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Bending Moment

  1. Jun 21, 2009 #1
    1. The problem statement, all variables and given/known data

    For the beam and loading, draw the shear and bending moment diagrams. Find the max and min abs vals of shear and bending moment.
    += pointing upwards, - = pointing downwards
    The beam is 1.4m long.
    Load A = -.54kN at x=0,
    Load B= pin support at x=.2m (Found to be +1.8kN)
    load C= -1.35kN, x= .7m
    load D= roller support at x= 1.1m (Found to be .63kN)
    load E= -.54 kN at x= 1.4m
    3. The attempt at a solution

    Im shooting myself in the foot over this because its so simple and ive reworked it about 500 times and keep getting conflicting answers... The bending moment should be the same for the same point regardless of what side i take it from, but i keep getting different values....
    going from left end of beam, fixing right side.
    From 0<x<.2 --> B.M = -540*x
    From .2<x<.7 --> B.M = -540*x + 1800*(x-.2)

    Now go from right side, fixing left end.

    From 0<x<.3 --> B.M = -(540)*x
    From .3<x<.7 --> B.M = -540*x + 630*(x-.3)

    I am getting conflicting values for x=.7m for my bending moment... what am i doing wrong, someone please help before i go crazy...
    Last edited: Jun 21, 2009
  2. jcsd
  3. Jun 22, 2009 #2


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    Science Advisor
    Homework Helper

    NBAJam100: Your reaction forces are incorrect. You forgot to check equilibrium to ensure your reactions are correct. First, rework the problem to obtain the correct reaction forces. Then everything should work out fine.
  4. Jun 22, 2009 #3
    ahhh wow, i totally looked right past that. bleh, thanks a lot nvm.
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