What is this parameter fb0/fc0 used while defining material properties of concrete damage plasticity model in ABAQUS. How we can calculate this parameter for our model.
fb0 corresponds to the equibiaxial compressive strenght of concrete and fco the uniaxial ones. We can obtain the equibiaxial values in Kupfer article for normal strenght concrete. I have used 1,26 in my simulations for a concrete with 60 MPa of uniaxial compressive strength, but for higher strength this ratio decrases.
You can refer to this paper (http://www.sciencedirect.com/science/article/pii/S1644966512601058) for detailed information regarding each of the Concrete Damaged Plasticity parameters.
Long story short, fb0/fc0 is a ratio of the strength in the biaxial state to the strength in the uniaxial state. Abaqus documentation indicates a default value of 1.16 for this parameter, when no experimental data is available in order to precisely determine its value.