ABSTRACT
The design philosophy of the Eurocodes is based on the concept of limit states, i.e. states beyond which the structure no longer satisfies the design performance requirements. The Eurocodes treat the fire exposure to be an accidental situation and this requires only verification against the ultimate limit state (as opposed to the serviceability limit state). Ultimate limit states is associated with structural collapse or other similar forms of structural failure such as loss of equilibrium, failure by excessive deformation, formation of a mechanism, rupture or loss of stability. In the semi probabilistic approach, the design against the ultimate limit state is based
on the comparison between the resistance of the structure calculated with the design values of material properties, on one hand, and the effects of actions calculated with design value of actions, on the other hand. This is represented as:
Rfi,d,t(Xd,fi) > Efi,d(Ffi,d) (2.1)
where:
Rfi,d,t is the design value of the resistance in case of fire, Xd,fi is the design value of the material properties in case of fire, Efi,d is the design value of the effects of actions in case of fire, Ffi,d is the design value of the actions in case of fire.
