Prestressed cast-in-place box girder reinforcing method based on steel-concrete combined system

Abstract

The invention belongs to the technical field of reinforcing construction and transformation of bridge construction engineering, and particularly relates to a prestressed cast-in-place box girder reinforcing method based on a steel-concrete combined system. Compared with a traditional reinforcing method, the bridge strength can be improved, the bridge rigidity can be remarkably improved, and the overall performance of the bridge is effectively improved. Reinforcing operation is mainly carried out under the bridge, the bridge floor does not need to be closed or traffic flow does not need to be interrupted for a long time, and influences on traffic are reduced. According to the invention, a prefabricated part and segment assembly construction mode is adopted, so that the construction period is greatly shortened, and the construction efficiency is improved. Compared with a concrete section increasing method, the method has the advantages that only section steel needs to be added to the local part of the bridge bottom plate, the influence on an original structure is small, the added dead weight is light, damage and burden to the original structure of the bridge can be reduced, and the service life of the bridge is prolonged. According to the method, only the section steel needs to be added to the local part of the bridge bottom plate, the original structure of the bridge can be rechecked in the later period, and convenient conditions are provided for maintenance and management of the bridge.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge construction reinforcement construction and reconstruction, and specifically relates to a prestressed cast-in-situ box girder reinforcement method based on a steel-concrete composite system. Background Art

[0002] In bridge engineering, prestressed cast-in-place box girders are a common form of bridge structure. However, with the increase of operating time and operating load, box girders may suffer from strength loss, insufficient rigidity and other hazards, requiring maintenance and reinforcement. Although traditional reinforcement methods such as gluing steel plates and external prestressed tendons can improve the strength of bridges, they cannot improve rigidity. Although the concrete cross-section enlargement method can improve the rigidity of bridges, it requires a large number of embedded steel bars, which damages the original structure and increases the deadweight. In addition, due to the influence of on-site construction conditions and construction technology, the existing reinforcement schemes have limited reinforcement effects on bridges and cannot meet the needs of long-term use. In addition, the existing reinforcement methods have complicated construction procedures and long construction periods, often involving concrete curing procedures, and often require long-term bridge deck interruption construction, which brings great inconvenience to traffic. Summary of the invention

[0003] The present invention aims to provide a method for reinforcing a prestressed cast-in-place box girder based on a steel-concrete composite system, thereby achieving a dual improvement in bridge strength and stiffness, while reducing damage to the original structure of the bridge and reducing the increase in the bridge's own weight, effectively shortening the construction period and avoiding impact on traffic.

[0004] To achieve the above-mentioned purpose, the present invention is implemented by the following technical solutions: A method for reinforcing a prestressed cast-in-place box girder based on a steel-concrete composite system comprises the following steps: (S.1) Dividing the steel beam into a plurality of segments according to the size of the prestressed cast-in-place box beam and processing and manufacturing the segments to obtain a plurality of first steel beam segments and second steel beam segments; (S.2) fixedly connecting the plurality of first steel beam segments and the second steel beam segments obtained in step (S.1) to obtain edge steel beams or middle steel beams; (S.3) Assembling and connecting the cross beam and the middle steel beam obtained in step (S.2) to obtain a spliced ​​component; (S.4) using a lifting beam to lift the spliced ​​component obtained in step (S.3) to a corresponding position below the prestressed cast-in-place box girder, and then temporarily fixing the spliced ​​component to the prestressed cast-in-place box girder; (S.5) Use the lifting beam to hoist the edge steel beam to the corresponding position below the prestressed cast-in-place box beam, then temporarily fix the edge steel beam and the prestressed cast-in-place box beam, and perform steel glue bonding and glue injection construction on the contact surface between the prestressed cast-in-place box beam and the steel beam; (S.6) Reapply anti-corrosion paint to the steel beam.

