Asymmetric chord welding and manufacturing method of steel truss beam

Abstract

The present application relates to a kind of asymmetric chord of steel truss beam welding and manufacturing method, comprising the following steps:1, bottom plate, web, node plate and diaphragm assembly and welding;2, assembly and welding node plate box outside short joint web one;3, assembly and symmetric welding top plate;4, first time overturning again weld top plate in box body interior weld;5, assembly and weld web short joint component;6, second time overturning last weld top plate in box body exterior weld.The advantages of the welding method process are as follows:1, by optimizing the welding process of each structural member of chord, and adjusting the welding direction of individual structural member, so that each weld has better operating space, reduces the heat input of each weld, thereby ensuring the manufacturing quality of the entire chord;2, reasonable planning the welding sequence of each structural member, so that the post-welding deformation stress of each part of the manufactured chord tends to be balanced, which can reduce post-welding correction, improve manufacturing precision and reduce manufacturing cost.

Description

Technical Field

[0001] This invention relates to the field of steel truss manufacturing technology in steel structure bridges, and in particular to a method for manufacturing asymmetric chord members in steel truss beams. Background Technology

[0002] The design of modern steel railway bridges generally employs integral nodes or single-piece nodes. Integral nodes, with their external splicing structure, offer advantages such as improved node load-bearing capacity, easier on-site erection, and savings in high-strength bolts and steel. However, integral nodes have relatively dense welds, complex structures, and require high weld quality. The yield strength of the steel must be strictly controlled, and the welding sequence and direction are closely related to weld quality and manufacturing precision. In steel trusses with integral node structures, the upper and lower chords, nodes, and web members form the main truss's crucial load-bearing structure. The steel truss includes asymmetrical chords, typically composed of a bottom plate, top plate, diaphragms, web connecting plates, crossbeam short joints, and various stiffeners. This dense structure and limited welding space necessitate stricter welding requirements, deformation control, and high manufacturing precision to enhance the overall strength of the steel truss. This results in inconvenient and inefficient assembly and welding operations, and significant challenges in controlling weld quality. Summary of the Invention

[0003] This invention provides a method for manufacturing chord members of asymmetric steel trusses, solving the technical problems of inconvenient welding operations, low efficiency, and difficulty in controlling welding quality in existing technologies for asymmetric steel truss chord members.

[0004] To solve the above-mentioned technical problems, the present invention provides a welding manufacturing method for asymmetric chord members in steel trusses. The asymmetric beam chord members are manufactured on a jig and include the following steps:

[0005] Step (1): Assemble and position the base plate on the jig, assemble identical and aligned transverse diaphragms and end caps on the base plate, symmetrically assemble a pair of node plates and a pair or more pairs of web plates on both sides of the transverse diaphragms, so that a node plate is close to the extended wing protruding from one side edge of the base plate.

[0006] Step (2): Weld the vertical fillet welds of the transverse diaphragm, end sealing plate and the node plates or web plates on both sides, and weld the longitudinal fillet welds of the node plates, web plates and bottom plates.

[0007] Two flat fillet welds are made between the bottom of the vertically installed horizontal diaphragm and end sealing plate and the base plate.

[0008] Step (3): Assemble a short joint web plate at the outer side of the node plate box and at the outer extension of the bottom plate;

[0009] Step (4): weld vertical fillet weld one between short joint web one and the side of node plate which is away from the transverse diaphragm one, and weld horizontal fillet weld one between short joint web one and the extended wing one of bottom plate;

[0010] Step (5): assemble top plate on the web, cover the top plate on the pair of node plates and the pair of webs, make a node plate inserted into the slot on the top plate, the extension line of the slot can divide the top plate into the part which matches the size of the bottom plate and the extended wing two, and the extended wing two of the top plate is on the same side as the extended wing one of the bottom plate;

[0011] Step (6): weld vertical fillet weld two between the upper side of the top plate which is away from the extended wing two and the node plate and the web, and weld vertical fillet weld three between the upper side of the extended wing two and the outer side of the joint plate;

[0012] Step (7): assemble the stiffener between the node plates, and weld vertical fillet weld three between the stiffener and the node plates on both sides;

[0013] Step (8): rotate the above-mentioned component which is welded by 180° around the axis direction of the bottom plate, so that the bottom plate is on the top and the top plate is on the bottom, weld vertical fillet weld four between the node plate and the lower side of the top plate, weld vertical fillet weld five between the web and the lower side of the top plate, and symmetrically weld from the middle to both ends of the top plate, clear the root and weld vertical fillet weld six between the lower side of the extended wing two of the top plate and the node plate, and weld vertical fillet weld four between the upper side of the transverse diaphragm and the lower side of the top plate;

[0014] Step (9): assemble and position short joint web two at the angle between the web and the extended wing two of the top plate, so that the short joint web two is perpendicular to the extended wing two, weld vertical fillet weld four between the short joint web two and the web, and weld horizontal fillet weld two between the short joint web and the lower side of the extended wing two of the top plate;

[0015] Step (10): rotate the above-mentioned component which is welded by 180° around the axis direction of the bottom plate, so that the top plate is on the top and the bottom plate is on the bottom, clear the root and weld vertical fillet weld seven between the upper side of the side of the top plate which is close to the extended wing two and the inner side of the joint plate;

[0016] Step (11): assemble and position the web short connecting plate between the joint plates, and weld inclined fillet weld between the web short connecting plate and the joint plates on both sides.

[0017] Preferably, the welding method of vertical fillet weld one, vertical fillet weld four, vertical fillet weld five, vertical fillet weld six, vertical fillet weld seven, vertical fillet weld nine, vertical fillet weld eleven is to start from the middle position of the length direction of the bottom plate or the top plate, and to expand and symmetrically weld from the middle to both ends.

[0018] Preferably, the longitudinal fillet weld one, the longitudinal fillet weld two, the longitudinal fillet weld three, the longitudinal fillet weld four, the longitudinal fillet weld five, the longitudinal fillet weld six, the longitudinal fillet weld seven are welded by using the step-back welding method and the CO2 shielded welding method; the longitudinal fillet weld two 6 is welded by using the step-back welding method and the submerged arc automatic welding device; the vertical fillet weld one, the vertical fillet weld two, the horizontal fillet weld one, the horizontal fillet weld two, the vertical fillet weld three, the vertical fillet weld four and the inclined fillet weld are welded by using the CO2 shielded welding method.

[0019] Preferably, the longitudinal fillet weld one and the longitudinal fillet weld two are welded by using the partial penetration method.

[0020] Preferably, the longitudinal fillet weld three, the longitudinal fillet weld six and the longitudinal fillet weld seven are welded by using the full penetration method.

[0021] Preferably, after the welding process is completed, correction is performed, and a preset reverse deformation amount is provided when welding the top plate and the bottom plate.

[0022] Preferably, after the weld of each step is qualified, welding of the next step is performed.

[0023] Compared with the prior art, the manufacturing method of the asymmetric chord proposed in the application has the following advantages:

[0024] 1. By optimizing the welding process of each structural member of the asymmetric chord in the steel truss and optimizing the welding direction of the single structural member, each weld has a better operation space and is welded in a flat position, so that the heat input of each weld is minimized, thereby ensuring the manufacturing quality of the entire chord; and overall, convenient and efficient welding and low-deformation high-welding-quality manufacturing processing can be realized in a dense and narrow space.

[0025] 2. By reasonably planning and arranging the welding sequence of each structural member weld, that is, by setting a diagonal welding form, the deformation of each member caused by the weld two is resisted or balanced, so that the post-weld deformation stress of each part of the chord tends to be balanced after the chord is manufactured, the post-weld correction is maximally reduced, the manufacturing precision is improved, and the manufacturing cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic diagram of the arrangement of a standard segment of a steel truss;

[0027] Figure 2 is a schematic diagram of the three-dimensional structure of the chord of the steel truss in the application;

[0028] Figure 3 is a schematic diagram of the planar structure of the chord of the steel truss in the application;

[0029] Figure 4 The welding process flow chart of the chord of the steel truss beam in the application;

[0030] Wherein, 1 is vertical fillet weld one, 2 is longitudinal fillet weld one, 3 is horizontal fillet weld two, 4 is vertical fillet weld two, 5 is horizontal fillet weld one, 6 is longitudinal fillet weld two, 7 is longitudinal fillet weld three, 8 is vertical fillet weld three, 9 is longitudinal fillet weld four, 10 is longitudinal fillet weld five, 11 is horizontal fillet weld four, 12 is longitudinal fillet weld six, 13 is vertical fillet weld two, 14 is horizontal fillet weld two, 15 is longitudinal fillet weld seven, 16 is inclined fillet weld, 101 is bottom plate, 102 is web plate, 103 is top plate, 104 is joint plate, 105 is joint web plate one, 106 is joint web plate two, 107 is joint web plate three, 108 is extension wing one, 109 is extension wing two, and 110 is web plate short joint plate. DETAILED DESCRIPTION

[0031] The application will be further described in detail below in combination with the drawings and specific embodiments.

[0032] As Figure 1 shown, it is a structural schematic diagram of a segment of steel truss beam in the prior art steel bridge, which includes main truss, main cross truss, orthotropic steel bridge deck plate, etc., wherein the main truss includes upper chord, lower chord, vertical web and inclined web, and the main cross truss includes upper chord, lower chord and inclined web. It can be seen that the chord is connected with various members in the steel truss beam and plays a key supporting role. The purpose of the application is to improve the overall structural strength of the chord by optimizing the assembly and welding process of various members in the chord, i.e. to reduce the places where welding residual stress exists in the local stress concentration of the chord, so as to avoid the stress value of the chord exceeding its yield point. This is because the structure has a small defect or stress concentration, which is easy to produce plastic deformation, thus initiating a crack. With the increase of the number of external force cycles, the small crack will gradually expand, and finally lead to fatigue fracture of the chord.

[0033] The three-dimensional structure of the asymmetric chord designed by the application is shown in Figure 2 , and the cross-sectional structure is shown in Figure 3As shown, the chord whole box type, including the bottom plate 101, web 102, top plate 103, node plate 104, joint section plate 105, transverse diaphragm (not shown in the figure), and set at both ends of the chord end plate (not shown in the figure) and the joint section plate 105 connected with the web short connecting plate 110, etc. Along the length of the bottom plate 101, respectively, on both sides of the symmetrical welding a pair of node plate 104 and a pair of web 102, node plate 104 and web 102 are perpendicular to the bottom plate 101, each side of the node plate 104 and web 102 adjacent edge welding connected, the shape and length of the top plate 103 match the bottom plate 101, top plate 103 is arranged in parallel above the bottom plate 101, top plate 103 is provided with a slot, the length of the slot matches the size of the node plate 104, a node plate 104 vertically arranged on the bottom plate 101 can be inserted into the slot on the top plate 103, so that the top plate 103 both ends can be aligned with the bottom plate 101, and the top plate 103 covers both sides of the web 102, the top plate 103 and the bottom plate 101, and the vertically arranged node plate 104 or web 102 on both sides, together enclose a box structure of the rod.

[0034] The joint section plate 105 is provided on the side of the node plate 104 away from the bottom plate 101, which is used to weld with the joint of the web (not shown in the figure). The box structure is uniformly provided with a plurality of transverse diaphragms and end plates at both ends of the box between the web 102 box and the node plate 104 box. The shape and size of the transverse diaphragm and the end plate match the cross section of the box, and the four sides of each transverse diaphragm and end plate are welded and connected with the box. The top plate 103 and the bottom plate 101 extend out of the extension wing on the same outside along the length direction of the box, including the extension wing two 109 formed by the top plate 103 extending outwardly on the outside of the box, and the extension wing one 108 extending outwardly on the outside of the node plate box of the bottom plate 101. The long side of one side of the top plate 103 is aligned with the top long side of the web 102 and is welded and fixed, and the long side of the other side of the top plate 103 with the extension wing two 109 covers the web 102 and is welded and fixed. The top plate 103 is also welded and connected with the inserted pair of node plates 104. The short joint web two 107 perpendicular to the box is welded between the lower side of the extension wing two 109 of the top plate 103 and the outside of the web 102 box. The short joint web one 106 perpendicular to the box is welded between the upper side of the extension wing two 109 of the top plate 103 and the outside of the joint section plate 105, and between the lower side of the extension wing two 109 of the top plate 103, the upper side of the extension wing one 108 of the bottom plate 101 and the outside of the node plate 104 box. The web short connecting plate 110 is welded between a pair of joint section plates 105.

