High-frequency current is used to locally heat the metal surface and weld it under the action of external force. It does not use any welding wire or flux, and can be produced continuously in large quantities.
Advantages 1. High cross-sectional dimensional accuracy. Due to the use of high-quality steel coils, the shape accuracy of the cross-section after welding is excellent, making the structural assembly more convenient.
2. Excellent cross-sectional performance: The ratio of flange plate to web thickness can be increased. Compared with rolled steel, components with greater bending resistance and higher cross-sectional performance can be made under the same weight; when the cross-sectional performance is the same , the components are lighter.
3. The cross-sectional size can be customized according to user requirements. In case of large-scale use, it can be produced according to the cross-sectional size specified by the user.
4. The metallographic structure of the welding part is uniform, and the structures of the web material and the flange plate material are evenly fused.
1. Overview of the application of high-frequency welded H-shaped steel at home and abroad High-frequency welded H-shaped steel is a high-frequency welded thin-walled H-shaped steel with energy saving and sustainable recycling. It is an economical and widely used engineering building material for universities that conforms to the scientific outlook on development. Our company has introduced advanced production lines and production technologies from abroad. After a period of market development, it has been applied in industrial plants, public buildings, airport exhibition halls, steel structure residences, agricultural greenhouses and other fields. In recent years, high-frequency welded thin-walled H-shaped steel has been widely used in Japan, the United States and European countries, especially in building roof beams and battens, which account for a large proportion. Since the global production of hot-rolled steel sections has reached more than 20 million tons, which is mainly consumed on the columns and main beams of buildings, in order to reduce the amount of steel used, domestic and foreign projects urgently need a complementary building material. The uniqueness of high-frequency welded H-shaped steel The advantages emerged and market demand grew rapidly. According to statistics, the high-frequency welded thin-walled H-shaped steel produced in Japan is 200,000 tons per year, most of which are produced by Japan Zhuyou Metal. Most of them are used in civilian residences, with 1.5 to 2 million house buildings. 45% of industrial building roof bars in the United States, 60% in Europe, and 90% in Sweden use high-frequency welded H-shaped steel. At the same time, after entering China, more than 20 multinational companies such as Butler, ABC, USA, and BHP used a large number of high-frequency welded H-shaped steels as roofing bars, which served as a demonstration for the promotion and application of high-frequency welded thin-walled H-shaped steels at home and abroad.
2. The unique technological advantages of high-frequency welded H-shaped steel for roof purlins. The superior cross-sectional performance of high-frequency welded thin-walled H-shaped steel is due to technological advancement. Due to the use of high-frequency welding technology, the welding head directly supplies high-frequency current between the web and the flange for heating, and then welds the shape through the pressure welding roller. The power is concentrated on the weld part, and the heat impact generated by the welding is small, so it Welding is performed in a cold state. This avoids the problem of uneven thickness of the wings and webs, so the made steel flanges are smooth inside and outside, with high precision and beautiful appearance. In addition, high-frequency welding does not need to go through the pickling removal process, but it can still ensure that there are no impurities.
When the unit weight of high-frequency welded H-shaped steel is the same as that of traditional section steel, the specifications are economical, and its technical indicators such as section moment, section coefficient, pressure resistance, and load-bearing capacity are much higher than those of hot-rolled section steel. Moreover, special-shaped H-shaped steel can be easily produced (the upper and lower flanges are unequal width, and the upper and lower flanges are unequal thickness). Therefore, the cross-sectional form can be customized according to the cross-sectional size specified by the user, which facilitates design and selection and reduces waste. Due to its unique cross-section advantages, H-shaped steel is often used as roof purlins in industrial houses and civil buildings by design units.
High frequency welding H-shaped steel has economical specifications and can produce H-shaped steel with a web thickness of 2.3~8mm, a flange thickness of 3.2~10mm, a flange width of 50~250mm, and a web height of 70~500mm. The high-frequency welding thin-walled H-shaped steel production line can produce products of various specifications. The flange and web welding can be made of different steel grades. In particular, it can solve the production of thin specifications that are difficult to control in other welding, and can significantly save steel.