[0005] The method for reinforcing a prestressed cast-in-place box girder based on a steel-concrete composite system of the present invention gives full play to the advantages of the steel-concrete structure, adopts segmented assembly construction, does not need to wait for the concrete curing time, and is mainly constructed under the bridge, does not need to be interrupted for a long time, and effectively avoids the impact on traffic. At the same time, the reinforcement construction process is simple, which greatly shortens the construction period and improves the convenience of construction. In addition, the present invention divides the steel beam into multiple sections for prefabrication, and then transports it to the bridge site for assembly. The design flexibility of the prefabricated steel beam is strong, and a customized reinforcement plan can be carried out according to the actual situation of the bridge. The reinforced steel-concrete composite system of the present invention can significantly improve the strength and rigidity of the prestressed cast-in-place box girder, and the reinforcement effect is obvious.

[0006] Preferably, the number of the side steel beams is two, and the number of the middle steel beams is at least one.

[0007] Preferably, the side steel beams and the middle steel beams are arranged in parallel along the length direction of the prestressed cast-in-place box beam.

[0008] The parallel side steel beams and middle steel beams can form a stable frame system together, which enhances the overall stability of the prestressed cast-in-place box girder structure. It helps to resist external loads and deformation, thereby improving the durability of the overall structure. In addition, the parallel side steel beams and middle steel beams can better disperse the load, making the prestressed cast-in-place box girder more uniform when subjected to force, effectively avoiding excessive local stress, thereby improving the safety of the overall structure.

[0009] Preferably, in step (S.2), the first steel beam segment and the second steel beam segment are fixedly connected by high-strength bolts and the segment flanges are welded.

[0010] High-strength bolts have high load-bearing capacity and fatigue resistance, and can withstand large loads and dynamic loads without damage. At the same time, high-strength bolt connections are simple to construct and can be installed quickly without complex welding processes and long waiting periods, making construction convenient. The combination of high-strength bolt connections and welding makes the connection between the first steel beam segment and the second steel beam segment tighter and stronger, thereby improving the seismic performance of the overall structure and helping to reduce deformation and damage to the overall structure.

[0011] Preferably, in steps (S.4) to (S.5), chemical anchors are installed at the bottom of the prestressed cast-in-place box girder, and the spliced ​​components or edge steel beams are temporarily fixedly connected to the prestressed cast-in-place box girder through the chemical anchors.

[0012] The installation process of chemical anchor bolts is relatively simple, without the need for complicated welding or bolt tightening processes, thus effectively shortening the construction period. At the same time, chemical anchor bolts form a strong bond with the concrete substrate through chemical reactions, with high tensile and shear strengths. This helps ensure the stability between the spliced ​​components or edge steel beams and the prestressed cast-in-place box beams, and prevents them from displacement or deformation during construction.

[0013] Preferably, the fixed connection position in steps (S.2) to (S.5) should avoid the position of the original box girder prestressed tendons.

[0014] Avoiding the location of the original box girder prestressed tendons helps ensure the normal operation of the original box girder prestressed tendons, thereby maintaining the overall bearing capacity of the prestressed cast-in-place box girder. At the same time, it helps to reduce the risk of stress concentration, improve the overall safety of the structure and extend its service life, and is also conducive to later maintenance and inspection.

[0015] Preferably, the first steel beam segment includes a first steel beam segment top plate located below the prestressed cast-in-place box girder, a first steel beam segment bottom plate, and a first steel beam segment web located between and connected to the first steel beam segment top plate and the first steel beam segment bottom plate, a plurality of web stiffeners are arranged on the first steel beam segment web, and a plurality of chemical anchor holes are arranged on the first steel beam segment top plate and the first steel beam segment bottom plate.

[0016] The provision of the top plate and the bottom plate of the first steel beam segment helps to ensure the stability and load-bearing capacity of the first steel beam segment in the vertical direction. In addition, the provision of web stiffening can significantly enhance the shear strength and rigidity of the web of the first steel beam segment, preventing the web of the first steel beam segment from being excessively deformed or damaged when subjected to force. At the same time, web stiffening helps to improve the load-bearing capacity of the web of the first steel beam segment, enabling the first steel beam segment to better resist the effects of external loads.

