ISO 12215. Aluminum double bottom structure scantlings

Discussion in 'Class Societies' started by TANSL, Mar 20, 2015.

  1. 66647187
    Joined: Dec 2016
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    66647187 New Member

    Thanks for your practical reply to my question.

    the reason that why the above puzzles came to me is that I have checked a paper describing a bottom arrangement to reduce the bottom section modulus requirement about 40% because of the added pillar.

    So considering the economy of the scantlings, I think there should be some principle or rule to be followed. But I am not sure.


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

    That is not 100% correct.
    If you half the span you 1/4 the required modulus, since the modulus is proportional to L^2. So the reduction depends upon where the pillar is located and NOT fixed at 40%.

    See below:


    The pillar provides the "support", and so the spans for each member are reduced.
    Thus where ever you place the pillar provides the %'age reduction, with the max reduction being mid-span, i.e 1/4.
    Last edited: Apr 26, 2020
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