As the title as well mentioned IFC, here how to create the Quonset Hut on bimifc.de (same engine as acadlisp.de)

(ifc-new) (ifc-set-project "Quonset Hut" "Airfield" "Hangar" "GF" "Engineer" "Corps") (ifc-storey "Ground Floor" 0.0) (ifc-add-slab 0 0 8 15 0.2 0 "Concrete Pad") (ifc-add-wall 0 0 8 0.15 4.0 0.2 "Front Wall") (ifc-add-wall 0 14.85 8 0.15 4.0 0.2 "Rear Wall") (ifc-add-door 3 0 2.0 0.15 3.0 0.2 "Hangar Door") (ifc-add-window 1 14.85 1.5 0.15 1.5 0.2 "Rear Window") (ifc-storey "Roof" 4.0) (ifc-add-roof-barrel 0 0 8 15 3.0 4.0 "Steel Arch")