Cap Plasticity Model

[g8star]

Hi STKO,

Following up on a previous post (viewtopic.php?t=3235), geotechnical settlement analyses often require a cap plasticity model. The Bounding Cam Clay model does not appear to work in OpenSees, and I was directed to use the CapPlasticity model.

I’ve attached a single element simple shear test for the CapPlasticity soil model. Unfortunately, the model returns a nan Norm, even for the input properties described in the OpenSees github page (https://github.com/OpenSees/OpenSees/bl ... ticity.cpp). There is no other documentation for the model. The analysis works fine with the elastic isotropic and PIMY ndMaterial models, although the initial shear stress in the PIMY model does not appear to be correct.

Is there something that I’m doing wrong in the setup of the CapPlasticity model? Is there another cap plasticity model in STKO?

eltest_capplast.zip

(136.38 KiB) Downloaded 155 times

[STKO Team]

I did a quick debug and it returns NAN for both stress and tangent even when the input strain is zero.
I would not trust such a material.
Try to ask on the OpenSees github page or write an email to the authors

[g8star]

If neither the Bounding Cam Clay nor the Cap Plasticity model work, then does STKO have a model that supports cap plasticity? A cap plasticity model is necessary for geotechnical consolidation analyses. If STKO does not have a cap plasticity model it would severely limit its geotechnical capabilities.

I am an engineering consultant. While OpenSees is great at dynamic analyses, I also need software that supports a range of other geotechnical problems, like consolidation.