Transverse bending moment and shear force

Discussion in 'Class Societies' started by thinhuk, Feb 25, 2020.

  1. thinhuk
    Joined: Jul 2018
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    thinhuk Junior Member

    Hi everyone,
    Could anybody please explain how does transverse bending moment and shear force apply for scantling the cross-deck of catamaran?
    Accordingly BV NR396 C3.4.2.3 the transverse bending moment and shear force is calculated, but I just don't understand how does this bending moment apply for each frame and does this moment subdivide into n-beam of vessel then it is bending moment for each frame?
    Thanks in advance.
     

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  2. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    You should read Proboat Magazine issue 182, dec-jan 2020. It is all explain eaisly in that:

    upload_2020-2-25_17-44-4.png
    upload_2020-2-25_17-44-17.png
     
  3. fallguy
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    fallguy Senior Member

    Please consider sharing the results of your findings.

    I'd like to believe I just overbuilt my small cat.
     
  4. jehardiman
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    jehardiman Senior Member

    While the formula posted gives the total bending moment, the apportion of the moment (and shear) is done with a classic structural correlated deflection analysis.
     
  5. thinhuk
    Joined: Jul 2018
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    thinhuk Junior Member

    Thank you so much.
    This information was useful, I got the basic of understanding the transverse strength of catamaran especially at the cross deck.
    And now with the buckling checking accordingly BV rule, it still a massive, could you please drop me an example of calculating buckling of plate according to Class Rule?
     
  6. thinhuk
    Joined: Jul 2018
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    thinhuk Junior Member

    Yep, since I had read the magazine which Ad Hoc recommended, I had understood how combine the allowable stress and the deflection into calculated.
     

  7. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    Class defines the length x breath x thickness as variables using their formula. You obtain the max critical buckle stress allowed.
    Once you have calculated the global stresses, from those global loads noted in the images above, you then check these values against the Class max critical stress - that's it.
     
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