ES EN 1998:2015 states the following fundamental requirements:
Structures in seismic regions shall be designed and constructed in such a way that the following requirements are met, each with an adequate degree of reliability( ES EN 1998:2015, Art. 2.1):
- No-collapse requirement :
The structure shall be designed and constructed to withstand the design seismic action defined in section 3( ES EN 1998:2015, SECTION 3) without local or global collapses, thus retaining integrity and a residual load capacity after the seismic events.
*The design seismic action is expressed in terms of
a) The reference seismic action associated with a reference probability of exceedance, PNCR in 50 years or a return period, TNCR and
b) The importance factor yi( gamma i) to take into account reliability differentiation
* PNCR(IN 50 years)=10% and TNCR=475 years
-Damage limitation requirement
The structure shall be designed and constructed to withstand a seismic action having a larger probability of occurrence than the design seismic action, without the occurrence of damage and the associated limitations of use, the cost of which would be disproportionally high in comparison with the costs of the structure itself.
* The seismic action to be taken into account for the "damage limitation requirement" has a probability of exceedance PDLR, in 10 years and a return period, TDLR.
* In the absence of more precise information, the reduction factor applied on the design seismic action in accordance with 4.4.3.2(2)( ES EN 1998:2015) may be used to obtain the seismic action for the verification of the damage limitation requirement.
*PDLR(in ten years)=10% and TDLR=95 years
Definition of Terms:
PNCR: reference probability of exceedance in 50 years of the reference seismic actions for the no-collapse requirement.
TNCR: reference return period of the reference seismic action for no-collapse requirement.
PDLR: reference probability of exceedance in 10 years of the reference seismic actions for damage limitation requirement.
TDLR: reference return period of the reference seismic action for damage limitation requirement.
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