Prestressed beam - abaqus

Hi,

 I am modelling a prestressed RC beam with abaqus. For the beam I am using the C3D8 element and for the reinforcement and strands the BEAM element and I am using the EMBEDDED command to simulate the contact between the steel and the concrete.

I am trying to simulate the prestressed with the prestressed hold command, but I am not having success because I am not writting the correctly code.

Can someone help me and tell me how I can do this correctly? What should I write?

 Best regards,

Sara