how record the rotate in Hinges in steel frames?

[masoudshr]

Hi
I've a problem in opensees software, i trying to model a EBF(essentially bracing frame) frame in this software and analysis that with Pushover method. my problem is how to find rotate in hinges? can you help me ?
Thanks

[vesna]

What elements did you use to model your frame?

[masoudshr]

Hi,
Thanks.
element nonlinearBeamColumn for columns and element beamWithHinges for links and element corotTruss for bracing.

[vesna]

First of all I do not think that beamWithHinges is the right one to be used to model the links.

The recorder argument that you have to use to get plastic hinge rotations of your nonlinear beam-column elements is plasticDeformation.

[masoudshr]

Thanks for your helping
my other problem is when I using of this elements, how to find the rotations ? that is which commands i should use to export the rotations of this software?
may i ask you show me an example?

Thanks again

[vesna]

What do you mean by rotation of the element?

You can record nodal rotations in the following way:

recorder Node -file nodesD.out -time -node 1 2 -dof 3 disp; # records rotation of nodes 1 and 2 and saves it into file nodesD.out

[masoudshr]

thanks for your helping.
No, my means rotation of hinge in beam column element.

[vesna]

To get plastic rotation of plastic hinges for element 1 here is the command:

recorder Element -file Element1.out -time -ele 1 plasticDeformation

The file will contain 4 columns. The 1st is time, the 2nd is axial plastic deformation, the 3rd is plastic rotation at node i, and the 4rt is plastic rotation at node j.

[masoudshr]

hi,
Dear Vesna
thanks for your help
first I attach my source file of opensees software
may i ask you take a look to this file ?
(because the results of rotation of plastic hinges is too small (that is numbers like 0.25*10e-10)
, and i think a problem is in my modeling . if my modeling is true why the results is small?
and I've another question :
when a link beam having shear treatment, the plastic hing occur in the middle of it ,so how can i determine the rotation in the middle of link beam(which command i should use?)?
please download the source file of following link:
http://www.mediafire.com/?1g8z8mi3znk8i33
Thanks again

[masoudshr]

any body can't help me?????
please help I'm very confused....

[susan]

Hi masoudshr

i saw that your are in shahid bahonar university. i know that there is a person who has many experiences in opensess. He is Dr. Iman Mansouri (dept. of civil eng.) . i suggest that contact him.

good luck.

[masoudshr]

Dear Dr.vesna
can you help me?
please, I'm so confused and nobody else couldn't help me except you!!!
Thnaks

[le2night]

vesna wrote:
> First of all I do not think that beamWithHinges is the right one to be used
> to model the links.
>
> The recorder argument that you have to use to get plastic hinge rotations
> of your nonlinear beam-column elements is plasticDeformation.

I want to know exactly what rotation the plasticDeformation records. You once said that the basicDeformation recordes two rotations of two element ends, from chord rotation to tangent rotation. I think the rotations maybe reflect the situation of the deformation but sometimes it's meaningless. For example, a beam with two rigid ends,under the gravity loads, it may occur plastic rotation in the ends, but the chord rotation is 0 and the tangent rotation is 0 too, so the basicDeformation is 0. May I think the plastic rotation is 0? Thus, if that's right, the recorder would make no sense. And i tried a test, for a beam, the stress of right end has been inlinear and the left end just linear.However the two rotations of plasticDeformation are almost the same ,why ?

[alima2065]

Hi masoudshr
Please, read FEMA 356 Chapter 5 page 13. It is about definition of beams rotation.
Accordance this definition, if you have used nonlinearBeamColumn with fiber section or Beam With hinges, you can use node recorders (DOF 3) for start and end nodes of elements and then calculate Beam chord rotation. But if you want to calculate exact rotations, you must model hinges with rotational zero length springs.
I’m not sure.

[vesna]

Basic deformation recorder provides you information about rotations of the nodes relative to the chord. Plastic deformation recorder gives you information about plastic rotations of plastic hinges. These two are not comparable.