CONVERGENCE ISSUE

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Zeeshanbhat
Posts: 126
Joined: Wed May 27, 2020 3:48 pm

CONVERGENCE ISSUE

Post by Zeeshanbhat » Sat Sep 18, 2021 8:18 am

Dear Team,

I have modelled a single column using IMK Hysteretic model. The model is not converging in gravity analysis.
GG.PNG
GG.PNG (39.12 KiB) Viewed 166 times
I checked the model several times, but I could not find the error. Any Suggestions in this regard will be appreciated.
The model is attached below.
CONCENTRATED.rar
(77.63 KiB) Downloaded 12 times
Regards,
Zeeshan Bhat

STKO Team
Posts: 737
Joined: Tue Oct 29, 2019 8:45 am

Re: CONVERGENCE ISSUE

Post by STKO Team » Mon Sep 20, 2021 9:11 am

You are using the NormUnbalance test (absolute tolerance) with 1.0e-4 (newton). However you are modeling in N, and it fails at reducing the residual error that much.
If you use the normDispIncrement with 1.0e-8 it will converge easily.

However, check carefully the stiffness values that you are using in the IMK:
a 300x400 section has a second moment of intertia = 1.6e9
E is 2.5e5
so EI has an order of magnitude of 9+5=14. But the initial stiffness of your hinge is less than that, so most of the elastic bending deformation will concentrate in the zero length hinge, while it should concentrate in the elastic beam.

Check our webinar on lumped plasticity for more details

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