Bending Moment

  • Thread starter NBAJam100
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  • #1
NBAJam100
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Homework Statement



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

The Attempt at a Solution



Im shooting myself in the foot over this because its so simple and I've 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:

Answers and Replies

  • #2
nvn
Science Advisor
Homework Helper
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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.
 
  • #3
NBAJam100
145
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ahhh wow, i totally looked right past that. bleh, thanks a lot nvm.
 

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