×
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

Gas Flare

Gas Flare

Gas Flare

(OP)
Hello to all,

Is possible for RISA 3D handle the non linearity of the braces (cable) of a Gas Flare under wind load?

This Brace should be modelled as "Tension Only" members?

Thanks in advance

RE: Gas Flare

I don't believe that RISA does non-linear analyses.

 

RE: Gas Flare

It depends on what type of non-linearity you are looking for.  And, which program you are looking at.  

If you are looking for pure tension only behavior (member inactive whenever it goes into compression), the the program (RISA-3D) should handle that just fine.  

Based on your description, however, you are probably looking for geometric non-linearity associated with the cable curvature.... meaning that the deflection caused by an applied transverse load will end up being resisted more through cable tension than through flexure/ moment.  RISA-3D cannot generally account for that for cables.  

Folks do occasionaly use the program for these types of applications, but it is a tedious process involving manipulating the input geometry to approximate the anticipated deflected shape of the cable.  This procedure works in theory, but it's not something you want to do for much beyond verifying a calculation from another source.

For applications like this, it is generally a good idea to use a program which has an iterative / incremental non-linear solver that accounts for cable geometry. Programs like Tower Numerics (formerly RISATower and ERI-Tower) do this sort of thing for guyed monopole towers.  That may be similar enough to your application to work.

RE: Gas Flare

(OP)
Hello,

Thanks for your reply.

Could you tell me how to prestress (input)an element?

Regards

RE: Gas Flare

In RISA, you want to apply a negative thermal load to pre-stress rods or cables.  All you have to use is a distributed load with a direction for the load of "T". The magnitudes of the load will be a temperature rather than a force.  This will cause the cable to shrink and induce a pre-tension.    

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