element zeroLengthSection

[Alex Yang]

I established a precast assembled double column pier frame structure for quasi-static analysis, but the results show that R is negative in ReinforcingSteel::SetMP()
R is negative in ReinforcingSteel::SetMP()
R is negative in ReinforcingSteel::SetMP()
R is negative in ReinforcingSteel::SetMP()
R is negative in ReinforcingSteel::SetMP()
R is negative in ReinforcingSteel::SetMP()
R is negative in ReinforcingSteel::SetMP()
R is negative in ReinforcingSteel::SetMP()
R is negative in ReinforcingSteel::SetMP()
R is negative in ReinforcingSteel::SetMP()
WARNING: CTestNormDispIncr::test() - failed to converge
after: 6 iterations current Norm: 1.61995e-008 (max: 1e-008, Norm deltaR: 7.97907)
NewtnRaphson::solveCurrentStep() -the ConvergenceTest object failed in test()
StaticAnalysis::analyze() - the Algorithm failed at iteration: 0 with domain at load factor -468147
OpenSees > analyze failed, returned: -3 error flag
pushover analysis has been done。
I have tried many approaches, but useless.anyone can help me? I will share my command if you give an e-mail address.
here is my e-mail:[email protected]
thanks!

[STKO Team]

Reinforcing Steel material has many bugs... I would suggest: start with a simpler steel material, check if everything works, then move to Reinforcing Steel

[Alex Yang]

Thank you for your answer! I replaced reinforcing steel with steel 02, but the results showed that
WARNING - ForceBeamColumn3d::update - failed to get compatible element forces & deformations for element: 14(dW: << 2.31313e-005, dW0: 0.0344486)
WARNING - ForceBeamColumn3d::update - failed to get compatible element forces & deformations for element: 14(dW: << -5.2057e-005, dW0: 12.1848)
Domain::update - domain failed in update
DisplacementControl::update - model failed to update for new dU
WARNING NewtonRaphson::solveCurrentStep() -the Integrator failed in update()
StaticAnalysis::analyze() - the Algorithm failed at iteration: 0 with domain at load factor 1.75654e+006
OpenSees > analyze failed, returned: -3 error flag
I think it is the problems of element zeroLengthSection and post-tendon. but i cant asure it.

[STKO Team]

This is a typical non-convergence error with issues related to the force beam column element.
If you share your model (zip it and attach it here) it will be easier to find the issue

[Alex Yang]

Thank you! I will share my model.

[marafini.f]

Dear Alex,
which version of OpenSees are you using?
I tried to run your model with mine (3.3.0) but you need to input GJ in the fiber sections. Could you specify this value?
Thanks
Francesca

[Alex Yang]

Thank you! my opensees version is 2.5.0, and I tried version 3.3.0 yesterday. it works successfully, but the results obviously wrong. And you can input -GJ 4. which 4 means material tag has been defined above.

[Alex Yang]

I built my model again which can be run in opensees 3.3.0. but still has a non-convergence error.I will attach my model in this post. can you help? thanks.

[marafini.f]

Dear Alex,

Nonconvergence problems are typical of any nonlinear analysis. You can try different things, like changing the algorithm. NewtonLineSearch of ModifiedNewton with initial stiffness.

Your result is telling you that the NormX is low but the NormR seems to be very high. You should try to interpret that, why is your convergence failing in terms of forces equilibrium rather than displacement compatibility.

You can try also by testing your cyclic analysis in this way:

Code: Select all

integrator DisplacementControl 2008 2 0.0003
set ok [analyze 100]
if {$ok != 0} { error "non-convergence!" }

or refining your analysis by incrementing up to 0.00003 with 1000 duration.

If you had used STKO for your modelling you could have used the Adaptive Time Step option, it would have for sure helped you with your problem.

Enjoy your modeling
Francesca

[Alex Yang]

Thank you!