I am trying to model a RC building using OpenSees. In this building most members aren't centrally connected. The columns and beams usually have one common side and because I have modeled the beam in three parts due to different effective widths, the center of gravity of each section differs from the sections of the other parts. With those in mind, I chose to use some "reference axes" that weren't the same as the center of gravity axes of the sections and I used the transformation commands to offset the members to the correct location. Furthermore, I chose to use offsets also in the direction of the members at their ends so I could model the rigid sections of the joints. The elastic analysis didn't show any problem ( and I hope it is correct! )
I am trying now to model the plastic hinges at the end of the members to do a pushover analysis. At first, I want to run a concentrated plasticity model. For that, I have calculated the yielding moments of the sections and the chord rotations during yield and fracture. Those have a reference to the center of the sections and not the reference points I used in the model. I am thinking of using the zeroLength elements with Modified Ibarra-Medina-Krawinkler Deterioration Model. However, my question is, can I use the zeroLength element in the position of the local/central axis of the element or only at the nodes of the model (that means at the reference lines I described earlier). Can I put them between the rigid parts of the elements and the clear length if I haven't created a node for the original element there?
If the above cannot be done, should I change my original model and model all the elements at their centerlines and then using a lot of rigidlink elements to take care of the eccentricities and rigid portions of the elements? In an elastic analysis I should expect the same results as the original model, shouldn't I?
Thank you for your help! (and sorry for the long post, I hope I can be understood!
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