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How to get the place of max bending moment ?

  1. Nov 17, 2012 #1
    what i know is the the max BM at zero shear
    but it is said that max BM in the cantileaver beam is at the fixation
    how?
    is the shear there )0) ??
    there is reastion so how?
     
  2. jcsd
  3. Nov 17, 2012 #2
    Yes the max bending moment in a cantilver occurs at the root or fixed support.

    A cantilever has only one support so there must be a moment at that support to stop it toppling over.

    Check again with your notes or textbook.
    This only applies to simply supported spans. These must have two supports and there is a maximum in the BM curve at the same point as the vertical shear curve crosses the horizontal axis.


    Have you tried drawing some BM and SF diagrams?
    You should do this for both cantilevers and simply supported beams.

    Try also beam with an overhang at one or both ends
     
  4. Nov 17, 2012 #3

    AlephZero

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    Not quite. It only applies where the shear force is a continuous function, for example a distributed load along the beam. It doesn't apply at points on the beam where the shear load is discontinuous.
     
  5. Nov 17, 2012 #4
    thanks alot

    but please when the max BM at zero shear is applied
     
  6. Nov 17, 2012 #5
    It is not clear whom you were thanking for what.

    I suggested you draw some diagrams.

    Did you do this?

    I have attached a very simple comparison of a simply supported beam with a cantilever.

    Do you understand the diagrams I have drawn and how to obtain them?
     

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