ALUMINIUM STRUCTURES (EXCLUDING PREFABRICATED BUILDINGS OF HEADING 9406) AND PARTS OF STRUCTURES (FOR EXAMPLE, BRIDGES AND BRIDGE-SECTIONS, TOWERS, LATTICE MASTS, ROOFS, ROOFING FRAMEWORKS, DOORS AND WINDOWS AND THEIR FRAMES AND THRESHOLDS FOR DOORS, BALUSTRADES, PILLARS AND COLUMNS); ALUMINIUM PLATES, RODS, PROFILES, TUBES AND THE LIKE, PREPARED FOR USE IN STRUCTURES