Ground pre-assembling and sectional hoisting construction method of large special-shaped steel pipe lattice column

Abstract

The present application relates to a large special-shaped steel pipe lattice column ground pre-assembling and segmented hoisting construction method, belongs to the technical field of building steel structure construction, including site pretreatment and full-size lofting, reserving welding shrinkage allowance; erecting a full-length rigid jig, using V-shaped limiting pad to position and assemble the main chord and web in whole; welding all nodes on the ground except the vertical segmented interface, using a rigid lock at the interface; removing the rigid lock and disassembling the segments after overall re-measurement is qualified; hoisting the segments in the air, only welding the main chord interface, and synchronously setting temporary support on the roadbed box. The present application solves the contradiction between large special-shaped component transportation limitation and installation precision, transfers the high-altitude operation to the ground through ground overall pre-assembling, greatly reduces the safety risk, improves the special-shaped curved surface forming precision, shortens the construction period and reduces the cost.

Description

Technical Field

[0001] This invention relates to the field of building steel structure construction technology, specifically to a method for ground pre-assembly and segmented hoisting construction of large irregular steel pipe lattice columns. Background Technology

[0002] With the rapid development of large-scale public buildings in my country (such as high-speed railway stations, stadiums, and convention centers), large-span arched roof structures are becoming increasingly common. These buildings often have unique shapes, and their support systems generally adopt large-section irregularly shaped steel pipe lattice columns. These components are usually formed by intersecting welding of thick-walled circular tube main chord members, ring-shaped web members, and spatial diagonal web members, and are characterized by their extremely large overall size, extremely heavy weight, and complex shape (mostly frustum-shaped or irregular curved surfaces).

[0003] Due to limitations in road transport conditions, these giant lattice columns cannot be prefabricated in the factory and transported as a whole; they must be disassembled into individual pipes or sections for on-site transport. Currently, the industry mainly uses the following two traditional methods for the construction of such components: The method of hoisting and welding individual chord members at high altitude involves transporting all chords and web members to the site and hoisting them one by one to their designed positions at high altitude for positioning and welding. This method requires the erection of full-span scaffolding or a large operating platform, involves a huge amount of work at height, and is greatly affected by wind, temperature differences, and hoisting sway. Measurement and positioning are extremely difficult to control, welding quality is hard to guarantee, and the safety risks are extremely high.

[0004] The factory-prefabrication and high-altitude welding method involves dividing the lattice column into several independent segments in the factory, transporting them to the site, hoisting them into sections, connecting them with the main chord members at high altitude, and welding a large number of web members. Although this method reduces the hoisting of some individual parts, the amount of high-altitude welding is still very large. Moreover, since each segment is manufactured independently, there is a lack of a unified overall three-dimensional benchmark, which makes it difficult to control the misalignment and gaps at the joints during high-altitude welding, and it is difficult to guarantee the smoothness of irregular curved surfaces.

[0005] A search revealed that existing technologies (such as CN113374173B, CN202311067558.7, CN109372125A, etc.) mostly focus on single-section assembly jigs or simple segmented hoisting processes, all following the approach of "prefabrication in segments first, then high-altitude assembly." These existing technologies generally suffer from the following inherent defects: I. High safety risks: The work involves a large amount of hot work and hoisting operations at heights of 30-40 meters, with significant risks of falls from heights and being struck by objects.

[0006] 2. Poor forming accuracy: The lack of a unified benchmark for overall pre-assembly on the ground makes it easy for cumulative errors to occur during segmented splicing, resulting in misalignment of curved surfaces and uneven lines.

[0007] 3. Difficulty in controlling welding quality: High-altitude welding is greatly affected by the environment, and there is no rigid frame to restrain it. Components are prone to twisting and bending, and the weld inspection and repair rate is high.

[0008] IV. Uncontrollable construction period and cost: Large cranes occupy a long time, scaffolding and safety protection investment is large, and the construction period is severely restricted by the weather. Summary of the Invention

[0009] This invention addresses the shortcomings of existing technologies by providing a ground pre-assembly and segmented hoisting construction method for large irregular steel pipe lattice columns. This method resolves the contradiction between transportation limitations and installation accuracy of large irregular components. By pre-assembling the entire structure on the ground, high-altitude operations are transferred to the ground, significantly reducing safety risks, improving the forming accuracy of irregular curved surfaces, shortening the construction period, and reducing costs.

