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Application of Cold-formed Structure Welded Pipe

Cold formed steel is widely used in foreign construction industry, and is used as roof truss, purlin, truss, rigid frame, wall frame, keel, roof panel, wallboard, floor, doors and windows and even containers, pipes, cofferdams, steel sheet piles, breakwaters, etc. In recent years, the combination of cold-formed steel shell, shelves, single-layer and multi-layer houses have also been developed rapidly, from the airport to large shopping centers, from
From office buildings to stadiums, from conference centers to residential buildings, cold-formed steel products are widely used in architectural design materials. In developed countries, the construction industry is the largest user of cold-formed section steel. The cold-formed section steel accounts for 5% of the total steel, and the cold-formed section steel for construction industry accounts for about 70% of the total cold-formed section steel. From the perspective of structural mechanics and economy, the combination of cold-formed steel and H-shaped steel is the best combination in the construction industry, which can realize the industrialization of industrial plant and civil housing construction.

In Japan, before 1980, Japan only produced square and rectangular pipes below 200 mm * 200 mm and a small amount of open-ended cold-formed section steel, and H-section steel was used for columns of steel structure residential buildings in Japan. After the earthquake in Sendai, Japan in 1984, through the study of the steel structure houses damaged in the earthquake in Sendai, it is found that the weld between the column and the beam is easy to crack because of the limitation of the structural characteristics of the H-shaped steel, the butt welding of H-shaped steel and H-shaped steel is too few. Therefore, after 1984, Japan amended the building law to stipulate that the columns of steel structure residential buildings in Japan must adopt square and rectangular pipes, so as to increase the length of welding seams and improve the seismic resistance of residential buildings. With the popularization of cold-formed section steel in the application of building steel structure, the specification of cold-formed section steel production also increases. At present, the maximum specification of square rectangular pipe has reached 550 mm * 550 mm, and the maximum wall thickness is 22 mm. In 2002, the total output of cold-formed square tube for steel structure in Japan has reached 2 million tons. At present, the steel pipe specifications with the largest market demand are (200 mm * 200 mm) ~ (400 mm * 400 mm). These specifications cover more than 80% of the total amount of steel structure square and rectangular pipes in Japan, and other specifications account for less than 10% of the market share.

In the United States, according to the relevant survey data, the consumption of cold-formed square rectangular tube and hot-rolled H-section steel in the construction industry is about 1:1. In the 1990s, the proportion of cold-formed section steel used in the construction steel structure even exceeded the consumption of hot-rolled H-section steel. Among them, cold-formed structural welded pipe (including square rectangular pipe and original pipe) accounts for about 25% of the steel used for building steel structure. In addition, the United States also imports a certain number of structural steel pipes every year. According to the statistics of the 7th issue of 2003, the import volume of steel tubes for structural use in the United States was 28728 tons in May 2003, and the total import volume from January to May was 164 210 tons, 10% higher than that in the same period of 2002. In the United States, the proportion of all kinds of open-end cold-formed steel in the steel volume of building steel structure is also more than 20%.


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