The electronic pdf versions of the documents found through http://www.dnv.com/ are the officially binding versions. Copyright Det Norske Veritas.
![[Table of Contents]](/dwicons/b_toc.gif)
|
DNV-OS-C201 Structural Design of Offshore Units (WSD method)
|
Sec.7
A 500 Stochastic fatigue analysis
Sec.7 A
501 Stochastic fatigue analyses shall be based upon recognised
procedures and principles utilising relevant site specific data
or North Atlantic environmental data, see 107 and 108.
Sec.7 A
502 Simplified fatigue analyses may be used as a "screening" process
to identify locations for which a detailed, stochastic fatigue analysis
should be undertaken.
Sec.7 A
503 Fatigue analyses shall include consideration of the directional
probability of the environmental data. Provided it can be satisfactorily
verified, scatter diagram data may be considered as being directionally
specific. Relevant wave spectra and energy spreading shall be utilised
as relevant.
Sec.7 A
504 Structural response shall be determined based upon analyses
of an adequate number of wave directions. Transfer functions shall
be established based upon consideration of a sufficient number of
periods, such that the number, and values of the periods analysed:| — | adequately cover the distribution
of wave energy over the frequency range |
| — | satisfactorily describe transfer functions at, and around,
the wave "cancellation" and "amplifying" periods |
| — | satisfactorily describe transfer functions at, and around,
the relevant natural periods of the unit. |
It should be considered that "cancellation" and "amplifying" periods
may be different for different elements within the structure.
Sec.7 A
505 Stochastic fatigue analyses utilising simplified structural
model representations of the unit (e.g. a space frame model) may
be used to form basis for identifying locations for which a stochastic
fatigue analysis, utilising a detailed model of the structure, should
be undertaken, e.g. at critical intersections.
![[-]](/dwicons/i_colpse.gif)