[0010] The above-mentioned technical problems of the present invention are mainly solved by the following technical solutions: A method for ground pre-assembly and segmented hoisting of large irregular steel pipe lattice columns includes the following steps: Step 1: Site pretreatment and full-size layout: Select a hardened site near the hoisting operation surface and set up a full-length rigid assembly jig; according to the lattice column design, project a 3D model onto the ground to lay out a 1:1 solid model, and reserve the welding shrinkage allowance.

[0011] The steel structure building has a roof truss at the top, with the lower outer perimeter of the roof truss supported by external steel pipe lattice columns, and the lower inner perimeter of the roof truss supported by internal steel pipe lattice columns.

[0012] Step 2: Ground positioning and assembly: The main chords and web members of the outer steel pipe lattice columns and the inner steel pipe lattice columns are hoisted onto the jig and positioned as a whole according to the physical details on the ground, so that the spatial position of all members coincides with the design three-dimensional projection.

[0013] Step 3: Ground-based overall welding: On the ground-based jig, all intersecting nodes of the web members, except for the vertical segment interfaces, are fully penetrated welded to complete the node welding work of the entire column; for the main chord members at the vertical segment interfaces, temporary fixing connectors are used for rigid locking, but no permanent welding is performed.

[0014] Step 4: Overall re-measurement and segmented disassembly: The geometric dimensions of the integrally formed lattice column are re-measured. After the re-measurement is qualified, the temporary fixing connectors are removed, and the outer steel pipe lattice column and the inner steel pipe lattice column are disassembled into several segmented hoisting units.

[0015] Step 5: Segmented hoisting and high-altitude assembly: Each segmented hoisting unit is hoisted to its installation position in sequence and aligned according to the positioning benchmark during pre-assembly. Only the main chord at the vertical segment interface is welded at high altitude to complete the connection and fixation of the outer steel pipe lattice column and the inner steel pipe lattice column to the lower chord of the roof truss.

[0016] As a preferred method, in the first step, the specific method for reserving the welding shrinkage allowance is as follows: take the dimensions as a reference based on a single layout origin, and uniformly reserve a shrinkage compensation amount of 1 to 2 mm at each steel pipe intersection joint position to offset the cumulative deformation of multi-node welding.

[0017] Preferably, in the first step, the method for erecting the full-length rigid assembly frame is as follows: the frame columns are arranged along the entire length of the lattice column; for straight chord sections, no less than 2 support points are set in each section; for curved chord sections, no less than 3 support points are set in each section; a V-shaped limiting pad is set on the top of the frame column, and an I-beam is provided between the V-shaped limiting pad and the frame column.

[0018] Preferably, the V-shaped limiting pad has the following structural features: the V-shaped limiting pad has a V-shaped groove with the opening facing upwards, and the bottom of the V-shaped limiting pad is welded and fixed to the I-beam on the top surface of the jig; the outer wall of the main chord is placed inside the V-shaped groove, and the two inclined surfaces of the V-shaped groove are in contact with the arc surface of the main chord to constrain the axial sliding and circumferential rotation of the main chord.

[0019] Preferably, in the third step, the temporary fixing connector is a temporary reinforcement type plate; the material of the plate is the same as that of the main chord base material, and it is fixedly connected to the outer wall of the main chord at the segment interface using welding material that matches the base material.

[0020] Preferably, the mounting plate is installed as follows: 2 to 4 sets of mounting plates are symmetrically arranged around the circumference of the main chord at the segment interface, and each set of mounting plates is welded to the outer wall of the two main chord sections respectively, so as to achieve temporary rigid locking of the segment interface through the mounting plates; the mounting plates are connected to the main chords by intermittent fillet welds so as to facilitate non-destructive removal by gas cutting or grinding.

[0021] As a preferred option, in the third step of ground welding, an intermittent diffusion welding process is adopted: welding is performed from the center of the node outwards, and adjacent nodes are welded after a gap of 1 to 2 nodes. Thick-walled pipes are preheated before welding, and multi-layer and multi-pass welding is used to control the interpass temperature.

[0022] As a preferred option, in the fourth step, before removing the temporary fixing connectors, first stamp alignment marks on the outer wall of the steel pipe at the segment interface as a benchmark for rapid high-altitude matching; during the removal process, temporarily support and reinforce the segment interface, and alternately cut the support plate to release stress.

[0023] As a preferred option, the synchronous construction steps of the lattice column support system are also included: during the placement of the segmented hoisting units, temporary supports are set on the sides of the outer steel pipe lattice columns and the inner steel pipe lattice columns, and the bottom of the temporary supports is set on the roadbed box on the natural soil foundation; after the outer steel pipe lattice columns or the inner steel pipe lattice columns are installed and adjusted, the bottom of the temporary supports is welded and fixed to the roadbed box.

[0024] Preferably, the temporary support is made of steel pipe for vertical support, with a vertical bearing capacity design value of not less than 700kN. The contact area between the roadbed box and the ground meets the characteristic value requirements of the foundation bearing capacity, and the roadbed box is made of steel plate and steel keel with a thickness of not less than 20mm.

[0025] Preferably, the roadbed box comprises a rectangular frame structure composed of channel steel, with supporting steel plates on both the upper and lower ends of the channel steel. Several transverse H-beams are arranged within the frame composed of channel steel. Several longitudinal H-beams are spaced apart between the channel steel and the transverse H-beams, and between adjacent transverse H-beams. Supporting partitions, respectively welded and fixed to the channel steel and transverse H-beams, are provided between the longitudinal H-beams and the channel steel, and between adjacent longitudinal H-beams.

[0026] After the splicing and hoisting of the irregular steel pipe lattice column is completed, the vertical support column is removed, and the joint welding points of the irregular steel pipe lattice column are ground and touched up with paint.

[0027] The present invention can achieve the following effects: This invention provides a method for ground pre-assembly and segmented hoisting construction of large irregular steel pipe lattice columns, which has the following significant advantages compared with the prior art: I. Significantly Reduced Safety Risks of High-Altitude Operations: Overturning the traditional "segmentation first, assembly later" approach, this method adopts a process of "pre-assembly on the ground, followed by disassembly and segmented hoisting after overall forming." Over 95% of the welding of intersecting nodes and the assembly of web members are moved to safe ground areas, leaving only a very small number of main chord butt welds for high-altitude operations. This greatly reduces the frequency of high-altitude hot work and hoisting, fundamentally avoiding the risks of falls from heights and being struck by objects.

[0028] II. Significantly Improved Forming Accuracy of Irregular Curved Surfaces: By conducting 1:1 full-size layout on the ground, a unified single benchmark is established, eliminating the cumulative errors of segmented independent assembly. Combined with "V-shaped limiting pads" and "full-length rigid jigs," the self-weight deflection and slippage of thick-walled steel pipes are effectively constrained, ensuring the smoothness of the curved surface lines and the accuracy of geometric dimensions, thus solving the problem of misaligned edges at the interfaces of irregular components.

[0029] III. Effective Control of Welding Deformation and Quality: Overall welding is performed on a rigid ground-based jig, employing a global pre-reserved shrinkage allowance and intermittent diffusion welding process. This effectively offsets shrinkage deformation at multiple welding nodes, preventing component twisting and bending. Simultaneously, the stable ground environment, unaffected by wind, rain, or temperature differences, results in excellent weld formation quality and a significantly improved first-pass yield for UT (Ultra-Technical Testing) inspections, reducing the need for rework at heights.

[0030] IV. Shortened construction period and reduced overall costs: Ground assembly is highly efficient and unaffected by inclement weather; segmented hoisting units only require quick on-site alignment, eliminating the need for repeated high-altitude adjustments, significantly reducing the time spent by large crawler cranes. Furthermore, the elimination of full-scale scaffolding requires only a simple operating platform, significantly reducing costs associated with measures and labor, resulting in substantial economic benefits.

[0031] V. Overcoming Transportation Bottlenecks and Wide Applicability: Addressing the industry pain point that oversized and overweight components cannot be transported in whole trucks, this invention only requires disassembling the components into individual steel pipes for transport, pre-assembling them on-site, and then disassembling and hoisting them, perfectly solving the transportation restriction problem. This technology can be widely applied to the construction of various large-span irregular lattice columns in high-speed rail stations, airports, stadiums, etc., and has extremely high promotional value. Attached Figure Description

[0032] Figure 1 This is a structural schematic diagram of the steel structure building of the present invention.

