ã€Abstract】The closed section of the steel tower of Taizhou Changjiang Highway Bridge is on the curve transition section. It has a multi-directional connection relationship. It is difficult to control the size, flatness and connection accuracy of each interface. By adopting advanced and reasonable manufacturing technology, this book is ensured. Segment manufacturing accuracy. 1. Project Overview The steel tower of Taizhou Yangtze River Highway Bridge is another large-scale steel structure tower after the steel tower of the Third Yangtze River Highway Bridge in Nanjing. Its steel tower column has a herringbone structure in the longitudinal direction and a gantry frame structure in the horizontal direction. The tower column height is 191.5m. The structure of Taizhou steel tower is shown in Figure 1. The closed section of the steel tower is located at the transition of the curve and has four bolted joints. The lower oblique leg section of the section is a 1:4 straight section connected to the two straight sections of the lower tower column; the upper part of the section is on the curve of R=100m, which is connected with the curved section of the upper tower column; Beam joint, connected to the lower beam. The structure of the closed section is shown in Figure 2. The manufacturing of the closed section of the bridge has the following difficulties: 1 The structural form is complex, has a multi-directional connection interface, and is at the transition point between the straight line and the curve, and the assembly precision of the segment is difficult to control. 2 This section and the upper tower section require the metal contact rate of the end face, which is difficult to control the flatness and angle of the large end face. 3 This section has a special structure, and the traditional vertical pre-assembly has a high safety risk and the accuracy is not easy to control. 4 The design is made of thick plates and the welds are concentrated, which has a great influence on the accuracy of the bolt holes at the interface. In view of the difficulty in manufacturing the closed section of the bridge, it is difficult to achieve the design intent by using the traditional manufacturing process. Based on the successful experience of Nanjing Sanqiao Steel Tower, the assembly technology, end face machining technology, pre-assembly technology and hole making technology were optimized and improved to ensure the manufacturing precision requirements of the closing section. 2. Closed section assembly technology (1) Grading production is characterized by large size of the closed section and large welding deformation of the thick plate. The section adopts the step-by-step construction scheme of “plate→plate unit→block→section†to control the manufacturing precision and welding deformation of each stage in the stage. . Plate making: The shape and size of the curved plate are accurately staked by AutoCAD software. At the same time, according to the welding and processing requirements, the preset process is reserved, and the CNC precision cutting equipment is used to ensure the cutting precision of the plate curve. Plate unit production: The plate is subjected to roll rounding before assembly, and the assembled tire frame is designed according to the manufacturing line shape. When assembling, the curved plate is closely related to the tire frame to ensure the manufacturing of the linear shape; the stiffening rib is closely matched with the plate to ensure the welding quality and reduce the welding stress and deformation. Block production: The structures on both sides of the closed section are separately fabricated into blocks, which participate in the integral assembly of the segments, which is beneficial to structural deformation and size control. The two sides of the block are made of a special assembled tire frame as the outer tire, and the side transverse partition unit is the inner tube, and the "side wall plate unit → corner wall plate unit → corner side wall plate unit → side transverse partition unit → side web The order of the units is assembled. When the block is assembled, each plate unit shall control the vertical and horizontal position and elevation strictly according to the measurement standard to ensure the verticality of the cutting angle; according to the welding shrinkage rule, the welding shrinkage is added at the block mouth to avoid the negative bearing size after welding. An example of the assembled block on both sides is shown in Figure 3. 　 For more details, please refer to the attachment or the contents of Metalworking (Hot Processing) magazine.
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