A Structural Transition Section and Construction Method for a Steel Bridge Tower - Composite Structure Bridge Tower

Abstract

The present invention discloses a structure and construction method for the transition section between a steel bridge tower and a composite structure bridge tower. The structure includes an upper tower column made of steel structure, a lower tower column of steel-concrete composite structure, a middle tower column, a bearing steel plate and stiffening ribs. The middle tower column includes a transition section outer wall plate arranged on the outer periphery, a transition section inner wall plate arranged on the inner ring, and transition section stiffening ribs. The transition section inner wall plates are separated into a plurality of compartments by transition section steel diaphragms, and the compartments are filled with concrete. The middle tower column is divided into a first transition section and a second transition section. The cross-section of the first transition section remains unchanged in the vertical direction and is adapted to the cross-section at the bottom of the upper tower column. The inner ring of the cross-section of the second transition section gradually expands in the vertical direction until it is adapted to the cross-section of the lower tower column when reaching the bottom. The transition section structure of the present invention realizes the connection between the steel bridge tower and the steel-concrete composite structure bridge tower through the gradually changing cross-section structure of the middle tower column, with reasonable structural force and clear force transmission path.

Description

Technical Field

[0001] The present invention belongs to the technical field of bridge engineering, and more specifically, relates to a structure and construction method for the transition section between a steel bridge tower and a composite structure bridge tower. Background Art

[0002] With the development and application of long-span bridge engineering, higher requirements are put forward for the mechanical properties of bridge tower structures. Innovative research is still needed on the structural design of suitable bridge towers for long-span bridges. According to the cross-sectional form, common bridge tower structures can be divided into: concrete bridge towers, steel bridge towers, and steel-concrete composite structure bridge towers. Among them, the steel-concrete composite structure bridge tower refers to pouring concrete in a steel tower and combining steel and concrete through connectors to form an integral structure that jointly bears force. The steel-concrete composite structure bridge tower utilizes the restraint effect of the steel wall panel on the core concrete to improve the strength of the concrete, thereby improving the plasticity and toughness of the structure. At the same time, the core concrete can play a good supporting role for the steel wall panel, improving the ability of the steel tower wall to resist local buckling. In addition, the steel wall panel can also be used as a construction formwork for concrete, saving formwork costs and accelerating the construction progress.

[0003] In terms of the structural system, the bridge tower structure has also developed and innovated. Combining the above three types of bridge towers with different cross-sectional forms in the height direction forms a hybrid structure bridge tower. Among them, the steel tower-concrete tower hybrid structure bridge tower has been applied in engineering. Its upper tower column adopts a steel structure, and the lower tower column adopts a reinforced concrete structure, giving full play to the respective advantages of the steel bridge tower being easy for cable anchoring construction and the concrete bridge tower having large bearing capacity and stiffness, meeting the comprehensive requirements for the mechanical properties, engineering quality, and project cost of the bridge tower.

[0004] With the continuous development of bridge engineering, hybrid structure bridge towers formed by steel bridge towers and composite structure bridge towers have also begun to be applied in engineering. Its lower tower column adopts a steel-concrete composite structure, which can further exert the advantages of structural configuration and mechanical properties. Different from the combination of a steel tower and a concrete tower, the combination of a steel tower and a composite structure bridge tower must consider the transition of the steel structure in terms of cross-sectional form. Usually, a steel bridge tower is composed of an external steel shell and internal webs, while a composite structure bridge tower often adopts a hollow cross-section, with internal and external steel wall panels forming a pouring space for concrete. The steel structures of the two are usually not the same in cross-sectional form. It is necessary to set a transition section to smoothly transition between the two cross-sectional forms and transform the force model of the structure from pure steel structure force to the combined force of steel and concrete.

[0005] Therefore, it is necessary to propose a structure for the joint section between a steel bridge tower and a composite structure bridge tower that can effectively combine the steel tower and the steel-concrete composite structure bridge tower and achieve a smooth transition in cross-sectional structure and force form. Summary of the Invention

[0006] In view of the fact that the existing steel towers and composite structure bridge towers cannot achieve a smooth transition, the present invention provides a transition section structure for a steel bridge tower - composite structure bridge tower to solve such problems.

[0007] To achieve the above object, the present invention provides a transition section structure for a steel bridge tower - composite structure bridge tower, comprising: an upper tower column provided at the top, which is a steel structure; a lower tower column provided at the bottom, which is a steel - concrete composite structure; a middle tower column provided in the middle, including: a transition section outer wall plate provided on the outer periphery and a transition section inner wall plate provided on the inner ring. The transition section outer wall plate and the transition section inner wall plate are separated into a plurality of compartments by a transition section steel partition, and the compartments are filled with concrete; a bearing steel plate fixedly provided at the top of the middle tower column, the top of which is fixedly connected to the bottom of the upper tower column; and stiffening ribs, which are strip - shaped strengthening members extending along the axial direction, including a steel tower section stiffening rib with sides respectively fixed in the upper tower column, a transition section stiffening rib in the middle tower column, and a hybrid section stiffening rib in the lower tower column. The middle tower column is divided into a first transition section and a second transition section. The cross - section of the first transition section remains unchanged in the vertical direction and is adapted to the cross - section of the bottom of the upper tower column. The inner ring of the cross - section of the second transition section gradually expands in the vertical direction until it is adapted to the cross - section of the lower tower column at the bottom. Through the gradually changing cross - section structure of the middle tower column, a smooth transition between the steel bridge tower and the steel - concrete composite structure bridge tower is achieved, and the force - bearing model of the structure is transformed from pure steel structure force - bearing to joint force - bearing of steel and concrete.

