The development of light steel keel can be summarized by looking at its domestic!

The development of light steel keel can be summarized by looking at its domestic and international development and application status.

**International Development:**

The emergence and application of light steel keel walls originated from the North American wooden structural housing system. After the 1960s, steel gradually replaced the wooden skeleton. The main material used in this steel skeleton is now the thin-walled cold-formed steel made by mechanical shaping methods. The application of light steel keel walls abroad is very popular, mainly in the form of load-bearing walls combined with the keel floor system to construct a complete structural system for low-rise (mainly below 6 floors) buildings. The United States, Canada, Australia, and other countries have formed mature and complete sets of technologies in this regard.

**Domestic Development:**

With the development of modern construction in China, light steel keel has been widely used in hotels, terminal buildings, bus stations, train stations, amusement parks, shopping malls, factories, office buildings, renovation of old buildings, interior decoration settings, ceilings, and other places. The light steel (coated) keel ceiling has the advantages of being lightweight, high-strength, adaptable to waterproofing, earthquake resistance, dust prevention, sound insulation, sound absorption, and temperature control, and also has the advantages of short construction period and simple construction.

The light steel keel structural housing system, with its excellent characteristics of being lightweight, having good seismic resistance, long lifespan, and fast construction, has gradually become an important development direction for steel structure housing. By introducing the development process of light steel keel housing from both technical and application aspects, it is found that there is still a big gap between China's light steel structure housing technology and the advanced technologies of developed countries such as Europe, America, and Japan.

The development history of light steel keel is as follows:

- **Origin:** In the 1930s, under the leadership of Professor George Winter at Cornell University in the United States, research on cold-formed thin-walled steel structures began. In 1946, based on Professor Winter's research results, the American Iron and Steel Institute (AISI) issued the world's earliest specifications and guidelines for cold-formed thin-walled steel structures—Allowable Stress Design (ASD) specifications "Design Specifications for Cold-Formed Steel Structural Members."

- **North American Development:** It is estimated that the annual production of light steel keel in the United States is 1 million tons. Small factories generally produce 500-700 tons per month, medium-sized factories produce 1500-2000 tons per month, and large factories produce 3500-5000 tons per month, with small and medium-sized factories being the majority, totaling about 119. Each factory generally has 2-4 production lines, with product models up to 200-300 types. The Canadian Standards Association (CSA) issued the "Cold-Formed Steel Structural Design Code" in 1967. Canada and the United States have also established the North American Steel Construction Alliance (NASFA), achieving the unification of North American cold-formed steel structural design standards.

- **Chinese Development:** In 1978, the Beijing Institute of Architectural Design and the Beijing Lamp Factory cooperated to develop the Australian-American system of light steel keel partition walls and ceilings; in 1979, the Beijing Light Steel Structure Factory and the 10th Institute of the Ministry of Electronics Industry introduced Japanese light steel keel and developed a series of light steel keel close to the Japanese series, and designed a complete set of detailed construction application drawings; at the end of the 1970s, China invested in the construction of the Beijing New Building Materials General Factory, introducing a 15,000-ton keel rolling machine from the German (former West Germany) Knauf company. In 1988, the Beijing New Building Materials General Factory successfully manufactured a keel rolling machine with the same performance and specifications, with the product range developing from 7 to 15, capable of producing German and Japanese series products. In the second half of 1994, the factory also developed a T-bar coated keel series. After years of promotion, light steel keel has gradually been applied in key projects and high-rise buildings. By 1998, there were about 200 enterprises of scale, spread across more than 10 provinces, municipalities, and autonomous regions nationwide.

- **European Development:** Since the 1970s, many European institutions and private companies have conducted research and development on cold-formed steel components, connections, and structural systems. Austria, Czech Republic, France, Sweden, the United Kingdom, Germany, and others were among the earliest countries to form cold-formed steel design specifications. The European Convention for Constructional Steelwork (ECCS) has also completed some documents for the testing and design of cold-formed steel structures in construction. At the end of the 20th century, the European Committee for Standardization issued parts 1-3 of the European Standard 3 for cold-formed steel components and plates (Eurocode 3: part 1-3), marking the unification of European standards for cold-formed steel structures.

- **Asian Development:** The development of light steel keel structures in Asia began in the 1980s. In the 1990s, Japan increased its research and development in this field. In 1995, the members of the Japan Steel Club, led by Nippon Steel, jointly developed cold-formed steel structure technology (later known as the KC technical system) and published the "Design Manual for Light-Gauge Steel Buildings" in 2002, which was later promoted to the national standard. The entire industry in Japan is estimated to have an annual output of 500,000 tons, with about 15 manufacturers. In Japan, there are production standards and a complete set of construction laws and regulations, and its light steel keel standard is JISA6517.

Light steel keel, made by cold bending process, is a metal skeleton used in construction, characterized by strong versatility, fire resistance, and easy installation. It is divided into seven types according to the cross-sectional shape: U-type, T-type, H-type, L-type, V-type, C-type, and CH-type. It is widely used in luxurious villas, high-end hotels, office buildings, shopping malls, and other constructions as a non-load-bearing partition wall or ceiling structural component. When used in conjunction with various types of lining panels, it can improve indoor conditions and reflect different decorative arts and styles.