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Overhanging beam

  1. Feb 20, 2017 #1
    upload_2017-2-20_11-27-50.png

    The question is:

    How do I find all the reactions? I haven't worked with a similar problem before, so I'm kinda confused. Hope someone will help!

    Thanks from now.
     
  2. jcsd
  3. Feb 20, 2017 #2

    mfb

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    Finding all forces should be easy from the sketch. To calculate their values: Both net force overall and torque around a point of your choice have to be zero in equilibrium.
     
  4. Feb 20, 2017 #3
    '' Point of my choice has to be zero '' Does it mean I have to add a charnier? Sorry for the confusion
     
  5. Feb 20, 2017 #4

    mfb

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    You don't have to add anything. Pick a random point. Calculate all torques around that point from all the forces. The sum has to be zero.
     
  6. Feb 23, 2017 #5
    So if I want the moment ΣMz = 0; Dy * 6a - P*10a - p*5a*2,5a = 0
    and then isolate Dy and substitute it in ΣFy = 0; By + Dy = 5ap + P??
     
  7. Feb 23, 2017 #6

    mfb

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    If you introduce new variables, you should define them somewhere. An explanation what is what would be useful as well.
    Why 10a?
    ","? And assuming you mean 2.5, why 2.5?
    Sure.
     
  8. Feb 23, 2017 #7
    1) We have a single force at the end of the beam. So I say the force multiplied with the total lenght.

    2) From the left side of the beam to the half we have distributed load. So I want to find where the single force attacks, and that is on the half on the beam, right?

    Sorry for my bad English!
     
  9. Feb 23, 2017 #8

    mfb

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    What is the middle between "2a to the left" and "3a to the right"?
     
  10. Feb 25, 2017 #9
    Oh, so we have to split it up to 2a/2 = a and 3a/2 = 1.5a?
     
  11. Feb 25, 2017 #10

    mfb

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    You can split it in two pieces, but simply finding the middle works as well. The middle is not 2.5 a to the right of the support.
     
  12. Feb 26, 2017 #11
    1.5 a right?
     
  13. Feb 26, 2017 #12

    mfb

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    No.

    Draw it on a piece of paper if that helps. Or use signs: Where is the middle between -2 and +3?
     
  14. Feb 26, 2017 #13
  15. Feb 26, 2017 #14

    mfb

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    Stop guessing please. How do you calculate the average between two values?
     
  16. Feb 26, 2017 #15
    Not guessing, it's confusion.
    The average of -2 and 3 is: -2 + 3 / 2 = 1/2
     
  17. Feb 26, 2017 #16

    mfb

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    Right.
     
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