[0008] Furthermore, the bearing steel plate is provided with a pouring hole and an air vent, and a plurality of groups of stud bolts are fixedly provided at the bottom. After pouring concrete, the stud bolts form a second steel - concrete connector, making the bearing steel plate closely connected to the concrete, so as to form a steel shell - concrete composite structure together with the transition section outer wall plate and the transition section inner wall plate of the middle tower column.

[0009] Furthermore, through - holes are provided on the transition section stiffening ribs and the transition section steel partitions, and the perforated steel bars pass through the through - holes to form a steel bar mesh. After pouring concrete, a first steel - concrete connector is formed. Stud bolts are respectively and perpendicularly fixedly provided on the transition section outer wall plate, the transition section inner wall plate and the transition section steel partition. After pouring concrete, a second steel - concrete connector is formed.

[0010] Furthermore, the transition section inner wall plate includes a first transition plate and a second transition plate provided in sequence. The inner - ring cross - section formed by the first transition plate remains unchanged in the vertical direction, and the inner - ring cross - section formed by the second transition plate gradually shrinks in the vertical direction. Through the first transition plate and the second transition plate, the middle tower column is divided into a first transition section and a second transition section, which are respectively docked with the upper tower column and the lower tower column.

[0011] Furthermore, the lower tower column includes a combined section outer wall plate, a combined section inner wall plate, and a combined section steel partition plate. Among them, both ends of the combined section steel partition plate are fixedly connected to the combined section outer wall plate and the combined section inner wall plate respectively, dividing the space enclosed by the combined section outer wall plate and the combined section inner wall plate into multiple compartments, and filling concrete in the compartments to form a steel-concrete composite structure. On the inner side of the combined section outer wall plate and the outer side of the combined section inner wall plate, multiple groups of hybrid section stiffeners are arranged at intervals along the axial direction, and the layout positions of the hybrid section stiffeners correspond to the layout positions of the transition section stiffeners on the middle tower column.

[0012] Furthermore, through holes are formed on the hybrid section stiffeners and the combined section steel partition plate, and perforated steel bars pass through the through holes to form a steel mesh, which forms the first steel-concrete connector after concrete is poured. Welding studs are vertically and fixedly arranged on the combined section outer wall plate, the combined section inner wall plate, and the combined section steel partition plate respectively, which form the second steel-concrete connector after concrete is poured.

[0013] Furthermore, local stiffeners are fixedly arranged on the inner side of the combined section inner wall plate, and the slope of its top is the same as that of the second transition plate. It is fixedly connected to the inner side of the second transition plate by welding to support the gradually changing cross-section of the second transition section in the vertical direction, so that the axial load is smoothly transmitted to the steel wall plate of the combined tower.

[0014] Furthermore, the upper tower column includes a steel tower section outer wall plate, a steel tower section inner wall plate, a stiffening transition steel plate, and a steel tower section steel partition plate. There are two groups of the steel tower section inner wall plates, which divide the outer ring formed by the steel tower section outer wall plate into three parts. The box structures on both sides are separated into four compartments by the steel tower section steel partition plate, thus forming a single-box five-compartment structure, which is used for installing steel anchor boxes and cable layouts.

[0015] Furthermore, the layout positions of the steel tower section stiffeners correspond to the layout positions of the transition section stiffeners on the middle tower column. A stiffening transition steel plate is fixedly arranged on the outer side of the corresponding steel tower section stiffeners. The bottom of the stiffening transition steel plate is fixedly connected to the top of the bearing steel plate, and it is a semi-U-shaped structure. The steel tower section stiffeners symmetrically arranged in the box structures on both sides are transitionally connected through the stiffening transition steel plates to form a U-shaped plate structure, and the corresponding steel tower section stiffeners in the middle box structure are transitioned through the stiffening transition steel plates. Through the transition of the corresponding steel tower section stiffeners by the stiffening transition steel plates, the steel structure of the bottom section of the upper tower column is the same as that of the first transition section of the middle tower column.

[0016] According to another aspect of the present invention, a construction method for the transition section structure of a steel bridge tower - composite structure bridge tower is also provided, including the following steps:

[0017] S100: Erect the steel structure of the lower tower column. Segmentally weld and form the outer wall plate of the combined section, the inner wall plate of the combined section, the steel diaphragm of the combined section, and the stiffening rib of the hybrid section at the specified positions according to the construction drawings. Vertically and fixedly install stud welds on the outer wall plate of the combined section, the inner wall plate of the combined section, and the steel diaphragm of the combined section respectively according to the design requirements. After completion, drill through-holes on the steel diaphragm of the combined section and the stiffening rib of the hybrid section, pass the perforated steel bars through the through-holes and tie and weld them to form a steel bar mesh; after the construction of the stud welds and the steel bar mesh is completed, fill the lattice with concrete to form a steel-concrete composite structure;

[0018] S200: Erect the steel structure of the middle tower column. Segmentally erect the outer wall plate of the transition section and the outer wall plate of the combined section with the same verticality. Divide the inner wall plate of the transition section into the first transition plate and the second transition plate, and segmentally erect them according to the design slope; weld and fix the steel diaphragm of the transition section and the stiffening rib of the transition section according to the design requirements to make the cross-sectional steel structure of the bottom of the middle tower column the same as that of the lower tower column; after the construction of the stud welds and the steel bar mesh is completed in the middle tower column, weld local stiffening ribs on the inner side of the inner wall plate of the combined section, and weld and fix the top of the local stiffening rib to the inner side of the second transition plate;

[0019] S300: Weld and fix the bearing steel plate to the top of the middle tower column, and weld and fix stud welds at the vacant place at the bottom of the bearing steel plate;

[0020] S400: Pour concrete through the pouring hole of the bearing steel plate. The concrete uses shrinkage-compensating concrete with good fluidity. When the pouring is completed, concrete should be seen emerging from the air vent to ensure the compactness of the concrete;

[0021] S500: Erect the steel structure of the upper tower column on the bearing steel plate. Weld the outer wall plate of the steel tower section, the inner wall plate of the steel tower section, the stiffening transition steel plate, and the steel diaphragm of the steel tower section to the specified positions at the top of the bearing steel plate respectively to make the cross-sectional steel structure of the bottom of the upper tower column the same as that of the top cross-section of the middle tower column.

[0022] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following beneficial effects can be achieved:

[0023] 1. For the structure of the transition section between the steel bridge tower and the composite structure bridge tower of the present invention, by providing a middle tower column and dividing it into a first transition section and a second transition section, the cross-sectional steel structure of the first transition section is the same as that of the bottom cross-section of the upper tower column, and the second transition section adopts a gradually changing cross-section, so that the cross-sectional steel structure of its bottom is the same as that of the lower tower column cross-section, thus realizing the connection between the steel bridge tower and the steel-concrete composite structure bridge tower.

[0024] 2. A transition section structure of a steel bridge tower - composite structure bridge tower according to the present invention. By providing a bearing steel plate as the main force - transferring structure of the joint section, during the process of the force - bearing of the structure being transformed from pure steel structure to the combined force - bearing of steel and concrete, most of the loads are transferred by the bearing steel plate. The force - transferring path of the lower tower column concrete is: most of the loads → the bottom of the upper tower column → the bearing steel plate → the concrete → the foundation; a small part of the loads is transferred by the steel - concrete connectors, and its force - transferring path is: a small part of the loads → the outer wall plate of the transition section → the first steel - concrete connector (including perforated steel bars, through - holes, and the concrete in the holes) and the second steel - concrete connector (studs) of the transition section → the concrete → the foundation. The steel structure of the lower tower column has the same cross - section form as that of the upper tower column and the middle tower column, and its force - transferring path is: loads → the outer wall plate of the upper tower column → the outer wall plate of the transition section → the outer wall plate of the combined tower of the lower tower column → the foundation. The stiffening transition steel plate at the bottom of the upper tower and the steel structure variable - cross - section structure of the middle tower column are the main structures for realizing the load transfer of the inner wall plates of the steel structure, and its force - transferring path is: loads → the inner wall plate and the stiffening transition steel plate of the upper tower column → the inner wall plate of the transition section, the steel diaphragm of the transition section, the first transition plate, and the second transition plate → the inner wall plate and the steel diaphragm of the combined tower of the lower tower column → the foundation. By providing a bearing steel plate and steel - concrete connectors, part of the loads borne by the steel tower section are transferred to the concrete, and by correspondingly arranging the combined structure of the stiffeners of the corresponding steel tower section and the stiffening transition steel plate, the steel diaphragms of the transition section, and the steel diaphragms of the combined section axially, and correspondingly arranging the stiffeners of the corresponding steel tower section, the stiffeners of the transition section, and the stiffeners of the hybrid section axially, the loads can be smoothly transferred to the steel structure of the lower tower column. The transition section structure is reasonably stressed and has a clear force - transferring path, and can be applied to the hybrid structure bridge tower project adopting a steel bridge tower and a composite structure bridge tower.

[0025] 3. A transition section structure of a steel bridge tower - composite structure bridge tower according to the present invention. The outside of the stiffeners of the corresponding steel tower section is transitioned by fixedly providing a stiffening transition steel plate, so that the cross - section of the bottom of the upper tower column is the same as the steel structure of the first transition section of the middle tower column. While not affecting the installation of the steel anchor box, axial load transfer can be effectively carried out.

[0026] 4. A transition section structure of a steel bridge tower - composite structure bridge tower according to the present invention. The perforated steel bars pass through the through - holes to form a steel bar mesh, and after pouring concrete, a first steel - concrete connector is formed. Multiple groups of studs are welded at the bottom of the bearing steel plate and inside the middle tower column and the lower tower column, and after pouring concrete, a second steel - concrete connector is formed; through the first steel - concrete connector and the second steel - concrete connector, vertical shear resistance and lateral tensile and pull - out resistance are provided, enabling the steel and concrete to form a composite structure and jointly participate in force - bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of a transition section structure of a steel bridge tower - composite structure bridge tower in an embodiment of the present invention;

[0028] Figure 2 is Figure 1 Steel structure schematic diagram of the A-A section in

[0029] Figure 3 is Figure 1 Steel structure schematic diagram of the B-B section in

[0030] Figure 4 is Figure 1 Steel structure schematic diagram of the C-C section in

[0031] Figure 5 is Figure 2 、 3 Structural schematic diagram of the E-E section in

[0032] Figure 6 is Figure 2 、 3 Structural schematic diagram of the F-F section in

[0033] Figure 7 is Figure 2 、 3 Structural schematic diagram of the G-G section in

[0034] Figure 8 Structural schematic diagram of the pressure-bearing steel plate;

[0035] In all the drawings, the same reference numerals denote the same technical features, specifically:

[0036] 1 - Upper tower column, including: 11 - Outer wall plate of the steel tower section, 12 - Inner wall plate of the steel tower section, 13 - Stiffening transition steel plate, 14 - Steel diaphragm of the steel tower section;

[0037] 2 - Middle tower column, including: 21 - Outer wall plate of the transition section, 22 - Inner wall plate of the transition section, 221 - First transition plate, 222 - Second transition plate, 23 - Steel diaphragm of the transition section;

[0038] 3 - Lower tower column, including: 31 - Outer wall plate of the combined section, 32 - Inner wall plate of the combined section, 33 - Steel diaphragm of the combined section, 34 - Local stiffening rib;

[0039] 4 - Pressure-bearing steel plate, including: 401 - Casting hole, 402 - Air vent,

[0040] 5 - Stud;

[0041] 6 - Through hole;

[0042] 7 - Perforated steel bar;

[0043] 8 - Stiffening rib, including: 801 - Stiffening rib of the steel tower section, 802 - Stiffening rib of the transition section, 803 - Stiffening rib of the mixed section;

[0044] 9-Concrete. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0046] like Figures 1-8 As shown, the present invention provides a steel bridge tower-composite structure bridge tower transition section structure, including an upper tower column 1 of a steel structure, a lower tower column 3 of a steel-concrete composite structure, a middle tower column 2 for realizing a smooth transition between the upper tower column 1 and the lower tower column 3, and a pressure-bearing steel plate 4 and a stiffening rib 8. The middle tower column 2 includes a transition section outer wall plate 21 arranged on the periphery, a transition section inner wall plate 22 arranged on the inner circle, and a transition section stiffening rib 802 arranged on the transition section outer wall plate 21 and the transition section inner wall plate 22. The transition section inner wall plates 22 are separated into a plurality of cells by a transition section steel partition plate 23, and the cells are filled with concrete 9. The middle tower column 2 is divided into a first transition section and a second transition section, wherein the cross section of the first transition section remains unchanged in the vertical direction and matches the cross section at the bottom of the upper tower column 1. The inner circle of the cross section of the second transition section gradually expands in the vertical direction until it reaches the bottom and matches the cross section of the lower tower column 3. The pressure-bearing steel plate 4 is fixedly connected to the upper tower column 1, and the bottom is fixedly connected to the middle tower column 2, which transmits the axial load of the upper tower column 1 downwardly. The stiffening rib 8 is a strip reinforcement member, which extends axially, and the sides are respectively fixed in the upper tower column 1, the middle tower column 2, and the lower tower column 3, thereby improving the stability and torsion resistance of the overall structure, and at the same time transmitting part of the axial load to the foundation. The transition section structure of the present invention realizes the connection between the steel bridge tower and the steel-concrete composite structure bridge tower through the gradual cross-sectional structure of the middle tower column 2, and utilizes the axial force load on the steel tower column of the pressure-bearing steel plate 4 to transfer to the concrete 9, so that the structure is transitioned from the pure steel structure stress to the steel-concrete composite structure stress. The structural stress is reasonable and the force transmission path is clear. It can be applied to the hybrid structure bridge tower project using steel bridge towers and composite structure bridge towers.

[0047] like Figures 1-4 As shown, in the embodiment of the present invention, the stiffening ribs 8 include steel tower section stiffening ribs 801 arranged in the upper tower column 1, transition section stiffening ribs 802 arranged in the middle tower column 2, and mixed section stiffening ribs 803 arranged in the lower tower column 3. The layout positions of the multiple groups of steel tower section stiffening ribs 801, transition section stiffening ribs 802 and mixed section stiffening ribs 803 correspond to each other in the axial direction, thereby ensuring that the axial load loaded on the stiffening ribs 8 is effectively transmitted to the foundation along the axial direction.

[0048] As shown Figure 1 in 4 Figures 5-7, in the embodiment of the present invention, the lower tower column 3 is arranged at the bottom and includes a combined section outer wall plate 31, a combined section inner wall plate 32 and a combined section steel partition plate 33. Among them, both ends of the combined section steel partition plate 33 are fixedly connected to the combined section outer wall plate 31 and the combined section inner wall plate 32 respectively. By providing multiple groups of combined section steel partition plates 33, the space enclosed by the combined section outer wall plate 31 and the combined section inner wall plate 32 is divided into multiple compartments, and concrete 9 is filled in the compartments to form a steel-concrete composite structure, improving the plastic and toughness properties of the structure. Further, multiple groups of hybrid section stiffening ribs 803 are arranged at intervals along the axial direction on the inner side of the combined section outer wall plate 31 and the outer side of the combined section inner wall plate 32 respectively. Through holes 6 are formed on the stiffening ribs 803 and the combined section steel partition plate 33, and perforated steel bars 7 pass through the through holes 6 to form a steel mesh. After pouring concrete, a first steel-concrete connector is formed. The multi-layer steel meshes arranged along the axial direction are combined with the concrete 9, enhancing the structural strength and shear resistance of the lower tower column 3; further, stud welds 5 are vertically and fixedly arranged on the combined section outer wall plate 31, the combined section inner wall plate 32 and the combined section steel partition plate 33 respectively. After pouring concrete, a second steel-concrete connector is formed; through the first steel-concrete connector and the second steel-concrete connector, vertical shear resistance and lateral tensile resistance are provided, enabling the steel and concrete to form a composite structure and jointly participate in the force.

[0049] As shown Figure 1 in 3As shown in FIGS. 5-7, in the embodiment of the present invention, the middle tower column 2 is provided in the middle, and includes a transition section outer wall plate 21, a transition section inner wall plate 22 and a transition section steel diaphragm 23. Among them, the transition section inner wall plate 22 includes a first transition plate 221 and a second transition plate 222 arranged in sequence. The inner circle cross-section formed by the first transition plate 221 remains unchanged in the vertical direction, and the inner circle cross-section formed by the first transition plate 221 gradually shrinks in the vertical direction; through the first transition plate 221 and the second transition plate 222, the middle tower column 2 is divided into a first transition section and a second transition section, which are respectively butted with the upper tower column 1 and the lower tower column 3. Both ends of the transition section steel diaphragm 23 are fixedly connected to the transition section outer wall plate 21 and the transition section inner wall plate 22 respectively. By providing multiple groups of combined section steel diaphragms 33, the space enclosed by the transition section outer wall plate 21 and the transition section inner wall plate 22 is divided into multiple compartments, and concrete 9 is filled in the compartments to form a steel-concrete composite structure, which improves the plasticity and toughness of the structure of the middle tower column 2. The arrangement position of the transition section steel diaphragm 23 corresponds to that of the combined section steel diaphragm 33, and its width gradually shrinks in the second transition section of the middle tower column 2 to adapt to the cross-section change. Further, multiple groups of transition section stiffeners 802 are arranged at intervals along the axial direction on the inner side of the transition section outer wall plate 21 and the outer side of the transition section inner wall plate 22 respectively. The arrangement position of the transition section stiffeners 802 corresponds to that of the hybrid section stiffeners 803, and its width gradually shrinks in the second transition section of the middle tower column 2 to adapt to the cross-section change. Further, through holes 6 are formed in the stiffeners 802 and the transition section steel diaphragm 23, and perforated steel bars 7 pass through the through holes 6 to form a steel mesh sheet, which forms a first steel-concrete connector after pouring concrete. Welding studs 5 are vertically and fixedly arranged on the transition section outer wall plate 21, the transition section inner wall plate 22 and the transition section steel diaphragm 23 respectively, and a second steel-concrete connector is formed after pouring concrete.

