Hi, 

The time period is 1.07 sec.

Hi,

I performed the pushover analysis to get the response. The PO curve shows the reasonable response with strength degradation after the peak response reach. I hope the PO curve gives the satisfactory results with some published results for three story and four story steel frames. However, the response curve after the peak did not match exactly. I think this deviation should be due to the selection of different parameters after the peak reached.

Dear Baikuntha

First, for selecting nonlinear parameters of elements and panel zone, I suggest you to take a look at these papers (In case you haven't seen them yet):

1- "Deterioration Modeling of Steel Components in Support of Collapse Prediction of Steel Moment Frames under Earthquake Loading", Dimitrios G. Lignos, and Helmut Krawinkler, DOI: 10.1061/(ASCE)ST.1943-541X.0000376.

2- "Modeling of steel moment frames for seismic loads", Douglas A. Foutch, Seung-Yul Yun, Journal of Constructional Steel Research 58 (2002) 529–564

I don't think there is any question about definition and assignment of parameters that has no answer available in these papers, since these are very comprehensive studies in the matter of steel moment frames.

But about the issue you have encountered, I guess there are some details you should consider more carefully. The first thing I can think of, Since you have both panel zones and plastic hinges in your model, you should consider how one affects the other.

For example, in a specific story of frame, if one panel zone fails, the rest of plastic hinges in relative column and beam it has connected together, will become non-effective. In other words, if you assign the properties of panel zone poorly, it can totally overshadow all other parameters you have chosen for plastic hinges.

Anyway I hope you can find the solution

Good luck

Dear Behnam,

Thanks for your response with relevant documents and even more, the explanation of assigning and evaluating the effect of parameters that affect the response. I am also assigning parameters with these two papers in addition to other two dissertation papers to understand the IDA analysis.

Dear all,

Thank  you all for providing valuable references and feedback to improve the model.

When I used the simple two story one bay model with panel zone available in opensees, there was one mistake of using EqualDOF that lead to get wrong time period and response. After removing all EqualDOF from the opensees code, I got the acceptable results.

Now, I have to select appropriate nonlinear parameters and modify my opensees code for the three story SAC building. I hope it will provide some good results.

Next, I have to understand the influence of gravity load on the IDA response.

If you have any concern or issues, I am glad to share my results or codes for your better understanding.

I appreciate all of your suggestions that help me to get good results.

Hi Sadhad,

From my experience, the time period is one of the best parameters,but in some case such as base isolation or braced frame structures, the time period seems misleading. In such cases, I have to explore more to assure the reliable time period. I got different time periods for braced frame and base isolation systems.

Hi, 

I've done some IDA analysis in these papers. These might help:

http://thescipub.com/abstract/10.3844/ajassp.2008.1793.1803

ftp://128.46.154.21/spujol/Andres/files/14-0094.PDF

http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=1632741

http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=1858144

Hi Mohammad,

Thank you for  a couple of your IDA research that could be helpful to select the appropriate nonlinear parameters.

Hi. 

I think you apply the gravity load incorrectly or the section properties for leaning column are very low. If you just model for example one of two moment frames,  the total seismic weight you have to assign is half of weight of the building then you should apply the amount of gravity load associated with moment frame  and the rest you have to apply to leaning column. 

Interesting..