I modeled a four-story frame using the Ibarra-Krawinkler deterioration model and I have faced convergence problems in dynamic analysis! I adopted the adaptive strategy which is introduced in OpenSees Message Board, However, it is not successful. The tcl file is attached. I would be grateful if anybody could help me.
Dear Mohesen,
The convergence problem in numerical analysis can be solved in two ways, the first one is the factors influencing convergence i.e. material properties and finite element properties. The second is to define the acceptable criteria to set the limiting force or displacement in the program. The set value may be the force or displacement. If we have define these limiting values properly then convergence criteria is easily satisfied during the analysis. All the best in your research..
I think that you must chose one of your result and then plot a curve of convergence and divergence with respect to the either No. of nodes or No. of element .When the curve reach the beginning of the steady state region then this mean that you reach the require convergence
I think that you must chose one of your result and then plot a curve of convergence and divergence with respect to the either No. of nodes or No. of element .When the curve reach the beginning of the steady state region then this mean that you reach the require convergence
Dear Mohsen,
please check the section "convergence tests" through below link...
http://opensees.berkeley.edu/OpenSees/manuals/usermanual/3214.htm
be lucky
Thanks a lot for your replies.
Actually, I want to calculate the residual deformation under different scales of a single earthquake record. When the scale factor is small, there is no problem. However, for large ones, I face with convergence problems. As I said in the first post, I have tried different "algorithm" and "test" objects to fix the convergence, but no success is achieved!
Hi,
I faced the same problem, although I tried many ways I am still struggling. I used the Smart Analysis algorithm but still not working.
Here is the link of smart analysis:
http://www.hanlindong.com/en/2019/opensees-converge/
Could you please help if you found the issue? I use the Modified Ibbra Krawinkler model...
Thanks,
I faced the same issue while performing the collapse performance tests of steel buildings. The reason for this non convergence is probably the steep decline in the stress strain curve of the material of interest. I would recommend to use hysteretic material instead, with a gradual decline in the stress carrying capacity beyond the peak. The softening slope can significantly affect the rate of convergence. Hope it helps.
Dear Mohsen,
One of the possible option is to carryout hit and trial approach by varying the dynamic analysis parameters. Let me presume all the relevant modeling steps are correct and list the following.
1) Minimize the time step of analysis. ( 0.001 or even less), (Note! This may lead to large number of data points)
2) Reduce the convergence criteria with tolerance ( 1.0e-4 or may vary)
3) Increase the maximum iteration ( example 500 or more)
4) Go for different possible algorithms one by one including NewtonLineSearch.
Also make sure that the time history records are in proper scale! It is better to use normalized ground motion records and do the scaling in the acceleration series option ( scale factor * g).
Lastly but not least; This is a crude approach, hence have a validation for any so obtained output with standard results, then move ahead.
Good Luck and Best Regards
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