[0035] The above rod needs to be prefabricated, wherein the web, the node plate, one side of the top plate and the two sides of the slot, the first short joint web and the second short joint web welding place of the short joint web, and the welding place of the short joint web of the web, are all pre-set single V-shaped groove or double V-shaped groove, the root face is set according to the thickness of the plate, the gap is 0-1mm, the groove angle is 40-45°, so that the weld between the web, the node plate and the top plate on both sides is a groove weld, and the weld of the first short joint web and the second short joint web outside the node plate is also a groove weld, so that the weld has a certain penetration or penetration, and the overall mechanical properties of the chord are guaranteed. The bottom plate is assembled and positioned on the jig, and after the position of the bottom plate is adjusted, a pair of webs is assembled, the webs are positioned to the bottom plate, and then two node plates are assembled. According to the pre-designed position, a plurality of transverse partitions are evenly spaced in the space surrounded by the bottom plate and the webs on both sides. After the bottom plate, the web, the node plate and the transverse partition are welded, the top plate is positioned, and the top plate and the web and the node plate are preliminarily welded, and then the first 180 degree overturning is carried out. The edges of other rod members in contact with the chord are welded.

[0036] The present application is directed to the structure of the chord, in order to improve the weld quality of the chord and the overall welding strength of the steel truss, an optimized welding manufacturing process is proposed.

[0037] The asymmetric steel truss chord of the present application is made on a special jig, and the following steps are included in the order:

[0038] 1. Assembly and welding of the bottom plate, web, node plate and transverse partition, as shown in ① and ⑤ of the description: Figure 4

[0039] Step (1): Assemble and position the bottom plate on the jig, assemble the same size and aligned multiple transverse partitions (not shown in the figure) and end sealing plates (not shown in the figure) on the bottom plate, and symmetrically assemble a pair of node plates and one or more pairs of webs on both sides of the transverse partitions.

[0040] Step (2): Weld the vertical fillet weld 1 of the transverse partition, the end sealing plate and the node plate or the web on both sides, weld the longitudinal fillet weld 2 of the node plate, the web and the bottom plate, and partially penetrate the longitudinal fillet weld 2, the longitudinal fillet weld 2 on both sides of the bottom plate is welded synchronously, and the longitudinal fillet weld 2 on each side is symmetrically welded from the middle to both ends of the bottom plate.

[0041] Weld the vertical transverse partition, the end sealing plate and the bottom plate.

[0042] 2. Assembly and welding of the first short joint web outside the node plate box, as shown in ② of the description: Figure 4

[0043] Step (3): Assemble the first short joint web at the outer extension wing one of the node plate box and the bottom plate.​​

[0044] Step (4): weld vertical fillet weld one 4 between short joint web one and node plate box outside, weld horizontal fillet weld one 5 between short joint web one and bottom plate extension wing one;

[0045] 3. Assembly and welding of top plate, as shown in Figure 4 , ②, ⑥:

[0046] Step (5): assemble top plate on web, cover top plate above a pair of webs and extend to a pair of node plates, and make top plate have one side of extension wing two on the same side of the box as extension wing one on the bottom plate;

[0047] Step (6): weld upper side of top plate away from one side of extension wing two to part of longitudinal fillet weld two 6 on the inside of node plate box, weld upper side of top plate away from one side of extension wing two to part of longitudinal fillet weld two 6 on the inside of web box, fully penetrate weld upper side of extension wing two of top plate to longitudinal fillet weld three 7 on the outside of node plate box, and symmetrically weld from the middle to both ends of the top plate, complete welding of longitudinal fillet weld two 6 and longitudinal fillet weld three 7;

[0048] Step (7): assemble stiffener plate (not shown in the figure) between node plates, weld vertical fillet weld three 8 between stiffener plate and node plates on both sides;

[0049] Until step (7), the box formed by each member in the chord including the bottom plate, web, node plate and top plate has been welded and positioned to form a box structure, and the top plate needs to be reinforced and welded, and welded short joint web two is added on one side of the box.