The production line of high-frequency welded H-shaped steel is easy to process, and the specifications can be changed quickly and conveniently. The production batch can be large or small at one time. Because of its light weight, it is easy to cut and weld. It can be processed, designed and combined at will, and can also be manufactured according to user requirements. Special dimensions to meet the needs of special projects.
Since the production process is less restricted by equipment conditions, the product specifications are many, light and thin, which allows many engineering components with complex steel structures and numerous specifications to be pre-processed in the factory and then assembled at the construction site, shortening the on-site construction cycle.
Compared with hot-rolled H-shaped steel and I-shaped steel, the construction cost of high-frequency welded H-shaped steel is lower, which is converted into the price of the same length. Since it can be supplied to a fixed length, the loss during use is significantly reduced; under the same load-bearing conditions, high-frequency welded H-shaped steel has a lower construction cost. The self-weight of H-shaped steel is much lighter than that of hot-rolled steel, which reduces the weight of the house structure, so the foundation cost of the building can be greatly reduced; under the same load-bearing conditions, the structural size is reasonable and can increase the indoor effective use area by more than 5%. Reduce space loss, thus reducing the overall cost by about 20% compared with conventional buildings. In addition, the reduction of the total weight also reduces the mechanical costs such as transportation and hoisting.
The characteristics of high-frequency welded thin-walled H-shaped steel can be summed up in two words: light and thin. The reason why it is light and thin is that it is heavier and thicker than hot-rolled H-shaped steel. Its characteristics are incomparable with those of hot-rolled steel and other types of steel. At the same time, they are also determined by its process characteristics. High-frequency 3d printing arc welding table legs of light H-shaped steel is a continuous welding of three longitudinally cut steel strips. It has strong continuous production capacity and can form a certain production scale. Especially it can solve the production of thin specifications whose shapes are difficult to control by other welding. The performance and quality of its welding parts are as follows:
1. Take the tissue deposition width as W and W/TW*100%*100% as the deposition rate to ensure it is greater than 100%;
2. The joint line between the web material and the flange material is undercut on one side of the flange plate material to confirm tissue fusion;
3. Perform a tensile test by applying force in the direction of the web of the welded part to confirm that the base material of the web is fractured and shows a fracture stress above the standard stress, that is, the base material is broken but the weld is continuous.
In recent years, the characteristics of high-frequency welded light H-shaped steel, such as lightness, thinness and easy processing, have been evident in the applications in industrial plants, warehouses, supermarkets, agricultural scaffolding, grain depots, three-dimensional parking garages, comprehensive buildings, and residential buildings. superiority. For example: it can shorten the construction period by 30-50%, increase the usable area by more than 5%, reduce wet work, reduce the comprehensive cost of construction by 20%, etc. Therefore, the national architectural design department recognized its advanced technology and significant benefits, and included it in the key promotion projects of scientific and technological achievements of the Ministry of Construction; it won the national key new product certificate. In 2001, the Ministry of Construction issued the China Construction Industry Certificate specifically for high-frequency H-shaped steel products. Industry Standard. (JG/T137—2001)
3. Analysis of the application of high-frequency welded H-shaped steel as purlins in construction projects
1. Demonstration on the design of high-frequency welded H-shaped steel for roof purlins in public buildings
Guangzhou International Convention and Exhibition Center, the framework of the roof enclosure system uses high-frequency welded thin-walled H-shaped steel as purlins. This project is located in South China, a region prone to typhoons, and the wind load is particularly heavy. According to the “Guangzhou International Convention and Exhibition Center Wind Dynamic Pressure Test Report” provided by the Guangdong Provincial Academy of Building Sciences, the maximum wind load can reach 5.45kn/m2. Such large wind pressure coupled with the large span of the lower main structure, up to 5m, is a big test for the design of roof purlins. At the same time, considering the appearance of the building, the total thickness of the roof enclosure system (the total thickness of the base plate, panel + decorative plate) is at least 285mm; therefore, the maximum allowable height of the purlin is 242mm. This purlin connection method not only effectively controls the total height of the purlins, but also allows the primary and secondary purlins to be connected to the roof panels at the same time. The roof panels and the primary and secondary purlins are connected to the roof panels at the same time, forming a tight connection between the roof panels and the primary and secondary purlins. The overall structure effectively solves the lateral stability problem of H-shaped steel secondary purlins and improves the wind load resistance of the roof enclosure system.
