Design method of UHPC tenon-and-mortise structure fabricated box girder bridge

Abstract

The invention relates to the field of building bridges, and discloses a UHPC tenon-and-mortise structure fabricated box girder bridge design method.The UHPC tenon-and-mortise structure fabricated box girder bridge comprises a bottom plate tenon structure, a web mortise structure, a top plate tenon structure and a transverse partition plate, the web mortise structure is arranged on the bottom plate tenon structure, the top plate tenon structure is arranged on a mortise structure at the top of a web, and a transverse partition plate inserting groove A is formed in the top of a bottom plate; web inserting blocks are fixedly connected to the front ends and the rear ends of the left side and the right side of the bottom plate correspondingly, web inserting grooves are formed in the inner sides and the tops of the bottoms of the webs correspondingly, inserting blocks are fixedly connected to the two sides of the bottom of the top plate correspondingly, and transverse partition plate inserting grooves B and C are formed in the inner sides of the middles of the webs and the bottom of the middle of the top plate correspondingly; dovetail joint joints A, B and C are fixedly connected to the front sides and the rear sides of the bottom plate, the web plate and the top plate. By adopting the unique tenon-and-mortise structure design, a traditional box girder bridge design method is abandoned, the construction process is greatly simplified, the construction speed is increased, the transportation cost and time are reduced, and the hidden danger of durability is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of building bridges, and in particular to a design method for a UHPC mortise and tenon structure assembled box girder bridge. Background Art

[0002] The same technology is the conventional construction method of ordinary concrete box girder bridge. This method is mainly used in the second-generation bridges mainly composed of steel bars and concrete, including simply supported box girder bridges, continuous box girder bridges and continuous rigid frame bridges. The reasonable span range of different bridge types is different, but it is mostly limited to 50 to 200 meters. At present, the box girder bridge with the largest span is the Chongqing Shibanpo double-track bridge with a main span of 330 meters. Its main beam structure is ordinary concrete + steel box girder transition section. The maximum span of the prestressed concrete continuous box girder bridge is the Xuanshuituo Minjiang Bridge with a span of (101+180+101) meters. However, no matter what type of box girder bridge, its span limitation is very obvious and cannot surpass arch bridges, cable-stayed bridges and suspension bridges. From the perspective of construction methods, concrete box girder bridges can be divided into prefabrication and cast-in-place methods. Among them, the prefabrication installation method can be divided into three types: prefabricated beam installation, prefabricated segmental block assembly and whole span box girder prefabrication and hoisting. The cast-in-place method is generally divided into segmental cast-in-place and integral cast-in-place. Bridges built using prefabricated installation methods are also called prefabricated bridges. They have gradually become the mainstream bridge type and are the development trend of the bridge industry because of their advantages such as standardized component production, fast and convenient on-site installation, and energy-saving and environmentally friendly construction. For example, the non-navigable bridge of the Hong Kong-Zhuhai-Macao Bridge is a prefabricated box girder bridge produced using standardized production, which has outstanding advantages such as good design quality and high construction efficiency. However, due to the limitations of the material itself, ordinary concrete bridges cannot effectively break through the conventional span, construction efficiency is also hindered, and the cost is difficult to reduce.

[0003] Ultra-high performance concrete (UHPC) is a new type of cement-based composite material with ultra-high strength and ultra-toughness. It is a new generation of concrete material with advantages that ordinary concrete cannot match, providing a material basis for the development of the bridge industry. It can be foreseen that bridges built with ultra-high performance concrete have superior performance in terms of span, construction speed, and cost. However, most of the UHPC bridges are currently in the theoretical research stage. Most existing projects apply it to the pavement layer of steel bridge decks, lacking the practice of the main beam itself. So far, there has been no UHPC box girder bridge. Theoretical research is also relatively scarce. There are very few literatures on the feasibility study of the design of UHPC box girder bridges. In summary, it can be considered that the current engineering community has a very limited understanding of UHPC box girder bridges, and new theories are urgently needed to open up research areas and accelerate the development of the industry.

[0004] The design method of the UHPC mortise and tenon structure assembled box girder bridge proposed in the present invention solves this problem. By adopting the traditional Chinese mortise and tenon technology and combining it with modern high-performance materials, a new bridge type can be created, laying the foundation for the third-generation bridge. The third-generation bridge refers to a bridge designed and constructed using intelligent, industrialized and high-performance materials. The purpose of the present invention is to solve its technical problems and provide a new idea for the engineering community to achieve innovation from scratch. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a design method for a UHPC mortise and tenon structure assembled box girder bridge, which solves the problem that the existing ordinary concrete box girder bridge has obvious span limitations, mostly 50-200 meters, and a limited maximum span. Although the construction method has advantages such as prefabrication and installation, it is difficult to break through the conventional span, improve construction efficiency and reduce construction costs due to material limitations.