[0050] 4. First overturning and welding of inside welds of top plate in the box, hoist the above-mentioned welded component, rotate 180° around the axis direction of the bottom plate, with the bottom plate on top and the top plate on bottom, as shown in Figure 4 , ③, ⑦:

[0051] Step (8): weld longitudinal fillet weld four 9 between node plate inside and lower side of top plate, weld longitudinal fillet weld five 10 between web inside and lower side of top plate between node plates, and symmetrically weld from the middle to both ends of the top plate, complete welding of longitudinal fillet weld four 9 and longitudinal fillet weld five 10; clean and weld longitudinal fillet weld six 12 between lower side of extension wing two of top plate and outside of node plate box;

[0052] Weld flat fillet weld four 11 between upper side of transverse partition plate and lower side of top plate;

[0053] 5. Assembly and welding of short joint components at web, as shown in Figure 4 , ⑦:

[0054] Step (9): Assemble and position the short web plate two at the angle between the web plate outside and the top plate outside extension wing two, so that the short web plate two is perpendicular to the box, weld the vertical fillet weld four 13 between the short web plate two and the web plate outside, and weld the horizontal fillet weld two 14 between the short web plate and the lower side of the top plate outside extension wing two;

[0055] 6. Second time to flip and weld the top plate at the outside weld of the box, hoist the above-mentioned welded component, rotate again by 180° along the bottom plate axis direction, the top plate is on the top and the bottom plate is on the bottom, as shown in Figure 4 ④, ⑧ in the middle:

[0056] Step (10): Clean up and weld the vertical fillet weld seven 15 between the upper side of the top plate close to the outside extension wing two and the node plate inside.

[0057] Step (11): Assemble and position the web plate short connecting plate between the joint segment plates, and weld the inclined fillet weld 16 between the web plate short connecting plate and the two side joint segment plates.

[0058] The welding sequence of the transverse diaphragm, end closure plate and web plate in step 1 is shown in Figure 4 ①, ⑤ in the middle, which is to let the vertical web plate, node plate and transverse diaphragm form a stable frame structure first, so as to avoid damage to the base material by too many temporary supports.

[0059] Among them, the longitudinal fillet weld one 2, the longitudinal fillet weld two 6, the longitudinal fillet weld three 7, the longitudinal fillet weld four 9, the longitudinal fillet weld five 10, the longitudinal fillet weld six 12, the longitudinal fillet weld seven 15 are symmetrically welded by spreading from the middle position of the length direction of the bottom plate or the top plate to both ends, wherein the two symmetric longitudinal fillet welds one 2 on both sides of the upper side of the bottom plate are welded synchronously, and the two symmetric longitudinal fillet welds four 9 on both sides of the lower side of the top plate are welded synchronously, so that the component can be balanced and contracted with the center of symmetry, and the deformation of deviating to one side is reduced. Moreover, the longitudinal fillet weld one 2, the longitudinal fillet weld two 6, the longitudinal fillet weld three 7, the longitudinal fillet weld four 9, the longitudinal fillet weld five 10, the longitudinal fillet weld six 12, the longitudinal fillet weld seven 15, the horizontal fillet weld one 5, the horizontal fillet weld two 14, and the vertical fillet weld one 4, the vertical fillet weld two 13 are all bevel welds, and the rest of the vertical fillet weld one 1, the vertical fillet weld two 3, the vertical fillet weld three 8, the vertical fillet weld four 11 are all open-flame fillet welds.

[0060] Further, the longitudinal fillet weld one 2 and the longitudinal fillet weld two 6 are welded by the method of partial penetration.

[0061] Further, the longitudinal fillet weld three 7, the longitudinal fillet weld six 12, the longitudinal fillet weld seven 15 are welded by the method of full penetration.

[0062] Longitudinal fillet weld one 2, longitudinal fillet weld three 7, longitudinal fillet weld four 9, longitudinal fillet weld five 10, longitudinal fillet weld six 12, longitudinal fillet weld seven 15 are welded by using the segmented back welding method and the CO2 shielded welding method. Longitudinal fillet weld two 6 is welded by using the segmented back welding method and the submerged arc automatic welding device. Transverse fillet weld one 5, transverse fillet weld two 14, vertical fillet weld one 4, vertical fillet weld two 13, vertical fillet weld one 1, vertical fillet weld two 3, vertical fillet weld three 8, vertical fillet weld four 11 and oblique fillet weld 16 are all welded by using the CO2 shielded welding method.

