how to model...

[gst]

Hello All,
I want to model an RC frame and run a cyclic analysis. After that I want to add 2 struts to the same RC frame and start a new analysis but considering the final state of the frame elements.
I already have the model of the RC frame runing but I don't know how to add new elements to that frame and run the example again.
Do you have an idea to doing this?
Thank you all!!!
G.

[ismailqeshta]

If you are new to Opensees, you may consider going through some of the basic examples to learn how to use the commands and scripts. Then, you can have your questions here and anyone of us will be happy to help you.

In general, you need to add the additional nodes with their coordinates. The elements of these new nodes need to be defined. Then you will need to assign their materials, and fixity (if any). You may also consider some modifications on the gravity loads and masses, depending on your aim of the model. Other details are also important, but this again depends on your model.

[gst]

Thanks for your answer, maybe my explanation was not good. It is a retroffiting problem.
I have an RC frame running and with the final state of the frame I want to introduce some new elements to retroffit the frame. It is not a different frame, it is the original frame damaged due to the response of the first run.
In fact, the real problem is an RC frame with a masonry infill (I have developed a new element and material for masonry infills and they work very well) and I want to remove the panel and add a Steel plate shear wall to retroffit the original wall. That's why I need to start a new run with new elements in a previous model already run.

I cannot find any example to model this kind of problem. I'm trying with a simple RC frame and then add to struts and if everything goes well then try the Infill frame.

Hope you can understand my problem.
Thank you very much for your help.
G.

[ismailqeshta]

You may have a look at the following reference that addresses the modelling of retrofitted elements using wraps,

X. Zhang, K.J.R. Rasmussen, H. Zhang, Formulation and implementation of three-dimensional doubly symmetric beam-column analyses with warping effect in OpenSees Research Report R917, School of Civil Engineering, Centre for Advanced Structural Engineering, University of Sydney 2011.

[EricsonEncinaZ]

I haven't done something like what you want but I would say that similarly to the case when you run a gravity analysis and then a pushover, you can use loadConst and wipeAnalysis to reset the interpreter and use the last stage of your model as the initial state of the new analysis. Then using the command "remove", you would be able to remove the existing damaged elements, and then adding the necessary nodes and elements you could start a new analysis. Be careful when removing an element, because I think that just the element is removed and not its nodes, so you should remove the nodes as well, so you don't have un-connected nodes flying free. I hope this is useful.

[gst]

Thank you very much to all of you, I've solved the problem!!

[luigimitidieri]

Hello I'm MONICA and I have a similar problem.
I have performed a pushover analysis of a RC frame, and now I want to run again the push over analysis but for the frame model in a specific step of previous pushover analysis, so the two frame that I want analyse are different - initial and damaged.

Thanks so much for the help.

[selimgunay]

You can run the first pushover analysis to the step that you want and then start another pushover analysis. The new pushover analysis will start from the damaged state of the frame.

[luigimitidieri]

Thank for the help, but if I run a second push over analysis I have the error message

Domain::addLoadPattern - cannot add as LoadPattern with tag200already exists in model
WARNING could not add load pattern to the domain Load Pattern: 200
Scale Factor: 1
Constant Series: factor: 1
Nodal Loads:
Elemental Loads:
Single Point Constraints:
expected integer but got "Constant"
OpenSees >

I think that the code doesn't re-start from the last step.

[ahmadbsr]

Thank you very much to all of you, I've solved the problem!!

How did you solve it ?