actions are classified according to their duration and combined in different proportions for each design situation.

Figure 2.5 illustrates the relationship between these various elements of limit state design.

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  • Randy
    What are the structural design principles in eurocode?
    3 months ago

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