“Flower of the Century” – Hunan Helong Stadium is located in the center of Changsha. It is the main venue of the Fifth National Urban Games. The venue was designed by the Hunan Provincial Architectural Design Institute, and Zhejiang Jinggong Steel Structure Co., Ltd. is responsible for the main structure design. It is a shape A novel, modern and fully functional stadium.
When the designers of Zhejiang Jinggong Steel Structure received the design drawings from the Architectural Design Institute, what made it difficult for the designers was that the choice of roof purlins was particularly unsuitable. Most of the choices were C-shaped steel and I-beam steel, with large specifications and high steel content. High, the choice of C-shaped steel is also a non-standard material that requires customized processing. When the designer was recalculating, he found that there was a big misunderstanding in the design of the project, that is, no wind tunnel test was done. In order to ensure the safety and feasibility of the structure, the feasibility of the structure was repeatedly emphasized when bidding, and it was proposed to adopt Lightweight and high-strength high-frequency welded H-shaped steel is used as the main purlin, and the design institute and Tongji University were assisted in conducting wind tunnel tests to prove that the results obtained were relatively correct. Then according to the intention of the design institute, more than three types of software were reviewed, and 3D3S, STS, REA, American, German and other steel structure software were used to review against JG/T137-2001 product standards, and it was concluded that 300*150*4* 6. High-frequency welding of H-shaped steel as the main purlin is very scientific and reasonable, especially in terms of wind resistance and stability. It also saves materials and saves more than 100 tons of steel compared with the original use, saving the country money.
High-frequency welded H-shaped steel is used to make public building roof purlins. Its production and construction are very simple, because the manufacturer can make it fixed to a certain length, or it can be assembled and processed according to the user’s needs, and the connecting holes can be pre-punched. This This greatly facilitates the production and installation of construction units. During construction and installation, the commonly used C-shaped and Z-shaped steels are prone to distortion and instability during installation. However, high-frequency welding cnc machining 5m drum for centrifugal fanof H-shaped steel does not cause this phenomenon, and there is no need to use gusset plates to connect to the main steel frame. This will Greatly save production time and construction speed. For example, the steel roof purlins of the Shanghai Pudong International Airport Terminal and the newly completed main terminal of Guangzhou New Baiyun Airport and the roof purlins of the connecting buildings on the east and west sides are made of high-frequency welded H-shaped steel, which is beautiful and beautiful after completion.
2. Selection and construction of high-frequency welded H-shaped steel for industrial factory roof purlins
The main factory building of Zhejiang Jinggong Steel Structure Company has a span of 30m. Each span is equipped with a 25-ton, 10-ton, and 16-ton bridge crane. The crane lifting height is 9 meters, the cornice elevation is 14.5 meters, and there is a circular arc-shaped Capron gas tower in the middle of the span. The columns and roof trusses all use combined lattice columns and beams, and the purlins are all made of high-frequency welded H-shaped steel, with a total steel consumption of 3,050 tons. Engineering purlin design. According to the design of German experts, 114*120*5*8H steel and 60*40*3.2 rectangular tubes were used to make structural beams. The weight per meter was 35.5kg, and there were support systems at the top and bottom. The production was troublesome and the construction progress was slowed down. It cannot keep up, and the cost is high. During the design process, Jinggong Steel Structure first thought of I-beams, and there are still some bays of 15m in this project. If I-beams are chosen, No. 50 I-beams are required, and additional welding is required. The weight of angle steel per meter is 115kg, and the stability is not good; if you choose 300*150*6*8 angle steel, the weight per meter is 115kg, and the stability is not good; if you choose 300*150*6*8 High-frequency welded H-shaped steel meets the requirements in all aspects of strength, stability, stiffness, local stability, etc., and the weight per meter is reduced to 32.22KG. Then during the design process, in order to achieve energy saving effects, 350*175 was selected *3.2*4.5 High-frequency welded H-shaped steel is used as purlins. After reviewing and proofreading aspects such as strength, stiffness, overall stability and local stability, the steel content is suddenly reduced to 20.93kg per meter. In terms of purlins, it is The construction side saved more than 300 tons of materials. The German design experts gave a thumbs up and said “OK” repeatedly, and asked to bring back a copy of the information on high-frequency welding of H-shaped steel, praising the product for its good promotion value and use. value.
