Welding technology is the soul of building steel structure, and the quality of welding determines the success or failure of building steel structure. The structural form of the steel structure itself and the complexity of the welded joints make the welding of the steel structure of the building different from the traditional metal components such as ships and pressure vessels. Zhang Youquan, deputy secretary-general of China Engineering Construction Welding Association, combined with years of theoretical and practical experience, summarized and analyzed the structural characteristics of building steel structures. From the aspects of welding technology, qualifications of employees, welding engineering management, etc. The direction of development. The newspaper will serialize the article "Development of Construction Steel Structure Welding Technology in China" in three times, so stay tuned. --editor
Welding technology is one of the most important major technologies in steel structure engineering construction. It is not only to ensure the quality of steel structure engineering, but in a sense, welding gives life to steel structures. Without welding, the steel structure is just a few scattered, cold and lifeless steel parts. It is welding, let the blast furnace stand, swallow (mine) stone spit (iron) water, smelt steel; it is welding, let the oil and gas long-distance pipeline open, become the economic artery; it is welding, let the "Bird's Nest" (National Stadium) towering, to Beijing The 2008 Olympics will be enhanced; it is welding, so that the new CCTV building will be the first to show the world a new China.
With the deepening of China's reform and the rapid development of the economy, the steel structure industry has entered a period of rapid development. In 2011, China's steel output has exceeded 690 million tons, the annual output of steel structure has reached 30 million tons, and the output of welding materials is about 5 million tons. The development of steel structures has promoted the application and development of new welding techniques, new processes, new equipment and new materials. In turn, the scientific and technological progress of welding new technologies, new processes, new equipment and new materials has provided technical support and guarantee for the rapid development of the steel structure industry. Especially since the beginning of the 21st century, China’s national economy has continued to maintain rapid and steady development. Under the guidance of developing coastal and western development and revitalizing the strategic deployment of the old industrial bases in Northeast China, many major national projects such as the West-East Gas Pipeline, West-East Power Transmission, South-to-North Water Transfer, Railway Construction and Speed ​​Increase, and the Beijing 2008 Olympic Games and Shanghai World Expo Project are comprehensive. The construction of new sports culture venues, convention centers, terminal buildings, landmark buildings and other large, new, exotic, fine and special architectural steel structures all over the land of China, China's steel structure technology has a new situation. According to incomplete statistics, at the end of 2011, there are currently more than 350 super high-rise buildings over 200 meters in China, ranking the top 10 skyscrapers in the world, and China has 7 seats. Super high-rise projects promote regional development and occupy an indispensable position in China's regional economy. According to the 2012 Skyscraper Report, the total number of skyscrapers under construction in China has exceeded 200 (only office buildings and hotels are counted), which is equivalent to the total number of existing skyscrapers in the United States. Relevant data shows that China will have 800 skyscrapers in five years, equivalent to four times that of the United States today. 80% of them will be built in inland areas with underdeveloped economies. It is no exaggeration to say that China has become the world's largest steel structure production and use country, and some production and installation technologies have reached the world's leading advanced level.
First, the basic structural form of building steel structure and complex nodes
Throughout the domestic steel structure projects in recent years, all reflect the characteristics of "big, special, new". Super-high-rise, large-span, world-class ultra-large-scale buildings are commonplace, and the structural shapes are novel and unique, and they are unconventional and have a strong visual impact. Along with this, there are many steel structure systems, complicated joint structures, many forms of welded joints, and the welding techniques in component fabrication and on-site installation are becoming more and more difficult. For example, the asymmetric and irregular ball joints of the National Aquatics Center “Water Cubeâ€; the multi-branch nodes of the space bending and torsion members of the National Stadium “Bird's Nestâ€; the tree-shaped cast steel joints of the Guangzhou Opera House; the weathering steel structure of the Guangzhou TV Tower and Super-large cast steel joints of Shenzhen Universiade.
As the height of the building increases and the span of the structure increases, the seismic performance design of the main steel structure increases with the seismic performance design. The joint weld of the frame beam and the column, the joint weld of the shear plate and the column, the joint weld of the beam web and the column, and the joint weld of the column are the main parts of the structure, and basically the groove is penetrated. First-grade welds, 100% ultrasonic flaw detection, have very high requirements on welding quality.
Second, promote the application of advanced welding technology with high efficiency, high quality, low cost and low emission
With the needs of economic development and the advancement of science and technology, the strength grades of various steel structural steels are getting higher and higher, and the size parameters are getting larger and larger. The steel structures such as “Bird's Nest†(National Stadium) and CCTV New Building adopt the strength level. The steel of Q420 and Q460 has a maximum thickness of 110 mm. Its production and installation continue to demand more efficient, more automated, and better quality welding technology. Such as submerged arc automatic welding (monofilament, double wire or multifilament) welding, CO2 gas shielded welding (solid wire or flux cored wire) welding, electroslag welding, gas electric vertical welding, stud welding, etc.; Inverter welding machine with energy saving, environmental protection and excellent welding quality.
The Welding Institute of China Metallurgical Group Construction Research Institute has long been committed to the research and development of steel structure welding technology. In the 1970s, it established the first welding in China in WISCO and the 20th Metallurgical Construction Company in China in the early 1980s. H-beam, light welded H-beam production line. Welded H-beam production line adopts steel plate leveling, multi-head precision cutting machine blanking, pneumatic assembly, submerged arc automatic welding or CO2 gas shielded welding automatic welding, flange edge straightening orthopedics, H-beam three-way precision cutting machine or circular sawing The advanced production process of the ruler, especially in the light-welded H-beam production line, developed the double-head CO2 gas shielded welding (solid wire or flux cored wire) automatic welding, developed and produced the double wire angle submerged arc automatic welding machine, greatly improved Production efficiency and product quality; in the construction and construction of super high-rise steel structures such as CITIC Building, CO2 gas shielded welding (solid wire or flux cored wire) automatic and semi-automatic welding machine and process have been developed, which greatly improves production efficiency and product quality. At present, China's major steel structure production enterprises, whether large state-owned enterprises or joint ventures or private enterprises, have been widely adopted as the basic general model of steel structure production. Of course, with the advancement of science and technology, the equipment and processes of various production processes have changed a lot: such as computer automatic nesting, double wire or multi-wire submerged arc automatic welding, double wire or multi-wire CO2 gas shielded welding. Improve welding production efficiency.
Before the installation of the site, the arc welding was mainly used, the production efficiency is low, and the technical level of the welder is also high. Since the 1980s, the semi-automatic welding of CO2 gas shielded welding (solid wire or flux cored wire) has been gradually promoted. It has basically become the main welding method for on-site installation of building steel structures, which greatly improves production efficiency and welding quality.
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