Question about Truss Module and plasticity

I am modeling a reinforced concrete beam using almost an identical model to the reinforced concrete beam that is provided in the COMSOL tutorials/models. I need to model the rebar as elastic-perfectly plastic, i.e. it is elastic until it reaches its yield strength, at which point the strain increases with no increase or decrease in stress. The rebar I am modeling will yield once the strain reaches 0.002. In the Truss module, there is only an option for an elastic analysis. Is there a way of incorporating elastic-perfectly plastic behavior into the truss module or is there another way I can simulate elastic-perfectly plastic conditions in the rebar?

Thanks in Advance