Portal - frame scaffolding is one of the most widely used scaffolding in construction. Because the main frame is in the shape of a “portal”, it is called portal - frame scaffolding or gantry scaffolding, also known as scaffolding or portal gantry.

Portal - frame scaffolding is one of the most widely - used scaffolding in construction. Since the main frame is in the shape of a "portal", it is named portal - frame or gate - type scaffolding, also known as scaffolding or gantry. This type of scaffolding is mainly composed of main frames, cross frames, cross - bracing, scaffold boards, adjustable bases, etc. Portal - frame scaffolding was first successfully developed as a construction tool in the United States in the late 1950s. Due to its advantages such as simple assembly and disassembly, convenient movement, good load - bearing capacity, safe and reliable use, and good economic benefits, it has developed very rapidly. By the 1960s, countries such as Europe and Japan had successively introduced and developed this type of scaffolding. In countries like Europe and Japan, the usage amount of portal - frame scaffolding is the largest, accounting for about 50% of all types of scaffolding. Moreover, many professional companies producing various systems of portal - frame scaffolding have been established in these countries. Since the 1970s, China has successively introduced portal - frame scaffolding systems from countries such as Japan, the United States, and the United Kingdom, and has applied them in the construction of some high - rise building projects, achieving good results. It can not only be used as internal and external scaffolding for building construction, but also as floor slab and beam formwork supports and mobile scaffolding, etc., having multiple functions, so it is also known as multi - functional scaffolding. In the early 1980s, some domestic manufacturers began to imitate portal - frame scaffolding. Since 1985, ten portal - frame scaffolding production factories have been established successively. In the construction projects in some areas, portal - frame scaffolding has begun to be widely promoted and applied, and has been welcomed by the vast majority of construction units. However, due to the different product specifications of each factory and inconsistent quality standards, certain difficulties have been brought to the use and management work of construction units. At the same time, because some factories use steel pipe materials and specifications that do not meet the design requirements, the portal frames have low rigidity, large weight, are easy to deform during transportation and use, have poor processing accuracy, and short service life, which has seriously affected the popularization of this new technology. By the 1990s, this type of scaffolding had not been developed, and its application in construction had become less and less. Many portal - frame scaffolding factories were closed or switched to other products, and only a few units with good processing quality continued to produce. Therefore, it is necessary to develop a new type of portal - frame scaffolding in combination with the characteristics of Chinese architecture. Portal - frame scaffolding is a standardized steel - pipe scaffolding composed of basic structures such as portal frames, cross - bracing, connecting rods, snap - on scaffold boards or horizontal frames, locking arms, etc., and then equipped with horizontal reinforcing rods, scissors braces, sweeping rods, sealing rods, brackets and bases, and is connected to the main structure of the building by using wall - connecting members. Portal - frame steel - pipe scaffolding can be used not only as external scaffolding, but also as internal scaffolding or full - hall scaffolding.