×
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

Accidental Torsion Modelling

Accidental Torsion Modelling

Accidental Torsion Modelling

(OP)
How is the accidental torsion modelled, say, in a 3D steel frame (RISA/STAAD)?  Is it more appropriate to apply a force couple, or a nodal moment?  Which is most common?

RE: Accidental Torsion Modelling

If you are inputting the force by hand, then I would just apply the force at the required accidental eccentricity distance from the centroid, then create another case where you input the force on the other side of the centroid.

If the programs are automatically generating the building mass for you (based on applied gravity loads) and applying the seismic resultant force at the centroid, I would take that resultant, multiply it times the required eccentricity, then place a moment at the centroid to represent the accidental torsion (one case for the resultant being at each side of the centroid, if you are confident in the program resultant). Actually, I would expect the programs to allow you to enter the accidental eccentricity to be considered.

I am just not sure how you made the model or the options in each program. But make sure you don't apply the force/torsion twice, one internal to the program and one input by hand.

RE: Accidental Torsion Modelling

In STAAD use the "OFFSET" command, then invoke the torsion desing. STAAD has a good steel torsion module.

Regards,
Lutfi

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