fatigue analysis

[aryop]

hi,

i am a newbie in offshore strctural design,
can anybody please explain about the step in doing fatigue analysis for offshore structures?
the design parameter, data needed etc?
thanks

 

[London]

Fatigue design is possibly the most complex analysis undertaken for a typical offshore structure - it would be too much to cover in a post.

But in a broad overview, the methodology can be something like this:

Determine the modal response of the structure based on an agreed operating weight of the structure, and linearise the foundation to an equivalent pile stiffness, if required.

Determine the wave response of the structure under a set of waves with different periods. The wave selection is important.

Determine the fatigue damage for the weldments under the wave spectra at the site

Then ensure the resulting fatigue life is adequate with the necessary safety factor on the design life.

This is the overview. The other source for this information is a design code. Suggest a look at API RP 2A for further information.