A standard engineering background (BS degree) is all that's really required. Some experience in Structural engineering would always be preferred. I have seen new grads hired that were basically walked through the process. You may end up peer reviewing basic structural calcs and drawings, perform calcs using Design Data Sheets, and familiarize yourself with standard structural software (NASTRAN, FEMAP etc.) via tutorials before being shepherded through your first few models. There's a massive wealth of experience on staff and, at least when I was there, they were very good about tutoring new hires.