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Homework Help: Structural analysis:trusses

  1. Oct 31, 2011 #1
    1. demonstrate with a series of sketches that the truss is simple. Find the force in member BE

    2. Snapshot_20111030_2.jpg
    the blurry dimensions:

    lower lengths left to right: 2 ft, 1 ft, 1ft, 2ft
    vertical lengths: bottom to top: 2 ft, 1.5 ft, 1.5 ft
    top length both 3 ft
    load is 300 lb/ft

    3. started by simple inspection of the joints to see if there were any zero force members but inconclusive as they either have external forces acting on them or no colinear members. Im not sure otherwise prove that the truss is "simple". Or is it just that by inspection of the joints there are no zero force members and I need to sketch/show that the truss is stable and not capable of movement in any direction?
  2. jcsd
  3. Oct 31, 2011 #2
    Quote from Vector Mechanics for Engineers: Statics by Ferdinand P. Beer

    "[When adding two members to a rigid truss] the resulting truss will [also] be rigid if each time two new members are added, they are attached to two existing joints and connected at a new joint. A truss which can be constructed in this manner is called a simple truss."

    Basically if you start with one of the triangle trusses in the figure you form new triangles everytime by adding two members and having them meet at one new joint. That is the definition of a simple truss.

    Hope that makes sense!
  4. Oct 31, 2011 #3
    it does, i got the problem correct
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