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


Warping torsion, *.PRO files, Material nonlinearity, API

Warping torsion, *.PRO files, Material nonlinearity, API

Warping torsion, *.PRO files, Material nonlinearity, API

A few elementary questions:

1.    When SAP2000 analyses a beam (frame element) in torsion, does it consider the warping torsion? I haven’t found the warping constant among the frame section properties.
2.    Is it possible to create *.PRO files, or the only *.PRO files available are those supplied with the software?
3.    In the material definition, the stress-train curve can be determined by the user. How is it taken into account in a non-linear analysis? In other words, if we want to run a nonlinear analysis considering material nonlinearity, do we have to define NL links, or is there also a possibility to use the nonlinear definition of the stress-strain curve for the material of the element? If not, where is it taken into account?
4.    The application program interface (API) document is not supplied with the educational version that I now use to learn the program. Is it possible to find it somewhere on the WWW and download it?

RE: Warping torsion, *.PRO files, Material nonlinearity, API


1) No. Unfortunately SAP2000 doesn't consider torsion in the design of steel profiles. Incredible, but true! (Risa3d, Strap or Staad does)
2)yes. It´s possible. You have to contact CSI and try to get the MS Excel program that generate the '.pro' files.
3) yes. You can account for the NL effects using material nonlinearity. Not only using Nlinks. Look for material advanced properties buttom.
4) look at the CSI site.

RE: Warping torsion, *.PRO files, Material nonlinearity, API

doesnt SAP allow you to be able to calculate a torsion constant?
i know people were using it to verify their hand calculations for a take home test

i figured if SAP calculates torsional rigidity, it would be able to make use of it

RE: Warping torsion, *.PRO files, Material nonlinearity, API

Thanks for the answers.
However I still have a problem with 3: As an example, I have a simple model of a beam on 3 supports. The material is defined as nonlinear and a nonlinear static analysis case is defined as well. The maximum moment that that beam can take is about 100 KNm, while the results show no difference between the linear analysis case and the nonlinear one and the moment on the support is 147 KNm. What's missing?
The model should be attahced if I opperated well this option...

RE: Warping torsion, *.PRO files, Material nonlinearity, API

Dror, I took a quick look at your model. First, the only way to consider nonlinear material behavior is to assign frame hinges which wasn't done. You can assign frame hinges using FEMA or fiber hinge which uses material stess-strain values. In the Analysis case nonlinear parameters, you have specified the monitoring of joint 1. But joint 1 sits on a pinned restraint, so you're not going to get any nonlinear deflection there.

I suggest drawing "special joints" at intermediate points along the frames away from restraints and using one of those joints to monitor reactions. Also, don't use the final state only option. Use save results at multiple states and start off with program default for number of states. It's usually a good idea to run P-delta with all of your nonlinear analysis.

Your distributed lineal load (converts to 2.26 Kip/ft) may or may not be heavy enough to cause nonlinear behavior. Admittedly I didn't spend a lot of time experimenting with it, so I can't know for sure. Good luck

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!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close