In general the derricks are structures build up from beams -either milled profiles or tubes- in all FEA programmes you can find "beam" elements but you should first define the geometry of the structure and get the basic data to define the beam elements.

Send a readable sketch of the structure with the applied loads and you can get more input.

I recommend that you contract a professional structural engineer. There is risk involved, and you want someone who can present a good case in court, when or if the structure fails, kills people, or shuts down a job site. Cover your own ass first.

Chris

Type derrick standard or jack knife?

Is it to be a single, double, triple or quaduple?

Maximum weight load of the drilling string?

I am a mechanical engineer and unfortunatley i have to model a derrick similiar to one being used on oil rigs. Since its not my domain...

Doesn't this seem like a prescription for disaster? I'd suggest passing the project on to someone who is interested. If you are behind schedule and have little interest in the project, it is very unlikely that you will do a good job. Then... when someone gets hurt... what happens?