A prestressed concrete box girder transverse active reinforcement structure and construction method

Abstract

The present invention discloses a transverse active reinforcement structure and construction method for a prestressed concrete box girder. The transverse reinforcement structure is connected to the bottom plate and the top plate of the prestressed concrete box girder by bolts, so as to reduce the transverse span of the top plate, change the transverse structural system, and improve the transverse stiffness and transverse bearing capacity of the box girder; by adjusting the lower cooperative force adjustment nut, prestress is applied to the reinforcement structure, so that the reinforcement structure and the original structure are subjected to force in a cooperative manner, and the longitudinal structural cracks of the top plate are closed, thereby achieving the purpose of active reinforcement. Thereby solving the problem of insufficient transverse prestress or insufficient transverse bearing capacity and stiffness of the prestressed concrete box girder. The main advantages of the present invention are: the structural form is simple, the components are all processed in the factory, and can be assembled on site, the construction process is simpler than the traditional reinforcement method, it is an active reinforcement method, the reinforcement structure and the original structure have better cooperative force performance, and the effect of one-time reinforcement and subsequent adjustment can be achieved.

Description

Technical Field

[0001] The invention belongs to the field of bridge engineering, and specifically relates to a prestressed concrete box girder transverse active reinforcement structure and a construction method; the invention is suitable for prestressed concrete box girders with insufficient transverse prestress or insufficient transverse bearing capacity and stiffness. Background Art

[0002] Under the action of wheels, the top plate of the in-service prestressed concrete box girder produces transverse bending stress. When the transverse reinforcement is insufficient, or due to concrete creep, fatigue and other reasons, the transverse prestressing is insufficient or the transverse bearing capacity and stiffness are insufficient, longitudinal structural cracks are formed in the top plate and the transverse stiffness decreases.

[0003] At present, there are many methods for the longitudinal reinforcement of bridges, including: increasing the beam cross-section method, gluing steel plates, gluing fiber composite materials, external prestressed reinforcement method and changing the structural system method. However, the method for transverse reinforcement of the box girder top plate is mainly to gluing steel plates transversely and increasing the thickness of the pavement layer.

[0004] The steel plate reinforcement method is a passive reinforcement. In the bridge reinforced by the passive reinforcement method under load, the new and old materials cannot bear the force together in the initial stage. After the section cracks, the concrete in the tensile zone of the main beam cannot bear any tensile strain. Although the steel plate is pasted on the surface of the bridge reinforced by the steel plate, the internal cracks of the main beam concrete still exist, so it cannot solve the problems of cracking of the top plate concrete and insufficient bearing capacity. At the same time, when the transverse prestressing is insufficient, the existing transverse prestressing tendons cannot be supplemented, and adding prestressed steel strands will make the construction very complicated and cause greater damage to the structure itself. Therefore, the durability of the bridge cannot be improved well, and the reinforcement cost is also very high.

[0005] Increasing the thickness of the pavement layer and increasing the area of ​​the cross-section compression zone are beneficial to improving the bending strength and stiffness, but the increase in height is limited and the deadweight is also increased, which is also a burden on the main beam; at the same time, this reinforcement method takes a long time to complete and affects traffic.

[0006] In view of the problems of insufficient transverse prestress or insufficient transverse bearing capacity and stiffness of prestressed concrete box girders and the defects of existing reinforcement technology, it is urgent to develop an effective reinforcement structure and reinforcement method so that the reinforced structure can be stressed in coordination with the original structure and the longitudinal structural cracks of the top plate can be closed to achieve the purpose of active reinforcement. Summary of the invention

[0007] The purpose of the present invention is to provide a prestressed concrete box girder transverse active reinforcement structure and construction method, so as to overcome the relevant technical defects of the above-mentioned prior art, improve the bearing capacity and durability of the existing bridge structure, and at the same time improve the construction efficiency, shorten the bridge reinforcement period, and save maintenance costs.

[0008] The purpose of the present invention is achieved through the following solutions:

[0009] A prestressed concrete box girder transverse active reinforcement structure, characterized in that it comprises a prestressed concrete box girder and an upper reinforcement mechanism and a lower reinforcement mechanism; the upper reinforcement mechanism and the lower reinforcement mechanism are connected by a hollow steel pipe and are jointly arranged in the prestressed concrete box girder to form an active reinforcement structure.

