Weird behavior using PlaneStressUserMaterial

[DeltaGL]

Hello everybody,

Reproducing an out-of-plane bending test of a slab by simulation, I came across a malfunction in the hysteretic behavior of PlaneStressUserMaterial because concrete increases its tensile much more than its threshold, reproducing an unreal situation (tensile strength larger than 1.5 MPa).

Have you ever come across something similar using the Materials for Modeling Concrete Walls?

Everything converges pretty well and the materials definitions are as follows:

#Concrete
PlaneStressUserMaterial 3 40 7 -25.0 1.5 0.0 -0.003 -0.015 9.3e-08 0.08
nDMaterial PlateFromPlaneStress 4 3 12500000000.0

#Steel
uniaxialMaterial Steel02 5 672.0 210000.0 0.005 18.0 0.925 0.15
nDMaterial PlateRebar 6 5 0.0
nDMaterial PlateRebar 7 5 90.0

The model was run using STKO 2.0.3 and OpenSees version 3.3.0 (64-Bit)

Look at sigma11 in tensile in the picture attached, it is huge (86MPa) comparing with its threshold (1.5MPa)

Thank you for your help, guys!

Best,
David

[DeltaGL]

I attach the model

[marafini.f]

Dear DeltaGL,

We are not really familiar with the PlaneStressUserMaterial, it's not possible to use the tester in STKO given how the source code for it was written. Also there is not much documentation about it.
We suggest you use the DamageTC3D material to model your slab. You can check out this forum, there are a lot of threads in reference to this material. And get back to use for more info if needed.

Enjoy your modelling.
Francesca