MOSES - Tension only Connector

Hi,

I am doing a frequency-domain structural check of a structure during transportation that is supported at four points and secured with deck using lashings that can take only tension. The lashings are along longitudinal and transverse direction of the barge. I am using Automated Offshore Installation Tool of MOSES. May I know if it is possible to define a connector type that can simulate lashings?

The objective is to get the member UC of the structure and axial loads in vertical support and lashings for sea-fastening design. 

Thanks

Sarthak

  • Hello Sarthak,

    The easiest way I can think of is to model the lashing as a very thin structural member.  You can always use the "-section" option to change the structural properties so that the strength of the class is only along the long axis.

    When you use the I_pconnect command make sure to make the end connections to take tension only.  I would suggest using the "I_pconnect" command with the "-rela" and "-relb" options.  The "-rel*" option tell MOSES how to interpret the connection.  If this is a tension only element then you want to make sure to release all moments, and two of the transverse forces.  Only leave the connection in the long axis active.

    I do not know the size of your cargo or the sea environment you will be checking.  I would think that the small section value properties you will use to represent lashing will not pass code check for tubular.  At the end of the automated tool commands you can ask for the forces in the lashings.

    strpost

       beam load -element (put lashing names here)

    end

    The above commands should put the lashing loads at the end of the standard output report.  You can use those loads to design the lashings.

    I hope this helps.

    Georgina Maldonado

  • Hi Georgina,

    Thanks for your reply.

    I understand your reply. I am not worried about the code check of tie-down thought. However, I think that even after using '-rel*' option while defining connector with i_pconnect, the connector can still take compression load as well in axial direction of the connector. It is just that there will be no force in other transverse directions and any moment. I do not intend to allow connector to have any compression load. 

    Am I missing something here? Please advise.

    Thanks

    Sarthak

  • Hi Sarthak,

    This is a frequency domain analysis and you are only interested in tension.  The tools automatically only add the dynamic loads to the part identified as tiedowns.  The frequency domain does not know the sign of the load.  You can take the tiedown load case and always use the maximum as the maximum tension.  By default the tiedown cases are multiplied by 2.  Please see the documentation for "-tieten" to use a multiplier of 1.

    Let me know if there are more questions.

    Georgina Maldonado

  • Hi Gerogina,

    Well noted and understand the reply.

    May you also advise if MOSES can perform plate buckling code check as per DNV?

    Thanks

    Sarthak

  • Hi Sarthak,

    MOSES will generate the Von Mises stresses. 

    Since SACS and MOSES are now part of the same company the plan is for SACS to start taking over all the structural regulatory code checks.  We are planning for SACS to be able to check plates according to C202 and C203.

    Let me know if there are more questions.

    Georgina Maldonado