[0010] The lower reinforcement mechanism includes a UHPC base, a bottom plate embedded steel plate, a lower connecting screw, a lower connecting screw fixing nut, a coordinated force adjustment nut, a lower connecting steel plate fixing nut, and a steel pipe lower connecting steel plate, wherein: the UHPC base is embedded and cast at the chamfers of the bottom plate and the web of the concrete box beam; the bottom plate embedded steel plate and the lower connecting screw are embedded in the UHPC base, and the lower connecting screw and the bottom plate embedded steel plate are relatively fixed by the lower connecting screw fixing nut, and the bolt holes of the steel plate are all designed at the corners of the steel plate; the steel pipe lower connecting steel plate and the box beam bottom plate are connected by the lower connecting screw, the lower connecting screw fixing nut, the coordinated force adjustment nut, and the lower connecting steel plate fixing nut.

[0011] The upper reinforcement structure includes a connecting steel plate on the steel pipe, a pre-embedded steel plate on the top plate, fixing bolts of the pre-embedded steel plate on the top plate, a steel base on the top plate, fixing bolts of the steel base on the top plate, a bow-shaped connecting steel plate, fixing bolts of the bow-shaped connecting steel plate, and an upper steel plate connecting bolt, wherein: the pre-embedded steel plate on the top plate is connected to the top plate of the box beam by the pre-embedded steel plate fixing bolts, the top plate steel base is connected to the pre-embedded steel plate on the top plate by the fixing bolts of the top plate steel base; the bow-shaped connecting steel plate is connected to the top plate steel base by the bow-shaped connecting steel plate fixing bolts; the connecting steel plate on the steel pipe is connected to the bow-shaped connecting steel plate by the upper steel plate connecting bolts.

[0012] The hollow steel pipe is welded to the lower connecting steel plate of the steel pipe and the upper connecting steel plate of the steel pipe.

[0013] The reinforcement structure is connected to the top plate, bottom plate and web plate of the prestressed concrete box girder by bolts to form an integral structure, reducing the transverse span of the top plate, changing the transverse structural system of the box girder, improving the transverse stiffness and transverse bearing capacity of the box girder, and restraining the downward deflection of the top plate, thereby avoiding longitudinal cracks in the top plate; at the same time, when the load acts on the concrete wing plate of the box girder, the hollow steel pipe provides a downward tensile constraint to the top plate, inhibiting the upward warping deformation of the top plate, thereby restraining the deformation of the wing plate, and also enhancing the torsional performance of the box girder to a certain extent.

[0014] The synergistic force adjustment nut is used to apply prestress to the hollow steel pipe. By symmetrically twisting the synergistic force adjustment nut, the longitudinal cracks in the top plate caused by insufficient transverse prestress, concrete shrinkage creep or load are closed. The reinforced structure cooperates with the original structure under the action of the later load to inhibit the occurrence of cracks. When the structure is damaged due to insufficient prestress again, the synergistic force adjustment nut is adjusted again to improve the structural stress performance.

[0015] A construction method for a prestressed concrete box girder transverse active reinforcement structure, the specific construction method is as follows:

[0016] Step 1: Determine the scope of reinforcement along the longitudinal position according to the condition of the bridge disease, and carry out concrete roughening, rebar planting, UHPC base formwork installation, bottom plate embedded steel plate installation, lower connection screw installation at a certain interval on the box girder concrete bottom plate and web chamfer, and then pour UHPC.

[0017] Step 2: According to the scope of reinforcement required, roughen the concrete within a certain range of the longitudinal center line of the top plate in the box, drill two rows of expansion bolt holes at a certain interval, insert the top plate embedded steel plate fixing bolts, hang the top plate embedded steel plate and pre-tighten it. In order to ensure the bonding effect, inject glue between the steel plate and the concrete and perform the final bolt tightening.

[0018] Step 3: After the strength of the structural adhesive between the top plate embedded steel plate and the box beam concrete top plate reaches the design strength, install the top plate steel base and the arched connecting steel plate.

[0019] Step 4: Tighten the fixing nut of the lower connecting screw until it is in close contact with the embedded steel plate of the bottom plate, and tighten the coordinated force adjustment nut to a certain distance from the fixing nut of the lower connecting screw. At this time, insert the lower connecting screw into the bolt hole of the lower connecting steel plate of the hollow steel pipe. The two transversely symmetrical hollow steel pipes and the bow-shaped connecting steel plate are connected to form a whole through the upper steel plate connecting bolts.

[0020] Step 5: Design the required prestress for the hollow steel pipe according to the bridge status. The prestress value that closes the longitudinal cracks in the concrete top plate can be used as a control indicator. Place a small portable jack between the connecting steel plate under the steel pipe and the embedded steel plate under the bottom plate to apply prestress to the hollow steel pipe. When the designed prestress is reached, turn the coordinated force adjustment nut in the opposite direction until it is completely fitted and fixed with the connecting steel plate under the steel pipe. Unload the jack and install the fixing nut of the lower connecting steel plate.

[0021] Step 6: After the bridge reinforcement is completed, according to the later operation status, the prestressing of the hollow steel pipe can be further adjusted by loosening the fixing nut of the lower connecting steel plate, turning the coordinated force adjustment nut upward, and finally tightening the fixing nut of the lower connecting steel plate to achieve one-time reinforcement and continuous adjustment.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The transverse active reinforcement structure of the present invention improves the transverse stiffness and transverse bearing capacity of the box beam by changing the transverse structural system, and effectively improves the problem of insufficient transverse prestressing of the prestressed concrete box beam leading to cracking of the top plate and insufficient transverse bearing capacity of the top plate. In addition, when the vehicle acts on the wing plate, the reinforcement structure can also play a certain role in limiting the deformation of the top plate and the wing plate. The transverse active reinforcement structure of the present invention has a simple structure and is easy to construct. The components are all processed in the factory and can be assembled on site.

[0024] The construction method of the present invention is simpler in construction process than the traditional reinforcement method. It is an active reinforcement method. By applying pre-stressing, the longitudinal cracks of the top plate are closed, so that the coordinated force performance of the reinforced structure and the original structure is better; it avoids a large number of crack closing and steel plate pasting work that is difficult to construct from above; the reinforced structure can be adjusted according to the structural state in the later stage to achieve the purpose of reinforcement again; at the same time, in the reinforcement process of the present invention, traffic is closed only when the pre-stressing is applied after all the embedded parts and components are connected, and the duration is very short, so the construction of this reinforcement method will hardly affect the passage of vehicles on the bridge deck. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the overall structural diagram of the reinforcement device;

[0026] Figure 2 is a transverse cross-sectional view of the lower local connection structure;

[0027] Figure 3 It is the plan view of the lower local connection structure;

[0028] Figure 4 is a longitudinal section view of the upper local connection structure;

[0029] Figure 5 is a front view of the upper local connection structure;

[0030] Figure 6 It is a schematic diagram of the reinforced structure without prestressing;

[0031] In the attached figure:

[0032] 1—top plate; 2—bottom plate; 3—web plate; 4—flange plate;

[0033] 5—UHPC base; 6—bottom plate embedded steel plate; 7—lower connecting screw; 8—lower connecting screw fixing nut; 9—cooperative force adjustment nut; 10—lower connecting steel plate fixing nut;

[0034] 11—hollow steel pipe; 12—steel plate connecting the lower part of the steel pipe; 13—steel plate connecting the upper part of the steel pipe;

[0035] 14—top plate embedded steel plate; 15—top plate embedded steel plate fixing bolts; 16—top plate steel base; 17—top plate steel base fixing bolts;

[0036] 18—Arch-shaped connecting steel plate; 19—Arch-shaped connecting steel plate fixing bolts; 20—Upper steel plate connecting bolts. DETAILED DESCRIPTION

[0037] In order to explain the content of the present invention in more detail and more clearly, the following description is given in conjunction with the accompanying drawings.

[0038] like Figure 1-Figure 5 As shown, the transverse active reinforcement structure of the prestressed concrete box girder mainly includes a concrete box girder top plate 1, a bottom plate 2, a web plate 3, a flange plate 4, a UHPC base 5, a bottom plate embedded steel plate 6, a lower connecting screw 7, a lower connecting screw fixing nut 8, a coordinated force adjustment nut 9, a lower connecting steel plate fixing nut 10, a hollow steel pipe 11, a steel pipe lower connecting steel plate 12, a steel pipe upper connecting steel plate 13, a top plate embedded steel plate 14, a top plate embedded steel plate fixing bolt 15, a top plate steel base 16, a top plate steel base fixing bolt 17, a bow-shaped connecting steel plate 18, a bow-shaped connecting steel plate fixing bolt 19, and an upper steel plate connecting bolt 20.

[0039] like Figure 1-3 As shown, reinforcement is embedded and UHPC base 5 is cast at the chamfers of the concrete box girder bottom plate 2 and the web plate 3 .