[0033] Figure 2 This is a schematic diagram of the connection structure between the lattice column and the roof truss of the present invention.

[0034] Figure 3 This is a schematic diagram of the structure of the V-shaped limiting pad of the present invention.

[0035] Figure 4 This is a schematic diagram of the structure of the horse plate of the present invention.

[0036] Figure 5 This is a schematic diagram of the connection structure between the temporary support and the outer steel pipe lattice column of the present invention.

[0037] Figure 6 This is a schematic diagram of the connection structure between the temporary support and the inner steel tube lattice column of the present invention.

[0038] Figure 7 This is a schematic diagram of the connection structure between the temporary support and the roadbed box of the present invention.

[0039] Figure 8 This is a schematic diagram of the internal structure of the roadbed box of the present invention.

[0040] Figure 9 This is a cross-sectional view of the roadbed box of the present invention.

[0041] Figure 10 This is a schematic diagram of the longitudinal structure of the roadbed box of the present invention.

[0042] In the diagram: 1. Outer steel pipe lattice column; 2. Inner steel pipe lattice column; 3. Roof truss; 4. Roof truss lower chord; 5. Main chord; 6. V-shaped limiting pad; 7. I-beam; 8. Mounting plate; 9. Temporary support; 10. Natural soil foundation; 11. Steel pipe; 12. Roadbed box; 13. Channel steel; 14. Longitudinal I-beam; 15. Transverse I-beam; 16. Support partition; 17. Support steel plate. Detailed Implementation

[0043] The technical solution of the invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0044] Example: Figure 1-10 As shown, this is applied to a large-span arched roof steel structure project for a large public building. The top of the steel structure building is a roof truss 3. The lower periphery of the roof truss 3 is supported by outer steel pipe lattice columns 1, and the lower interior of the roof truss 3 is supported by inner steel pipe lattice columns 2. Due to the huge size and irregular shape of the outer steel pipe lattice columns 1 and inner steel pipe lattice columns 2, they cannot be transported as a whole. Therefore, a ground pre-assembly and segmented hoisting construction method for large irregular steel pipe lattice columns is adopted, specifically including the following operational steps: Step 1: Site pretreatment and full-size layout. Select a flat, hardened site near the hoisting operation area and erect a full-length rigid assembly jig. Based on the lattice column design, project a 3D model onto the ground to create a 1:1 scale solid model, allowing for welding shrinkage allowance.

[0045] Specifically, the method for reserving welding shrinkage allowance is as follows: take the dimensions as a reference based on a single layout origin, and uniformly reserve a shrinkage compensation amount of 1 to 2 mm at each steel pipe intersection joint position to offset the cumulative deformation of multi-node welding.

[0046] Step 2: Ground positioning and assembly. The main chords 5 and web members of the outer steel pipe lattice column 1 and the inner steel pipe lattice column 2 are hoisted onto the jig. The overall positioning is carried out according to the solid details on the ground, so that the spatial position of all members coincides with the design three-dimensional projection.

[0047] The method for erecting the full-length rigid assembly frame is as follows: frame columns are arranged along the entire length of the lattice column. For straight chord sections, no less than 2 support points are set in each section; for curved chord sections, no less than 3 support points are set in each section; a V-shaped limiting pad 6 is set at the top of the frame column, and an I-beam 7 is provided between the V-shaped limiting pad 6 and the frame column.

[0048] Specifically, the V-shaped limiting pad 6 has the following structural features: the V-shaped limiting pad 6 has a V-shaped groove with the opening facing upwards, and the bottom of the V-shaped limiting pad 6 is welded and fixed to the I-beam 7 on the top surface of the jig; the outer wall of the main chord 5 is placed inside the V-shaped groove, and the two inclined surfaces of the V-shaped groove are in contact with the arc surface of the main chord 5 to constrain the axial sliding and circumferential rotation of the main chord 5 and ensure accurate positioning.

[0049] Step 3: Ground-based overall welding. On the ground-based jig, all intersecting nodes of the web members, except for the vertical segment interfaces, are fully penetrated welded to complete the node welding of the entire column; for the main chord 5 at the vertical segment interfaces, temporary fixing connectors are used for rigid locking, but no permanent welding is performed.

[0050] The temporary fixing connector is a temporary reinforcement type plate 8; the material of the plate 8 is the same as that of the main chord base material, and it is fixedly connected to the outer wall of the main chord 5 at the segment interface using welding materials that match the base material.

[0051] Specifically, the installation method of the mounting plate 8 is as follows: 2 to 4 sets of mounting plates 8 are symmetrically arranged around the circumference of the main chord 5 at the segment interface. Each set of mounting plates 8 is welded to the outer wall of the two main chord sections 5, and the mounting plates 8 achieve temporary rigid locking of the segment interface. The mounting plates 8 and the main chord 5 are connected by intermittent fillet welds to facilitate non-destructive removal by gas cutting or grinding. During the welding process, an intermittent diffusion welding process is adopted: welding is performed from the center of the node outwards, and adjacent nodes are welded after a gap of 1 to 2 nodes. Thick-walled pipes are preheated before welding, and multi-layer, multi-pass welding is used to control the interpass temperature to reduce welding deformation.

[0052] Step 4: Overall Re-measurement and Segmented Disassembly. The geometric dimensions of the integrally formed lattice column are re-measured. After the re-measurement is qualified, the temporary fixing connectors are removed, and the outer steel pipe lattice column 1 and the inner steel pipe lattice column 2 are disassembled into several segmented hoisting units.

[0053] Before removing the temporary fixed connectors, first punch alignment marks on the outer wall of the steel pipe at the segment interface as a benchmark for rapid matching at high altitude; during the removal process, temporarily support and reinforce the segment interface, and alternately cut the horse plate 8 to release stress and prevent deformation caused by sudden stress changes.

[0054] Step 5: Segmented hoisting and high-altitude assembly. Each segmented hoisting unit is hoisted to its installation position in sequence and aligned according to the positioning benchmark during pre-assembly. Only the main chord 5 at the vertical segment interface is welded at high altitude to complete the connection and fixation between the outer steel pipe lattice column 1 and the inner steel pipe lattice column 2 and the lower chord surface 4 of the roof truss 3.

[0055] In addition, this embodiment also includes a synchronous construction step for the lattice column support system: during the placement of the segmented hoisting unit, temporary supports 9 are set on the sides of the outer steel pipe lattice column 1 and the inner steel pipe lattice column 2, and the bottom of the temporary supports 9 is set on the roadbed box 12 on the natural soil foundation 10; after the outer steel pipe lattice column 1 or the inner steel pipe lattice column 2 is installed and adjusted, the bottom of the temporary supports 9 is welded and fixed to the roadbed box 12.

[0056] Specifically, the temporary support 9 is vertically supported by steel pipe 11, with a vertical bearing capacity design value of not less than 700kN. The contact area between the roadbed box 12 and the ground meets the characteristic value requirements of the foundation bearing capacity. The roadbed box 12 is made of steel plate and steel keel with a thickness of not less than 20mm to ensure the safety and stability of the support system.

[0057] Specifically, the roadbed box 12 includes a rectangular frame structure welded from channel steel 13, which ensures the overall profile stability of the box. Inside the rectangular frame formed by the channel steel 13, several transverse I-beams 15 are arranged, primarily bearing bending loads. To further enhance the rigidity and integrity of the roadbed box, several longitudinal I-beams 14 are welded between the channel steel 13 and the transverse I-beams 15, as well as between adjacent transverse I-beams 15, forming a grid-like load-bearing structure. Furthermore, to eliminate gaps between the steel components and prevent deformation, supporting partitions 16 are provided between the longitudinal I-beams 14 and the channel steel 13, as well as between adjacent longitudinal I-beams 14. The supporting partitions 16 are welded and fixed to the channel steel 13 and the transverse I-beams 15, effectively connecting the beams into a whole. Supporting steel plates 17 are welded to the upper and lower end faces of the channel steel 13 frame, serving as the load-bearing panels of the roadbed box.

