16' Loft Design Over 36' Building

I need help designing a 16' loft at one end of my 50' wide pole building. The loft will be used for storage of mixed-weight items, so it needs to be sturdy and well-constructed.

Requirements:
- Span the entire 36' without posts
- Beam height no taller than 12"
- Use 12" I-joists to run into the beam
- Combination of wood and steel materials

Ideal skills and experience:
- Structural engineering or advanced carpentry
- Experience with loft designs and load-bearing structures
- Knowledge of building codes and safety regulations

Please provide detailed plans and ensure structural integrity for mixed item storage. I dont need anything fancy just if this is realistic and if so what size of beam needed and what material