6 Application and development of prestressing technology in steel structure and space structure Yang Zongfang and space structure building, some of which are quite modern. After 1990, with the need for the construction of large-span public buildings, the combination of prestressed technology and spatial steel structures created a variety of new structural systems. Prestressing technology has also been developed and innovated in the above structure. The application of China's prestressing technology in steel structure was started in the late 1950s. In 1959, the coal transportation trestle 53, 1 steel truss of the Taiyuan Steel Plant Coking Plant first applied prestressing to the corridor outside the cable. Since then, China has promoted coagulation in construction projects; the structure is the main, and the application of the steel structure is stagnant. China's reform and opening up in the 1980s, the output of steel products increased, and the application of modern prestressed technology equipment and processes in concrete structures has matured, which has promoted the development of prestressed steel structures. However, during this period, the traditional flat steel structure beam arch and trestle bridge were still the mainstay. After the 1990s, with the need for the construction of large-span public buildings in China, the prestressed technology and the spatial steel structure have found a combination point, which has developed rapidly and created a variety of new spatial steel structure prestressed grids and reticulated cable nets The cable-arch cable-stayed system, etc., gives full play to the strength potential of the tension members, the structure is light, and the sense of the times is strong. In recent years, Yang Zongfang, a prestressed cable truss, was born in December 29. He was born in Huangyan, Zhejiang, and is a dragon in engineering at Shangmu University of Southeast University. professor. The Bian Erzheng Stress Center Deputy Director 210018 Nanjing received the first issue of 30, and also began to use the steel support system for the glass curtain wall. The most advanced cable-membrane structure in the world today has also started in China. This structural system has a very light weight and is easy to install. It has good development prospects in projects such as exhibition buildings, sports buildings, traffic buildings, and open-air theaters. I engineering application examples In the past ten or eight years, China has already completed the construction of prestressed steel structures and prestressed space structures as follows. In 1984. Tianbian Ninghe Sports Pavilion roof 42 1 father 421 flat grid frame, the use of bearing displacement method to introduce prestress. In 1986, the roof plane of Jilin Ice Skating Museum was 76.8, 67.4, and the meter used a prestressed double-layer suspension cable system. The load-bearing cable and the stabilizing cable are staggered by half a column distance, the shape is novel, and the drainage problem of the rectangular suspended cable roof is well solved. The amount of steel used is 35.8. In 1987, the Provincial Stadium looked like a butterfly with wings spread. The entire roof 21861. It is composed of a symmetrical cable net on both sides and a reinforced concrete floor arch in the middle. The cable net is prestressed twice. In 1989, the roof size of the gymnasium in Anhui Province was 87 long! The width 5169 adopts the steel truss of the cable truss structure system to press on the suspension cable. The lateral prestress is applied to the suspension cable, which plays the role of the suspension cable supporting the truss truss to stabilize the suspension cable. In 1989, the roof of Beijing Chaoyang Stadium was olive-shaped, and the size was 96166 cents. It adopted a cable net system on both sides of the central cable arch, and the cable net was prestressed in stages. In 1991, the roof size of the Beijing North Suburb Gymnasium used a tower cable stay and a double-layer steel mesh shell system. The stay cable is outsourced and the tube is filled with grout. In 1993, the warehouse roof of the Singapore Port Authority was designed by our country. The plane size is 310, and 192 is composed of 6 cable-stayed grids. There is a tower column in the center of each grid, and 4 sets of stainless steel rods are diagonally pulled. The overall structure of the ship supporting the sailing voyage is from 1994. The roof of the Panzhihua Gymnasium has a rectangular shape with a diagonal length of 64.9. It uses a point-supported prestressed double-layer steel mesh shell. Lay the cables along the side members and apply pre-stresses. The amount of steel used is 358, 2. In 1995, the large-span heavy-load beam of the gate building of Beijing West Railway Station adopted 451 prestressed steel truss. A linear beam is arranged in the middle of the lower chord, a linear beam is arranged on the side of the chord, and a broken beam is arranged on the upper and lower chords. Applied in two stages in 1996, the roof of the gymnasium of the Nanjing Institute of Physical Education was elliptical, with a size of 86, 62. It used 2 exposed space truss to support the flat grid. The two cantilever ends of the space truss are fixed downwards at the foot of