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Geometry in a Truss

  1. Oct 20, 2012 #1
    I'm to work out the internal forces in this truss. I know to get the reaction forces first, so I take the moment at the pin support to find the reaction at the roller support. I can't get my head around at how to find x through the geometry to add that force to the moment though. Is there not enough information in the diagram to find it? Or am I missing something simple? OHOCa.png
  2. jcsd
  3. Oct 20, 2012 #2
    Yes you need the 'rise' or vertical height of the truss as well as the span. Alternatively you need the pitch (angle to the horizontal) of the roof.

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    Last edited: Oct 20, 2012
  4. Oct 20, 2012 #3


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    Look at the truss carefully. What kind of triangle is formed by the members in the center of the truss?
  5. Oct 20, 2012 #4
    Well spotted steamking you are spot on.
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