Lightweight steel structures are mainly used in load-bearing buildings that do not bear heavy loads. They are constructed using lightweight H-shaped steel (welded or rolled; variable cross-section or uniform cross-section) to form a door-shaped steel frame for support, C-shaped and Z-shaped cold-formed thin-walled steel for roof trusses and wall beams, profiled steel plates or lightweight sandwich panels for roof and wall enclosure structures. These are assembled using high-strength bolts, ordinary bolts, and self-tapping screws and other connecting components and sealing materials to form a low-rise and multi-story prefabricated pre-stressed steel structure building system.