Tow Fatigue - How to count for structural natural frequencies?

Dear Sirs,

I'm doing spectral fatigue for Topside modules of a floating structure using Tow Fatigue. I have tried someway to include the effects of natrual frequencies of the structures into their responses but it seems that SACS does not support such dynamic effects. Please advise the current calculation procedure of TOW FATIGUE? Is there any way to count for such thing?

Thanks & Regards,

HoanVV.

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  • Hello Hoan V. V.

    Your question can be read several ways. Let me see if I understand.
    You are looking for a way to include the dynamic effects of the barge in the fatigue calculation. By natural frequencies are you thinking about the deformation of the barge?
    MOSES has the capabilities to do transportation fatigue in what is commonly known as stochastic analysis. This topic is also covered in OTC 4161, "A quasi-static approach for transportation analysis of offshore platforms".

    If you could clarify your request we could better offer a suggestion.

    Thank you,
  • Hello Georgina Maldonado-Aguirre,

    It's about TOW FATIGUE in SACS. My model contains the TLP Topside only, no TLWP hull because I just care about the fatigue of the TS in the drilling & operating phases. The program already calls for RAO inputs (motion of platform, TLP in my case), Wind Spec and Weibull Distribution of the wind speed. I'm just wonderring that it seems that SACS does not consider the dynamic effects of the structure itself.
    Please advise!

    Thanks & regards,
    Hoan V.V.

    Thanks & Regards,

    Hoan V.V.

Reply
  • Hello Georgina Maldonado-Aguirre,

    It's about TOW FATIGUE in SACS. My model contains the TLP Topside only, no TLWP hull because I just care about the fatigue of the TS in the drilling & operating phases. The program already calls for RAO inputs (motion of platform, TLP in my case), Wind Spec and Weibull Distribution of the wind speed. I'm just wonderring that it seems that SACS does not consider the dynamic effects of the structure itself.
    Please advise!

    Thanks & regards,
    Hoan V.V.

    Thanks & Regards,

    Hoan V.V.

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