A transition section structure suitable for truss-tower hybrid wind turbine towers

Abstract

This utility model discloses a transition section structure suitable for truss-tower hybrid wind turbine towers, belonging to the technical field of wind power generation equipment. It includes a central vertical tower, upper / lower support flange cast steel nodes, strut intersection cast steel nodes, upper / lower support rods, inter-column transverse connecting rods, and circumferential and vertical stiffening plates. The central vertical tower is connected to the upper / lower support rods via upper / lower support flange cast steel nodes. Both upper and lower support rods are inclined radially, with the upper support rod having an angle of 45°–55° with the horizontal plane and the lower support rod having an angle of -10°–10° with the horizontal plane. Adjacent strut intersection cast steel nodes are connected by inter-column transverse connecting rods. A grid-like stiffening plate is provided in the tower connection area to enhance local stiffness. The cast steel nodes adopt a gradual transition structure to optimize force transmission, and all components are connected by friction-type bolts. This structure, through inclined bracing force transmission, node optimization, and stiffening reinforcement, improves stability and fatigue resistance, simplifies construction, is suitable for complex wind farms, and meets the requirements of high-power units.

Description

Technical Field

[0001] This utility model relates to the field of wind power generation equipment technology, and in particular to a conversion section structure suitable for truss-tower hybrid wind power towers. Background Technology

[0002] Wind power generation, as an important form of renewable energy, is widely used globally. Wind turbine towers, as the core supporting structure of wind turbine generators, directly affect the operational safety, stability, and service life of these generators through their design and optimization. Existing wind turbine towers mainly include steel pipe towers, truss towers, and hybrid towers. Among these, truss towers are widely used in large-capacity wind turbine generators and in complex terrain environments due to their advantages such as high material utilization, light weight, and ease of transportation and installation.

[0003] However, traditional truss towers still face many challenges in practical applications: in complex wind farm environments, structural stability is easily affected and it is difficult to effectively resist dynamic loads such as wind vibration; the connection nodes are subjected to wind vibration, dynamic loads and fatigue effects for a long time, which can easily lead to stress concentration, potentially causing structural loosening or fatigue failure; the force transmission path in the connection area between the truss tower and the upper cylindrical tower section is unreasonable, and the overall force balance is poor, which restricts the application of wind power towers in large-megawatt units and complex wind farms.

[0004] To address the aforementioned issues, there is an urgent need for an optimized transition section structure. Through innovative structural design and connection methods, the overall stability, fatigue resistance, and ease of construction of truss-tower hybrid wind turbine towers can be improved to meet the high tower requirements of large-megawatt wind turbines and complex wind farm environments. Utility Model Content

[0005] The purpose of this utility model is to provide a transition section structure suitable for truss-tower hybrid wind turbine towers, in order to solve the problems of unreasonable connection between the truss tower and the upper cylindrical tower section, insufficient structural stability, weak fatigue resistance and poor construction convenience in existing truss-tower hybrid wind turbine towers, and to achieve the goals of optimizing the force transmission path, improving the structural stress balance, extending fatigue life, simplifying the installation process and enhancing the adaptability to complex wind farm environments.

[0006] To achieve the above objectives, this utility model provides a transition section structure suitable for truss-tower hybrid wind turbine towers, including a central vertical tower. The upper surface of the central vertical tower is uniformly provided with upper support flange cast steel nodes in a circular shape, the lower surface of the central vertical tower is uniformly provided with lower support flange cast steel nodes in a circular shape, and the central vertical tower is surrounded by cast steel nodes with intersecting struts in a circular shape.

[0007] The upper support flange cast steel node is connected to the upper end of the support rod intersection cast steel node through the upper support rod. The upper support flange cast steel node is provided with two upper support rods. The upper end of the support rod intersection cast steel node is respectively connected to the corresponding upper support rods on the opposite side of the two adjacent upper support flange cast steel nodes.

[0008] The lower support flange cast steel node is connected to the middle of the support rod intersecting cast steel node through the lower support rod, and each lower support flange cast steel node is connected to one lower support rod;

[0009] The side ends of the two adjacent struts at the intersection of the cast steel nodes are connected by inter-column transverse connecting rods;

[0010] The area connecting the central vertical tower to the upper and lower cast steel flange nodes is provided with circumferential stiffening plates and vertical stiffening plates.

