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Dror10 (Structural) (OP)
8 Jan 08 5:47
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?
ECStruct (Structural)
15 Jan 08 9:42
Answers:

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.
phatso86 (Civil/Environmental)
15 Jan 08 13:17
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
Dror10 (Structural) (OP)
28 Jan 08 13:28
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...
stressed (Civil/Environmental)
2 Feb 08 12:40
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

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