Shear friction modeling for Concrete specimens in SAP 2000

[B]How should I correlate cohesion and friction properties of concrete to stiffness when defining link properties in SAP2000?[/B]

I am modeling horizontal shear between two concrete blocks (no studs) in SAP2000.
How should I model horizontal shear using links? I can't input the value for cohesion and friction of concrete, only a stiffness option is given.
Which link type should I use for partially composite/ or fully composite action? Linear, Multi linear Elastic, friction isolator?
Is there any other way to model horizontal concrete shear in SAP 2000?