[0011] Preferably, the central vertical tower section is a vertical circular tube structure; the top of the central vertical tower section is provided with a T-shaped flange for connecting to the upper tower section;

[0012] The central vertical tower section is connected to the upper support flange cast steel node with a first group of bolt holes, and the central vertical tower section is connected to the lower support flange cast steel node with a second group of bolt holes. Both the first and second bolt hole groups are double-ring arc-shaped square hole groups, including an inner ring main load-bearing hole group and an outer ring auxiliary fastening hole group. The circumferential stiffening plate is located at the center between the inner ring horizontal bolt holes and the outer ring horizontal bolt holes. The vertical stiffening plate group connects the two circumferential stiffening plates, and the axis of the vertical stiffening plate coincides with the center distance line of the two vertical bolt holes.

[0013] Preferably, the upper support rod, the lower support rod, and the inter-column transverse connecting rod are all circular tube structures;

[0014] The upper support rod has an angle of 45° to 55° with the horizontal plane. The upper support rod includes an upper support rod body. The upper support rod body has a first connecting flange a connected to the upper support cast steel node and a first connecting flange b connected to the intersecting cast steel node of the support rod.

[0015] The lower support rod has an angle of -10° to 10° with the horizontal plane. The lower support rod includes a lower support rod body. The lower support rod body has a second connecting flange a connected to the lower support cast steel node and a second connecting flange b connected to the support rod intersecting cast steel node, respectively.

[0016] The two ends of the inter-column transverse connecting rod are respectively provided with a third connecting flange that connects to the cast steel node where the adjacent support rod intersects.

[0017] The first connecting flange, the second connecting flange, and the third connecting flange are all L-shaped flanges.

[0018] Preferably, the upper support flange cast steel node includes a lower dual-channel interface, a transition fusion section and a tower connection section, which together form an upwardly sloping inverted V-shaped structure;

[0019] The lower dual-channel interface consists of two independent annular cross-section interfaces. Each interface end is provided with an L-shaped flange with bolt hole groups, which is connected to the first connecting flange of the upper support rod by fasteners.

[0020] The two annular sections of the transition fusion section start from the L-shaped flange connection end. The initial section maintains an annular section, the section of the gradual change section gradually changes from a circle to an ellipse, and the two elliptical sections of the fusion section gradually approach each other and merge into a single arc-shaped rectangular tube.

[0021] The tower connecting section is composed of a rectangular arc plate that fits against the central vertical tower wall. The arc plate is provided with two rings of bolt holes with the axis of the arc-shaped rectangular tube as a reference. The position of each bolt hole is strictly aligned with the first bolt hole group on the central vertical tower.

[0022] Preferably, the cast steel node of the lower support flange adopts a round-to-square transition structure, including an outer connecting end, an inner connecting end, and a transition deformation section;

[0023] The outer connecting end has a circular cross section and is provided with an L-shaped flange with a group of bolt holes, which is connected to the second connecting flange of the lower support rod by fasteners;

[0024] The inner connecting end is a rectangular arc plate that fits against the outer wall of the central vertical tower, and it is provided with two rings of bolt holes corresponding to the second bolt hole group.

[0025] The transition deformation section connects the circular cross-section and the rectangular arc plate. Its cross-section gradually changes from a circle to an arc-shaped square, and the geometric parameters satisfy that the diameter of the circular end is consistent with the outer diameter of the lower support rod.

[0026] Preferably, the strut confluence cast steel node is a six-way pipe irregular structure, including a lower connection structure, a middle three-way branch structure and an upper double-fork branch structure, and each interface is welded with an L-shaped flange;

[0027] The lower connecting structure is a vertically arranged circular tube with an outer diameter that matches the tower leg column.

[0028] The central three-way branch structure includes a central branch and two lateral branches. The end of the central branch is a circular cross-section, the axis points to the center of the tower, and the outer diameter and inclination angle match the lower support rod. The two ends of the two lateral branches are both circular cross-sections, pointing to the adjacent intersecting cast steel nodes of the support rods, and the outer diameter matches the inter-column transverse connecting rod.

[0029] The upper double-branch structure is formed by the lower circular tube extending upward and then branching, including two upward-sloping circular sections, which are respectively connected to the two upper support rods, and the outer diameter matches the upper support rods.

[0030] Preferably, the T-type flange includes a vertical connecting section, a radial flange, and a transition cone section; the L-type flange includes an axial connecting section, a radial flange, and a transition fillet.

[0031] Therefore, the present invention adopts the above-mentioned conversion section structure suitable for truss-tower hybrid wind turbine towers, and has the following technical effects:

[0032] (1) This application forms a stable spatial force system by combining the upper and lower support rods to form a diagonal bracing force transmission system with the intersecting cast steel nodes of the six-way pipe irregular support rods. This system effectively resists dynamic loads and vibrations under complex wind fields and reduces stress concentration at the connection nodes. The circumferential stiffening plate and the vertical stiffening plate form a three-dimensional grid-like reinforcement system in the connection area of ​​the central vertical tower, which significantly improves the local stiffness and fatigue resistance of key parts.

[0033] (2) The upper support flange cast steel node of this application adopts an inverted V-shaped structure and a cross-section gradual transition design of "circle → ellipse → rectangle", while the lower support flange cast steel node adopts a circle to square transition structure of "circle → arc square" to achieve uniform load transfer from the support rod to the tower, avoid local stress concentration, and extend the fatigue life of the structure.

[0034] (3) This application adopts a modular design concept, and each component can be prefabricated. A reliable friction-type connection is formed by high-strength pre-tightened bolts, making the installation accuracy easy to control and significantly shortening the on-site construction cycle. The standardized cast steel nodes and fastener design facilitates large-scale production and reduces manufacturing costs.

[0035] (4) This application is designed for the high tower requirements of large megawatt wind turbines. It can effectively adapt to complex wind field environments, improve the load-bearing capacity and service life of wind turbine truss towers, and is suitable for high-power wind turbines and large rotor diameter truss-tower hybrid wind turbine towers. It has broad application prospects.

[0036] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0037] Figure 1 This is an isometric view of the structure of this utility model;

[0038] Figure 2 This is a top view of the structure of this utility model;

[0039] Figure 3 This is a front view of the structure of this utility model;

[0040] Figure 4 This is an axonometric view of the central vertical tower section of this utility model;

[0041] Figure 5 This is an isometric view of the upper support rod of this utility model;

[0042] Figure 6 This is an isometric view of the lower support rod of this utility model;

[0043] Figure 7 This is an axonometric view of the intercolumn transverse connecting rod of this utility model;

[0044] Figure 8 This is an isometric view of the cast steel joint where the struts intersect, according to this utility model.

[0045] Figure 9 This is an isometric view of the cast steel node of the upper support flange of this utility model;

[0046] Figure 10 This is an isometric view of the cast steel node of the lower support flange of this utility model.

[0047] Figure Labels

[0048] 100. Central vertical tower section; 101. Central vertical tower section body; 102. T-flange; 103. First bolt hole group; 104. Second bolt hole group; 105. Circumferential stiffening plate; 106. Vertical stiffening plate; 200. Upper support rod; 201. Upper support rod body; 202. First connecting flange a; 203. First connecting flange b; 300. Lower support rod; 301. Lower support rod body; 302. Second connecting flange a; 303. Second connecting flange b; 400. Intercolumn Horizontal connecting rod; 401, Inter-column horizontal connecting rod body; 402, Third connecting flange; 500, Cast steel node where struts intersect; 501, Lower connecting structure; 502, Middle three-way branch structure; 503, Upper double-fork branch structure; 600, Cast steel node of upper support flange; 601, Lower double-channel interface; 602, Transition fusion section; 603, Tower connecting section; 700, Cast steel node of lower support flange; 701, Outer connecting end; 702, Transition deformation section; 703, Inner connecting end. Detailed Implementation

[0049] The technical solution of this utility model will be further described below with reference to the accompanying drawings and embodiments.

[0050] Unless otherwise defined, the technical or scientific terms used in this utility model shall have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar terms used in this utility model do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0051] like Figures 1 to 3 As shown, a diagonal bracing transition section structure suitable for quadrilateral leg truss wind turbine towers adopts a modular design. The core components include a central vertical tower section 100, upper support rod 200, lower support rod 300, inter-column transverse connecting rod 400, cast steel joints at the strut intersections 500, cast steel joints at the upper support flanges 600, cast steel joints at the lower support flanges 700, circumferential stiffening plates 105 and vertical stiffening plates 106. All components are reliably connected by high-strength pre-tightened bolts. The specific structure is as follows:

[0052] like Figure 4 As shown, the central vertical tower 100 is a vertical circular tube structure, including a central vertical tower body 101. The central vertical tower 100 serves as the main load-bearing component, and its diameter and wall thickness are determined based on wind turbine load calculations. A T-flange 102 is welded to the top of the central vertical tower body 101. The T-flange 102 includes a vertical connecting section, a radial flange, and a transition cone section. It is manufactured using an integral molding process to ensure structural integrity and is used to connect to the upper tower. (The last sentence about the T-flange is incomplete and likely refers to the same material.)

[0053] The central vertical tower 100 has a first bolt hole group 103 at the connection end with the upper support flange cast steel node 600, and a second bolt hole group 104 at the connection end with the lower support flange cast steel node 700. Both are double-ring arc-shaped square hole groups, consisting of an inner ring main load-bearing hole group and an outer ring auxiliary fastening hole group, and are CNC machined with strict control over the hole spacing accuracy. A circumferential stiffening plate 105 and a vertical stiffening plate 106 are welded inside the connection area: the circumferential stiffening plate 105 is positioned at the center between the inner and outer ring horizontal bolt holes, mainly bearing circumferential stress; the vertical stiffening plate 106 connects the two circumferential stiffening plates 105, with its axis coinciding with the center distance line of the two vertical bolt holes, effectively resisting axial deformation; together, they form a grid-like reinforcement system, jointly bearing circumferential stress and resisting axial deformation, improving local stiffness and fatigue resistance.

[0054] like Figure 5 As shown, both the upper support rod 200 and the lower support rod 300 are circular tube structures, and the wall thickness of the rods is determined based on stress analysis. The upper support rod 200 has an angle of 45° to 55° with the horizontal plane and includes an upper support rod body 201. The upper support rod body 201 has a first connecting flange a202 and a first connecting flange b203 at both ends. The first connecting flange a202 is connected to the upper support cast steel node, and the first connecting flange b203 is connected to the support rod intersection cast steel node 500.

[0055] like Figure 6 As shown, the lower support rod 300 has an angle of -10 to 10° with the horizontal plane, and includes a lower support rod body 301. The lower support rod body 301 has a second connecting flange a302 and a second connecting flange b303 at both ends. The second connecting flange a302 is connected to the lower support cast steel node, and the second connecting flange b303 is connected to the support rod intersection cast steel node 500.

[0056] All of the above-mentioned connecting flanges are L-type flanges, including an axial connecting section, a radial flange, and a transition fillet. After welding with the rod body, they undergo stress-relieving heat treatment to improve the mechanical properties of the welded area.

[0057] like Figure 7 As shown, the inter-column transverse connecting rod 400 is a circular tube structure, including the inter-column transverse connecting rod body 401. The two ends of the inter-column transverse connecting rod body 401 are provided with third connecting flanges 402, which are also L-shaped flanges, used to connect adjacent struts to the intersecting cast steel nodes 500 to ensure the lateral stiffness of the overall structure.

[0058] like Figure 9As shown, the cast steel node 600 of the upper support flange adopts an upwardly sloping inverted V-shaped structure, including a lower dual-channel interface 601, a transition fusion section 602, and a tower connection section 603. The lower dual-channel interface 601 consists of two independent annular cross-section interfaces, and each interface end is provided with an L-shaped flange with bolt hole groups, which is connected to the first connecting flange a202 of the upper support rod 200 by fasteners.

[0059] The two annular sections of the transition fusion section 602 start from the connection end. The initial section maintains an annular section, the transition section gradually changes from a circle to an ellipse, and the two elliptical sections of the fusion section gradually approach and merge into a single arc-shaped rectangular tube, achieving a uniform transition of force. The tower connection section 603 is a rectangular arc plate that fits against the wall of the central vertical tower 100. The arc plate has two rings of bolt holes that are strictly aligned with the first bolt hole group 103, and is connected to the central vertical tower 100 by bolts.

[0060] like Figure 10 As shown, the cast steel node 700 of the lower support flange adopts a round-to-square transition structure, including an outer connecting end 701, a transition deformation section 702, and an inner connecting end 703. The outer connecting end 701 has a circular cross-section and an L-shaped flange with bolt hole groups, which is connected to the second connecting flange a302 of the lower support rod 300 by fasteners; the inner connecting end 703 is a rectangular arc plate that fits against the outer wall of the central vertical tower 100, and has two rings of bolt holes corresponding to the second bolt hole group 104; the transition deformation section 702 connects the circular cross-section and the rectangular arc plate, and the cross-section gradually changes from a circle to an arc-shaped square. The geometric parameters satisfy that the diameter of the circular end is consistent with the outer diameter of the lower support rod 300, so as to realize the smooth transfer of horizontal load to the tower.

[0061] like Figure 8 As shown, the strut confluence cast steel node 500 is a six-way pipe irregular structure, which adopts an integral casting process. It includes a lower connection structure 501, a middle three-way branch structure 502 and an upper double-fork branch structure 503. Each interface is welded with an L-shaped flange. The lower connecting structure 501 has a vertical circular tube cross-section, with its outer diameter matching that of the tower leg column; the middle three-way branch structure 502 includes a central branch and two lateral branches; the end of the central branch has a circular cross-section, with its axis pointing to the center of the tower, and its outer diameter and inclination angle matching that of the lower support rod 300, used to connect the lower support rod 300; the end of the two lateral branches has a circular cross-section, pointing to the cast steel node 500 where adjacent support rods intersect, and matching that of the inter-column transverse connecting rod 400, used to connect the inter-column transverse connecting rod 400; the upper double-forked branch structure 503 is formed by the lower circular tube extending upwards and then forking, with two upwardly inclined circular cross-sections connecting to the two upper support rods 200 respectively, and their outer diameters matching those of the upper support rods 200, achieving efficient transmission of multi-directional loads.

[0062] Working principle:

[0063] During installation, the central vertical tower 100 must be installed vertically at the center of the quadrilateral truss, with its verticality deviation controlled within the design allowable range; the upper support rod 200 is installed at an angle of 45° to 55° with the horizontal plane, with the angle error not exceeding the specified value; the lower support rod 300 has an angle between -10° and 10° with the horizontal plane; all bolted connections use high-strength bolts, and the preload is applied according to the design requirements to ensure a reliable friction-type connection; all flange connection surfaces must be precision machined to ensure that the flatness meets the design requirements.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solution of this utility model, and these modifications or equivalent substitutions cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of this utility model.

Claims

1. A transition section structure suitable for a hybrid truss-tubular wind tower, characterized in that: It includes a central vertical tower, the upper surface of which is uniformly provided with upper support flange cast steel nodes in a circular shape, the lower surface of which is uniformly provided with lower support flange cast steel nodes in a circular shape, and the central vertical tower is surrounded by cast steel nodes with intersecting struts in a circular shape. The upper support flange cast steel node is connected to the upper end of the support rod intersection cast steel node through the upper support rod. The upper support flange cast steel node is provided with two upper support rods. The upper end of the support rod intersection cast steel node is respectively connected to the corresponding upper support rods on the opposite side of the two adjacent upper support flange cast steel nodes. The lower support flange cast steel node is connected to the middle of the support rod intersecting cast steel node through the lower support rod, and each lower support flange cast steel node is connected to one lower support rod; The side ends of the two adjacent struts at the intersection of the cast steel nodes are connected by inter-column transverse connecting rods; The area connecting the central vertical tower to the upper and lower cast steel flange nodes is provided with circumferential stiffening plates and vertical stiffening plates.

2. The transition section structure suitable for the hybrid wind tower of truss-tube according to claim 1, characterized in that: The central vertical tower is a vertical circular tube structure; the top of the central vertical tower is equipped with a T-shaped flange for connecting to the upper tower. The central vertical tower section is connected to the upper support flange cast steel node with a first group of bolt holes, and the central vertical tower section is connected to the lower support flange cast steel node with a second group of bolt holes. Both the first and second bolt hole groups are double-ring arc-shaped square hole groups, including an inner ring main load-bearing hole group and an outer ring auxiliary fastening hole group. The circumferential stiffening plate is located at the center between the inner ring horizontal bolt holes and the outer ring horizontal bolt holes. The vertical stiffening plate group connects the two circumferential stiffening plates, and the axis of the vertical stiffening plate coincides with the center distance line of the two vertical bolt holes.

3. The transition section structure suitable for the hybrid wind tower of truss-tube according to claim 2, characterized in that: The upper support rod, the lower support rod, and the intercolumn transverse connecting rod are all circular tube structures; The upper support rod has an angle of 45° to 55° with the horizontal plane. The upper support rod includes an upper support rod body. The upper support rod body has a first connecting flange a connected to the upper support flange cast steel node and a first connecting flange b connected to the intersecting cast steel node of the support rod, respectively. The lower support rod has an angle of -10° to 10° with the horizontal plane. The lower support rod includes a lower support rod body. The lower support rod body has a second connecting flange a connected to the lower support flange cast steel node and a second connecting flange b connected to the support rod intersecting cast steel node, respectively. The two ends of the inter-column transverse connecting rod are respectively provided with a third connecting flange that connects to the cast steel node where the adjacent support rod intersects. The first connecting flange, the second connecting flange, and the third connecting flange are all L-shaped flanges.

4. The transition section structure suitable for the hybrid wind tower of truss-tube according to claim 3, characterized in that: The upper support flange cast steel node includes a lower dual-channel interface, a transition fusion section and a tower connection section, which together form an upward-sloping inverted V-shaped structure; The lower dual-channel interface consists of two independent annular cross-section interfaces. Each interface end is provided with an L-shaped flange with bolt hole groups, which is connected to the first connecting flange of the upper support rod by fasteners. The two annular sections of the transition fusion section start from the L-shaped flange connection end. The initial section maintains an annular section, the section of the gradual change section gradually changes from a circle to an ellipse, and the two elliptical sections of the fusion section gradually approach each other and merge into a single arc-shaped rectangular tube. The tower connecting section is composed of a rectangular arc plate that fits against the central vertical tower wall. The arc plate is provided with two rings of bolt holes with the axis of the arc-shaped rectangular tube as a reference. The position of each bolt hole is strictly aligned with the first bolt hole group on the central vertical tower.

5. The transition section structure suitable for the hybrid wind tower of truss-tube according to claim 4, characterized in that: The lower support flange cast steel node adopts a round-to-square transition structure, including an outer connecting end, an inner connecting end, and a transition deformation section; The outer connecting end has a circular cross section and is provided with an L-shaped flange with a group of bolt holes, which is connected to the second connecting flange of the lower support rod by fasteners; The inner connecting end is a rectangular arc plate that fits against the outer wall of the central vertical tower, and it is provided with two rings of bolt holes corresponding to the second bolt hole group. The transition deformation section connects the circular cross-section and the rectangular arc plate. Its cross-section gradually changes from a circle to an arc-shaped square, and the geometric parameters satisfy that the diameter of the circular end is consistent with the outer diameter of the lower support rod.

6. The transition section structure suitable for the hybrid wind tower of truss-tube according to claim 5, characterized in that: The strut confluence cast steel node is a six-way pipe irregular structure, including a lower connection structure, a middle three-way branch structure and an upper double-fork branch structure, with an L-shaped flange welded to each interface; The lower connecting structure is a vertically arranged circular tube with an outer diameter that matches the tower leg column. The central three-way branch structure includes a central branch and two lateral branches. The end of the central branch is a circular cross-section, the axis points to the center of the tower, and the outer diameter and inclination angle match the lower support rod. The two ends of the two lateral branches are both circular cross-sections, pointing to the adjacent intersecting cast steel nodes of the support rods, and the outer diameter matches the inter-column transverse connecting rod. The upper double-branch structure is formed by the lower circular tube extending upward and then branching, including two upward-sloping circular sections, which are respectively connected to the two upper support rods, and the outer diameter matches the upper support rods.

7. The transition section structure according to claim 6, characterized in that: The T-type flange includes a vertical connecting section, a radial flange, and a transition cone section; the L-type flange includes an axial connecting section, a radial flange, and a transition fillet.

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