Scantling Calc with large openings/scalop.

Discussion in 'Class Societies' started by Niru, Jul 23, 2014.

  1. Niru
    Joined: Jul 2010
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    Niru Mr.

    Good Day.

    Does anybody here have any idea :idea: whats the proper cross section
    before performing the standard scantling calc of the said member.

    from attached pic its a side transverse of wing ballast tank.

    ive done a rough calc showing a 1200 cubic inch SM
    comparing to required ABS of 36.35 cubic inch. though the member is not longitudinal strenght member of the ship, i still find the need to compute cause
    the same problem will arise with the solid floors with respect to the bottom framing.

    Many Thanks.
     

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  2. NavalSArtichoke
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    NavalSArtichoke Senior Member

    It's not clear what SM you are trying to calculate, but having 6 feet of side shell with no framing is probably not going to work.

    The side shell plating is usually longitudinally framed with support for the longitudinals coming from the transverse frames. It's not clear why you have this enormous scallop in the transverse frame.
     
  3. Niru
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    Niru Mr.

    Sorry.. Let Me Update The Attached Pic.
     
  4. Niru
    Joined: Jul 2010
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    Niru Mr.

    good day sir,

    I plan to calculate the actual SM of the side transverse.
    please see updated pic as reference.

    ***for info its a existing barge. trying to create a scantling calc.

    the question would be is the cross section of the side transverse.
    i made a rough calc with 30" as web and inner side plate and side shell plate as flange top and bottom. it produces a 1200+ cubic inch of SM which is way to large in comparison with the required ABS calc - 36.+ cubic inch.

    i guess from the first attached pdf the cross section is obviously wrong though i still made a rough calc showing a 15.+ cubic inch SM. ref line is the shell plate.

    ?

    niru
     

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  5. NavalSArtichoke
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    NavalSArtichoke Senior Member

    The updated views clear up some questions.

    It's not clear what particular ABS rule you are using for your calculation. My comments below are based on the assumption that this is a steel barge in offshore service.

    IMO, closing the scallop with the channel section, you would consider the channel to be part of the diaphragm plate at this location, with some added vertical stiffening due to the presence of the flanges. It's not shown on the sketch, but I assume you plan to weld the channel flange to the side shell longitudinals and weld around the periphery of the rest of the channel to join it to the existing structure.

    ABS doesn't have scantling rules for non-tight diaphragm plating, IIRC, and the channel is not acting as a beam if it is welded properly to the existing structure, so a section-modulus calculation would not be required. If the web thickness of the channel is the same or thicker than the existing plating to which it is attached, I would say that no further calculation is required.
     
  6. Niru
    Joined: Jul 2010
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    Niru Mr.

    very informative Sir!

    yes it is a barge converted to a double bottom, double shell and yes they have
    the same thk of 3/8" - c bar and the existing side transverse with large scallop

    btw whats IIRC?
     
  7. NavalSArtichoke
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    NavalSArtichoke Senior Member

    IIRC = if I recall correctly.
     
  8. Niru
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    Niru Mr.

    hehe. and i thought it was some kind of a new convention.
     
  9. Niru
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    Niru Mr.

    anyway for info im using...

    "RULES FOR BUILDING AND CLASSING STEEL BARGES 2014" - ABS.
     
  10. Niru
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    Niru Mr.

    ??? IMO means "If my opinion?" - ?
     

  11. NavalSArtichoke
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    NavalSArtichoke Senior Member

    Either that or the International Maritime Organization; it kinda depends on the context.
     
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