Steel Buildings in Europe

Part 3: Actions 3 - 4 3 COMBINATIONS OF ACTIONS 3.1 General The individual actions should be combined so as not to exceed the limit state for the relevant design situations. Actions that cannot occur simultaneously, e.g. due to physical reasons, should not be considered together in a same combination. Depending on its uses and the form and the location of a building, the combinations of actions may be based on not more than two variable actions – See Note 1 in EN 1990 § A1.2.1(1). The National Annex may provide additional information. 3.2 ULS combinations 3.2.1 Static equilibrium To verify a limit state of static equilibrium of the structure (EQU), it shall be ensured that: E d,dst ≤ E d,stb where: E d,dst is the design value of the effect of destabilising actions E d,stb is the design value of the effect of stabilising actions 3.2.2 Rupture or excessive deformation of an element To verify a limit state of rupture or excessive deformation of a section, member or connection (STR and/or GEO), it shall be ensured that: E d ≤ R d where: E d is the design value of the effect of actions R d is the design value of the corresponding resistance Each combination of actions should include a leading variable action or an accidental action. 3.2.3 Combinations of actions for persistent or transient design situations According to EN 1990 § 6.4.3.2(3), the combinations of actions can be derived either from expression (6.10) or from expressions (6.10a and 6.10b – whichever is more onerous). The choice between these two sets of expressions may be imposed by the National Annex. In general, expression (6.10) is conservative in comparison to the pair of expressions (6.10a and 6.10b), but it leads to a reduced number of combinations to consider.