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!

Stability and determinacy

  1. Sep 1, 2016 #1
    1. The problem statement, all variables and given/known data
    from the equation r = n+3 , some notes stated n = number of hinges , while some book stated n as number of joints ...Which is true ?

    2. Relevant equations


    3. The attempt at a solution
    taking the example 3.1 , if it's number of joints , then there are 1 hinge (pin) , right ? I dont really understand the notes on the internet ... What does joints in beam mean ?
     

    Attached Files:

    Last edited by a moderator: Sep 1, 2016
  2. jcsd
  3. Sep 1, 2016 #2

    phinds

    User Avatar
    Gold Member
    2016 Award

    your tiny attachment is unreadable.
     
  4. Sep 1, 2016 #3
     

    Attached Files:

  5. Sep 1, 2016 #4
    i checked it an open the uploaded image ...There's no problem . Perhaps you can refresh your browser and try ?
    http://imgur.com/a/IDi0d
     
  6. Sep 2, 2016 #5

    PhanthomJay

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    in this equation for beam determinancy, r is the number of possible force and moment reactions at the external supports, and n is the number of internal hinges (pins, or joints) that sometimes join 2 members together.

    In the example, the left support can support forces in 2 directions, and the other support just a vertical force, so r is 3 , and since there are no internal hinges in between supports, n is 0.

    These equations tend to cause confusion so don't dwell on them too much.
     
  7. Sep 2, 2016 #6
    although there's pin and roller , but there's only 1 member ( not joining 2 members together) , so n = 0 ?
     
  8. Sep 2, 2016 #7

    PhanthomJay

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Yes
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted