Manufacturing process of special-shaped hyperbolic steel box girder

Abstract

The invention provides a special-shaped hyperbolic steel box girder manufacturing process which comprises the steps that a steel box girder is assembled according to a reverse construction sequence, the reverse construction sequence refers to reverse construction from inside to outside and from bottom to top, firstly, a top plate is fixed to a jig frame, a transverse partition plate is assembled with the top plate as a datum plane, and then a web and a wing plate are assembled with the transverse partition plate as a positioning reference; and finally, the bottom plate is assembled. The manufacturing precision of the steel box girder can be better controlled, and the accuracy of the overall line shape and size of the appearance of the steel box girder is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of steel structure manufacturing technology, and more specifically to a process for manufacturing irregular hyperbolic steel box girders. Background Technology

[0002] Due to their unique shape and excellent mechanical properties, irregularly shaped hyperbolic steel box girders are increasingly being used in the construction of various types of bridges, such as urban landscape bridges and cross-sea bridges.

[0003] When traditional assembly methods are applied to the assembly of bottom-shaped hyperbolic steel box girders, significant core drawbacks include: 1. The deformation of the irregular hyperbolic steel box girder during the assembly process cannot be effectively controlled, making it difficult to guarantee the overall alignment accuracy; 2. The assembly efficiency is low, and the workload of manual adjustment and repeated measurement is large; 3. It cannot meet the high-precision assembly requirements of complex curved surface structures, and the construction quality and safety cannot be guaranteed. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a manufacturing process for irregularly shaped hyperbolic steel box girders, aiming to better control the manufacturing precision of steel box girders and ensure the accuracy of the overall shape and dimensions of the steel box girders.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A manufacturing process for irregularly shaped hyperbolic steel box girders, characterized by: The steel box girder is assembled in reverse order, which means that the construction is carried out in reverse order from the inside to the outside and from the bottom to the top. First, the top plate is fixed on the formwork, and the transverse diaphragms are assembled using the top plate as the reference surface. Then, the web plate and wing plate are assembled using the transverse diaphragms as positioning references. Finally, the bottom plate is assembled.

[0006] The fabrication process for this irregular hyperbolic steel box girder is carried out according to the following steps: Step 1: Erect the frame Using 16a I-beams as the main material, a jig was built according to the horizontal curve and pre-arch curve of the steel box girder. At the slope change position, the I-beams were finely adjusted using an adjustable screw mechanism. After the jig was built, the dimensions and alignment of the jig were measured multiple times using a total station and a level to ensure the accuracy of the jig dimensions. Step 2: Positioning and assembling the top plate unit First, position the middle reference top plate unit on the jig, and then position the top plate units on both sides. The longitudinal and transverse positioning baselines of the top slab should be aligned with the corresponding lines on the ground sample line; The top plate is fixed by a rigid connection with the formwork template; two top plate units are fixed by a connecting plate. Step 3: Positioning and assembling the diaphragm unit Using the top plate as a reference plane, locate the position of the transverse diaphragm on the top plate. The positioning of the transverse diaphragm should ensure that the plumb line is plumb. Step 4: Positioning and assembling the single-sided web plate unit The web is located based on the web edge line on the top plate unit; Lift the web plate with a lifting tool and assemble it with the top plate for positioning welding; during assembly, web plate assembly clamps can be used. According to the technical design standard that the upward arch value between the two support points should meet, after shims are used to support the web plate from the middle to both sides, weld the inner wall weld of the Ώ-shaped beam. When welding, first weld the weld between the web plate and the transverse diaphragm and the longitudinal stiffener, and then weld the weld between the top plate and the transverse diaphragm and the longitudinal stiffener. Step 5: Positioning and assembling the base plate unit Place the base plate on the platform, draw the inner lines of the two web plates, and then level it; The longitudinal and transverse positioning center lines of the base plate should be aligned with the corresponding lines on the ground sample line to determine the position of the base plate; Hang the base plate on the Ώ-shaped beam according to the marked position; Assemble and position the base plate from one end to the other, using tools to ensure that the base plate is tightly attached to the web and diaphragms, with a gap of no more than 1mm between the base plate and the web and diaphragms, to ensure the straightness of the overall line.

[0007] Furthermore: The tools used in step 5 include a pressure bar, a rail lifter, and a jack.

[0008] Compared with existing technologies, this invention features a unique reverse-order assembly of steel box girders. Because the construction proceeds from the inside out and from bottom to top in reverse order, it allows construction workers to operate on a relatively stable and safe working platform, greatly reducing labor intensity and safety risks. It also makes welding work more convenient, better ensuring the quality of full penetration welding and reducing welding defects. The beneficial effects are as follows: 1. Reduced work intensity and safety risks: The reverse construction method changes the traditional high-altitude and complex angle operation mode. Construction workers can operate at a lower height and on a relatively stable working platform, reducing the time spent climbing and working in confined spaces at high altitudes, effectively reducing work intensity, and also reducing the safety risks caused by high-altitude operations, thus improving the safety of the construction process. 2. Ensure welding quality: With optimized assembly sequence and ample operating space, welders can more easily weld each weld of the steel box girder. Especially for full penetration welds, welding parameters can be better controlled to ensure the penetration depth and welding quality of the weld, reduce the occurrence of welding defects such as porosity, slag inclusion, and lack of fusion, thereby improving the overall structural strength and durability of the steel box girder. 3. Improve production efficiency: The reverse engineering method makes the manufacturing process more compact and reasonable, and the connection between each process is smoother. It reduces the number of delays and rework caused by the difficulty of construction. At the same time, real-time monitoring of multiple monitoring and measurement points can detect and solve problems in time, avoiding the impact of problems on the construction period. Compared with the traditional assembly method, it can significantly shorten the manufacturing cycle, improve production efficiency, and meet the needs of rapid construction of projects. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the adjustable screw mechanism; Figure 2 This is a schematic diagram showing the positional relationship between the top plate and the main structure of the frame; Figure 3 This is a flowchart of the relevant processes for irregular hyperbolic steel box girders.

[0010] In the diagram, 1 is the top plate; 2 is the crossbeam; 3 is the longitudinal beam; 4 is the adjustable screw mechanism; 41 is the support column; 42 is the rib plate; 43 is the screw sleeve; 44 is the screw; and 45 is the limit sleeve. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0012] Please refer to Figures 1 to 2 The fabrication process of the irregular hyperbolic steel box girder in this embodiment is as follows: The steel box girder is assembled in reverse order, which means that the construction is carried out in reverse order from the inside to the outside and from the bottom to the top. First, the top plate is fixed on the formwork, and the transverse diaphragms are assembled using the top plate as the reference surface. Then, the web plate and wing plate are assembled using the transverse diaphragms as positioning references. Finally, the bottom plate is assembled.

[0013] The fabrication process for this irregular hyperbolic steel box girder is carried out according to the following steps: Step 1: Erect the frame Using 16a I-beams as the main material, a jig was built according to the horizontal curve and pre-arch curve of the steel box girder. At the slope change position, the I-beams were finely adjusted using an adjustable screw mechanism. After the jig was built, the dimensions and alignment of the jig were measured multiple times using a total station and a level to ensure the accuracy of the jig dimensions. Since the jig serves as a reference surface, its shape and dimensions directly affect the overall shape and dimensions of the steel box girder assembly in the later stages. Therefore, the jig should have high rigidity. Thus, 16a I-beams were selected as the main material of the jig to prevent deformation of the jig after bearing load. After the top plate is hoisted onto the long platform of the jig, mark the positioning lines of the transverse diaphragms and reinforcing ribs, as well as the inner lines of the left, middle and right webs, according to the spacing of the stiffeners plus 1 / 1000 of the welding shrinkage. The long platform must be sturdy and leveled. Step 2: Positioning and assembling the top plate unit First, position the middle reference top plate unit on the jig, and then position the top plate units on both sides. The longitudinal and transverse positioning baselines of the top slab should be aligned with the corresponding lines on the ground sample line; The top plate is fixed by rigid connection with the formwork, which reduces the shrinkage of the top plate panel due to welding stress during subsequent welding. This reduces the shrinkage of the top plate panel after welding, thereby reducing the deformation of the top plate panel after welding and reducing the workload of later straightening of the steel box girder. The two top plate units are not welded together, but are fixed by connecting them with a support plate. The top plate splicing adopts single-sided welding with bevel. When using submerged arc welding, the blunt edge should be 1-2mm. The allowable error of the top plate width is ±2.0mm. Before positioning, all joints within 100mm of each other should be cleaned of rust and paint and polished. Any irregular bevels should be corrected at the same time. Check whether the forming dimensions of the single plate meet the design requirements. Step 3: Positioning and assembling the diaphragm unit Using the top plate as a reference plane, locate the position of the transverse diaphragm on the top plate. The positioning of the transverse diaphragm should ensure that the plumb line is drawn. The installation of components such as diaphragms can enhance the internal structural stability of the steel box girder. Step 4: Positioning and assembling the single-sided web plate unit The web is located based on the web edge line on the top plate unit; Lift the web plate with a lifting tool and assemble it with the top plate for positioning welding; during assembly, web plate assembly clamps can be used. According to the technical design standard that the upward arch value between the two support points should meet, after shims are used to support the web plate from the middle to both sides, weld the inner wall weld of the Ώ-shaped beam. When welding, first weld the weld between the web plate and the transverse diaphragm and the longitudinal stiffener, and then weld the weld between the top plate and the transverse diaphragm and the longitudinal stiffener. During the assembly process, a high-precision total station is used to monitor the measurement points of key parts of the steel box girder in real time. After obtaining the three-dimensional coordinate data, it is compared with the preset theoretical coordinate values ​​to detect deviations in the assembly process in a timely manner. Key parts include the connection between the web and the flange, the turning points of the curve, and the interfaces of each segment. This comprehensive and real-time monitoring method can effectively ensure the accuracy of the steel box girder during the assembly process and avoid problems such as overall structural deformation caused by the accumulation of deviations. Step 5: Positioning and assembling the base plate unit Place the base plate on the platform, mark the inner lines of the two webs, and then level it; the reinforcing ribs and longitudinal stiffeners of the base plate should be pre-welded. The longitudinal and transverse positioning center lines of the base plate should be aligned with the corresponding lines on the ground sample line to determine the position of the base plate; Hang the base plate on the Ώ-shaped beam according to the marked position; Assemble and position the base plate from one end to the other, using tools to ensure that the base plate is tightly attached to the web and diaphragms, with a gap of no more than 1mm between the base plate and the web and diaphragms, to ensure the straightness of the overall shape; gas shielded welding is used for positioning welding. After the base plate and the Π-shaped beam are assembled and positioned by welding, the spiral tensioner, counterweight and jack are removed. The camber, lateral deviation, torsion value and the inclination value of the top plate of the steel box girder are checked to ensure that they meet the technical requirements.

[0014] In step 5, the tools used include a pressure bar, a rail lifter, and a jack.

[0015] In step 1: The main structure of the frame includes multiple rows of longitudinal beams laid along the length of the top plate, multiple crossbeams supported at the lower ends of the longitudinal beams and laid along the width of the top plate, and multiple sets of adjustable screw mechanisms configured for each row of longitudinal beams. Both the longitudinal and crossbeams are made of 16a I-beams. At slope changes, the height of each row of longitudinal beams can be finely adjusted using the adjustable screw mechanisms. After adjustment, the lower flange of the longitudinal beams and the upper flange of the crossbeams are spot-welded together. The top plate is supported by the integral surface formed by the top surfaces of the upper flanges of each row of longitudinal beams. The adjustable screw mechanisms are welded and fixed to the pre-embedded steel plates or channel steel in the ground. The adjustable screw mechanism includes a support column, a screw sleeve, a screw rod, and a limiting sleeve. The support column has ribs and is welded to a pre-embedded steel plate or channel steel in the ground at its base. It has a screw sleeve with internal threads at its top. The screw rod has external threads, and its lower part is threaded into the screw sleeve. The top of the rod has a screw hole, and its top abuts against the lower flange of the longitudinal beam to support it. The limiting sleeve is a flared sleeve, wider at the top and narrower at the bottom, with internal threads that rotate in the opposite direction to the external threads of the screw rod. For fine-tuning the height of the longitudinal beam, the adjustment method can be found as follows: A reinforcing bar or similar material can be threaded through the screw hole at the top of the screw rod. By applying force with the reinforcing bar, the screw rod can be rotated. The threaded engagement between the screw rod and the threaded sleeve allows the screw rod to rise or fall until the top of the screw rod reaches the set height position of the lower flange of the longitudinal beam. Then, an upper limit sleeve is fitted onto the screw rod, so that the lower end of the upper limit sleeve is pressed against the top of the threaded sleeve. The upper limit sleeve locks the current height position of the screw rod, preventing it from falling during assembly. After that, the longitudinal beam is placed on top of the screw rod, and then the longitudinal beam is spot welded to the cross beam below.

[0016] When welding the diaphragm, web, and top plate assembly unit in sequence, the following should be noted: The steel box girder is laid flat and supported. Carbon dioxide gas shielded welding is used. In principle, the weld between the top plate and the web is welded first, followed by the weld between the bottom plate and the web. The root cleaning method is to use single-sided bevel welding and reverse gas gouging. It is important to take measures to prevent welding deformation. After welding, the weld is inspected by ultrasonic testing according to the design requirements, and a visual inspection is performed for acceptance. When welds intersect, special attention should be paid to cleaning and grinding the weld root at the joint. Thoroughly clean slag and remove defects such as porosity between each layer. The grinding length of the weld joint should not be less than 50mm to ensure a smooth and good joint. The outer surface of the weld must be smooth and full, with a reinforcement height of 0-3mm. The surface must be ground smooth and free of bumps or depressions. When performing carbon dioxide gas shielded welding, a protective cover and preheater must be used to improve external conditions and prevent porosity. Short-circuit transition is not allowed. Draw cutting lines according to the allowance cutting diagram, cut the allowance and make bevels, and the welding current shall not be less than 180A.

[0017] After the diaphragm, web, and top plate assembly units are welded together, the lifting lugs and temporary matching connectors are installed and welded.

[0018] For reference Figure 3 The following is the manufacturing process of the board unit: I. Top and bottom plate units The top and bottom plate units, composed of steel plates and U-shaped ribs, are the basic components of the steel box girder. The top plate unit, in particular, directly bears the repeated wheel loads, making its fabrication quality especially critical. The assembly accuracy and welding quality of the top plate unit are important factors affecting fatigue performance. Its fabrication process is as follows: Top plate: Steel plate pretreatment → precision cutting → straightening → marking the longitudinal and transverse baselines of the plate unit and the position lines of the U-shaped ribs → assembling the U-shaped ribs without code positioning → placing the unit on the hydraulic anti-deformation sub-ship-shaped welding oscillating machine for welding → using cold straightening and flame straightening methods to correct the welding warping deformation of the plate unit, focusing on correcting the wave deformation of the edges to meet the flatness requirements → participating in subsequent assembly; Base plate: steel plate pretreatment → precision cutting → straightening → marking the longitudinal and transverse baselines of the plate unit and the position lines of the plate ribs → positioning and assembling the plate ribs without code → placing the unit on the hydraulic anti-deformation sub-ship shape welding oscillating machine for welding → using cold straightening and flame straightening methods to correct the welding warping deformation of the plate unit, focusing on correcting the wavy deformation of the edges to meet the flatness requirements → participating in subsequent assembly.

[0019] II. Web Unit The web unit consists of web plates and longitudinal ribs. The web unit and the top and bottom plate units are joined by full penetration welding. A single-sided welding and double-sided forming process with a ceramic backing is proposed to avoid the adverse effects of carbon penetration and deformation caused by carbon arc gouging. The manufacturing process includes: Steel plate pretreatment → precision cutting and blanking → straightening → marking → assembling stiffening plates → welding → repairing welding deformation → marking and machining of surrounding areas → participating in subsequent assembly. Among these: Before cutting, the steel plate needs to be pre-treated; when the gate cutter is used for precision cutting, a process allowance is reserved around the perimeter; the longitudinal and transverse baselines and stiffening rib position lines are marked as the reference for subsequent assembly; the longitudinal stiffening plates are assembled according to the lines, and the semi-automatic fillet welding carriage is used for welding, and the welding deformation is repaired after welding; the vertical stiffening plates are assembled and welded, and the welding deformation is repaired; the longitudinal and transverse baselines are repaired, and the processing lines around the web plate are marked with the longitudinal and transverse baselines as the reference, and the perimeter bevel is processed according to the lines, and after repair, it is used for subsequent assembly.

[0020] III. Horizontal diaphragm unit The diaphragm unit consists of diaphragms and reinforcing rings, and its manufacturing process includes: Steel plate pretreatment → CNC precision cutting of partition plates → straightening and chamfering → assembly of stiffening plates → welding → repair of welding deformation → participation in subsequent assembly. Among these: Before cutting, the steel plate needs to be pre-treated; CAD is used for precise layout, CNC precision cutting is used, and process allowance is reserved around the edge during cutting.

