1. Not finding help here? Sign up for a free 30min 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!

Method of joints for a truss

  1. Sep 30, 2008 #1
    Hi there!

    Can anyone take me through the method of joints procedure for this truss? I am having trouble working out the reaction forces at the pin at joint A. Is there supposed to be a vertical component to the reaction force as well a a horizontal (seeing as it is a pin)? And if so where does it go? is it part of the member AD or outside of it? I am confused.

    P.S. The answers are AB = 5 kN T, BC = 5*sqrt(2) kN C, CD = 15 kN C, AC = 5*sqrt(2) kN T, AD = 0. Where T = tension, C = compression.
     

    Attached Files:

  2. jcsd
  3. Sep 30, 2008 #2

    PhanthomJay

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Yes. A pin can support both a horizontal and vertical component of force. The roller at D, on the other hand, can only support a force normal to its surface; in this case, the roller at D can support a horizontal force only.
    All and any support reactions are external to the system; they are outside of the members. So at A, you have an unknown support reaction of Ax in the horizontal direction, and Ay in the vertical direction. At D, you have an unknown support reaction Dx in the horizontal direction. Use the 3 equilibrium equations of statics to solve for these unknowns. Then proceed with the method of joints to get the member forces. But first, what are the reactions?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Method of joints for a truss
Loading...