[0017] Preferably, the second steel beam segment includes a second steel beam segment top plate located below the prestressed cast-in-place box girder, a second steel beam segment bottom plate, and a second steel beam segment web located between and connected to the second steel beam segment top plate and the second steel beam segment bottom plate, a plurality of web stiffeners are arranged on the second steel beam segment web, and a plurality of chemical anchor holes are arranged on the second steel beam segment top plate and the second steel beam segment bottom plate.

[0018] The provision of the second steel beam segment top plate and the second steel beam segment bottom plate helps to ensure the stability and load-bearing capacity of the second steel beam segment in the vertical direction. In addition, the provision of web stiffening can significantly enhance the shear strength and rigidity of the web of the second steel beam segment, preventing the web of the second steel beam segment from being excessively deformed or damaged when subjected to force. At the same time, web stiffening helps to improve the load-bearing capacity of the web of the second steel beam segment, enabling the second steel beam segment to better resist the effects of external loads.

[0019] Preferably, the cross beam is arranged perpendicularly to the middle steel beam, and the cross beam includes a cross beam top plate, a cross beam bottom plate, and a cross beam web located between and connected to the cross beam top plate and the cross beam bottom plate, and a plurality of main beam stiffeners are arranged on the cross beam web.

[0020] The cross beam is set vertically with the middle steel beam, which is conducive to forming a stable frame structure and enhancing the rigidity and stability of the overall structure. It further enables the cross beam to effectively bear loads from different directions and distribute the loads to the middle steel beam and other supporting structures. In addition, the setting of the main beam reinforcement can significantly enhance the shear strength and rigidity of the web of the cross beam, effectively preventing the web of the cross beam from being deformed or damaged too much when subjected to force. This improves the overall bearing capacity of the cross beam, enabling it to better resist the effects of external loads.

[0021] Preferably, both ends of the cross beam are respectively connected to the adjacent side steel beams and the middle steel beams through connecting plates.

[0022] The connection plate is set to form an integral frame between the cross beam and the adjacent side steel beam and middle steel beam, which helps to enhance the integrity and stability of the structure. At the same time, it can effectively transfer load and shear force, reduce stress concentration, and optimize the load transfer path. In addition, it helps to simplify the construction process and facilitate later maintenance and replacement.

[0023] Therefore, the present invention has the following beneficial effects: (1) Compared with traditional reinforcement methods, the present invention can not only improve the strength of the bridge, but also significantly improve the stiffness of the bridge, thereby effectively improving the overall performance of the bridge; (2) The reinforcement work of the present invention is mainly carried out under the bridge, without the need to close the bridge deck for a long time or interrupt the traffic flow, thus reducing the impact on traffic; (3) The present invention adopts prefabricated components and segment assembly construction methods, which greatly shortens the construction period and improves construction efficiency. At the same time, the application of connection methods such as high-strength bolts and chemical anchors simplifies the construction steps and further improves the convenience of construction; (4) Compared with the concrete cross-section enlargement method, the present invention only needs to add steel sections to the bridge bottom plate, which has little impact on the original structure and has a light added deadweight, which helps to reduce damage and burden on the original structure of the bridge and improve the service life of the bridge; (5) The present invention only requires adding steel sections to the bottom plate of the bridge, which is helpful for the later review of the original structure of the bridge, convenient for the evaluation of the reinforcement effect, and provides convenient conditions for the maintenance and management of the bridge. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the longitudinal section diagram of the steel reinforcement arrangement.

[0025] Figure 2 This is the plan view of the steel reinforcement layout.

[0026] Figure 3 End section diagram for steel reinforcement arrangement.

[0027] Figure 4 This is a cross-sectional view of the mid-span arrangement of the steel reinforcement.

[0028] Figure 5 Schematic diagram of steel reinforcement.

[0029] Figure 6 This is the elevation view of the first steel beam segment.

[0030] Figure 7 for Figure 6 Cross-sectional view along the AA direction.

[0031] Figure 8 for Figure 6 Cross-sectional view along the BB direction.

