I'm struggling to obtain the right behavior of gfrp bars, in the process of validating my model i achieve a bilinear behavior in the displacement x force graph when using gfrp bars as reinforcement, but in the research that i'm using the experimental behavior was linear. Even though i've tried to change a lot of parameters in my model I still couldn't obtain something close.

The model has steel stirrups and upper layer reinforcement and only the lower reinforcement uses GFRP bars.

The bars were modeled as wire T3D2 and the beam as solid c3d8r

For the properties data:

For concrete i'm using de young's modulus, poisson and CDP

For GFRP bars young's modulus, poisson and tensile strenght also rupture strenght

Anyone knows what can i do to correct the behavior that i'm having?

In the image i show the behavior that i need in black and what i am obtaining in the other colors