[0063] The asymmetric steel truss chord manufacturing method further comprises correcting after the welding process is completed. Since the vertical fillet weld one 1, the longitudinal fillet weld one 2, the longitudinal fillet weld two 6, the longitudinal fillet weld three 7, the vertical fillet weld three 8, the longitudinal fillet weld four 9, the longitudinal fillet weld five 10, the longitudinal fillet weld six 12, the transverse fillet weld two 14, the longitudinal fillet weld seven 15 and the oblique fillet weld 16 are welded, a certain amount of post-weld shrinkage deformation will be generated to different degrees. The deformation degree is measured after the welds are cooled to room temperature. If the deformation is too large, post-weld correction is performed in time. When the top plate and the bottom plate are assembled, a preset counter-deformation amount is ensured to guarantee the post-weld dimensional accuracy of the structure. After the welds of each step are qualified by inspection, the next step of welding can be performed.

[0064] In order to improve the quality of the welds at the node plate and avoid the problem of stress concentration, the welding of the node plate is not carried out at the beginning, but is carried out in the welding process of the bottom plate and the top plate. In order to improve the welding quality, the node plate is turned over twice during the whole welding process, so that all the longitudinal welds are welded in the horizontal position, which can simplify the welding difficulty and ensure the welding quality. Since the groove opening precision control requirement of the plate is very high, the cost and time consumption are very large. In the welding process of the transverse diaphragm and the end sealing plate, the components and plates are not opened, so the vertical fillet welds 1, 3, 8 and 11 are not opened. The groove fillet welding is adopted for the top plate and the node plate, which has an important influence on the structure and quality of the whole chord. The welding quality requirement is high. Especially, there are many fillet welds at the node plate, the bottom plate, the top plate, the extended wing 1 of the bottom plate and the corresponding extended wing 2 of the top plate. The weld between the top plate near the outer side of the chord and the node plate, i.e. the longitudinal weld 6, is partially penetrated. Then, four welds are formed at the cross intersection of the top plate and the node plate near the inner side of the chord. The four welds are twice diagonal welding in sequence, i.e. longitudinal fillet weld 7, longitudinal fillet weld 9, longitudinal fillet weld 12 and longitudinal fillet weld 15. At this time, the longitudinal fillet weld 7 is located at the outer side of the chord, so it is handled together with the longitudinal fillet weld 6 before turning over. After 180° turning over, the top plate and the node plate are fixed relative to the web, and the partially penetrated longitudinal fillet weld 6 is already stable and formed. Then, the two symmetrical longitudinal fillet welds 9 are welded in the horizontal position. At this time, the longitudinal fillet weld 9 is located inside the box and is opposite to the longitudinal fillet weld 7, which can resist the deformation caused by welding and reduce the correction process in the later stage. At the same time, the longitudinal fillet weld 9 is located below the longitudinal fillet weld 6, which can resist the deformation caused by welding and reduce the correction process in the later stage. Next, the longitudinal fillet weld 12 and the opposite longitudinal fillet weld 15 are welded in sequence. Similarly, the longitudinal fillet weld 15 is opposite to the longitudinal fillet weld 12, which are welded in sequence. The later welded one can resist the deformation caused by welding and reduce the correction process in the later stage. Under such reasonable and ingenious welding sequence, the welding quality can be ensured while the correction process in the later stage is reduced.