[0032] Fig. 9 for Figure 6 Cross-sectional view along CC direction.

[0033] Fig.10 for Figure 6 Cross-sectional view along DD direction.

[0034] Fig.11 This is the elevation view of the second steel beam segment.

[0035] Fig.12 for Fig.11 Cross-sectional view along the AA direction.

[0036] Fig.13 for Fig.11 Cross-sectional view along direction BB.

[0037] Fig.14 for Fig.11 Cross-sectional view along CC direction.

[0038] Fig.15 This is the elevation view of the beam.

[0039] Fig.16 for Fig.15 Cross-sectional view along the AA direction.

[0040] Fig.17 for Fig.15 Cross-sectional view along direction BB.

[0041] Fig.18 This is a schematic diagram of the overall installation process.

[0042] In the figure: prestressed cast-in-place box girder 1; first steel beam segment 2; second steel beam segment 3; side steel beam 4; middle steel beam 5; cross beam 6; hanging beam 7; chemical anchor 8; original box girder prestressed tendon 9; first steel beam segment top plate 10; first steel beam segment bottom plate 11; first steel beam segment web 12; web stiffening 13; chemical anchor hole 14; second steel beam segment top plate 15; second steel beam segment bottom plate 16; second steel beam segment web 17; cross beam top plate 18; cross beam bottom plate 19; cross beam web 20; main beam stiffening 21; connecting plate 22; segment splicing part 23. DETAILED DESCRIPTION

[0043] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments of the specification. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0044] Example 1 This embodiment provides a method for reinforcing a prestressed cast-in-place box girder based on a steel-concrete composite system.

[0045] A method for reinforcing a prestressed cast-in-place box girder based on a steel-concrete composite system comprises the following steps: (S.1) (S.11) Segment division: According to the transportation conditions of the construction site and the construction space conditions, additional steel sections should be added to the bottom plate of the prestressed cast-in-place box girder 1 to Figure 1 The segments shown divide the steel beam into several segments and are subsequently processed and manufactured to obtain several first steel beam segments 2 and second steel beam segments 3.

[0046] (S.12) On-site verification: Before manufacturing the first steel beam segment 2 and the second steel beam segment 3, the design dimensions on the drawings must be verified with the actual situation of the on-site prestressed cast-in-place box girder 1. The material, specification, size and data of each assembly part should be checked before cutting. If any problems are found, they should be rectified in time.

[0047] (S.13) Segment assembly: The assembled parts should be assembled into segments by welding in the factory in advance according to the design drawings. V-shaped grooves should be used for welding between steel plates. The weld grade requires a first-level penetration weld, and the weld height should not be less than the plate thickness. After welding is completed, quality inspection should be carried out in accordance with the current national standards such as the "Steel Structure Welding Code" (GB50661-2011) and the "Steel Structure Engineering Construction Quality Acceptance Code" (GB50205-2020). All welds must be visually inspected and must not have cracks, unfused, slag inclusions, unfilled arc pits, and defects beyond the requirements of the "Steel Structure Welding Code". After the welding of each component is completed, all welds should be subjected to ultrasonic testing separately. The pass rate of the first flaw detection of the weld should be controlled at 100% to ensure the quality of the weld and the reliability of the structure.

[0048] (S.14) Segment surface treatment: Grind the weld surface and perform hot-dip galvanizing anti-corrosion treatment on the steel plate surface in accordance with the "Hot-dip Galvanizing Standard" (GB / T13912-2002).

[0049] (S.2) (S.21) Segment transportation and on-site assembly: transport several first steel beam segments 2 and second steel beam segments 3 prefabricated in the factory to the prestressed cast-in-place box beam 1, assemble and fix them on-site, and form segment joints 23 between the first steel beam segments 2 and the second steel beam segments 3 or between adjacent second steel beam segments 3, and finally obtain the side steel beam 4 or the middle steel beam 5 (i.e., the longitudinal beam). Figure 2-14 As shown, the webs of the first steel beam segment 2 and the second steel beam segment 3 are first fixedly connected with M24 high-strength bolts (φ27 holes), and then the flanges are welded.