[0021] In addition, this embodiment proposes a layout and material cutting method before assembly: I. Laying out 1) Using computer 3D modeling technology, a detailed model of the steel box girder structure is established. For some parts with large curvature changes (such as wing plates), the splicing method and size of the plates are adjusted to make the lines smoother and reduce the manufacturing difficulty caused by excessive height difference. 2) According to the hoisting plan, the model is disassembled into units, and then the units are further disassembled into parts; 3) Obtain the precise theoretical dimensions for part cutting by decomposing the model, and then determine the process dimensions for cutting based on the joint processing requirements and welding shrinkage: Material cutting process dimensions = theoretical dimensions + welding shrinkage + machining allowance; After the layout simulation, precision manufacturing technology is applied to the entire construction process to ensure that the fabrication of steel box girder structural components meets the technical requirements of construction drawings, tender documents and specifications. II. Material feeding After the steel plate is rolled flat by a rolling mill and pre-treated, the blanking method is determined according to the specific shape and size of the part. The blanking methods are as follows: The CNC equipment with automatic scribing function is used for scribing, and then the complex structural parts such as node plates, cross diaphragms, partitions, and support stiffening plates are precision cut by CNC cutting machines with CAM system. For some single-sided bevel weld edges, a trolley is used to precisely cut the bevel, and after cutting, the cut edges are ground with a grinding wheel; For long rectangular parts such as the lid and belly of a box, a multi-nozzle gantry cutting machine is used for precision cutting. The sloping edges of the top and bottom plates with unequal thickness joints are machined using a CNC milling machine to ensure the angle of the machined slope. The joint edges of the node plates and cover plates are beveled using an edge planer to improve the bevel processing accuracy.

[0022] III. Parts processing and straightening 3.1 Edge processing The main processing equipment used includes milling machines and boring machines. The surface finish of the rough-machined surface is higher than Ra 25μm, and the surface finish of the precision-machined surface is higher than Ra 5.5μm, with a machining depth of 3-6 mm. Grinding and tightening of the edges result in a surface finish of Ra 5.5μm and a perpendicularity of less than 0.3mm. Welding bevels are formed using milling machines or flame cutting. Specifically: 1) The milling depth of the edge should not be less than 3 mm (when the edge hardness does not exceed HV350, the milling is not subject to this restriction), the surface roughness of the machined surface should not be higher than 25 μm, the surface roughness of the clamping force transmission surface should not be higher than 5.5 μm, and the perpendicularity deviation between the clamping machined surface and the plate surface should be less than 1% of the plate thickness and not greater than 0.3 mm. 2) The allowable deviation for the machining of planed edges shall be in accordance with the process specifications; 3) The allowable deviations in the machining dimensions specified in the process should meet the allowable deviations in the dimensions of the finished parts; 3.2 Parts Machining 1) The stiffening rings for the manholes and pipeline holes of the diaphragm are formed by three-core rollers or hydraulic presses; cold bending operations are all carried out in the workshop with an ambient temperature not lower than -5℃; 2) The transition bevel and plate edge processing are done using an edge planer; 3) Holes are machined using both CNC drilling machines and radial drilling machines; 4) All polished and tightened surfaces are machined using a milling machine; 5) The planing (milling) depth of the parts should not be less than 2mm, and the surface roughness Ra of the machined surface should not be greater than 25μm; the perpendicularity deviation between the machined surface and the plate surface should be less than 0.01t (t is the plate thickness) and should not be greater than 0.3mm; 6) When cold-working the main load-bearing parts, the ambient temperature should not be lower than -5℃, and the inner bending radius should not be less than 15 times the thickness of the plate. If it is less, hot bending should be used, and the hot bending temperature should be controlled between 900-1000℃. No cracks should appear on the edges of the bent parts. 7) The allowable deviation for the machining of planed edges shall be in accordance with the process specifications; 8) The allowable deviations of the machining dimensions specified in the process should meet the requirements for the allowable deviations of the finished component dimensions; 3.3 U-rib machining The main processes are: roller plate → pretreatment → blanking → straightening → marking → beveling → bending → trimming → end sealing. The specific manufacturing process is as follows: 1) Parts cutting; sheet metal is cut into blanks using a flame stripping machine; 2) Leveling; After cutting, the U-rib strips are leveled on an eleven-roll leveler to eliminate internal stress; 3) Milling: The straight edges and ends of the U-rib strips are milled on a mobile five-head milling machine; 4) Drilling holes in the U-ribs; use a drilling template to drill bolt holes at both ends of the U-ribs; 5) Beveling; U-rib beveling is performed on a milling machine equipped with a double-head milling power head and clamped using an angle stack clamping fixture. 6) U-rib bending; The U-rib is bent into shape in one step on a linkage electro-hydraulic servo CNC bending machine, and the bending line of the U-rib is marked through the position of the hole group; 7) Storage of U-rib finished products; After the U-ribs are made, they are transported and stored using U-shaped rib racks; Key technological points include: a. After the strip is pulled, the stress in the steel plate is eliminated by a leveling machine; b. After cutting, the straight edges and ends are milled a second time to ensure the dimensions of the strip; c. Use a milling machine to create the bevel, ensuring bevel accuracy; d. Before bending, the bolted U-ribs are drilled using a drilling template to create a group of holes; eU ribs are formed by bending in one step using a bending machine; f. Different top plate thicknesses correspond to different U-rib heights and opening widths; clearly mark and identify the different U-ribs. 3.4 Component Correction 1) Remove burrs and slag from the edges of the blank before straightening. The surface of the straightened steel should not have obvious dents or other damage; 2) The steel plates are leveled using nine-roll and eleven-roll leveling machines; 3) Cold straightening is recommended for parts straightening. The ambient temperature during cold straightening should not be lower than -12℃. The surface of the straightened steel should not have obvious dents or other damage. 4) The temperature for hot straightening should be controlled between 600 and 800°C. After straightening, the parts should be allowed to cool slowly with the air. Before they reach room temperature, they should not be hammered or cooled rapidly with water.

