The technique of steel structure construction for adding floors is a new type of building reinforcement and reform approach that is gradually being promoted today. It offers significant advantages over concrete structures in terms of technology, economy, and safety, but its application internationally is not yet widespread and the design is not yet perfect.

The research on steel structure superstructure in China has a head start in the retrofitting of existing buildings. To adapt to the rapid development of structural reinforcement, renovation, and steel structure superstructure projects, and to better complete the superstructure and renovation of old buildings, China has successively established academic bodies such as the Technical Research Committee for Building Superstructure Retrofitting and the Reinforcement Technology Standard Committee, creating an active academic discussion and experience exchange environment for steel structure superstructure renovation projects.

This technique is applied to buildings with multiple floors or those unsuitable for direct addition on the existing structure. This type of addition modification technology is commonly referred to as an envelope frame addition structure. The envelope frame addition structure is mainly categorized into two types: the separated and the integrated. The former involves the complete disconnection of the envelope frame from the old building; while the latter indicates that the envelope frame is integrated with the old building's structure.