[0050] As an implementation method, the number of the side steel beams 4 is two, and the number of the middle steel beam 5 is at least one.

[0051] As an implementation method, the side steel beams 4 and the middle steel beams 5 are arranged in parallel along the length direction of the prestressed cast-in-place box beam 1 .

[0052] The parallel side steel beams 4 and the middle steel beams 5 can together form a stable frame system, which enhances the overall stability of the prestressed cast-in-place box beam 1 structure. It helps to resist external loads and deformation, thereby improving the durability of the overall structure. In addition, the parallel side steel beams 4 and the middle steel beams 5 can better disperse the load, making the prestressed cast-in-place box beam 1 more uniform when subjected to force, effectively avoiding the situation of excessive local stress, thereby improving the safety of the overall structure.

[0053] High-strength bolts have high load-bearing capacity and fatigue resistance, and can withstand large loads and dynamic loads without damage. At the same time, high-strength bolt connections are simple to construct and can be installed quickly without complex welding processes and long waiting periods, making construction convenient. The combination of high-strength bolt connections and welding makes the connection between the first steel beam segment 2 and the second steel beam segment 3 tighter and stronger, thereby improving the seismic performance of the overall structure and helping to reduce deformation and damage to the overall structure.

[0054] As an embodiment, the first steel beam segment 2 includes a first steel beam segment top plate 10, a first steel beam segment bottom plate 11, and a first steel beam segment web 12 located between and connected to the first steel beam segment top plate 10 and the first steel beam segment bottom plate 11 below the prestressed cast-in-place box girder 1. A plurality of web stiffeners 13 are provided on the first steel beam segment web 12, and a plurality of chemical anchor holes 14 are provided on the first steel beam segment top plate 10 and the first steel beam segment bottom plate 11.

[0055] The provision of the first steel beam segment top plate 10 and the first steel beam segment bottom plate 11 helps to ensure the vertical stability and load-bearing capacity of the first steel beam segment 2. In addition, the provision of the web stiffener 13 can significantly enhance the shear strength and rigidity of the first steel beam segment web 12, preventing the first steel beam segment web 12 from being excessively deformed or damaged when subjected to force. At the same time, the web stiffener 13 helps to improve the load-bearing capacity of the first steel beam segment web 12, enabling the first steel beam segment 2 to better resist the effects of external loads.

[0056] As an embodiment, the second steel beam segment 3 includes a second steel beam segment top plate 15, a second steel beam segment bottom plate 16, and a second steel beam segment web 17 located between and connected to the second steel beam segment top plate 15 and the second steel beam segment bottom plate 16 below the prestressed cast-in-place box girder 1. A plurality of web stiffeners 13 are provided on the second steel beam segment web 17, and a plurality of chemical anchor holes 14 are provided on the second steel beam segment top plate 15 and the second steel beam segment bottom plate 16.

[0057] The provision of the second steel beam segment top plate 15 and the second steel beam segment bottom plate 16 helps to ensure the stability and load-bearing capacity of the second steel beam segment 3 in the vertical direction. In addition, the provision of the web stiffener 13 can significantly enhance the shear strength and rigidity of the second steel beam segment web 17, preventing the second steel beam segment web 17 from being excessively deformed or damaged when subjected to force. At the same time, the web stiffener 13 helps to improve the load-bearing capacity of the second steel beam segment web 17, enabling the second steel beam segment 3 to better resist the effects of external loads.

[0058] (S.22) Scanning of steel bars and prestressed tendons: Since the web of the original prestressed cast-in-place box girder 1 contains the prestressed tendons of the original prestressed cast-in-place box girder 1, and the web, bottom plate and top plate contain the steel bars of the original prestressed cast-in-place box girder 1, it is necessary to scan the web, bottom plate and top plate when installing the steel section, so that the position of the chemical anchor hole 14 avoids the position of the prestress and steel bars of the original prestressed cast-in-place box girder 1 (that is, it should avoid the position of the prestressed tendons 9 of the original box girder), so as to ensure the construction quality of the chemical anchor 8 while avoiding damage to the structure of the original prestressed cast-in-place box girder 1.

[0059] Avoiding the position of the original box girder prestressed tendons 9 helps ensure the normal operation of the original box girder prestressed tendons 9, thereby maintaining the overall bearing capacity of the prestressed cast-in-place box girder 1. At the same time, it helps to reduce the risk of stress concentration, improve the overall safety of the structure and extend its service life, and is also conducive to later maintenance and inspection.

[0060] (S.23) Anchor bolt anchoring: The top plate of the steel beam is connected to the concrete box beam with a double-nut M16 imported inverted cone chemical anchor bolt 8 (φ20 hole). The drilling depth is set according to the product manual and is not less than 130mm. The drilling position on the anchor steel plate must be consistent with the drilling and setting out results of the original structure on site.

[0061] The installation process of the chemical anchor bolt 8 is relatively simple and does not require complicated welding or bolt tightening processes, thereby effectively shortening the construction period. At the same time, the chemical anchor bolt 8 forms a strong bond with the concrete substrate through chemical reaction, and has high tensile and shear strength. It helps to ensure the stability between the spliced ​​components or edge steel beams 4 and the prestressed cast-in-place box beam 1, and prevents them from displacement or deformation during the construction process.

[0062] (S.24) Treatment of the top and bottom concrete contact surfaces of steel beams: The concrete surface should be polished until fresh coarse aggregate is exposed, and the top surface of the steel plate should be roughened.

[0063] (S.3) Installation of splicing components: Figure 15-17 As shown, the cross beam 6 is assembled and connected with the middle steel beam 5 obtained in step (S.2) (the assembly process is the same as that in step (S.2)) to obtain a spliced ​​component.

[0064] As an implementation mode, the cross beam 6 is arranged vertically to the middle steel beam 5. The cross beam 6 includes a cross beam top plate 18, a cross beam bottom plate 19, and a cross beam web 20 located between and connected to the cross beam top plate 18 and the cross beam bottom plate 19, and a plurality of main beam stiffeners 21 are arranged on the cross beam web 20.

[0065] The cross beam 6 is arranged vertically with the middle steel beam 5, which is conducive to forming a stable frame structure and enhancing the rigidity and stability of the overall structure. Further, the cross beam 6 can effectively bear loads from different directions and distribute the loads to the middle steel beam 5 and other supporting structures. In addition, the setting of the main beam stiffener 21 can significantly enhance the shear strength and rigidity of the cross beam web 20, and effectively prevent the cross beam web 20 from being excessively deformed or damaged when subjected to force. Thereby improving the overall bearing capacity of the cross beam 6, so that it can better resist the effects of external loads.

[0066] As an implementation mode, both ends of the cross beam 6 are respectively connected to the adjacent side steel beams 4 and the middle steel beams 5 through connecting plates 22 .

[0067] The connection plate 22 is provided to enable the cross beam 6 and the adjacent side steel beams 4 and middle steel beams 5 to form an integral frame, which helps to enhance the integrity and stability of the structure. At the same time, it can effectively transfer load and shear force, reduce stress concentration, and optimize the load transfer path. In addition, it also helps to simplify the construction process and facilitate later maintenance and replacement.

[0068] (S.4) (S.41) Installation of beam hoist: A beam hoist is installed at the guardrail positions on both sides of the prestressed cast-in-place box girder 1 for lifting the steel beam. A trial lift should be carried out before the formal lifting to ensure construction safety during the formal lifting.

[0069] (S.42) Lifting of the steel beam 5: Use the lifting beam 7 on the beam lifting machine to lift the spliced ​​components assembled in step (S.3) to the corresponding position below the prestressed cast-in-place box beam 1, and temporarily fix it to the concrete main beam (i.e., the prestressed cast-in-place box beam 1) through the M16 chemical anchor bolt 8.