the column using prestressed diagonal cables. The roof of the building is shaped like a seagull fluttering and flying. The string beams supported by inclined steel columns have a span of 8048. The upper string of the 52 string beams is a square tube, and the lower string is a steel cable. The two columns of steel columns in the boarding gallery of this project are inclined outwards, and space stay cables are needed to ensure the overall stability of the roof system in the vertical and horizontal directions. In 1998, the span of Guangzhou Baiyun Airport Hangar 51 was adopted with a prestressed steel arch structure. After the whole structure was assembled on site, the steel strands in the retractable lower chord steel pipe were used to apply prestress to make the entire roof structure arch. , Without the need for lifting equipment, the construction speed is fast and the cost is low. The supporting system of the curtain wall adopts the prestressed cable truss for the first time. The cable is made of stainless steel stranded wire, which is light in structure and transparent, which reflects the overall beauty. In 1998, the Shenzhen Happy Valley Center Theater was round and used a cable-membrane dome structure. The inner edge of the membrane body is attached to the central ring, and the outer edge of the membrane body is connected to the steel arch beam. The steel columns are arranged along the circumference of the inner side of the steel arch beam, and the entire cable dome is supported by diagonal slings. A jack is used to lift the steel column at the foot of the column to apply prestress to the entire system. In 1999, the canopy cantilever 60 of Haihongkou football stadium stands was adopted as a membrane structure system supported by saddle-shaped space steel tube cable truss. In 1999, the roof frame of Xi'an International Exhibition Center, the stay cable was fixed on the reinforced concrete tower, prestressed twice. In 1999, the plane size of Anshan Gymnasium was 1281861. The roof structure adopts a cable-skewered double-layer grid system, which is more reasonable than the cable-stayed grid structure, and saves anchor 50. It is convenient for construction. In 1999, the main stadium of Hangzhou Huanglong Sports Center was round, and the canopy roof structure with a diameter of 247.75 adopted a cable-stayed net shell system. The inner ring beam is suspended by a stay cable, and the upper end of the stay cable is anchored to the 85,1 high prestressed concrete tower tube at both ends of the stadium. In 20 years, the wiper cover structure of the exhibition hall of the Changchun International Convention and Exhibition Center adopted a diagonal cable system 631. Both ends of the diagonal cable are hinged, and the upper end is fixed on a steel mast, prestressed in batches. In 20 years, the main stadium of the Guangzhou New Stadium was oval, with a size of 60, sunken, and its roof was composed of the main truss 1600 radial split frame ring beam cable support. The cable is divided into a ring-shaped plane cable, a radial plane cable and a vertical cable. The pulling force is 25. The pitch of the roof of the stadium is 76.6. The main cable is used to hang the arch to the top of the inclined column. The cable is pulled from the top of the inclined column to the upper chord between the horizontal cable arch and the lower chord of the lower arch. In 2000, the roof of the Qingdao Yizhong Stadium was suspended. Picks 37 and 15 use steel truss ring beam cable membrane unit system. Each cable-membrane unit is composed of an inner ring cable valley cable ridge cable upright cable and a membrane body. Ten thousand seats. The steel canopy of the Zhoutai stand is supported by 21 sets of independent tower columns, and the forward stand cantilever 54 1; the cantilever 8, and the cable is fixed at the foot of the column with 1 force. In 2001, the 4 exhibition halls and entrance halls of the Shanghai New International Expo Center, with a total area of ​​90,200. The size of each exhibition hall is 72192 cents. It adopts a spindle-shaped steel truss. The supports are hinged up and down, and the roof is a membrane structure. The anti-lateral force support between the columns is made of 076 steel rods, which are hinged at both ends. The tension is 9 and a specially developed cylinder hydraulic jack is used to solve the tension problem. The surface size of the light canopy is 54 to 30. It adopts prestressed cable-net structure system and point-supported glass roof. The upper and lower chords of the cable net structure are made of 9 aluminum-clad steel strands, and 60801 prestress is applied; the vertical rod is a stainless steel tube, and the diagonal web is a stainless steel rod with a pretension. In 2001, the stands on both sides of the stadium of Zhejiang Yiwu Sports Exhibition Center The canopy cantilever 5 adopts two symmetrically arranged space tensile membrane structure systems. The system is composed of steel truss steel mast valley cable side cable sling cable and membrane material. In 2001, the plane of Qinhuangdao Gymnasium was elliptical, with a size of 2,98. The entire shape is like a Kunpeng with wings spread. The wings are made of steel truss system, and the middle part is made of 961 three-dimensional lattice arch and Somo. Stretch film structure system. The membrane structure adopts double-layer membrane material, and adopts the inner and outer membrane simultaneous lifting method to apply prestress. 2 Development of prestressing technology 2.1 Tibetan and prestressing methods In steel structures and space structures, there are various methods of applying prestressing, such as tension, pressure and jacking. Among them, the use of hydraulic jacks, manual hoist chains, and other tensile prestressed tendons and cables is the most commonly used type. In a structural tensile structure and a special construction structure, the overall pressure or overall jacking method is used for tension. It is a novel construction method with the advantages of simple, economical and reliable. Anhui Stadium, Shanghai Yangpu Stadium, Chaozhou Stadium and other cable truss roofs use steel truss 1 to press on the suspension cable to apply lateral prestress to the suspension cable. The specific method is to use the pre-embedded screw rod at the top of the side column, and simultaneously press down the support of each truss end by tightening the nut. The canopy of the stand of Yiwu Stadium uses the valley cable to press down to make the membrane pre-stressed. The cable dome of Shenzhen Happy Valley Center Theater uses a jacking steel pestle at the foot of the column. Prestress the entire system. 2.2 The pre-stressed cable layout method The prestressed cable layout principle is to make the structure produce the most unloading rods and the least load-increasing rods under the premise of satisfying the function of the building, so as to maximize the bearing capacity of high-strength steel cables Save steel and reduce costs. The way of city rope can be divided into the structure of the inner rope, which refers to the height of the structure and the outer rope of the structure. In recent years, external cables have developed rapidly, and diagonal cables, slings, anti-wind cables, etc. are all external cables. The stiffness of the tension structure of the flexible space structure is provided by the prestress. The arrangement of the cable system and the corresponding prestress value should meet the requirements of the structural geometry. 2.3 Tensile force of prestressed cable The tensile force of prestressed cable should be based on the characteristics of structural system. Get the size requirements. The cable arrangement is determined. The tensile stress of the steel cable arranged in the body can be taken as 0.60.7; for a pair of external cable chord cables, etc., the tensile stress can be taken as 0.20.4.1 ≠for the cable truss, the steel cable can only bear the axial tensile force. Under the most unfavorable load, no pressure is allowed in the cable element. Generally, the retained tensile force value is set to ensure the normal operation of the cable truss. For flexible space structures, the prestress value of the steel cable should first meet the spatial shape requirements of the structure. When internal force analysis is carried out on this basis, the tension of the cable must not be less than zero and the displacement of the key point should be smaller than the maximum limit of 1 Multiple pre-stresses developed in each year, each additional pre-load is applied with a second pre-stress. In this way, the internal force caused by the load acting on the basic structure can be transferred to the steel cable to the maximum extent, and the maximum economic effect can be obtained. 2.4 Development of prestressed cables Prestressed cables mainly use high-strength steel wire bundles and some adopt round steel bars. = 61 claw cable anchors for steel wire bundles, upset head anchors, cold cast anchors, etc. can be used; for steel strands, clip anchors, cold pressed screw anchors, extrusion anchors, etc. can be used. For the cable with pinned lugs at both ends, the anchors at both ends should be provided with lugs or another cable head with lugs should be screwed on the anchors. In order to facilitate the shortening of the length of the cable after tension, the application of the prestressed concrete-filled steel tube structure at the cable end is studied. Zhuang Zhou Wu Jianhua Xie Xingxing's features and prestressing technology, especially suitable for large-span and heavy-load harsh environments and complex body structures System. In-depth study of it will help to promote the development of building structures towards large-span and large-space heavy and dynamic loads, and it can simplify construction and reduce construction costs. 378 Literature ID Code 8 Article Code Adjusting screw is installed between the anchor and the cable head. The anti-corrosion measures for prestressed cables include galvanized or epoxy prestressed ribs; grease-free or paraffin-extruded plastic sheathed unbonded ribs; cement in pipes, and a multi-layer anti-corrosion method that integrates the above measures. In the 1990s, the steel twisted cable system developed by Chinese manufacturers was made of galvanized steel wire cold-cast anchor black high-density polyethylene inner jacket and color high-density polyethylene outer jacket. Recently, the steel cable group anchor cable system newly developed by Chinese manufacturers adopts galvanized steel cable coated with anti-corrosion grease and high-density polyethylene sheath, plus bundle protection, casing and other protective measures; low stress Cable group anchors in the state. The steel strands of this system can be single-stranded and single-stretched. Finally, the overall short-distance tensioning is performed, which is convenient for construction. 2.5 Development of prestressed tensioning equipment The prestressed cable can adopt conventional single tensioning jacks or group anchor jacks according to the extension of the end support structure. For the case where the two ends of the prestressed cable are installed on the hinge pin of the supporting structure, if the tensile force is not greater than 501, manual hoist tension can be used. Use the adjusting screw to shorten the length of the cable; if the tension is too low, a special tensioning device should be made. For example, the pull force of the cable stayed in Shanghai Pudong Airport is 2003, and 2 sets of ordinary jacks are used for the tension device; the pull force of the lateral resistance tie rod of Shanghai New International Expo Center is 9 (kN), which is specially developed for this purpose; 4 cylinder jack. 3 Conclusion The prestressed technology is used for steel structures and space structures. It can make full use of the material's strength potential and improve the structural stress state. Improve structural rigidity and save steel. Reduce cost. At the same time, it enables architects to give full play to their imagination. Design a more beautiful structural shape. With the increase of China's steel output and varieties, the development prospects of this new structure in the 21st century are very broad. In order to promote the development of prestressed steel structures and space structures, continuous improvement and innovation are needed in construction. For example, improving the existing cable structure to facilitate commercial production; developing special tensioning equipment for cable rods to make it light and practical; discussing the optimization of multiple prestress and applied prestress values, and developing new prestressed construction methods, etc. For the large span of our country, build the entry, Yi first ranks. Contribute to the construction of sports venues for the Beijing Olympic Games in 1988. At present, the concrete-filled steel tube structure is used in industrial and civil multi-layer and high-rise building overpasses and special structural projects, and has received good results. However, because its main characteristics are high compressive bearing capacity and good plasticity, it can only be used as a column, including a detachable column and a multi-lattice structure. It is not suitable for bending members, so its use is limited. . Even if it is used as a column, when its slenderness ratio exceeds 90, elastic fire stability will occur, and the characteristics of steel pipe coagulation 1 do not exist. How to expand its scope of application is a worthy study. Combining the advantages of concrete-filled steel tubes with prestressed technology to form prestressed concrete-filled concrete-filled steel tube composite members or structures can greatly expand its scope of application. For example, prestressed concrete-filled steel tube beams can be used in bending members; prestressed braces It can be applied to large-span structures in space. 1 Features of prestressed concrete-filled steel tube structure The prestressed concrete-filled steel tube structure has a steel tube boat. Born in July 2014. Associate Professor, Doctor of Engineering, Department of Civil Engineering, Zhejiang University, Fenghua, Zhejiang, 310027. The advantages of the 399060 concrete structure funded by the Hangzhou National Natural Science Foundation have the following characteristics. The partial load is transmitted through the prestress technology, thereby reducing the internal force of the structure; Pre-stress the rods, share part of the internal force, and replace the ordinary steel with high-strength steel; apply overall pre-stress to the truss grid and other structures to adjust the internal force of the structure, combined with the support displacement and reaction force adjustment, reduce the peak value of the internal force and make the structure suffer The force is more reasonable and optimized; increase the structural rigidity and natural frequency, reduce the structural deformation and dynamic impact, increase the structural span, and increase the structural bearing capacity. According to preliminary estimates, the use of prestressed grids is comparable to ordinary grids in steel villages, and the cost of section 1 is 15. The use of pre-formed concrete-filled steel tube space truss saves 6070 steel than ordinary steel roof truss and steel from grids According to the research literature, the concrete-filled steel tube structure and the prestressing technology are organically combined, which is generally used only as a construction column and a pressure arch of a bridge. It is a large or medium-sized structure or component, and has not been applied to air Cotton Fleece,Cotton Voile,E-Liquid Cotton,Pure Cotton QD Cloudy Inernational Pre Ltd , https://www.qdcloudy.com