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Simple bending moment calculation

  1. Mar 10, 2017 #1

    Really need some help with figuring out the max bending moment in the diagram shown below (I'm aware this is extremely simple but time and stress appear to have the better of me, so any help is appreciated)


    I think I've worked out the reactions at each support by doing m=wL as the following

    0.785 x 0.08 = 0.63
    0.785 x 0.28 = 0.22

    I'm also aware that I could be completely wrong with what I've just put above.

  2. jcsd
  3. Mar 11, 2017 #2


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    The beam would probably just tip over with the forces acting in the directions shown .

    We need to understand the actual loading system more clearly before calculating bending moments .

    Can you post a sketch showing the actual mechanical assembly that your line drawing represents ?
  4. Mar 11, 2017 #3
    I don't think the reactions are correct. As drawn, ΣM = 0 = 0.2R + 0.785(0.08) : R = - 0.314 kN : The "-" sign simply implies you have the right reaction, R, acting the opposite direction. ΣF = 0 = - 0.785 - 0.314 + L : The left reaction, L = 1.099 kN : Given the reactions you should be able to calculate the moment.
    Draw shear and moment diagrams.
  5. Mar 13, 2017 #4
    Thanks a lot for your help.
  6. Mar 13, 2017 #5
    Draw a shear diagram first.
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