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Homework Help: What does Young's Modulus x 2nd Moment of Area Equal

  1. Jan 21, 2015 #1
    Hi all

    I need to find the relative stiffnes of certain I beams from here


    Im assuming all I need to do times the Youngs Modulus by the 2nd Moment of Area

    In my head im making it more complicated than it should be so I hope this is all it is

    As its all relative units etc dont matter - would that be correct??

    Thanks for any info too
  2. jcsd
  3. Jan 21, 2015 #2
    Will I also have to divide by the beam length too??
  4. Jan 21, 2015 #3


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    Your post is a little vague. Is there a problem associated with your question? It would help if you could post as much information as you can.

    In general, the stiffness of a beam in resisting bending is usually determined by its moment of inertia, or the second moment of area. The quantity EI is also called the 'bending stiffness' or the 'flexural rigidity'.
  5. Jan 22, 2015 #4
    There is a problem regarding a frame and the moment distribution method and I need to find the force that that will cause first yield to take place on the fram. It seems a bit involved to put the whole question here so thought Id ask a basic question and the first I think is to get the relative flextural rigidity of the beams of the frames

    the beams for example are the following sizes

    It is made from structural steel sections of mild steel as follows:
    Column AB: universal column section 203x203x60, see section b-b for orientation.
    Beam BC: universal beam section 406x178x74, see section a-a for orientation
    Column CD: universal column section 254x254x89, see section b-b for orientation

    So to start the calcs off and moment distribution the relative stiffness is needed hence me asking the above - sorry if vaugue
  6. Jan 22, 2015 #5


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    Apparently, there is some sort of figure associated with this problem. Can you post it?
  7. Jan 26, 2015 #6
    These are british sections. Do you have standard tables giving you the 2nd M of A for each one?
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