Time History Analysis on 3D RC Frame: Convergence problem at only one column

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elifyildirim
Posts: 4
Joined: Mon Jan 21, 2019 5:50 am
Location: Bogazici University

Time History Analysis on 3D RC Frame: Convergence problem at only one column

Post by elifyildirim » Mon Jul 19, 2021 6:00 am

Hi everyone,

I modeled a 3D RC frame+shear wall structure and performed time history analysis. All columns, beams, and walls have been modeled with fiber section forcebeamcolumn elements. Shear walls were modeled with rigid elements using rigid elasticbeamcolumns.
Periods, reactions from gravity analysis, pushover curves in X and Y seem reasonable.

However, when I perform time history analysis, only one column raises a problem and I could not find the reason. For example, while using a 20-sec ground motion, the analysis has stopped at 15 sec due to convergence problem at that column. My model has a code that changes algortihm to avoid convergence problems.

In the StressStain results of that column, I see no stress at section 1 but abnormal stress on section 5 (like twice). [#integration points=5]

I checked nodes, element connections, loads, diaphragms, and fiber sections. I could not find any problem regarding modeling.

Can anyone make any suggestions?

Thank you very much in advance.

mhscott
Posts: 868
Joined: Tue Jul 06, 2004 3:38 pm
Location: Corvallis, Oregon USA
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Re: Time History Analysis on 3D RC Frame: Convergence problem at only one column

Post by mhscott » Mon Jul 19, 2021 1:14 pm

Make things elastic in order to isolate the error, then start adding back nonlinearity.

https://portwooddigital.com/2020/08/21/ ... -a-sprint/

selimgunay
Posts: 913
Joined: Mon Sep 09, 2013 8:50 pm
Location: University of California, Berkeley

Re: Time History Analysis on 3D RC Frame: Convergence problem at only one column

Post by selimgunay » Mon Jul 19, 2021 9:20 pm

You can try reducing the number of fibers, especially in the cover.

elifyildirim
Posts: 4
Joined: Mon Jan 21, 2019 5:50 am
Location: Bogazici University

Re: Time History Analysis on 3D RC Frame: Convergence problem at only one column

Post by elifyildirim » Sun Jul 25, 2021 12:21 am

thank you very much for your suggestions!

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