[0070] (S.5) (S.51) Lifting of side steel beam 4: Use the lifting beam 7 on the lifting beam 7 machine to lift the side steel beam 4 to the corresponding position below the prestressed cast-in-place box beam 1, and temporarily fix the side steel beam 4 to the concrete main beam (i.e., the prestressed cast-in-place box beam 1) through the M16 chemical anchor bolt 8. Finally, connect the side steel beam 4 to the cross beam 6 through the M24 high-strength bolts to ensure that the steel beam forms a whole.

[0071] (S.52) Steel beam glue injection: During the high-speed intensive construction period, the upper flange of the steel beam (i.e., the contact surface between the steel beam and the bottom of the prestressed cast-in-place box beam 1) is glued with steel glue, and the double nuts are tightened before the glue solidifies. The tightening torque of the double nuts is 50N·m. (During the high-speed intensive construction period, no vehicles pass on the bridge, and the bridge will not vibrate, so that the bonding effect of the injected steel glue can be guaranteed).

[0072] The main construction sequence of glue injection construction is as follows: setting of glue injection holes, edge sealing, preparation of structural glue, and pouring.

[0073] ① Setting of injection holes: Glue injection holes are set on any side of the adhesive surface of the horizontal steel plate, and a hose is inserted every 0.5 meters around the rest of the periphery as an exhaust pipe. For inclined or vertically installed steel plates, glue injection holes are set at the lowest point, and exhaust pipes are set at the highest point; ② Edge sealing: glue the injection nozzle to the injection hole of the steel plate, insert the exhaust pipe at the edge of the steel plate, cover the expansion bolt head with a bowl, and then seal the edge of the steel plate with steel plate edge sealing glue to complete the edge sealing. The spacing between the injection nozzles is 2 to 3m; ③Prepare structural adhesive: Prepare structural adhesive according to the proportions specified in the product manual provided by the supplier. Use a low-speed stirrer to mix the steel plate edge sealing adhesive and steel bonding injection adhesive evenly and use them up within the applicable period. The steel bonding injection adhesive should be prepared and used after the edge sealing is completed and the steel plate edge sealing adhesive is fully cured and has sufficient strength; ④ Pouring: The glue of the inclined or vertically installed steel plate is injected from bottom to top. The steel-bonding grouting glue is poured from the injection nozzle into the gap between the steel plate and the concrete with a pump. The pouring work continues until glue flows out of all exhaust pipes. During the pouring process, the steel plate is knocked with a rubber hammer to confirm whether it is poured densely. It is required to ventilate and test the pressure before grouting. The steel-bonding grouting glue is pressed into the injection nozzle at a pressure of 0.2-4MPa. When slurry appears in the exhaust hole, stop pressurizing, plug the hole with steel plate edge sealing glue, and then maintain a low pressure for more than 10 minutes.

[0074] (S.6) Re-coating of anti-corrosion coating: After the steel plate is confirmed to be pasted and solidified, all injection nozzles and exhaust pipes are removed, and dirt and rust on the surface of the steel plate are cleaned, and the exposed steel plate is treated with anti-corrosion coating. The overall installation process is shown in the figure below. Fig.18 shown.

[0075] The above description is only a detailed description of the preferred embodiments and principles of the present invention. For ordinary technicians in this field, according to the ideas provided by the present invention, there will be changes in the specific implementation methods, and these changes should also be regarded as the protection scope of the present invention.

Claims

1. A method for reinforcing a prestressed cast-in-place box girder based on a steel-concrete composite system, characterized in that: The following steps are involved: (S.1) According to the size of the prestressed cast-in-place box girder (1), the steel beam is divided into a plurality of segments and processed to obtain a plurality of first steel beam segments (2) and second steel beam segments (3); (S.2) fixing and connecting the plurality of first steel beam segments (2) and second steel beam segments (3) obtained in step (S.1) to obtain edge steel beams (4) or middle steel beams (5); (S.3) Assembling and connecting the cross beam (6) and the middle steel beam (5) obtained in step (S.2) to obtain a spliced ​​component; (S.4) using a lifting beam (7) to lift the spliced ​​component obtained in step (S.3) to a corresponding position below the prestressed cast-in-place box girder (1), and then temporarily fixing the spliced ​​component to the prestressed cast-in-place box girder (1); (S.5) Using the lifting beam (7), the side steel beam (4) is hoisted to the corresponding position below the prestressed cast-in-place box beam (1), and then the side steel beam (4) is temporarily fixedly connected to the prestressed cast-in-place box beam (1), and the steel glue is glued and injected on the contact surface between the prestressed cast-in-place box beam (1) and the steel beam; (S.6) Reapply anti-corrosion paint to the steel beam.

