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Homework Help: Influence line for trusses

  1. Jan 23, 2017 #1
    1. The problem statement, all variables and given/known data
    Pls refer to the second photo , the red line part ....I don't understand the meaning of when 1 unit load move at C , the unit load is inclusive in the right system... I can understand the FBG sin45 + 1 = RE

    2. Relevant equations

    3. The attempt at a solution
    When the in unit load move at b , shouldn't the equation become like this ? FBG sin45 + 1 = RE

    Why the author didn't consider the unit load when the unit load is moved to B ?

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  2. jcsd
  3. Jan 24, 2017 #2
    When 1 unit load moved to B , the equation of vertical forces should be like this , right ? 1-FBGsin45 - FBH = 0.25 , i dont understand why the author used 0.25-FGBsin45 = 0 , by dosing so , he ignored the unit load and also the FBH.... How can it be correct ?
  4. Jan 26, 2017 #3
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