Underground Steel Shelter Drawings

I'm looking for engineered drawings to build a medium-sized, rectangular steel structure that can be safely buried underground and used as an emergency shelter. The access point will be a hatch with a ladder.

Key requirements:
- Medium size (100-500 sq ft)
- Rectangular shape
- Access via hatch with ladder

Ideal skills and experience:
- Structural engineering expertise
- Experience with underground structures
- Proficiency in creating detailed, safety-compliant engineered drawings

Please ensure designs meet safety and building code requirements.