Subsea Pipeline Detail Fatigue Analysis - Force Model

[atedionyahoo]

Case: Subsea Pipeline Detail Fatigue Analysis by Force Model (Direct Wave)

Ref.: DNV-RP-F105 (Feb 2006), sec. 5.3.2

Question: To calculate the in line stress range (due to drag and inertia loads) I do not know what boundary conditions to be considered? (e.g. pin-pin or fix-fix, or etc)

 

[BigInch]

For a continuous beam over supports the fixed end moment is usually considered to be 1/10 w* L^2, full fixity is 1/12 * wL^2, pinned end would be 0. I'd suggest 90%.

 

[SFLM]

atedionyahoo,

It depends on where the span is. The span generated for crossing pipelines is different than a span on a rough seabed. However, if you need a detailed analysis, you definitely need the actual configuration of the span from a FEA. In this case, no boundary condition is required since it is inherent to the analysis.

Cheers
Steve

 

[archeratslt]

I think you can calculate the stresses based on Leff. which is the length of the pipe with simiar behaviour but for fix-fix (or pin-pin i can't remember)