Refer to parametrichouse.com/rectangle-to-surface/
1. Start with rectangle
2. Create Shell geometry using Rectangle and Height
3. Create Circe and extrude and make cylinder.
4. Split shell roof and Cylinder, and build a shell roof with a circular opening
5. This Surface to be converted to Mesh to embrace opening
6. Finally convert mesh to surface back.
7. Export Surface to .igs
8. Import surface from igs file to SAP2000