2. The method for reinforcing a prestressed cast-in-situ box girder based on a steel-concrete composite system according to claim 1, characterized in that: The number of the side steel beams (4) is two, and the number of the middle steel beams (5) is at least one.

3. A method for reinforcing a prestressed cast-in-place box girder based on a steel-concrete composite system according to claim 1 or 2, characterized in that: The side steel beams (4) and the middle steel beams (5) are arranged in parallel along the length direction of the prestressed cast-in-place box beam (1).

4. The method for reinforcing a prestressed cast-in-situ box girder based on a steel-concrete composite system according to claim 1, characterized in that: In step (S.2), the first steel beam segment (2) and the second steel beam segment (3) are fixedly connected by high-strength bolts and the segment flanges are welded.

5. The method for reinforcing a prestressed cast-in-situ box girder based on a steel-concrete composite system according to claim 1, characterized in that: In steps (S.4) to (S.5), chemical anchor bolts (8) are installed at the bottom of the prestressed cast-in-place box girder (1), and the spliced ​​components or edge steel beams (4) are temporarily fixedly connected to the prestressed cast-in-place box girder (1) through the chemical anchor bolts (8).

6. The method for reinforcing a prestressed cast-in-situ box girder based on a steel-concrete composite system according to claim 1, characterized in that: The fixed connection position in steps (S.2) to (S.5) should avoid the position of the original box girder prestressed tendon (9).

7. The method for reinforcing a prestressed cast-in-situ box girder based on a steel-concrete composite system according to claim 1, characterized in that: The first steel beam segment (2) comprises a first steel beam segment top plate (10) located below the prestressed cast-in-place box beam (1), a first steel beam segment bottom plate (11), and a first steel beam segment web plate (12) located between and connected to the first steel beam segment top plate (10) and the first steel beam segment bottom plate (11), a plurality of web stiffeners (13) being arranged on the first steel beam segment web plate (12), and a plurality of chemical anchor bolt holes (14) being arranged on the first steel beam segment top plate (10) and the first steel beam segment bottom plate (11).

8. The method for reinforcing a prestressed cast-in-situ box girder based on a steel-concrete composite system according to claim 1, characterized in that: The second steel beam segment (3) comprises a second steel beam segment top plate (15) located below the prestressed cast-in-place box beam (1), a second steel beam segment bottom plate (16), and a second steel beam segment web plate (17) located between and connected to the second steel beam segment top plate (15) and the second steel beam segment bottom plate (16), a plurality of web stiffeners (13) being arranged on the second steel beam segment web plate (17), and a plurality of chemical anchor bolt holes (14) being arranged on the second steel beam segment top plate (15) and the second steel beam segment bottom plate (16).

9. The method for reinforcing a prestressed cast-in-situ box girder based on a steel-concrete composite system according to claim 1, characterized in that: The cross beam (6) is arranged perpendicularly to the middle steel beam (5), and the cross beam (6) comprises a cross beam top plate (18), a cross beam bottom plate (19), and a cross beam web plate (20) located between and connected to the cross beam top plate (18) and the cross beam bottom plate (19), and a plurality of main beam stiffeners (21) are arranged on the cross beam web plate (20).

10. The method for reinforcing a prestressed cast-in-situ box girder based on a steel-concrete composite system according to claim 1, characterized in that: The two ends of the cross beam (6) are respectively connected to the adjacent side steel beam (4) and the middle steel beam (5) via connecting plates (22).

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