Wind Spectra

Dear Sir,

Refer to SACS fatigue manual, only 'Harris' wind spectrum is available in SACS.

However, both API RP2A and NORSOK recommended to use 'Froya' Wind Spectrum.

Is SACS able to model 'Froya' wind spectrum?

Many thank !

Parents Reply
  • Hoan,

    There isn't an easy answer to that question since the answer depends upon  your analysis. The wind speeds you define in your wind data are used to calculate the fatigue damage based upon the distribution you have input in the dynamic response input file. The more wind speeds that you use, the more stress ranges you will have to determine the fatigue damage and the more accurate your result will be. You can certainly perform a sensitivity study to determine if you have adequately captured the fatigue damage.

    In regards to determining the weibull distribution fitting, would you determine the distribution from a wind time history? I can add something along those lines to the list of requested enhancements.

    Regards,

    Geoff

Children
  • Hi Geoff,
    Thanks for your prompt response.

    OK, I will try with a sensivity check to find out a reasonable number of wind speeds to be input. But still I'm curious if Dynamic Response use Rayleigh distribution to determine the maxima of the stress processes. If that's true, the number might be found by a random simulation, I guess.

    For the Weibull fitting, yes, we have to use a wind scatter as inputs. I have completed a tool for this work using method of moments. It is quite simple but save much time. It will be more comfortable to users if SACS could support.

    Thanks & Regards,

    Hoan V.V.