Application of cold-formed steel in construction industry
Cold-formed steel is widely used in the foreign construction industry, and is used as roof trusses, purlins, trusses, rigid frames, wall frames, keels, roof panels, wall panels, floor slabs, doors and windows and even containers, pipes, cofferdams, steel sheet piles, breakwaters Wait. In recent years, reticulated shells, shelves, single-story and multi-story houses made of cold-formed steel have also developed rapidly, from airports to large shopping malls
From office buildings to stadiums, from conference centers to residential houses, cold-formed steel products are widely used as architectural design materials. In developed countries, the construction industry is the largest user of cold-formed steel. Cold-formed steel accounts for 5% of the total steel, and cold-formed steel for the construction industry accounts for about 70% of the total cold-formed steel. Cold-formed steel products are used in construction. The main industries are cold-formed rectangular tubes for structural use and cold-formed steel for construction use. From the perspective of structural mechanics and economy, the combination of cold-formed steel and H-shaped steel is the best combination for the construction industry, and it can realize the industrialization of industrial plants and residential buildings.
In Japan, before 1980, Japan only produced square rectangular tubes of less than 200 mm * 200 mm and a small amount of cold-formed steel with open ends. H-shaped steel was used for the central pillars of Japanese steel structures. After the 1984 Sendai earthquake in Japan, a study of the steel structure houses damaged during the Sendai earthquake found that the weld between the column and the beam was easily cracked, due to the limitation of the characteristics of the H-shaped steel structure. H-beam butt welding, too few welds. Therefore, after 1984, Japan adopted amendments to the building law, which stipulated that steel residential columns in Japan must use square rectangular tubes to increase the length of the weld seam, thereby improving the seismic resistance of the house. With the popularization of cold-formed steel in the application of building steel structures, the specifications of cold-formed steel production have also increased. At present, the maximum size of square rectangular pipes has reached 550 mm * 550 mm, and the maximum wall thickness is 22 mm. In 2002, the total output of cold-formed square tubes for steel structures in Japan has reached 2 million tons. At present, the largest steel pipe specifications in the market are (200 mm * 200 mm) ~ (400 mm * 400 mm). These specifications of cold-formed rectangular rectangular tubes cover more than 80% of the total steel square and rectangular pipes in Japan. Specifications account for less than 10% of the market.
In the United States, according to relevant survey data, the relationship between the use of cold-formed rectangular tubes and hot-rolled H-beams in the construction industry is about 1: 1. In the 1990s, the proportion of cold-formed steel used in construction steel structures even exceeded The amount of hot rolled H-beam. Among them, cold-formed welded pipes (including square rectangular pipes and original pipes) account for about 25% of the steel used in construction steel structures. In addition, the United States imports a certain number of structural steel pipes each year. World Steel Statistics Monthly Report! Statistics for the 7th year of 2003 showed that the import volume of structural steel pipes in the United States in May 2003 was 28 728 t, and the cumulative imports from January to May were 164 210 t, an increase of 10% over the same period in 2002. The proportion of various open-formed cold-formed steels in the United States in the amount of steel used in building steel structures is also more than 20%.