Claims

1. A method of welding a non-symmetrical chord of a steel truss girder, the non-symmetrical chord being manufactured on a jig, characterized in that, Comprising the following steps: Step (1): Assemble and position the bottom plate on the cradle, assemble the same and mutually aligned transverse diaphragms, end sealing plates on the bottom plate, and symmetrically assemble a pair of node plates and one or more pairs of webs on both sides of the transverse diaphragm, so that one node plate is close to the extended wing protruding from the side edge of the bottom plate; Step (2): Weld the vertical standing corner weld one (1) of the transverse diaphragm, the end sealing plate and the node plate or the web on both sides, weld the vertical standing corner weld one (2) of the node plate, the web and the bottom plate; Weld the bottom of the vertically arranged transverse diaphragm and end sealing plate to the flat corner weld two (3) of the bottom plate; Step (3): Assemble and position the short joint web one at the extended wing one of the node plate box and the bottom plate; Step (4): Weld the vertical corner weld one (4) of the short joint web one and the node plate away from the transverse diaphragm, and weld the horizontal corner weld one (5) of the short joint web one and the extended wing one of the bottom plate; Step (5): Assemble the top plate on the web, cover the top plate on the pair of node plates and the pair of webs, insert one node plate into the slot on the top plate, and the extension line of the slot can divide the top plate into a part matched with the size of the bottom plate and an extended wing two, and the extended wing two of the top plate is on the same side as the extended wing one of the bottom plate; Step (6): Weld the upper side of the extended wing two away from the top plate to the longitudinal corner weld two (6) of the node plate and the web, and the upper side of the extended wing two to the longitudinal corner weld three (7) of the joint section plate outside; The joint section plate (105) beyond the top plate (103) is arranged on the side of the node plate (104) away from the bottom plate (101); Step (7): Assemble the stiffener between the node plates, and weld the vertical standing corner weld three (8) of the stiffener and the node plates on both sides; Step (8): The above welded component is rotated by 180° around the axis direction of the bottom plate, so that the bottom plate is on the top and the top plate is on the bottom, the longitudinal corner weld four (9) of the node plate and the lower side of the top plate is welded between the node plates, the longitudinal corner weld five (10) of the web and the lower side of the top plate is welded, and the welding is symmetrically applied from the middle to both ends of the top plate; The lower side of the extended wing two of the top plate is welded to the longitudinal corner weld six (12) of the node plate; The upper side of the transverse diaphragm is welded to the flat corner weld four (11) of the lower side of the top plate; Step (9): Assemble and position the short joint web two at the included angle between the web and the extended wing two of the top plate, so that the short joint web two is perpendicular to the extended wing two, weld the vertical corner weld two (13) of the short joint web two and the web, and weld the horizontal corner weld two (14) of the short joint web two and the lower side of the extended wing two of the top plate; Step (10): The above welded component is rotated by 180° around the axis direction of the bottom plate, so that the top plate is on the top and the bottom plate is on the bottom, the upper side of the top plate close to the extended wing two is welded to the longitudinal corner weld seven (15) of the joint section plate inside; Step (11): Assemble and position the web short connecting plate between the joint section plates, and weld the inclined corner weld (16) of the web short connecting plate and the joint section plates on both sides; The welding method of the longitudinal fillet weld one (2), longitudinal fillet weld two (6), longitudinal fillet weld three (7), longitudinal fillet weld four (9), longitudinal fillet weld five (10), longitudinal fillet weld six (12), longitudinal fillet weld seven (15) is to start from the middle position of the length direction of the bottom plate or the top plate, and to spread from the middle to both ends and symmetrically weld.

2. The method of welded fabrication of a chord according to claim 1, characterized in that, The longitudinal fillet weld one (2), longitudinal fillet weld three (7), longitudinal fillet weld four (9), longitudinal fillet weld five (10), longitudinal fillet weld six (12), longitudinal fillet weld seven (15) are welded by using the segmented back welding method and the CO2 shielded welding method; the longitudinal fillet weld two (6) is welded by using the segmented back welding method and the submerged arc automatic welding device; the vertical fillet weld one (1), flat fillet weld two (3), vertical fillet weld three (8), flat fillet weld four (11), the horizontal fillet weld one (5), horizontal fillet weld two (14), vertical fillet weld one (4), vertical fillet weld two (13) and the inclined fillet weld (16) are welded by using the CO2 shielded welding method.

3. The method of claim 1, wherein The longitudinal fillet weld one (2), longitudinal fillet weld two (6) are welded by using the partial penetration method.

4. The method of claim 1, wherein The longitudinal fillet weld three (7), longitudinal fillet weld six (12), longitudinal fillet weld seven (15) are welded by using the full penetration method.

5. The method of claim 1, wherein After the welding process is completed, correction is performed, and a preset reverse deformation amount is preset when the top plate and the bottom plate are welded.

6. The method of claim 1, wherein After the weld of each step is qualified by inspection, the welding of the next step is performed. After the weld of each step is qualified by inspection, the welding of the next step is performed.

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