[0058] In summary, the ground pre-assembly and segmented hoisting construction method for this large irregular steel pipe lattice column effectively solves the problem of transporting the giant irregular lattice column due to its overall excessive size. Ground pre-assembly ensures the forming accuracy of the irregular curved surface, significantly reduces the amount of high-altitude welding and safety risks, shortens the construction period, and reduces the overall cost.

[0059] High-altitude safety risks are significantly reduced: except for the segmented interfaces, all intersecting nodes and web member welding are completed on the ground, with only two circumferential seams at high altitudes, greatly reducing high-altitude hot work and hoisting operations. Calculations show that safety protection costs are reduced by more than 60%.

[0060] Controllable precision in the forming of irregular curved surfaces: Relying on a full-length rigid frame and 1:1 overall layout to establish a unified three-dimensional benchmark, there is no segmented independent assembly error, the axis, elevation, and smoothness of the curved surface meet the requirements of architectural design, and the first-time acceptance rate of dimensions is significantly improved.

[0061] Welding deformation is controllable and rework rate is low: multiple shape control methods, including rigid ground jig constraint, global uniform shrinkage allowance, and interval diffusion welding, avoid twisting and lateral bending; no wind or temperature difference interference on the ground, excellent weld formation quality, and significantly improved UT flaw detection first pass rate.

[0062] Significant savings in construction time and equipment costs: After pre-assembly on the ground, only three segmented hoisting operations are required, eliminating the need for repeated hoisting and correction of individual parts, and significantly reducing the workload of large cranes; the elimination of full-coverage high-altitude scaffolding reduces the cost of temporary measures.

[0063] It has strong adaptability to the construction environment: ground welding is not limited by strong winds, rain, or low temperatures, and can be carried out in all weather conditions. Only the hoisting process is affected by the weather, which greatly increases the number of effective construction days.

[0064] Solving the pain points of oversized transportation: The factory only transports individual steel pipes, avoiding the approval process and high transportation costs for oversized transportation of large and irregularly shaped components.

[0065] The process is highly versatile: it can be adapted to various large-section irregular lattice columns and large-span spatial trusses in high-speed railway stations, exhibition halls, and stadiums; the number of segments can be flexibly adjusted according to the weight of the components and transportation conditions; the jig can be reused, resulting in outstanding comprehensive economic benefits.

[0066] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention are covered by the patent scope of the present invention.

Claims

1. A method for ground pre-assembly and segmented hoisting construction of large irregular steel pipe lattice columns, characterized in that... The following steps are included: Step 1: Site pretreatment and full-size layout: Select a hardened site near the hoisting operation surface and set up a full-length rigid assembly jig; according to the lattice column design, project a 3D model onto the ground to lay out a 1:1 solid model, and reserve the welding shrinkage allowance; The top of the steel structure building is a roof truss (3). The lower periphery of the roof truss (3) is supported by an outer steel pipe lattice column (1), and the lower interior of the roof truss (3) is supported by an inner steel pipe lattice column (2). Step 2: Ground positioning and assembly: hoist the main chords and web members of the outer steel pipe lattice column (1) and the inner steel pipe lattice column (2) onto the jig, and perform overall positioning based on the physical details on the ground so that the spatial position of all members coincides with the design three-dimensional projection; Step 3: Ground-based overall welding and forming: On the ground-based jig, all intersecting nodes of the web members, except for the vertical segment interfaces, are fully penetrated welded to complete the node welding work of the entire column; for the main chord members at the vertical segment interfaces, temporary fixing connectors are used for rigid locking, but no permanent welding is performed; Step 4: Overall re-measurement and segmented disassembly: The geometric dimensions of the lattice column after overall forming are re-measured. After the re-measurement is qualified, the temporary fixed connection is removed, and the outer steel pipe lattice column (1) and the inner steel pipe lattice column (2) are disassembled into several segmented hoisting units. Step 5: Segmented hoisting and high-altitude assembly: Each segmented hoisting unit is hoisted to the installation position in sequence, and aligned according to the positioning benchmark during pre-assembly. Only the main chord at the vertical segment interface is welded at high altitude to complete the connection and fixation of the outer steel pipe lattice column (1) and the inner steel pipe lattice column (2) with the lower chord surface (4) of the roof truss (3).

