Earthquake resistance to Eurocode 8

[Agent Coconut]

Hi Enginners,

I have a project where the clients has specific several engineering parameter for us beforehand.
The parameter is listed as below:-
- Design Code - Eurocode 8 (Fine)
- PGA = 0.05g (Lesser than National Annex)
- Return period = 2,475 years (Why?)

My question is, Eurocode is based on 475 years for no collapse requirement and 95 years for damage control.
How do I change the equation/coefficient of parameter when come to design when client specific 2,475years?

 

[HTURKAK]

My points ,
- EN 1998 has 6 parts and 1998 Part 1: General rules, seismic actions and rules for buildings ..
- There is a near collapse (NC) limit state concept . It is used as a conservative approximation of structural collapse and in Eurocode 8, Part 3, the NC limit state is defined as follows:
LS of Near Collapse (NC). The structure is heavily damaged, with low residual lateral
strength and stiffness, although vertical elements are still capable of sustaining vertical
loads. Most non-structural components have collapsed. Large permanent drifts are
present. The structure is near collapse and would probably not survive another
earthquake, even of moderate intensity.
- NC limit state is typically based on a mean return period of 2475 years (2% probability of being exceeded in 50 years).

The standards are minimum requirements IMO , provide legal shield for the designer. Moreover , the client / owner has the right to ask more to design with more stringent requirements. Sometimes the owner may ask for designing with higher importance factor .

Suggest you to look to the following doc. (Performance Based Design , performance requirements )