stress-strain response of confined Concrete issue

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Tharuki
Posts: 6
Joined: Tue May 13, 2025 1:39 pm

stress-strain response of confined Concrete issue

Post by Tharuki » Sat Jun 21, 2025 6:05 am

Hi,
I am working on a high rise building. I get a wrong stress strain response for confined concrete once I defined the RectangularFiberSection for the column. Can you help me with this issue? I have attached the file.
Thank you in advance!
Attachments
HighRise.zip
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Screenshot 2025-06-21 113247.png
Stress strain response
Screenshot 2025-06-21 113247.png (14.57 KiB) Viewed 2195 times


Tharuki
Posts: 6
Joined: Tue May 13, 2025 1:39 pm

Re: stress-strain response of confined Concrete issue

Post by Tharuki » Tue Jun 24, 2025 10:14 am

Dear STKO Team,
I have already replaced those files. However the same error is occuring. Also this error is occuring when I run the model.

StaticAnalysis::analyze() - the Algorithm failed at step: 0 with domain at load factor 1
OpenSees > analyze failed, returned: -3 error flag
Reducing increment factor due to non convergence. Factor = 0.5
WARNING: numeric analysis returns 1 -- Umfpackgenlinsolver::solve
WARNING NewtonLineSearch::solveCurrentStep() -the LinearSysOfEqn failed in solve()
StaticAnalysis::analyze() - the Algorithm failed at step: 0 with domain at load factor 0.5
OpenSees > analyze failed, returned: -3 error flag
Reducing increment factor due to non convergence. Factor = 0.25
WARNING: numeric analysis returns 1 -- Umfpackgenlinsolver::solve
WARNING NewtonLineSearch::solveCurrentStep() -the LinearSysOfEqn failed in solve()
StaticAnalysis::analyze() - the Algorithm failed at step: 0 with domain at load factor 0.25
OpenSees > analyze failed, returned: -3 error flag
Reducing increment factor due to non convergence. Factor = 0.125
WARNING: numeric analysis returns 1 -- Umfpackgenlinsolver::solve
WARNING NewtonLineSearch::solveCurrentStep() -the LinearSysOfEqn failed in solve()
StaticAnalysis::analyze() - the Algorithm failed at step: 0 with domain at load factor 0.125
OpenSees > analyze failed, returned: -3 error flag
Reducing increment factor due to non convergence. Factor = 0.0625

Can you please help me to solve this problem. I have attached the model here.
Thank you in advance!
Attachments
NEWMESH.zip
New Model
(747.67 KiB) Downloaded 106 times

STKO Team
Posts: 3066
Joined: Tue Oct 29, 2019 8:45 am

Re: stress-strain response of confined Concrete issue

Post by STKO Team » Fri Jun 27, 2025 8:14 am

I have already replaced those files. However the same error is occuring. Also this error is occuring when I run the model.
Now the error is different: you are using positive values for concrete strain and negative values for stresses. While OpenSees now converts all of them to negative values, the Automatic Confinement tool expects those values to be ALL NEGATIVE. Just make them negative
WARNING: numeric analysis returns 1 -- Umfpackgenlinsolver::solve
This error instead is due to a singularity. From a quick check of your model I can see that the last 7 geometries in your model are not connected to anything. Double check your model

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