Steel to concrete beam connection

Hi everyone,

I am designing a steel structure where some members are pinned connected to a concrete beam thru embedded metal. I wish to know how to model this connection. Should I put “Pinned support” or “Fixed but” (Mx, My, Mz are released). I tried both supports but these beams are failing even though there were no loads applied on them.

I would appreciate your response. Thank you.

Stratguy