2. The ground pre-assembly and segmented hoisting construction method for large irregular steel pipe lattice columns according to claim 1, characterized in that, In the first step, the specific method for reserving the welding shrinkage allowance is as follows: take the dimensions as a reference based on a single layout origin, and uniformly reserve a shrinkage compensation amount of 1 to 2 mm at each steel pipe intersection joint position to offset the cumulative deformation of multi-node welding.

3. The ground pre-assembly and segmented hoisting construction method for large irregular steel pipe lattice columns according to claim 1, characterized in that, In the first step, the method for erecting the full-length rigid assembly frame is as follows: the frame columns are arranged along the entire length of the lattice column. For the straight chord section, no less than 2 support points are set for each section; for the curved chord section, no less than 3 support points are set for each section; a V-shaped limiting pad (6) is set on the top of the frame column, and an I-beam (7) is provided between the V-shaped limiting pad and the frame column.

4. The ground pre-assembly and segmented hoisting construction method for large irregular steel pipe lattice columns according to claim 3, characterized in that, The V-shaped limiting pad (6) has the following structural features: the V-shaped limiting pad (6) has a V-shaped groove with the opening facing upwards; the bottom of the V-shaped limiting pad (6) is welded and fixed to the I-beam (7) on the top surface of the jig; the outer wall of the main chord (8) is placed inside the V-shaped groove, and the two inclined surfaces of the V-shaped groove are in contact with the arc surface of the main chord (5) to constrain the axial sliding and circumferential rotation of the main chord (5).

5. The ground pre-assembly and segmented hoisting construction method for large irregular steel pipe lattice columns according to claim 1, characterized in that, In the third step, the temporary fixed connection is a temporary reinforced board (8); the material of the board (8) is the same as that of the main chord base material, and it is fixedly connected to the outer wall of the main chord (5) at the segment interface using welding material that matches the base material.

6. The ground pre-assembly and segmented hoisting construction method for large irregular steel pipe lattice columns according to claim 5, characterized in that, The installation method of the mounting plate (8) is as follows: 2 to 4 sets of mounting plates (8) are symmetrically arranged around the circumference of the main chord at the segment interface. Each set of mounting plates (8) is welded to the outer wall of the two main chords (5) respectively, and the temporary rigid locking of the segment interface is achieved by the mounting plates (8). The mounting plates (8) and the main chords (5) are connected by intermittent fillet welds so that they can be removed without damage by gas cutting or grinding.

7. The ground pre-assembly and segmented hoisting construction method for large irregular steel pipe lattice columns according to claim 1, characterized in that, In the third step of ground welding, an intermittent diffusion welding process is adopted: welding is performed from the center of the node outward, and adjacent nodes are welded after a gap of 1 to 2 nodes. Thick-walled pipes are preheated before welding, and multi-layer and multi-pass welding is used to control the interpass temperature.

8. The ground pre-assembly and segmented hoisting construction method for large irregular steel pipe lattice columns according to claim 1, characterized in that, In the fourth step, before removing the temporary fixed connectors, first stamp alignment marks on the outer wall of the steel pipe at the segment interface as a reference for high-altitude rapid matching; during the removal process, temporarily support and reinforce the segment interface, and alternately cut the horse plate (8) to release stress.

9. The ground pre-assembly and segmented hoisting construction method for large irregular steel pipe lattice columns according to claim 1, characterized in that, It also includes the synchronous construction steps of the lattice column support system: during the placement of the segmented hoisting unit, temporary supports are set on the sides of the outer steel pipe lattice column (1) and the inner steel pipe lattice column (2), and the bottom of the temporary support (9) is set on the roadbed box (12) on the natural soil foundation (10); after the outer steel pipe lattice column (1) or the inner steel pipe lattice column (2) is installed and adjusted, the bottom of the temporary support (9) is welded and fixed to the roadbed box (12).

10. The ground pre-assembly and segmented hoisting construction method for large irregular steel pipe lattice columns according to claim 9, characterized in that, The temporary support (9) is vertically supported by steel pipe (11), and its vertical bearing capacity design value is not less than 700kN. The contact area between the roadbed box (12) and the ground meets the requirements of the foundation bearing capacity characteristic value. The roadbed box (12) is made of steel plate and steel keel with a thickness of not less than 20mm.

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