Hi everyone,
I am doing nonlinear analysis for my soil-pile-structure problem and after about 12 hours of run, I face a convergency error which is at the middle time for my analysis. I increased the number of iterations but again I got this error after a long time of running.
I will appreciate your suggestions in this case.
Many thanks,
Covergency Problem
Moderators: silvia, selimgunay, Moderators
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duttaANURAG
- Posts: 37
- Joined: Fri Mar 23, 2018 2:56 am
- Location: NERIST
Re: Covergency Problem
Whenever there is a convergence problem i.e. your problem is not getting converged in opensees, the reasons could be -
1. There is some problem in your model. Check for norms in that case while you do the analysis.
2. If your model is correct and big, then push the model. For geotechnical analysis,when models are big, you better push the analysis commands (Check geotechnical analysis video of Opensees days to have a good idea).
3. Try for a very smaller model at first, it will give you a better insight into your model and the analysis commands.
4. Geotechnical analysis is complex in nature. Have patience. Things will work out.
Best Wishes
1. There is some problem in your model. Check for norms in that case while you do the analysis.
2. If your model is correct and big, then push the model. For geotechnical analysis,when models are big, you better push the analysis commands (Check geotechnical analysis video of Opensees days to have a good idea).
3. Try for a very smaller model at first, it will give you a better insight into your model and the analysis commands.
4. Geotechnical analysis is complex in nature. Have patience. Things will work out.
Best Wishes
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selimgunay
- Posts: 917
- Joined: Mon Sep 09, 2013 8:50 pm
- Location: University of California, Berkeley
Re: Covergency Problem
Are you running a nonlinear static or dynamic analysis? Please try adaptive solution algorithms where you increase the tolerance or reduce the time steps only when it is needed to achieve convergence
Re: Covergency Problem
Hi,
Many thanks for your response.
I was doing a nonlinear dynamic analysis. I increased the iterations, but again I got convergence error. I noticed that I need to do the plastic gravity analysis also for the soil domain before applying my load. I decided to do this but I got convergence error again.
I am using 9_4_QuadUP element. I am using fixed B.C. for the soil domain and first doing elastic gravity analysis and there is no problem. While I update the stage of my material to 1 to do plastic gravity analysis, I get "failed to converge error" but analysis goes on!
I changed the B.C. but no difference.
I will appreciate your kind suggestions in this respect.
Bests,
Many thanks for your response.
I was doing a nonlinear dynamic analysis. I increased the iterations, but again I got convergence error. I noticed that I need to do the plastic gravity analysis also for the soil domain before applying my load. I decided to do this but I got convergence error again.
I am using 9_4_QuadUP element. I am using fixed B.C. for the soil domain and first doing elastic gravity analysis and there is no problem. While I update the stage of my material to 1 to do plastic gravity analysis, I get "failed to converge error" but analysis goes on!
I changed the B.C. but no difference.
I will appreciate your kind suggestions in this respect.
Bests,
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selimgunay
- Posts: 917
- Joined: Mon Sep 09, 2013 8:50 pm
- Location: University of California, Berkeley
Re: Covergency Problem
Which material are you using? It sounds like the convergence problem may be on the element level and not on the integration
Re: Covergency Problem
Hi,
I have just soil domain in this stage and I am using PDMY02 material. Would you please share the eigenvalue analysis command for soil domain in OpenSees in order to check the frequencies?
Many thanks,
I have just soil domain in this stage and I am using PDMY02 material. Would you please share the eigenvalue analysis command for soil domain in OpenSees in order to check the frequencies?
Many thanks,