×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

zero-rods in truss

zero-rods in truss

zero-rods in truss

(OP)
Hello, first of all I am new on forum, so correct me if this folder is not ok for such question :)
my problem is about zero stress rods at truss this is prabably right solution, bolded rods are not zero-stessed. As I start to match zero-stressed I understand, 1, 2, 3, but why 4th rod would be zero stressed, could someone explain it to me? Thank you in advance :)

RE: zero-rods in truss

It's acting like a tied arch if the loads are symmetric.

Remove the symmetry in the loading and you will see loads in the other members.

RE: zero-rods in truss

Sorry Agent666, but I disagree. The members would still have zero stress if the loading is made unsymmetrical.

Members 1 and 3 have zero stress because there is no applied vertical load at either Joint 1L or Joint 3L where L denotes the lower end of the member. A vertical load applied at either joint will produce a force in the member.

Members 2 and 4 have zero stress because there is no applied load at Joint 2U or 4U where U denotes the upper end of the member. An applied load at Joint 2U having a component normal to the chord member will produce a force in member 2.

Similarly, an applied load at Joint 4U having a component normal to the main diagonal member will produce a force in member 4.

BA

RE: zero-rods in truss

(OP)
thanks BAretired, all clear

RE: zero-rods in truss

A word of warning, if you run this with computer program, you may get small forces in those zero members. This is because strain in the loaded members may change the geometry of the zero load members and thus cause strain in them.

Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin

RE: zero-rods in truss

paddington,

That may be true if some members are entered as continuous, but using the traditional assumption for truss design, namely that all joints are deemed pinned, there should be no force in any of members 1 through 4.

BA

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources