Issue in convergence

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Asad005
Posts: 49
Joined: Sat Dec 07, 2019 6:50 am
Location: Italy

Issue in convergence

Post by Asad005 » Sat Feb 29, 2020 10:57 am

I am applying load on a beam-column joint assembly with the zero-length rotational springs at the interface and in centre of joint.
1. I have tried a lot but still, the model does not go forward beyond 1.5 seconds. I changed the time series from linear to now to constant for beam-tip load and axial load. While for the displacement applied at the top of the column I used time-series from 0, 0.08 to 3.2 along the y-axis.

2. Is this okay to use the displacement and load interchangeably as in the considered case the experimental test was displacement control while I clicked the option of load-control in Static analysis window?

3. Can you plz help me out. The end condition includes beam top and column bottom end are hinged and allow only Rz while the top of the column has also 2 dofs i.e. Ux and Uy. All zero-length rotational springs have only one DoF of Rz.

The received error is shown below:
CTestNormDispIncr::test() - iteration: 30 current Norm: 2678.64 (max: 1e-06, Norm deltaR: 5.54895e+10)
CTestNormDispIncr::test() - iteration: 31 current Norm: 26564.3 (max: 1e-06, Norm deltaR: 5.36857e+11)
WARNING - ForceBeamColumn2d::update - failed to get compatible element forces & deformations for element: 2(dW: << 179.039)
Domain::update - domain failed in update
LoadControl::update - model failed to update for new dU
WARNING AcceleratedNewton::solveCurrentStep() -the Integrator failed in update()
StaticAnalysis::analyze() - the Algorithm failed at iteration: 150 with domain at load factor 1.51
OpenSees > analyze failed, returned: -3 error flag
Press any key to continue . . .

4. Can we perform the displacement control method, by applying gradually increasing displacement on the top of the column? What will be the procedure if we do so by choosing the displacement control method ((rather than a load-control option)) in the static analysis?

STKO Team
Posts: 2297
Joined: Tue Oct 29, 2019 8:45 am

Re: Issue in convergence

Post by STKO Team » Mon Mar 02, 2020 9:04 am

2. Is this okay to use the displacement and load interchangeably as in the considered case the experimental test was displacement control while I clicked the option of load-control in Static analysis window?
As long as the load/imposed-displacement is applied only on 1 node, it is perfectly the same to do:
  • a load-control with prescribed displacement
  • a displacement-control with applied load
3. Can you plz help me out. The end condition includes beam top and column bottom end are hinged and allow only Rz while the top of the column has also 2 dofs i.e. Ux and Uy. All zero-length rotational springs have only one DoF of Rz.
This should be fine if you are doing your model in 2D (XY plane). Is this the case? Zip your SCD file and attach it here. Or send it to us by e-mail.

Asad005
Posts: 49
Joined: Sat Dec 07, 2019 6:50 am
Location: Italy

Re: Issue in convergence

Post by Asad005 » Mon Mar 02, 2020 10:02 am

More than thanks for ur assistance.

Gabriele.Neri
Posts: 14
Joined: Wed Feb 21, 2024 9:14 am

Re: Issue in convergence

Post by Gabriele.Neri » Sun May 19, 2024 11:09 am

Dear STKO team,

I'm trying to perform a pushover analysis with a Modal-proportional-load-pattern, but I have several issues during the analysis. (shown "issues_pushover")
Can you help me?

Thanks in advance
Attachments
MODAL_Push.zip
(186.41 KiB) Downloaded 70 times
issues_pushover.png
issues_pushover.png (15.45 KiB) Viewed 1206 times

STKO Team
Posts: 2297
Joined: Tue Oct 29, 2019 8:45 am

Re: Issue in convergence

Post by STKO Team » Mon May 20, 2024 8:52 am

Can you try with tes = NormDispIncr tol=1.0e-6 and initial number of steps = 1000?

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