[0050] Preferably, a local stiffener 34 is fixedly arranged on the inner side of the combined section inner wall plate 32, and its top has the same slope as the second transition plate 222. It is fixedly connected to the inner side of the second transition plate 222 by welding to support the gradually changing cross-section in the vertical direction of the second transition section, so that the axial load can be effectively transmitted to the combined tower steel wall plate.

[0051] As Figure 8As shown, the pressure-bearing steel plate 4 is fixedly arranged at the top of the middle tower column 2, on which a pouring hole 401 and an air vent 402 are opened. After the framework construction of the middle tower column 2 and the lower tower column 3 is completed, the concrete 9 can be poured through the pouring hole 401, and compensated shrinkage concrete with good fluidity is used for pouring. When the pouring of the concrete 9 is completed, concrete should be seen emerging from the air vent 402 to ensure the compactness of the concrete 9. Further, multiple groups of stud nails 5 are fixedly arranged on the pressure-bearing steel plate 4, which form a second steel-concrete connecting member after the concrete 9 is poured, so that the pressure-bearing steel plate 4 is closely connected with the concrete 9, thereby forming a steel shell-concrete composite structure with the outer wall plate 21 and the inner wall plate 22 of the transition section of the middle tower column 2. By means of the pressure-bearing contact of the pressure-bearing steel plate 4, the top surface of the concrete 9 is in a compressed state, ensuring the effective transmission of the axial load.

[0052] As Figure 1 , 2 As shown in FIGS. 5-7, in the embodiment of the present invention, the upper tower column 1 is arranged at the top, including a steel tower section outer wall plate 11, a steel tower section inner wall plate 12, a stiffening transition steel plate 13 and a steel tower section steel diaphragm 14. There are two groups of the steel tower section inner wall plates 12, which divide the outer ring formed by the steel tower section outer wall plate 11 into three parts, and the box structures on both sides are separated into four compartments by the steel tower section steel diaphragm 14, thereby forming a single-box multi-room structure for installing steel anchor boxes and arranging stay cables. Multiple groups of steel tower section stiffening ribs 801 are respectively arranged on the steel tower section outer wall plate 11 and the steel tower section inner wall plate 12, and the layout positions of the steel tower section stiffening ribs 801 correspond to the layout positions of the transition section stiffening ribs 802 on the middle tower column 2.

[0053] To not affect the installation of the steel anchor box and the stay cable, and at the same time ensure the transmission of the axial load, a stiffening transition steel plate 13 is fixedly arranged outside the corresponding steel tower section stiffening rib 801, and the bottom of the stiffening transition steel plate 13 is fixedly connected to the top of the pressure-bearing steel plate 4. It is a semi-U-shaped structure or a right-angled trapezoidal structure. When designing, it is preferred to use the semi-U-shaped structure of the stiffening transition steel plate 13 for transition, and its force transmission effect is better than that of the right-angled trapezoidal structure. As Figure 1 , 2 As shown in FIGS., the corresponding steel tower section stiffening ribs 801 in the box structures on both sides are transition-connected through the stiffening transition steel plate 13 to form a U-shaped plate structure, and the corresponding steel tower section stiffening ribs 801 in the middle box structure are transitioned through the stiffening transition steel plate 13; through the transition of the corresponding steel tower section stiffening ribs 801 by the stiffening transition steel plate 13, the steel structure of the bottom section of the upper tower column 1 is the same as that of the first transition section of the middle tower column 2, which can effectively transmit the axial load while not affecting the installation of the steel anchor box.

[0054] In the embodiment of the present invention, during the construction of the transition section structure, the steel structure of the lower tower column 3 is erected on the foundation. The outer wall plate 31 of the combined section, the inner wall plate 32 of the combined section, the steel partition plate 33 of the combined section and the stiffening rib 803 of the hybrid section are respectively welded and formed in segments at the designated positions according to the construction drawings. And stud welds 5 are vertically and fixedly arranged on the outer wall plate 31 of the combined section, the inner wall plate 32 of the combined section and the steel partition plate 33 of the combined section respectively according to the design requirements. After completion, through holes 6 are made in the steel partition plate 33 of the combined section and the stiffening rib 803 of the hybrid section. The perforated steel bars 7 are passed through the through holes 6 and tied and welded to form a steel bar mesh; after the construction of the steel structure of the lower tower column 3 is completed, the second transition section steel structure of the middle tower column 2 is erected. Among them, the outer wall plate 21 of the transition section is erected in segments while maintaining the same verticality as the outer wall plate 31 of the combined section. The second transition plate 222 is erected in segments according to the slope required by the design. The stiffening rib 802 of the transition section and the steel partition plate 33 provided in the second transition section are gradually widened in width from bottom to top according to the design and welded and fixed. The second transition section steel structure of the middle tower column 2 is erected on the top of the first transition section, and its erection method is the same as that of the lower tower column 3. After the construction of the stud welds 5 and the steel bar mesh is completed in the middle tower column 2, the local stiffening rib 34 is welded on the inner side of the inner wall plate 32 of the combined section, and the top of the local stiffening rib 34 is welded and fixed to the inner side of the second transition plate 222; the tops of the outer wall plate 21 of the transition section, the inner wall plate 22 of the transition section, the steel partition plate 23 of the transition section and the stiffening rib 802 of the transition section are all fixedly connected to the bottom of the bearing steel plate 4 by welding, and stud welds 5 are welded and fixed in the vacant places at the bottom of the bearing steel plate 4; concrete 9 is poured through the pouring hole 401 of the bearing steel plate 4. The concrete 9 is shrinkage-compensating concrete with good fluidity. When the pouring is completed, it should be seen that the concrete 9 emerges from the air vent 402 to ensure the compactness of the concrete 20; after the concrete 9 is poured and formed, the steel structure of the upper tower column 1 is erected on the bearing steel plate 4. The outer wall plate 11 of the steel tower section, the inner wall plate 12 of the steel tower section, the stiffening transition steel plate 13 and the steel partition plate 14 of the steel tower section are respectively welded to the designated positions at the top of the bearing steel plate 4 to complete the construction of the transition section structure.

[0055] In the embodiment of this statement, to ensure the safety of the overall structure under load, the first steel-concrete connector and the second steel-concrete connector should have sufficient shear bearing capacity. Among them, the diameter of the stud weld 5 is 16-22 mm, the length is 150-200 mm, and the vertical distance between adjacent stud welds does not exceed 300 mm; the width of the stiffening rib 8 provided with the through hole 6 is not less than 120 mm, the diameter of the through hole 6 is 45-60 mm, and the diameter of the perforated steel bar 7 is 16-22 mm; the through hole 6 can be selected from round hole type, oval hole type, round hole with slot type or oval hole with slot type according to the force and construction requirements; the horizontal distance between adjacent through holes 6 at the same height does not exceed 500 mm to ensure the effective connection between steel and concrete.

[0056] In the embodiment of the present invention, to ensure that the pressure-bearing steel plate 4 has a large stiffness, its thickness is not less than 40 mm or not less than 0.6 times the outer wall plate 21 of the transition section.

[0057] In the embodiment of the present invention, by providing the middle tower column 2 and dividing it into a first transition section and a second transition section, the steel structure of the cross-section of the first transition section is the same as that of the bottom cross-section of the upper tower column 1, and the second transition section adopts a gradually changing cross-section, so that the steel structure of its bottom cross-section is the same as that of the cross-section of the lower tower column 3, thus realizing the connection between the steel bridge tower and the steel-concrete composite structure bridge tower.

[0058] In the embodiment of the present invention, by providing the pressure-bearing steel plate 4 as the main force-transferring structure of the joint section, during the process of the structure changing from pure steel structure force-bearing to steel and concrete jointly force-bearing, most of the loads are transferred by the pressure-bearing steel plate 4. The force-transferring path of the lower tower column concrete is: most of the loads → the bottom of the upper tower column 1 → the pressure-bearing steel plate 4 → the concrete 9 → the foundation; a small part of the loads is transferred by the steel-concrete connectors, and its force-transferring path is: a small part of the loads → the outer wall plate 21 of the transition section → the first steel-concrete connector (including the perforated steel bar 7, the through-hole 6 and the concrete in the hole) and the second steel-concrete connector (the stud 5) of the transition section → the concrete 9 → the foundation. The steel structure of the lower tower column has the same cross-section form as that of the upper tower column and the middle tower column, and its force-transferring path is: the loads → the outer wall plate 11 of the upper tower column → the outer wall plate 21 of the transition section → the combined tower outer wall plate 31 of the lower tower column → the foundation. The stiffening transition steel plate 13 at the bottom of the upper tower and the steel structure variable cross-section structure of the middle tower column are the main structures for realizing the load transfer of the inner wall plates of the steel structure, and its force-transferring path is: the loads → the inner wall plate 12 of the upper tower column and the stiffening transition steel plate 13 → the inner wall plate 22 of the transition section, the steel diaphragm 23 of the transition section, the first transition plate 221 and the second transition plate 222 → the inner wall plate 32 and the steel diaphragm 22 of the combined tower of the lower tower column → the foundation. By providing the bearing plate 4 and the steel-concrete connectors, part of the loads borne by the steel tower section are transferred to the concrete, and the combined structures of the stiffeners of the corresponding steel tower sections and the stiffening transition steel plate 13, the steel diaphragms 23 of the transition section, and the steel diaphragms 33 of the combined section are correspondingly arranged axially, and the stiffeners 801 of the corresponding steel tower sections, the stiffeners 802 of the transition section, and the stiffeners 803 of the hybrid section are correspondingly arranged axially, so that the loads can be smoothly transferred to the steel structure of the lower tower column. The transition section structure is reasonably stressed and has a clear force-transferring path, and can be applied to the hybrid structure bridge tower project adopting the steel bridge tower and the composite structure bridge tower.

[0059] The present invention also provides a construction method for the transition section structure of the steel bridge tower - composite structure bridge tower, including the following steps:

[0060] S100: Erect the steel structure of the lower tower column 3. Segmentally weld the outer wall plate 31 of the combined section, the inner wall plate 32 of the combined section, the steel diaphragm 33 of the combined section, and the stiffening rib 803 of the hybrid section into shape at the designated positions according to the construction drawings. Vertically and fixedly install stud welds 5 on the outer wall plate 31 of the combined section, the inner wall plate 32 of the combined section, and the steel diaphragm 33 of the combined section respectively according to the design requirements. After completion, drill through-holes 6 in the steel diaphragm 33 of the combined section and the stiffening rib 803 of the hybrid section. Pass the perforated steel bars 7 through the through-holes 6 and tie and weld them to form a steel bar mesh; after the construction of the stud welds 5 and the steel bar mesh is completed, fill the cell with concrete to form a steel-concrete composite structure;

[0061] S200: Erect the steel structure of the middle tower column 2. Segmentally erect the outer wall plate 21 of the transition section to maintain the same perpendicularity as the outer wall plate 31 of the combined section. Divide the inner wall plate 22 of the transition section into the first transition plate 221 and the second transition plate 222, and segmentally erect them according to the design slope; weld and fix the steel diaphragm 2 and the stiffening rib 802 of the transition section according to the design requirements, so that the cross-sectional steel structure at the bottom of the middle tower column 2 is the same as that of the lower tower column 3; after the construction of the stud welds 5 and the steel bar mesh is completed inside the middle tower column 2, weld local stiffening ribs 34 on the inner side of the inner wall plate 32 of the combined section, and weld and fix the top of the local stiffening rib 34 to the inner side of the second transition plate 222;

[0062] S300: Weld and fix the bearing steel plate 4 to the top of the middle tower column 2, and weld and fix stud welds 5 at the vacant place at the bottom of the bearing steel plate 4;

[0063] S400: Pour concrete 9 through the pouring hole 401 of the bearing steel plate 4. The concrete 9 is shrinkage-compensating concrete with good fluidity. When the pouring is completed, concrete 9 should be seen emerging from the air vent 402 to ensure the compactness of the concrete;

[0064] S500: Erect the steel structure of the upper tower column 1 on the bearing steel plate 4. Weld the outer wall plate 11 of the steel tower section, the inner wall plate 12 of the steel tower section, the stiffening transition steel plate 13, and the steel diaphragm 14 of the steel tower section to the designated positions at the top of the bearing steel plate 4 respectively, so that the cross-sectional steel structure at the bottom of the upper tower column 1 is the same as that in the cross section at the top of the middle tower column 2.

[0065] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not used to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A transition structure for a steel bridge tower - composite structure bridge tower, Characterized in that, It includes; The upper tower column (1) provided at the top, which is made of steel structure; The lower tower column (3) provided at the bottom, which is a steel - concrete composite structure; The middle tower column (2) provided in the middle, including: the transition section outer wall plate (21) provided on the outer periphery and the transition section inner wall plate (22) provided on the inner circle. The transition section outer wall plate (21) and the transition section inner wall plate (22) are separated into multiple compartments by the transition section steel diaphragm (23), and the compartments are filled with concrete (9); The bearing steel plate (4) fixedly provided at the top of the middle tower column (2), the top of which is fixedly connected to the bottom of the upper tower column (1); And the stiffening rib (8), which is a strip - shaped strengthening member extending along the axial direction, including the steel tower section stiffening rib (801) whose sides are respectively fixed in the upper tower column (1), the transition section stiffening rib (802) in the middle tower column (2), and the hybrid section stiffening rib (803) in the lower tower column (3); The middle tower column (2) is divided into a first transition section and a second transition section. The cross - section of the first transition section remains unchanged in the vertical direction and is adapted to the cross - section of the bottom of the upper tower column (1); the inner circle of the cross - section of the second transition section gradually expands in the vertical direction until it reaches the bottom and is adapted to the cross - section of the lower tower column (3). Through the gradually changing cross - section structure of the middle tower column (2), a smooth transition between the steel bridge tower and the steel - concrete composite structure bridge tower is realized, and the force - bearing model of the structure is transformed from pure steel structure force - bearing to steel and concrete jointly force - bearing.

2. A transition structure for a steel bridge tower - composite structure bridge tower according to claim 1, Characterized in that, The bearing steel plate (4) is provided with a pouring hole (401) and an air vent hole (402), and a plurality of groups of stud bolts (5) are fixedly provided at the bottom. After pouring concrete, the stud bolts (5) form a second steel - concrete connecting member, making the bearing steel plate (4) closely connected to the concrete (9), and thus forming a steel shell - concrete composite structure with the transition section outer wall plate (21) and the transition section inner wall plate (22) of the middle tower column (2).

3. A transition structure for a steel bridge tower - composite structure bridge tower according to claim 2, Characterized in that, The transition section stiffening rib (802) and the transition section steel diaphragm (23) are provided with through - holes (6), and the perforated steel bars (7) pass through the through - holes (6) to form a steel bar mesh. After pouring concrete, a first steel - concrete connecting member is formed. The stud bolts (5) are respectively vertically fixed on the transition section outer wall plate (21), the transition section inner wall plate (22) and the transition section steel diaphragm (23). After pouring concrete, a second steel - concrete connecting member is formed.

4. A transition structure for a steel bridge tower - composite structure bridge tower according to any one of claims 1 - 3, Characterized in that, The inner wall plate (22) of the transition section includes a first transition plate (221) and a second transition plate (222) arranged in sequence. The cross-section of the inner circle formed by the first transition plate (221) remains unchanged in the vertical direction, and the cross-section of the inner circle formed by the second transition plate (222) gradually shrinks in the vertical direction. Through the first transition plate (221) and the second transition plate (222), the middle tower column (2) is divided into a first transition section and a second transition section, which are respectively docked with the upper tower column (1) and the lower tower column (3).

5. A steel bridge tower - combined structure bridge tower transition section structure according to any one of claims 1 - 3, characterized in that, the lower tower column (3) includes a combined section outer wall plate (31), a combined section inner wall plate (32) and a combined section steel partition plate (33); wherein, both ends of the combined section steel partition plate (33) are respectively fixedly connected to the combined section outer wall plate (31) and the combined section inner wall plate (32), dividing the space enclosed by the combined section outer wall plate (31) and the combined section inner wall plate (32) into multiple compartments, and concrete (9) is filled in the compartments to form a steel - concrete composite structure; multiple groups of hybrid section stiffening ribs (803) are respectively arranged at intervals along the axial direction on the inner side of the combined section outer wall plate (31) and the outer side of the combined section inner wall plate (32), and the arrangement positions of the hybrid section stiffening ribs (803) correspond to the arrangement positions of the upper transition section stiffening ribs (802) on the middle tower column (2).

6. A steel bridge tower - combined structure bridge tower transition section structure according to claim 5, characterized in that, perforated holes (6) are formed on the hybrid section stiffening ribs (803) and the combined section steel partition plate (33), and the perforated steel bars (7) pass through the perforated holes (6) to form a steel mesh sheet, forming a first steel - concrete connector after pouring concrete; stud welds (5) are respectively vertically and fixedly arranged on the combined section outer wall plate (31), the combined section inner wall plate (32) and the combined section steel partition plate (33), forming a second steel - concrete connector after pouring concrete.

7. A steel bridge tower - combined structure bridge tower transition section structure according to claim 5, characterized in that, a local stiffening rib (34) is fixedly arranged on the inner side of the combined section inner wall plate (32), and its top has the same slope as the second transition plate (222), and is fixedly connected to the inner side of the second transition plate (222) by welding, supporting the gradually changing cross-section of the second transition section in the vertical direction, and transmitting the axial load to the foundation.

8. A steel bridge tower - combined structure bridge tower transition section structure according to any one of claims 1 - 3, characterized in that, the upper tower column (1) includes a steel tower section outer wall plate (11), a steel tower section inner wall plate (12), a stiffening transition steel plate (13) and a steel tower section steel partition plate (14); there are two groups of the steel tower section inner wall plates (12), dividing the outer circle formed by the steel tower section outer wall plate (11) into three parts, and the box structures on both sides are separated into four compartments by the steel tower section steel partition plate (14), thereby forming a single - box multi - cell cross-section for installing steel anchor boxes and cable layouts.

9. A steel bridge tower - combined structure bridge tower transition section structure according to claim 8, It is characterized in that the layout position of the stiffening rib (801) of the steel tower section corresponds to the layout position of the transition section stiffening rib (802) on the middle tower column (2). A stiffening transition steel plate (13) is fixedly arranged outside the corresponding steel tower section stiffening rib (801). The bottom of the stiffening transition steel plate (13) is fixedly connected to the top of the pressure-bearing steel plate (4), and it is of a semi-U-shaped structure. The corresponding symmetrically arranged steel tower section stiffening ribs (801) in the two side box structures are transitionally connected through the stiffening transition steel plates (13) to form a U-shaped plate structure, and the corresponding steel tower section stiffening ribs (801) in the middle box structure are transitioned through the stiffening transition steel plates (13). The corresponding steel tower section stiffening ribs (801) are transitioned through the stiffening transition steel plates (13) so that the steel structure of the bottom section of the upper tower column (1) is the same as the steel structure of the first transition section of the middle tower column (2).

10. A construction method for the transition section structure of a steel bridge tower - composite structure bridge tower according to any one of claims 1 - 9, It is characterized in that it includes the following steps: S100: Build the steel structure of the lower tower column (3). Segmentally weld the outer wall plate (31) of the composite section, the inner wall plate (32) of the composite section, the steel diaphragm (33) of the composite section, and the stiffening rib (803) of the hybrid section at the designated positions according to the construction drawings. Vertically and fixedly arrange stud nails (5) on the outer wall plate (31) of the composite section, the inner wall plate (32) of the composite section, and the steel diaphragm (33) of the composite section respectively according to the design requirements. After completion, make through holes (6) on the steel diaphragm (33) of the composite section and the stiffening rib (803) of the hybrid section. Pass the perforated steel bars (7) through the through holes (6) and tie and weld them to form a steel bar mesh. After the construction of the stud nails (5) and the steel bar mesh is completed, fill the grid with concrete to form a steel - concrete composite structure; S200: Build the steel structure of the middle tower column (2). Segmentally build the outer wall plate (21) of the transition section to keep the same perpendicularity as the outer wall plate (31) of the composite section. Divide the inner wall plate (22) of the transition section into a first transition plate (221) and a second transition plate (222), and segmentally build them according to the design slope. Weld and fix the steel diaphragm (23) of the transition section and the stiffening rib (802) of the transition section according to the design requirements so that the cross-sectional steel structure of the bottom of the middle tower column (2) is the same as that of the lower tower column (3). After the construction of the stud nails (5) and the steel bar mesh is completed inside the middle tower column (2), weld local stiffening ribs (34) on the inner side of the inner wall plate (32) of the composite section, and weld and fix the top of the local stiffening rib (34) to the inner side of the second transition plate (222); S300: Weld and fix the pressure-bearing steel plate (4) to the top of the middle tower column (2), and weld and fix stud nails (5) at the vacant places at the bottom of the pressure-bearing steel plate (4); S400: Pour concrete (9) through the pouring hole (401) of the pressure-bearing steel plate (4). The concrete (9) is compensated shrinkage concrete with good fluidity. When the pouring is completed, it should be seen that the concrete (9) emerges from the air vent (402) to ensure the compactness of the concrete; S500: Build the steel structure of the upper tower column (1) on the pressure-bearing steel plate (4), and weld the outer wall plate (11) of the steel tower section, the inner wall plate (12) of the steel tower section, the stiffening transition steel plate (13), and the steel diaphragm (14) of the steel tower section to the designated positions at the top of the pressure-bearing steel plate (4) respectively, so that the steel structure in the bottom cross-section of the upper tower column (1) is the same as that in the top cross-section of the middle tower column (2).

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