1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: (Statics) Truss with no vertical members, will it work

  1. Oct 12, 2011 #1
    1. The problem statement, all variables and given/known data

    Supposed to support a 50 kN weight at a pin joint at the center of a void as cost effectively as possible using trusses (e.g., trusses and pin joints have costs)

    2. Relevant equations

    Basic sum of moments and sum of forces = 0

    3. The attempt at a solution

    Why can't I just use two horizontal members from the edges of the void to the weight. Since the trusses are ideal and can't expand the weight won't fall. But I'm having a hard time figuring out the equations. Maybe this solution is statically indeterminate? At the center pin joint I get sum of all forces in x direction = tension in truss 1 - tension in truss two. In the y direction I just get -50 kN. But somehow the forces in the y direction have to equal 0. When I look at it I know it will work (I think there would just be a very strong moment in the trusses). But when I do the equations I'm confused. Does the 50 kN translate into a moment? Why can't we have ideal trusses without vertical components?
  2. jcsd
  3. Oct 12, 2011 #2
    How about providing a diagram of your truss. How is it anchored to the edges of the void? Are you saying the beams do not streach or bend?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook