A high variable steel-concrete composite beam pushing system and construction method

Abstract

The application relates to a variable-height steel-concrete composite beam pushing system and a construction method, the system comprising: a supporting device for supporting a main beam and providing a platform for pushing the main beam forward; a pushing device arranged on the supporting device and used for pushing the main beam; and a balancing device comprising: a cable tower arranged at the top of the main beam and located at the middle of the main beam in the longitudinal bridge direction; and at least two cables used for connecting the cable tower and the two ends of the main beam and overcoming the gravity of the end of the main beam. Through the arrangement of the balancing device, the cable tower and the cables are matched, the gravity of the cantilever of the main beam is transmitted to the cable tower through the cables, the cable force reaches the design requirement through the tensioning of the cables, the gravity of the cantilever of the main beam is borne by the cables and the cable tower, and thus the deformation amount of the cantilever of the main beam caused by the gravity is reduced, that is, the problem that the large-cantilever main beam has small rigidity and large deformation during the variable-height cross-section steel box beam crossing construction by using the conventional pushing method is solved.

Description

Technical Field

[0001] This application relates to the technical field of continuous beam bridge construction, and in particular to a variable-height steel-concrete composite beam jacking system and construction method. Background Technology

[0002] Currently, prefabricated bridge technology is being used more and more widely in modern urban transportation engineering construction. Due to its novel structure, rapid construction, and economical cost, it is being adopted in a large number of designs.

[0003] Because construction in urban areas frequently requires crossing existing roads, railways, waterways, and other obstacles, and the spans are generally large, various bridge types can be selected, including: prestressed concrete continuous beams with variable-height sections, continuous steel box girders with uniform height, cable-stayed bridges, suspension bridges, and arch bridges. Considering factors such as economy, schedule, safety, and construction environment, steel-concrete composite beams with variable-height sections offer significant advantages by minimizing their own weight and allowing for prefabricated construction.

[0004] In related technologies, when using the design scheme of steel-concrete composite beams with variable height sections, conventional cross-span construction often adopts the in-situ hoisting method using scaffolding. However, in areas with high safety risks, such as urban main roads, highways, and railways where the erection of scaffolding is restricted, the method of off-site construction and rotation into place is adopted.

[0005] However, the cross-span construction methods in related technologies are complex and have long construction cycles, which are not conducive to rapid construction. The conventional jacking method is more commonly used on steel box girders with equal height sections. When applied to cross-span construction of steel box girders with variable height sections, it is difficult to solve the problems of low stiffness and large deformation of the large cantilever main beam. Summary of the Invention

[0006] This application provides a variable-height steel-concrete composite beam jacking system and construction method to solve the problems of low stiffness and large deformation of the large cantilever main beam when using the conventional jacking method to construct variable-height cross-section steel box girders.

[0007] On the one hand, this application provides a variable-height steel-concrete composite beam jacking system, the technical solution of which is:

[0008] A variable-height steel-concrete composite beam launching system includes:

[0009] Support device, which is used to support the main beam and provide a platform for pushing the main beam forward;

[0010] A jacking device, which is mounted on the support device and used to jack the main beam;

[0011] A balancing device, comprising:

[0012] Towers are installed on top of the main girder and located in the middle of the main girder along the longitudinal direction of the bridge.

[0013] At least two cables are used to connect the tower and the two ends of the main beam and to overcome the gravity at the ends of the main beam.

[0014] In some embodiments, the jacking device includes a first sliding block assembly mounted on the support device and slidable along the jacking direction of the main beam. The first sliding block assembly is used to support the main beam at the bottom of the main beam, and the support point is located at the middle of the main beam along the longitudinal direction of the bridge.

[0015] In some embodiments, the balancing device further includes a second sliding block assembly, which is disposed on the support device and can slide along the pushing direction of the main beam. The second sliding block assembly is used to connect to the bottom of the main beam and support the main beam, and the connection point is located at the rear end of the main beam along the pushing direction.

[0016] In some embodiments, the balancing device includes a counterweight disposed on the main beam at the rear end of the main beam along the jacking direction.

[0017] In some embodiments, the bottom of the pylon is hinged to the main beam, and the hinge axis is arranged along the transverse direction of the bridge.

[0018] In some embodiments, the first slide block assembly includes a plurality of first slide blocks, which are spaced apart along the transverse direction of the bridge. The first slide blocks are slidable along the pushing direction of the main beam, and the support device includes a track that slides with the first slide blocks.

[0019] In some embodiments, the cable is connected to the tower via a tensioning assembly, which is used to adjust the tension of the cable.

[0020] In some embodiments, the tower includes a reaction seat at the top, and the tensioning assembly includes:

[0021] The tensioning jack is mounted on the reaction seat;

[0022] The tension rod is connected to the tension jack, and the cable passes through the reaction seat and is then connected to the tension rod.

[0023] On the other hand, this application also provides a method for jacking construction of variable-height steel-concrete composite beams, which uses the variable-height steel-concrete composite beam jacking construction system described above for construction, including:

[0024] Install a jacking device on the support device;

[0025] The balancing device is constructed on the main beam. First, the cable tower is constructed on the main beam. Then, the cables are installed to connect the ends of the main beam and the cable tower. After completion, the main beam is hoisted onto the support device.

[0026] Push the main beam to the designed position.

[0027] In some embodiments, a counterweight is provided on the main beam, and the counterweight is located at the rear end of the main beam along the jacking direction.

[0028] The beneficial effects of the technical solution provided in this application include:

[0029] This application provides a variable-height steel-concrete composite beam jacking system. It utilizes a support device to provide a platform for jacking the main beam, and a jacking device mounted on the support device pushes the main beam forward. During construction, the support device is positioned on one side of the building to be crossed. After the main beam is installed on the support device, it is jacked forward by the jacking device to reach the designed position after crossing the building. When hoisting the main beam onto the support device, the tallest section of the main beam, the middle crossbeam, rests on the support device. A balancing device is installed on the main beam. Through the cooperation of the pylon and cables, the gravity of the main beam cantilever is transferred to the pylon via the cables. By tensioning the cables to achieve the designed tension, the gravity of the main beam cantilever is borne by the cables and the pylon, thereby reducing the deformation of the main beam cantilever due to gravity. This solves the problem of low stiffness and large deformation of the large cantilever main beam when using conventional jacking methods for variable-height cross-section steel box girder crossing construction. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a structural schematic diagram of the variable-height steel-concrete composite beam launching system provided in the embodiments of this application;

[0032] Figure 2 This is a schematic diagram of the jacking device in the variable height steel-concrete composite beam jacking system provided in the embodiments of this application;

[0033] Figure 3 This is a schematic diagram of the structure of the first sliding block in the variable height steel-concrete composite beam jacking system provided in the embodiments of this application;

[0034] Figure 4 This is a schematic diagram of the tensioning component in the variable height steel-concrete composite beam launching system provided in the embodiments of this application;

[0035] Figure 5 for Figure 1 Schematic diagram of the cross-sectional structure along line AA;

[0036] Figure 6 for Figure 1 Schematic diagram of the cross-sectional structure along line BB;

[0037] Figure 7 for Figure 1 A cross-sectional view of the structure along the CC line.

[0038] In the diagram: 1. Main beam; 11. Middle crossbeam; 2. Support device; 21. Spread foundation; 22. Steel pipe column; 23. Connecting system; 24. Distribution beam; 25. Longitudinal beam; 26. Track; 3. Jacking device; 31. First slide block; 311. Main body; 312. Slot; 313. MGB sliding plate; 32. Pad; 33. Jacking jack; 34. Rail clamp; 4. Balancing device; 41. Tower; 411 42. Reaction seat; 421. Cable; 422. Steel strand; 423. Anchor cup with ear plate; 444. Anchor cup with internal and external threads; 45. Hinge seat; 46. Tensioning assembly; 47. Tensioning jack; 48. Tensioning rod; 49. Tool anchor; 40. Working anchor; 41. Support foot; 42. Front anchor beam; 43. Rear pad beam; 444. Fork lug; 45. Second slide block; 6. Counterweight; 7. Main pier; 8. Side pier. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] This application provides a variable-height steel-concrete composite beam jacking system and construction method, which can solve the problems of low stiffness and large deformation of the large cantilever main beam when using the conventional jacking method for spanning variable-height cross-section steel box girders.

[0041] Reference Figure 1 As shown, this is a variable-height steel-concrete composite beam jacking system provided in an embodiment of this application. The variable-height steel-concrete composite beam jacking system includes a support device 2, a jacking device 3, and a balancing device 4. The support piles are used to support the main beam 1 and provide a platform for jacking the main beam 1 forward. The jacking device 3 is installed on the support device 2 to jack the main beam 1. The balancing device 4 includes a pylon 41 and at least two cables 42. The pylon 41 is installed on the top of the main beam 1 and is located at the middle of the main beam 1 in the longitudinal direction. The cables 42 are used to connect the pylon 41 and the two ends of the main beam 1 and to overcome the gravity at the ends of the main beam 1.

[0042] Reference Figure 1 and Figure 5-7As shown, specifically, the support device 2 includes an enlarged foundation 21 on the ground, which is formed by concrete casting. Vertical steel pipe columns 22 are set on the enlarged foundation 21. Multiple steel pipe columns 22 are distributed along the longitudinal and transverse directions of the main beam 1. The steel pipe columns 22 are installed by flange connection. The steel pipe columns 22 are connected to each other to form an integral structure through a connecting system 23. The connecting system 23 consists of multiple steel pipes and is fixed to the columns by welding with intersecting lines. Multiple distribution beams 24 are installed on the top of the steel pipe columns 22. A single distribution beam 24 is set along the transverse direction, and multiple distribution beams 24 are set at intervals along the longitudinal bridge frame. Diagonal braces are welded between the distribution beams 24 and the steel pipe columns 22 to improve the structural strength. Multiple longitudinal beams 25 are set on the distribution beams 24 along the longitudinal direction of the bridge. Multiple longitudinal beams 25 are set at intervals along the transverse direction of the bridge. Then, the construction platform is installed on the longitudinal beams 25. With the above setup, the support device 2 is constructed by connecting steel pipes and steel beams through welding or flanges, which is convenient for construction and allows for on-site construction according to actual needs.

[0043] Reference Figure 1-2 As shown, the jacking device 3 includes a first sliding block assembly, which is installed on the support device 2 and can slide along the jacking direction of the main beam 1. The first sliding block assembly is used to support the main beam 1 at the bottom of the main beam 1, and the support point is located at the middle of the main beam 1 along the longitudinal direction of the bridge.

[0044] Reference Figure 1-2 and Figure 5 As shown, specifically, the first sliding block group includes multiple first sliding blocks 31, which are spaced apart along the transverse direction of the bridge and can slide along the pushing direction of the main beam 1. The support device 2 includes a track 26 that is slidably assembled with the first sliding blocks 31. In this embodiment, there are two first sliding blocks 31, and correspondingly, two tracks 26 are provided on the support device 2. The two first sliding blocks 31 are slidably assembled on the two tracks 26 respectively. In this embodiment, in order to provide better support for the main beam 1, there are two sets of first sliding blocks, and the two sets of first sliding blocks are arranged in a double-jointed manner and continuously arranged along the longitudinal direction of the bridge.

[0045] Reference Figure 3 As shown, the first slide block 31 includes a main body 311. L-shaped slots 312 are connected to both sides of the bottom of the main body 311. The slots 312 are bolted to the main body 311, allowing for sliding assembly with the track 26 and preventing the first slide block 31 from disengaging from the track 26. An MGB sliding plate 313 is provided between the main body 311 and the track 26 to reduce frictional resistance between the first slide block 31 and the track 26. A pad 32 is fixed to the top of the first slide block 31, which contacts the main beam 1 to support it. The pad 32 is manufactured according to the linear matching of the bottom of the main beam 1 to provide stable support for the main beam 1. This arrangement allows the main beam 1 to slide on the support device 2 for jacking construction.

[0046] Reference Figure 1-2 As shown, the jacking device 3 also includes two jacking jacks 33. The jacking jacks 33 are connected to the slide and the rail 26. Specifically, one end of the piston rod is hinged to the slide, and one end of the main body 311 is hinged to a rail clamp 34. The rail clamp 34 is bolted to the rail 26 through the bolt holes reserved on the flange plate of the rail 26, thereby providing support for the jack when it is started.

[0047] Reference Figure 1 As shown, further, in the balancing device 4, the pylon 41 is hinged to the main beam 1, and the hinge axis is set along the transverse direction of the bridge. Specifically, when installing the pylon 41, multiple hinge seats 43 are first welded to the middle of the main beam 1 along the longitudinal direction of the bridge. The multiple hinge seats 43 are spaced apart along the transverse direction of the bridge. Then, the pylon 41 is installed and hinged to the hinge seats 43.

[0048] Reference Figure 1 and Figure 5-6 As shown, furthermore, at least two cables 42 are provided, and both ends of the main beam 1 must be connected to the tower 41 via cables 42. In this embodiment, each end of the main beam 1 is connected to the tower 41 via three cables 42. When connecting the cables 42, a front anchor beam 45 is welded to the front end of the main beam 1 for cable 42 connection, and a rear pad beam 46 is welded to the rear end of the main beam 1 for cable 42 connection. Fork lugs 47 are welded and fixed on both the front anchor beam 45 and the rear pad beam 46. The cable 42 includes a steel strand 421, an anchor cup 422 with lugs connected to both ends of the steel strand 421, and an anchor cup 423 with internal and external threads. The cable 42 is connected to the front anchor beam 45 and the rear pad beam 46 by bolting and fixing the fork lugs 47 and the anchor cup 422 with lugs. Among them, the anchor cup 422 with lugs, the steel strand 421, and the anchor cup 423 with internal and external threads are custom-made parts and are assembled into a whole in professional engineering.

[0049] Reference Figure 1 and Figure 4 As shown, further, the cable 42 is connected to the tower 41 via a tensioning assembly 44, which is used to adjust the tension of the cable 42.

[0050] Reference Figure 1 and Figure 4As shown, specifically, the tower 41 includes a reaction seat 411 located at the top, and the tensioning assembly 44 includes a tensioning jack 441 disposed on the reaction seat 411. The tensioning jack 441 is a through-hole jack, which is connected to a tensioning rod 442. The tensioning rod 442 passes through the jack and is bolted with a tool anchor 443. The tool anchor 443 restricts its separation from the tensioning jack 441 and transmits the pressure of the jack to the cable 42 through the tensioning rod 442 after the tensioning rod 442 is connected to the cable 42. 2. The cable passes through the reaction seat 411 and connects to the tension rod 442. Specifically, the internally and externally threaded anchor cup 423 is fitted onto the tension rod 442 and threadedly assembled with it. A working anchor 444 is bolted to the outside of the internally and externally threaded anchor cup 423. The working anchor 444 is supported on the reaction seat 411. To provide installation space for the working anchor 444, a support leg 445 is installed on the reaction seat 411. The support leg 445 and the reaction seat 411 form a space to accommodate the working anchor 444. The tension jack 441 is installed on the support leg 445. Through the above arrangement, the tension of the cable 42 can be adjusted by the tension jack 441 to achieve a suitable cable force and improve the support effect on the end of the main beam 1.

[0051] Reference Figure 1 As shown, the balancing device 4 further includes a second sliding block assembly, which is disposed on the support device 2 and can slide along the pushing direction of the main beam 1. It is used to connect to the bottom of the main beam 1 and support the main beam 1, and the connection point is located at the rear end of the main beam 1 along the pushing direction.

[0052] Reference Figure 1 and Figure 7 As shown, specifically, the second slide block assembly includes multiple second slide blocks 48, which are spaced apart along the transverse direction of the bridge. In this embodiment, there are two second slide blocks 48, and the two second slide blocks 48 are respectively installed on two slide rails. In this embodiment, the structure of the second slide block 48 is the same as that of the first slide block 31. The top of the second slide block 48 is also fixed with a pad 32, which is a structure designed to adjust the cross slope to match the bottom line of the main beam 1. It is welded and fixed to the rear pad beam 46 on the main beam 1 so as to support the rear end of the main beam 1 through the second slide block 48. Correspondingly, the rear pad beam 46 is fixed at the bottom of the main beam 1 near the rear end. Because the main beam 1 has a relatively high central crossbeam, after it is erected on the first sliding block assembly, it forms a lever structure with the central part as the fulcrum and both ends suspended. Therefore, the installation of the second sliding block assembly can add a fulcrum to improve the stability of the main beam 1. Furthermore, the second sliding block assembly is located at the rear end of the main beam 1, so it will not affect the front end of the main beam 1 from crossing the building to the designed position. At the same time, the second sliding block assembly is fixed to the main beam 1 and connected to the track 26, which can also limit the sagging of the front end of the main beam 1.

[0053] Reference Figure 1As shown, the balancing device 4 further includes a counterweight 5 on the main beam 1, and the counterweight 5 is located at the rear end of the main beam 1 along the jacking direction. By adding the counterweight 5, the weight at the rear end of the main beam 1 can be increased, and the main beam 1 can be supported from the bottom of the main beam 1 through the second sliding block group, so that the two ends of the main beam 1 do not move up and down. At the same time, when jacking the main beam 1 and crossing the building, since the bottom of the front end of the main beam 1 is not supported, its front end is in a suspended state. The rear counterweight and the second sliding block group can prevent the front end of the main beam 1 from falling down, so as to successfully complete the crossing construction of the main beam 1 and put it into place.

[0054] This application embodiment also provides a method for jacking construction of variable-height steel-concrete composite beams, which uses the variable-height steel-concrete composite beam jacking construction system described above for construction, including:

[0055] Install the jacking device 3 on the support device 2, and hoist the main beam 1 onto the support device 2.

[0056] A balancing device 4 is constructed on the main beam 1. After the cable tower 41 is constructed on the main beam 1, a cable 42 is installed to connect the end of the main beam 1 and the cable tower 41.

[0057] Push the main beam 1 to the design position.

[0058] Specifically, it includes the following steps:

[0059] 1. Pour the enlarged foundation 21, install the steel pipe column 22 using flange connection, then weld the connection system 23, then install the distribution beam 24 and fix it to the steel pipe column 22, and then construct the longitudinal beam 25 on the distribution beam 24.

[0060] The enlarged foundation 21 requires a foundation bearing capacity greater than 250 kPa or other design requirements. The connecting system 23 is a steel pipe, which is welded firmly to the column steel pipe with an intersecting line to resist the deformation caused by the jacking and ensure the strength, rigidity and stability of the support device 2.

[0061] 2. Install the rail 26 on the top of the distribution beam 24, and then install the first slide 31 and the second slide 48 on the rail 26 to ensure that it can move longitudinally and does not deviate laterally; then install the jacking jack 33 and the customized rail clamp 34. The rail clamp 34 is bolted to the rail 26 through the bolt holes reserved on the flange plate of the rail 26.

[0062] When installing the first slide block 31 and the second slide block 48, firstly, the MGB slide plate 313 is pasted to the bottom of the main body 311, then the main body 311 is placed on the track 26, and then two slots 312 are symmetrically installed and bolted to the main body 311, with the two slots 312 located on both sides of the flange of the track 26. Then, the pad 32 is fixed on the top of the first slide block 31 and the top of the second slide block 48.

[0063] After installation, the first slide block 31 and the second slide block 48 are temporarily fixed on the track 26 for subsequent connection with the main beam 1.

[0064] 3. Use a crane to lift the main beam 1 so that it naturally falls onto the first sliding block assembly, and position the first sliding block assembly at the middle of the longitudinal direction of the main beam 1.

[0065] 4. Weld the front anchor beam 45, hinge seat 43 and rear pad beam 46 onto the main beam 1 and install the counterweight 5. After the hinge seat 43 is welded, it is hinged to the tower 41. After the rear pad beam 46 is welded, it is welded and fixed to the pad 32 on the second slide 48.

[0066] Specifically, after the front anchor beam 45 and the rear pad beam 46 are welded, a fork lug 47 is welded on each of them. Before the tower 41 is connected to the hinge seat 43, the cable 42 is first installed on the reaction seat 411 on the tower 41, so that the internal and external threaded anchor cup 423 passes through the reaction seat 411 and is connected to the working anchor 444. The top of the cable 42 is kept flat and the lower end of the cable 42 is in a free state. Then the tower 41 is hoisted. After the tower 41 is installed, the lower end of the cable 42 is connected to the fork lug 47 by a pin through traction. Then the support leg 445, tension rod 442, tension jack 441 and tool anchor 443 are installed in sequence, and the tension rod 442 is connected to the internal and external threaded anchor cup 423.

[0067] 5. Then, start the tensioning jack 441 to tension the cable 42 until the design cable force is reached, and make the elevation of the main beam 1 closure joint reach the design operating deviation range to meet the closure accuracy requirements.

[0068] 6. The two jacking jacks 33 are wirelessly controlled to push synchronously. After each jacking advance of 30cm, the rail clamp 34 is released, the jacking jacks 33 return to their original position, and the rail clamp 34 moves forward. The jacking is carried out in a step-by-step manner until the main beam 1 is pushed to the design position.

[0069] 7. Restart the jacks to tension the cables 42 until the elevation of the main beam 1 closure joint reaches the design allowable deviation range, meets the closure accuracy requirements, and complete the closure construction. After the closure is completed, remove the balancing device 4.

[0070] 8. After the closure is completed, first construct the bridge side pier 7, install the beam-dropping jack on the top of the side pier 7 to lift the main beam 1 as a whole structure, and then remove the jacking device 3.

[0071] 9. Remove support device 2 and restore the original terrain for all construction work.

[0072] This application has the following advantages:

[0073] 1. In the process of jacking construction, this application adopts a balancing device 4 consisting of a pylon 41, a cable 42, and a counterweight 5, which solves the problem of low stiffness and large deformation of the I-beam main beam 1 without the bridge deck being stacked, and realizes the requirement of jacking without the deck and increasing the spanning capacity.

[0074] 2. By adopting the first slide block 31 and the slot 312 design of the track 26, the MGB slide block 313 sliding control measure, and the wireless CNC synchronous jacking technology, the problem of lateral correction of the jacking of the wide structure is solved, and the accuracy of bidirectional jacking and mid-span closing is guaranteed.

[0075] 3. By setting the main jacking at the middle crossbeam 11 of the main beam 1, and setting the second sliding block group and the rear pad beam 46 at the rear end of the main beam 1 to adjust the height and assist the jacking, the problem of horizontal jacking of variable cross sections is solved, the construction efficiency is improved, and the application range is wider.

[0076] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0077] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0078] The above are merely specific embodiments of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A variable-height steel-concrete composite beam jacking system, characterized in that, include: Support device (2), which is used to support the main beam (1) and provide a platform for the main beam (1) to be pushed forward; A jacking device (3) is mounted on the support device (2) and is used to jack the main beam (1); Balancing device (4), comprising: Tower (41), which is used to be installed on top of the main beam (1) and located in the middle of the main beam (1) along the longitudinal direction of the bridge; At least two cables (42) are used to connect the tower (41) and the two ends of the main beam (1) and to overcome the gravity at the ends of the main beam (1); The balancing device (4) further includes a second sliding block assembly, which is disposed on the support device (2) and can slide along the pushing direction of the main beam (1). The second sliding block assembly is used to connect to the bottom of the main beam (1) and support the main beam (1), and the connection point is located at the rear end of the main beam (1) along the pushing direction. The rear end of the main beam (1) is welded with a rear pad beam (46), which is used for the connection of the cable (42). The second slide block assembly is welded and fixed to the rear pad beam (46). The jacking device (3) includes a first slide block assembly, which is installed on the support device (2) and can slide along the jacking direction of the main beam (1). The first slide block assembly is used to support the main beam (1) at the bottom of the main beam (1), and the support point is located in the middle of the main beam (1) along the longitudinal direction of the bridge. The first slide block assembly includes a plurality of first slide blocks (31), which are spaced apart along the transverse direction of the bridge. The first slide blocks (31) can slide along the jacking direction of the main beam (1). The support device (2) includes a track (26) that slides with the first slide blocks (31). The first slide block (31) includes a main body (311), and L-shaped slots (312) are connected to both sides of the bottom of the main body (311). The slots (312) are bolted to the main body (311). The two slots (312) are used to achieve sliding assembly with the track (26) to limit the first slide block (31) from disengaging from the track (26). The second slide block assembly includes multiple second slide blocks (48), which are spaced apart along the transverse direction of the bridge; the second slide blocks (48) are mounted on the track (26); a pad (32) is provided on the top of the second slide block (48), and the pad (32) is fixed to the rear pad beam (46) on the main beam (1); The variable height steel-concrete composite beam is a steel-concrete composite beam that is high in the middle and low on both sides; the main beam (1) is not superimposed with the bridge deck.

2. The variable-height steel-concrete composite beam jacking system according to claim 1, characterized in that: The balancing device (4) includes a counterweight (5) disposed on the main beam (1), the counterweight (5) being located at the rear end of the main beam (1) along the jacking direction.

3. The variable-height steel-concrete composite beam jacking system according to claim 1, characterized in that: The bottom of the pylon (41) is hinged to the main beam (1), and the hinge axis is set along the transverse direction of the bridge.

4. The variable-height steel-concrete composite beam jacking system according to claim 1, characterized in that: The cable (42) is connected to the tower (41) via a tensioning assembly (44), which is used to adjust the tension of the cable (42).

5. The variable-height steel-concrete composite beam jacking system according to claim 4, characterized in that, The tower (41) includes a reaction seat (411) located at the top, and the tensioning assembly (44) includes: Tensioning jack (441), which is mounted on the reaction seat (411); The tension rod (442) is connected to the tension jack (441), and the cable (42) passes through the reaction seat (411) and is connected to the tension rod (442).

6. A method for jacking construction of variable-height steel-concrete composite beams, characterized in that, Construction using the variable-height steel-concrete composite beam jacking system as described in claim 1 includes: Install the jacking device (3) on the support device (2); The balancing device (4) is constructed on the main beam (1). First, the cable tower (41) is constructed on the main beam (1). Then, the cable (42) is installed to connect the end of the main beam (1) and the cable tower (41). After completion, the main beam (1) is hoisted onto the support device (2). Push the main beam (1) to the design position.

7. The method for jacking construction of variable-height steel-concrete composite beams according to claim 6, characterized in that: A counterweight (5) is installed on the main beam (1), and the counterweight (5) is located at the rear end of the main beam (1) along the jacking direction.

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