In the design of the small car light project of the Sino-Japanese joint venture, cold-formed thin-walled battens cannot be used due to a certain hanging load under the roof panel. However, if rolled H-shaped steel is used, the amount of steel will be slightly larger. After analysis and comparison, High-frequency welded H-shaped steel is used as the roof rafters, with a cross-section of H300*200*6*8 specifications and a spacing of 2.4M and 3M. After analysis and comparison, it was determined that only high-frequency welding of H-shaped steel was more economical and reasonable.
It can be seen that the steel consumption of high-frequency welded H-shaped steel according to conventional design is significantly less than that of rolled H-shaped steel. For example, the roof purlins of this project can save nearly 20 tons year-on-year when completed and put into production, and the use effect is good.
3. The advantages of high-frequency welded H-shaped steel as structural beams in residential buildings
Low and multi-story steel structure residential structures are mainly composed of columns and beams, while high-rise buildings are mainly composed of secondary beams. In the steel structure residential system, in terms of industrialization, the high-frequency welded H-shaped steel residential structure system has obvious advantages over systems composed of other building materials. Drawing on relevant successful experiences at home and abroad, in recent years many companies have built a number of low-rise, high-rise, high-rise, high-rise, high-frequency welded H-shaped steel as the frame structure systems in Guangdong, Shenzhen, Xinjiang, Zhejiang, Tianjin, Dalian, Wuhan, Shanghai and other places. There are more than 200 multi-story residential buildings. For example, the frame beams of the first steel structure high-rise residential building in Shanghai are all made of high-frequency welded H-shaped steel. Its width and thickness can be changed arbitrarily according to the design requirements. The thickness of the web can be made larger than the rolled H-shaped steel under the condition of satisfying local stability. The section steel is thin, which means that under the premise of the same amount of steel, the cross-sectional moment of inertia is 20~30% higher than that of rolled H-shaped steel. This is equivalent to saving 20~30% for frame beams that mainly bear bending moments. % of steel usage. In order to unify the components and nodes of the Zhongfucheng residential project, all steel beams adopt unified specifications, with a cross-section of H320*150*5*8. This standardizes the beam nodes of the entire project and facilitates construction and installation.
High-frequency welded H-shaped steel has the characteristics of wide limbs and thin web members. The beam-column component is one of the basic materials of the light steel residential frame structure system. The beams and columns of the main stress-bearing components are made of high-frequency welded H-shaped steel. The structural system can fully The high-frequency welded H-shaped steel’s lateral resistance in the strong axis direction is used to form a steel frame in the strong axis direction; in the weak axis direction, steel supports are used to resist lateral forces to form a supported hinged frame. The steel structure residential project organized and implemented by the Ministry of Construction includes two 5-story steel structure residential buildings. The steel beams in the residential part are all made of high-frequency welded H-shaped steel. As mentioned above, the cross-sectional dimensions can be customized according to user requirements, which makes the residential part Steel beams use about 25% less steel than rolled H-shaped steel. Since the steel beams and steel columns in the residential part of this project all use hinged nodes, the steel beam design is all calculated using H steel composite beam sections. The cast-in-place concrete floor slab is under pressure, which can save 15% of the steel consumption of the steel beams and also reduce the cost of steel beams. The height of the steel beam is increased to increase the use space.
High-frequency welded lightweight H-shaped steel has load-bearing advantages. Reasonable use of high-frequency welded H-shaped steel in steel structure residences and low- and multi-story residences can give full play to its advantages and achieve the purpose of saving steel and reducing construction costs during work.
The span space of the steel structure residential communities in Dongguan and Songjiang, Guangdong Province increases the effective indoor use area by 5% compared with the corresponding brick concrete. The amount of steel used for the same component when using hot-rolled H-shaped steel is greater than when using high-frequency welded lightweight H-shaped steel, and the weight ratio is the largest at 1.68.