SACS - Frequency Domain Transportation

Dear Sir,

I have short question. Can we perform 'Frequency Domain Transportation in SACS' ??

The assumption is

1) We have Barge RAO

2) We know critical seastate i.e. wave spectrum, Hs, Tp

The following queries is needed some guidance.

1) How to generate 'Response spectrum of each structural member' ? I do not see any way to input wave spectrum in towinp.

2) How to let SACS keep 'extreme statistic response value i.e. most probable maximum extreme (mpme) axial, moment etc' of each member in the common solution ?

3) How to combine extreme statistic response value for each element with static common solution file ? Should it be PRST and PRSC like earthquake response specturm as it is no sign anymore.

4) The last one is the same question as above. However, it is for frequency domain analysis for wave response. How to perform the 3 questions above in the wave response analysis. I do not see anyway to keep extreme statistic response value from the wave response in the common solution file as well. It can be calculate during fatigue analysis i.e. rms etc. However, if I do not want to do fatigue. I just would like to perform 'Wave Response in Frequency Domain' and use 'Extreme statistic response value (3.72*RMS, it is assumed that the response has 1000cycles)'  to combine with static analysis. How I can do that??

Regards,

Kasiphon

Parents
  • Kasiphon,

    Currently we only support frequency domain analysis in tow fatigue. I have been talking with our developers about implementing the maximum probable stress calculations based upon the stress RAO's as a possible enhancement for a future release of SACS. I imagine it would be implemented similarly to how you describe it as a solution like the seismic common solution file which contains one "load case" that contains the maximum probable stress for each element in the structure. 

    Currently if you want to perform a tow analysis you are limited to using either tow accelerations or vessel motions for the strength analysis.

    Regards,

    Geoff

    Answer Verified By: Kasiphon Kurojjanawong 

  • Hi Geoff,

    I am very please to heard this news.

    As It is under development now. I would suggest to have the options as below.

    1) I would suggest SACS to keep the solution at least the 'Root Mean Square (RMS)' value rather than most probable maximum (mpm) value. RMS is more useful than mpm as it can be factored with some value to get other statistic value including mpm value.

    2) If SACS intend to keep only one solution to save time and disk space, I would suggest to have the option for user to key-in their own statistic value rather than let's SACS decide to keep the value at mpm only. Btw, you can set the default to be mpm value, if no statistic value provide by user.

    It would be great, if SACS will provide some kind like this option as well in the wave response for the future development.

    Regards,

    Kasiphon

Reply
  • Hi Geoff,

    I am very please to heard this news.

    As It is under development now. I would suggest to have the options as below.

    1) I would suggest SACS to keep the solution at least the 'Root Mean Square (RMS)' value rather than most probable maximum (mpm) value. RMS is more useful than mpm as it can be factored with some value to get other statistic value including mpm value.

    2) If SACS intend to keep only one solution to save time and disk space, I would suggest to have the option for user to key-in their own statistic value rather than let's SACS decide to keep the value at mpm only. Btw, you can set the default to be mpm value, if no statistic value provide by user.

    It would be great, if SACS will provide some kind like this option as well in the wave response for the future development.

    Regards,

    Kasiphon

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