[0023] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A manufacturing process for an irregularly shaped hyperbolic steel box girder, characterized by: The steel box girder is assembled in reverse order, which means that the construction is carried out in reverse order from the inside to the outside and from the bottom to the top. First, the top plate is fixed on the formwork, and the transverse diaphragms are assembled using the top plate as the reference surface. Then, the web plate and wing plate are assembled using the transverse diaphragms as positioning references. Finally, the bottom plate is assembled.

2. The fabrication process for the irregular hyperbolic steel box girder according to claim 1, characterized in that: Follow these steps to implement: Step 1: Erect the frame Using 16a I-beams as the main material, a jig was built according to the horizontal curve and pre-arch curve of the steel box girder. At the slope change position, the I-beams were finely adjusted using an adjustable screw mechanism. After the jig was built, the dimensions and alignment of the jig were measured multiple times using a total station and a level to ensure the accuracy of the jig dimensions. Step 2: Positioning and assembling the top plate unit First, position the middle reference top plate unit on the jig, then position the top plate units on both sides; ensure that the longitudinal and transverse positioning reference lines of the top plate are aligned with the corresponding lines on the ground sample line; the top plate is fixed by rigid connection with the jig template; the two top plate units are fixed by connection with the support plate. Step 3: Positioning and assembling the diaphragm unit Using the top plate as a reference plane, locate the position of the transverse diaphragm on the top plate. The positioning of the transverse diaphragm should ensure that the plumb line is plumb. Step 4: Positioning and assembling the single-sided web plate unit Position the web plate according to the web plate edge line on the top plate unit; lift the web plate with a lifting tool and assemble and position it with the top plate; during assembly, the web plate assembly clamp can be used, and according to the technical design standard that the camber value between the two support points should meet, after shims are used from the middle to both sides, weld the inner wall weld of the Ώ-shaped beam. When welding, first weld the weld between the web plate and the transverse diaphragm and the longitudinal stiffener, and then weld the weld between the top plate and the transverse diaphragm and the longitudinal stiffener. Step 5: Positioning and assembling the base plate unit Place the base plate on the platform, mark the inner lines of the two webs, and then level it. The longitudinal and transverse positioning center lines of the base plate should be aligned with the corresponding lines on the ground pattern to determine the position of the base plate. Hang the base plate on the Π-shaped beam according to the marked position. Assemble and position the base plate from one end to the other by welding. Use tools to make the base plate fit tightly against the webs and diaphragms, with a gap of no more than 1mm between the base plate and the webs and diaphragms, to ensure the straightness of the overall line.

3. The fabrication process for the irregular hyperbolic steel box girder according to claim 2, characterized in that: The tools used in step 5 include a pressure bar, a rail lifter, and a jack.

Images