[0006] To achieve the above purpose, the present invention is implemented through the following technical solutions: UHPC mortise and tenon structure assembled box girder bridge, including a bottom plate mortise structure, a web plate mortise structure, a top plate mortise structure and a diaphragm, the bottom plate mortise structure is provided with a web plate mortise structure, the web plate top mortise structure is provided with a top plate mortise structure. The bottom plate, web plate and top plate are all provided with diaphragm plug-in grooves for connecting the diaphragms.

[0007] Preferably, the bottom plate tenon structure includes a bottom plate, a cross partition plug-in groove A is opened on the top of the bottom plate, the front and rear ends on the left and right sides of the bottom plate are fixedly connected with web plug-in blocks, and the front and rear sides of the bottom plate are fixedly connected with dovetail tenon joints A.

[0008] Preferably, the web mortise structure includes a web, a top plate plug-in groove is opened on the top of the web, a bottom plate plug-in groove is opened on the bottom of the inner wall of the web near the bottom plate, a cross partition plug-in groove B is opened in the middle of the inner wall of the web, and dovetail tenon joints B are fixedly connected on the front and rear sides of the web.

[0009] Preferably, the top plate tenon structure includes a top plate, a cross partition plug-in groove C is opened in the middle of the bottom of the top plate, the front and rear ends of the left and right sides of the bottom of the top plate are fixedly connected with web plug-in blocks, and the front and rear sides of the top plate are fixedly connected with dovetail tenon joints C.

[0010] Preferably, the inner wall of the transverse partition insertion groove C of the top plate is inserted into the top of the transverse partition.

[0011] Preferably, the outer wall of the top plate plug-in block is plugged into the inner wall of the web plate plug-in groove.

[0012] Preferably, the inner wall of the transverse partition insertion groove A of the bottom plate is inserted into the bottom of the transverse partition.

[0013] Preferably, the outer wall of the bottom plate plug-in block is plugged into the inner wall of the web plate plug-in groove.

[0014] Preferably, the inner wall of the diaphragm inserting groove B of the web is inserted into the side of the diaphragm.

[0015] The design method of the UHPC mortise and tenon structure prefabricated box girder bridge includes the following steps:

[0016] S1. Casting of bridge piers and 0# blocks: accurately locate according to the design, build formwork, use high-quality concrete according to the mix ratio to cast bridge piers and 0# blocks, and vibrate to compact them;

[0017] S2. Insert the bottom plate: Align the web plate plug-in block of the prefabricated bottom plate to the corresponding position on the 0# block, so that the dovetail joint A of the bottom plate initially fits with the adjacent structure, slowly lower it, and fine-tune it until the position of the cross partition plug-in slot A is accurate;

[0018] S3. Embedding the diaphragm: Determine the position of the diaphragm on the embedded bottom plate according to the design, insert the bottom of the diaphragm into the diaphragm insertion slot A of the bottom plate, lift the diaphragm to a vertical position, align its two sides with the corresponding interfaces of the adjacent structure, and use the guide device to assist in embedding;

[0019] S4. Insert the webs on both sides: After checking the structural integrity of the webs’ mortise and tenon structures, align the bottom plate inserting slot at the bottom of the web with the web plate inserting block of the installed bottom plate, slowly lift and insert, so that the web’s diaphragm inserting slot B is precisely aligned with the diaphragm, and its dovetail joint B fits tightly with the adjacent components, and fix with force;

[0020] S5. Insert the top plate: lift the top plate to the top of the box beam, insert the web plate plug-in block of the top plate into the web plate top plate plug-in slot, make the diaphragm plug-in slot C accurately dock with the top of the diaphragm, adjust the dovetail joint C of the top plate to fit with the surrounding structure during the lowering process, deal with the gap at the connection point, and form a stable whole with the lower part;

[0021] S6. Apply transverse limit device: When the box girder reaches a certain length, install transverse limit device at the predetermined position according to the force analysis, adjust the preload force and clearance, and ensure that the top plate does not have vertical displacement;

[0022] S7. Tensioning external prestressing: Install tensioning equipment and anchorage according to the plan, accurately tension steel strands, control force, acceleration and elongation, improve bearing capacity, crack resistance and durability, and maintain the integrity of the box girder;

[0023] S8. Embed the bottom plate of the next segment: Based on the above segment, repeat the S2 step process to embed the bottom plate of the next segment, and pay attention to the connection accuracy;

[0024] s9. Repeat the cycle: Continue to repeat steps S3-S8, and conduct quality inspection and review after each section is completed until all sections are installed and the main beam is installed.

[0025] The present invention provides a design method for a UHPC mortise and tenon structure assembled box girder bridge. It has the following beneficial effects:

[0026] 1. The present invention adopts a unique mortise and tenon structure design, abandons the complex joint processing method of traditional box girder bridges, and directly adopts dry joints without considering multiple joint forms, which greatly simplifies the construction process and effectively improves the construction speed. The traditional box girder bridge faces problems of carrying capacity and multiple joint connections during prefabrication and installation. The process is complicated, the process requirements are high, and the technical difficulty is high. The present invention reduces the hidden dangers of structural durability caused by improper joint processing. At the same time, the transportation load is only about one-fourth of the original, which significantly reduces transportation costs and time.

[0027] 2. The present invention is based on the dovetail UHPC box girder bridge structure and adds the top and bottom plate key teeth to greatly improve the bearing capacity level, so that the span can be further increased, and it is expected to break through the span limitation of the existing box girder bridge. Compared with the traditional suspension bridge, the present invention uses UHPC materials and has no steel and cable system, avoiding the problems of difficult suspension bridge design, complex construction process and high cost, achieving effective cost reduction, and providing a more economical and feasible solution for the construction of large-span bridges.

[0028] 3. The present invention utilizes the ultra-high strength, ultra-toughness and durability of the UHPC material itself to eliminate cracking while meeting the design strength requirements, greatly increasing the service life of the bridge by several times from the existing standard of 100 years. And because the material does not crack, there is no need to spend manpower and material resources on inspection, maintenance and reinforcement, which effectively reduces the operational risk, ensures that the bridge can serve healthily throughout its life cycle, and greatly improves the durability of the bridge.

[0029] 4. The present invention uses UHPC materials to build bridges. The material has green properties and can reduce natural resource consumption and significantly reduce carbon emissions compared to traditional concrete bridges. Promoting the application of the present invention in the bridge construction industry will help advance the green construction process.

[0030] 5. The present invention proposes an unprecedented design method, which innovatively combines traditional Chinese mortise and tenon technology with modern high-performance materials, breaking through the dilemma that the second-generation traditional bridge design theory is close to perfection but difficult to innovate. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A perspective view of the present invention;

[0032] Figure 2 It is a schematic diagram of the top plate tenon structure of the present invention;

[0033] Figure 3 It is a schematic diagram of the bottom plate tenon structure of the present invention;

[0034] Figure 4 It is a schematic diagram of the web mortise structure of the present invention;

[0035] Figure 5 It is a schematic diagram of the structure of the diaphragm of the present invention;

[0036] Figure 6 It is a schematic diagram of the structure of the diaphragm of the present invention;

[0037] Figure 7 It is a schematic diagram of the main beam of the present invention;

[0038] Figure 8 It is a schematic diagram of the cross-sectional structure of the present invention;

[0039] Fig. 9 It is a schematic diagram of the transverse anti-falling beam device of the present invention;

[0040] Fig.10 It is a schematic diagram of the longitudinal bridge direction of the bottom plate of the present invention;

[0041] Fig.11 The figure is a flow chart of the method of the present invention.

[0042] Among them, 1. bottom plate tenon structure; 101. bottom plate; 102. dovetail tenon joint A; 103. web plate plug-in block; 104. partition plate plug-in slot A; 2. web plate mortise structure; 201. web plate; 202. top plate plug-in slot; 203. dovetail tenon joint B; 204. bottom plate plug-in slot; 205. partition plate plug-in slot B; 3. partition; 4. top plate tenon structure; 401. top plate; 402. partition plate plug-in slot C; 403. web plate plug-in block; 404. dovetail tenon joint C. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] Example:

[0045] Please see attached Figure 1 - Attachment Fig.10 An embodiment of the present invention provides a UHPC mortise and tenon structure assembled box girder bridge, comprising a bottom plate mortise and tenon structure 1, a web plate mortise and tenon structure 2, a top plate mortise and tenon structure 4 and a cross diaphragm 3. The bottom plate mortise and tenon structure 1 is provided with a web plate mortise and tenon structure 2, and the top plate mortise and tenon structure 4 is provided with a top plate mortise and tenon structure 4 on the top of the web plate mortise and tenon structure 2. The bottom plate mortise and tenon structure 1, the web plate mortise and tenon structure 2, the cross diaphragm 3 and the top plate mortise and tenon structure 4 are all made of UHPC material, and the UHPC material has the characteristics of ultra-high strength, ultra-toughness and durability.

[0046] The bottom plate tenon structure 1 includes a bottom plate 101. The bottom plate 101 is a key load-bearing component at the bottom of the box girder. Its large-area plane structure can evenly disperse the vertical loads from the upper structure and vehicles, and effectively transfer these loads to the piers. A diaphragm plug-in groove A104 is opened on the top of the bottom plate 101. The diaphragm plug-in groove A104 provides a precise and stable connection point for the installation of the diaphragm, so that the diaphragm and the bottom plate can fit closely, jointly bear the lateral load and enhance the overall stability of the structure. The front and rear ends on the left and right sides of the bottom plate 101 are fixedly connected with web plug-in blocks 103. The web plug-in blocks 103 are not only easy to install during the installation process, but also easy to install. It plays a positioning and guiding role, ensuring that the web can be accurately installed in the predetermined position, and when the structure is subjected to stress, it can smoothly transfer the shear force and part of the vertical load from the web to the bottom plate, making the force flow transmission of the entire structure smoother. The front and rear sides of the bottom plate 101 are fixedly connected with dovetail joints A102, which significantly enhance the longitudinal connection strength and stability between the bottom plate and adjacent structures such as piers or other box girder segments, and effectively prevent the bottom plate from being displaced or detached under longitudinal action. With the ultra-high strength of UHPC materials, it can withstand huge longitudinal tension and pressure, and ensure the integrity of the bridge structure under complex stress environments.

[0047] The web mortise structure 2 includes a web 201, which plays a vital role in the box girder structure. A top plate plug-in groove 202 is provided at the top of the web 201, which provides an accurate docking position for the installation of the top plate, so that the top plate can be closely connected with the web. When subjected to vertical load, the pressure from the top plate is evenly distributed to the web, and the load is transmitted to the entire structural system through the connection with the bottom plate. A bottom plate plug-in groove 204 is provided at the bottom of the outer wall of the web 201 close to the bottom plate 101, and the bottom plate plug-in groove 204 cooperates with the web plug-in block 103 of the bottom plate to form a stable vertical connection, which can not only effectively transmit the vertical shear force, but also enhance the vertical integrity of the structure and prevent relative slippage or separation between the web and the bottom plate. The web 201 is close to the bottom plate 1 A diaphragm insertion groove B205 is provided in the middle of the outer wall of 01. The diaphragm insertion groove B205 enables the diaphragm to be smoothly inserted and tightly combined with it. Under the action of lateral force, it works together with the diaphragm to resist lateral deformation and evenly distribute the lateral load to the entire web structure. The ultra-strong toughness of UHPC material is utilized to effectively avoid web damage caused by excessive lateral force. The front and rear sides of the web 201 are fixedly connected with dovetail joints B203. The dovetail joints B203 further enhance the longitudinal connection reliability between the web and adjacent components such as other webs or diaphragms. Through the mortise and tenon connection with other components, a continuous force transmission path is formed, so that the entire box girder structure can maintain coordinated deformation when subjected to various complex load combinations, avoiding the occurrence of local stress concentration.

[0048] The top plate tenon structure 4 includes a top plate 401, and a diaphragm plug-in groove C402 is provided at the bottom of the top plate 401. As the top covering part of the box girder, the top plate 401, in addition to bearing its own weight and possible upper live load, has a diaphragm plug-in groove C402 at the bottom connected to the top of the diaphragm, which effectively transfers the upper load to the diaphragm and further disperses it to the entire structural system. A web plug-in block 403 is fixedly connected to the bottom of the top plate 401, and the web plug-in block 403 is plugged into the top plate plug-in groove 202 of the web, so that the top plate and the web are closely combined. Under the action of vertical load, the load is evenly distributed to the web, ensuring the vertical integrity of the structure. The outer walls of the front and rear sides of the top plate 401 are fixedly connected with dovetail joints C404. The dovetail joints C404 enhance the lateral connection strength between the top plate and adjacent structures such as other top plate segments or guardrails and other auxiliary structures, and prevent the top plate from being displaced or lifted up under the action of longitudinal force. With the characteristics of UHPC materials, the top plate can withstand various adverse factors such as wind, sun, rain erosion, and dynamic loads generated by vehicle driving for a long time, maintain the integrity and sealing of the structure, provide good protection for the internal structure of the bridge, and also provide a smooth and safe road surface support for vehicle driving, ensuring that the bridge can function normally within its designed service life.

[0049] The inner wall of the partition plug-in groove C402 is plugged into the top of the partition 3, the inner wall of the partition plug-in groove A104 is plugged into the bottom of the partition 3, the outer wall of the bottom plate plug-in block 103 is plugged into the inner wall of the web plate plug-in groove 204, the inner wall of the web plate partition plug-in groove B205 is plugged into the outer wall of the partition 3, and the outer wall of the top plate plug-in block 403 is plugged into the inner wall of the web plate plug-in groove 202.

[0050] The design method of the UHPC mortise and tenon structure prefabricated box girder bridge includes the following steps:

[0051] S1. Casting of bridge piers and 0# blocks: accurately locate according to the design, build formwork, use high-quality concrete according to the mix ratio to cast bridge piers and 0# blocks, vibrate and compact them, and lay the foundation for the subsequent foundation;

[0052] S2. Insert the bottom plate: Align the web plate plug-in block of the prefabricated bottom plate with the corresponding position on the 0# block, so that the dovetail joint A of the bottom plate initially fits with the adjacent structure, slowly lower it, and fine-tune it until the position of the cross partition plug-in slot A is accurate, ensuring that the bottom plate is tightly connected to the 0# block and temporarily fixed;

[0053] S3. Embedding the diaphragm: Determine the position of the diaphragm on the embedded bottom plate according to the design, insert the bottom of the diaphragm into the diaphragm insertion slot A of the bottom plate, lift the diaphragm to a vertical position, align its two sides with the corresponding interfaces of the adjacent structure, and use the guide device to assist in embedding to ensure that the diaphragm is vertically and tightly connected with the bottom plate and the surrounding area to enhance the lateral rigidity;

[0054] S4. Embed the webs on both sides: After checking the structural integrity of each tenon of the web, align the bottom plate plug-in slot at the bottom of the web with the web plate plug-in block of the installed bottom plate, slowly lift and embed, so that the web's diaphragm plug-in slot B is accurately connected with the diaphragm, and its dovetail joint B fits tightly with the adjacent parts, apply force to fix, and strictly control the verticality and flatness;

[0055] S5. Insert the top plate: lift the top plate to the top of the box beam, insert the web plate plug-in block of the top plate into the web plate top plate plug-in slot, make the diaphragm plug-in slot C accurately dock with the top of the diaphragm, adjust the dovetail joint C of the top plate to fit with the surrounding structure during the lowering process, deal with the gap at the connection point, and form a stable whole with the lower part;

[0056] S6. Apply transverse limit device: When the box girder reaches a certain length, install transverse limit device at the predetermined position according to the force analysis, adjust the preload force and clearance, and ensure that the top plate does not have vertical displacement;

[0057] S7. Tensioning external prestressing: Install tensioning equipment and anchorage according to the plan, accurately tension steel strands, control force, acceleration and elongation, improve bearing capacity, crack resistance and durability, and maintain the integrity of the box girder;

[0058] S8. Embed the bottom plate of the next segment: Based on the above segment, repeat the S2 step process to embed the bottom plate of the next segment, and pay attention to the connection accuracy;

[0059] s9. Repeat the cycle: Continue to repeat steps S3-S8, and conduct quality inspection and review after each section is completed until all sections are installed and the main beam is installed.

[0060] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. UHPC mortise and tenon structure assembled box girder bridge, characterized by: The invention comprises a bottom plate tenon structure (1), a web plate tenon structure (2), a top plate tenon structure (4) and a transverse partition (3). The bottom plate tenon structure (1) is provided with a web plate tenon structure (2), and the web plate top tenon structure (2) is provided with a top plate tenon structure (4). The bottom plate, the web plate and the top plate are all provided with transverse partition insertion grooves for connecting the transverse partition (3).

2. The UHPC mortise and tenon structure assembled box girder bridge according to claim 1 is characterized in that: The bottom plate tenon structure (1) comprises a bottom plate (101), a top of the bottom plate (101) being provided with a transverse partition plate insertion groove A (104), the front end and the rear end of both sides of the bottom plate (101) being fixedly connected with web plate insertion blocks (103), and the front and rear sides of the bottom plate (101) being fixedly connected with dovetail tenon joints A (102).

3. The UHPC mortise and tenon structure assembled box girder bridge according to claim 2 is characterized in that: The web mortise structure (2) comprises a web (201), a top plate plug-in groove (202) is provided at the top of the web (201), a bottom plate plug-in groove (204) is provided at the bottom of the inner wall of the web (201) close to the bottom plate (101), a transverse partition plug-in groove B (205) is provided in the middle of the inner wall of the web (201), and dovetail joints B (203) are fixedly connected to the front and rear sides of the web (201).

4. The UHPC mortise and tenon structure assembled box girder bridge according to claim 3 is characterized in that: The top plate tenon structure (4) comprises a top plate (401), a transverse partition plate insertion groove C (402) is provided in the middle of the bottom of the top plate (401), web plate insertion blocks (403) are fixedly connected at the front and rear ends of the left and right sides of the bottom of the top plate (401), and dovetail tenon joints C (404) are fixedly connected at the front and rear sides of the top plate (401).

5. The UHPC mortise and tenon structure assembled box girder bridge according to claim 4 is characterized in that: The inner wall of the top plate plug-in groove C (402) is plugged into the top of the transverse partition (3).

6. The UHPC mortise and tenon structure assembled box girder bridge according to claim 4, characterized in that: The outer wall of the top plate plug-in block (403) is plugged into the inner wall of the web plate plug-in groove (202).

7. The UHPC mortise and tenon structure assembled box girder bridge according to claim 4, characterized in that: The inner wall of the bottom plate plug-in groove A (104) is plug-in-connected with the bottom of the transverse partition (3).

8. The UHPC mortise and tenon structure assembled box girder bridge according to claim 4, characterized in that: The outer wall of the bottom plate plug-in block (103) is plugged into the inner wall of the web plate plug-in groove (204).

9. The UHPC mortise and tenon structure assembled box girder bridge according to claim 4, characterized in that: The inner wall of the web inserting groove B (205) is inserted into the outer wall of the transverse partition (3).

10. The design method of the UHPC mortise and tenon structure assembled box girder bridge according to any one of claims 1 to 9, comprising the following steps: S1. Casting of bridge piers and 0# blocks: accurately locate according to the design, build formwork, use high-quality concrete according to the mix ratio to cast bridge piers and 0# blocks, and vibrate to compact them; S2. Insert the bottom plate: Align the web plate plug-in block of the prefabricated bottom plate to the corresponding position on the 0# block, so that the dovetail joint A of the bottom plate initially fits with the adjacent structure, slowly lower it, and fine-tune it until the position of the cross partition plug-in slot A is accurate; S3. Embedding the diaphragm: Determine the position of the diaphragm on the embedded bottom plate according to the design, insert the bottom of the diaphragm into the diaphragm insertion slot A of the bottom plate, lift the diaphragm to a vertical position, align its two sides with the corresponding interfaces of the adjacent structure, and use the guide device to assist in embedding; S4. Insert the webs on both sides: After checking the structural integrity of the webs’ mortise and tenon structures, align the bottom plate inserting slot at the bottom of the web with the web plate inserting block of the installed bottom plate, slowly lift and insert, so that the web’s diaphragm inserting slot B is precisely aligned with the diaphragm, and its dovetail joint B fits tightly with the adjacent components, and fix with force; S5. Insert the top plate: lift the top plate to the top of the box beam, insert the web plate plug-in block of the top plate into the web plate top plate plug-in slot, make the diaphragm plug-in slot C accurately dock with the top of the diaphragm, adjust the dovetail joint C of the top plate to fit with the surrounding structure during the lowering process, deal with the gap at the connection point, and form a stable whole with the lower part; S6. Apply transverse limit device: When the box girder reaches a certain length, install transverse limit device at the predetermined position according to the force analysis, adjust the preload force and clearance, and ensure that the top plate does not have vertical displacement; S7. Tensioning external prestressing: Install tensioning equipment and anchorage according to the plan, accurately tension steel strands, control force, acceleration and elongation, improve bearing capacity, crack resistance and durability, and maintain the integrity of the box girder; S8. Embed the bottom plate of the next segment: Based on the above segment, repeat the S2 step process to embed the bottom plate of the next segment, and pay attention to the connection accuracy; s9. Repeat the cycle: Continue to repeat steps S3-S8, and conduct quality inspection and review after each section is completed until all sections are installed and the main beam is installed.

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