ModIMKPInching uniaxial material

[mariateresa]

Hi!
I'm using the uniaxialMaterialModIMKPinching in order to model plastic hinges into a RC frame.
I have performed some dynamic non linear analyses and I have observed some anomalies in the behaviour of the recorded Moment-rotation relationship of some plastic hinges in some beams and columns: after some steps of the analysis, even if the behaviour should be still linear elastic (rotation demand is minor than the rotation at yielding), the moment drops to zero while the rotation is varying.
This problem comes out only in the case of some plastic hinges, even if all the plastic hinges of the frame are defined almost in the same way (I mean, with very similar parameters for the uniaxial material).

This is one of the case in which I observed the described anomaly:
uniaxialMaterial ModIMKPinching $matTagBilinPinch 8.279e+003 2.872e-002 2.872e-002 4.809e+001 -4.809e+001 1.000e+000 1.000e+000 1.000e+000 2.657e+002 2.657e+002 2.657e+002 2.657e+002 1.000e+000 1.000e+000 1.000e+000 1.000e+000 4.190e-002 4.190e-002 7.831e-002 7.831e-002 0.000e+000 0.000e+000 1.335e-001 1.335e-001 1.000e+000 1.000e+000

Moreover, I'm sure that I'using the latest OpenSees version.
What could be the problem?
Thank you in advance

[vesna]

This is a contributed material. The best would be to contact material developer for his comments. It would be great if you share the outcomes of your conversation with the OpenSees community.

[saijbz]

dear vesna
how can i contact material developer

[vesna]

Here is his contact info: Dr Dimitrios Lignos: dimitrios.lignos AT mcgill DOT ca

[ambitionpdf]

I am in the same problem.
What is the solution?