[0040] Furthermore, the bottom plate embedded steel plate 6 and the lower connecting screw 7 are embedded in the UHPC base 5 , and the lower connecting screw 7 is relatively fixed to the bottom plate embedded steel plate 6 by the lower connecting screw fixing nut 8 .

[0041] like Figure 4 and Figure 5 As shown, the top plate embedded steel plate 14 is connected to the box girder top plate 1 through the top plate embedded steel plate fixing bolts 15 , and the top plate steel base 16 is connected to the top plate embedded steel plate 14 through the top plate steel base fixing bolts 17 .

[0042] Furthermore, the arched connecting steel plate 18 is connected to the top plate steel base 16 by two arched connecting steel plate fixing bolts 19 .

[0043] Furthermore, the hollow steel pipe 11 is welded with the lower connecting steel plate 12 and the upper connecting steel plate 13 to form a whole.

[0044] Furthermore, the lower connecting steel plate 12 of the steel pipe is connected to the bottom plate 2 of the box beam through the lower connecting screw 7, the lower connecting screw fixing nut 8, the coordinated force adjustment nut 9, and the lower connecting steel plate fixing nut 10.

[0045] Furthermore, the steel pipe upper connecting steel plate 13 and the arched connecting steel plate 18 are connected by upper steel plate connecting bolts 20 .

[0046] Furthermore, the reinforcement structure is connected with the top plate 1, bottom plate 2 and web plate 3 of the prestressed concrete box girder by bolts to form an integral structure, thereby reducing the transverse span of the top plate 1, changing the transverse structural system of the box girder, improving the transverse stiffness and transverse bearing capacity of the box girder, and restraining the downward deflection of the top plate 1, thereby avoiding the occurrence of longitudinal cracks in the top plate 1; at the same time, when the load acts on the concrete wing plate 4 of the box girder, the hollow steel pipe 11 provides a downward tensile constraint to the top plate 1, suppressing the upward warping deformation of the top plate 1, thereby restraining the deformation of the wing plate 4, and also enhancing the torsional performance of the box girder to a certain extent.

[0047] like Figure 6 As shown, prestress is applied to the hollow steel pipe 11 by symmetrically twisting the cooperative force adjusting nut 9, so that the longitudinal cracks of the top plate 1 caused by insufficient transverse prestress, concrete shrinkage creep or load are closed, and the reinforced structure cooperates with the original structure under the action of the later load to suppress the generation of cracks; when the structure is again damaged due to insufficient prestress and the structure is damaged, the cooperative force adjusting nut 9 is adjusted again to improve the structural force performance.

[0048] The construction method of the prestressed concrete box girder transverse active reinforcement structure of the present invention comprises the following steps:

[0049] According to the condition of the bridge, the scope that needs to be reinforced along the longitudinal position is determined. At a certain interval, at the chamfers of the box girder concrete bottom plate 2 and the web plate 3, concrete roughening, reinforcement planting, UHPC base 5 formwork installation, bottom plate embedded steel plate 6 installation, lower connection screw 7 installation are carried out, and then UHPC is poured.

[0050] According to the scope of reinforcement required, the concrete within the range of about 40cm from the longitudinal center line of the top plate in the box is roughened, two rows of expansion bolt holes are drilled at a certain interval, the top plate embedded steel plate fixing bolts 15 are inserted, the top plate embedded steel plate 14 is hung and pre-tightened, and in order to ensure the bonding effect, glue is injected between the steel plate and the concrete and the final bolt tightening is performed.

[0051] After the strength of the structural adhesive between the top plate embedded steel plate 14 and the box beam concrete top plate 1 reaches the design strength, the top plate steel base 16 and the arched connecting steel plate 18 are installed.

[0052] Tighten the lower connecting screw fixing nut 8 until it is in close contact with the embedded steel plate 6 of the bottom plate, and tighten the coordinated force adjustment nut 9 to a distance of about 5-10 cm from the lower connecting screw fixing nut 8. At this time, insert the bolt hole of the lower connecting steel plate 12 of the hollow steel pipe into the lower connecting screw 7, and the two laterally symmetrical hollow steel pipes and the bow-shaped connecting steel plate 18 are connected to form a whole through the upper steel plate connecting bolts 20.

[0053] Design the required prestress of the hollow steel pipe 11 according to the bridge status, place a small portable jack between the lower connecting steel plate 12 of the steel pipe and the bottom plate embedded steel plate 6 to apply prestress to the hollow steel pipe 11, and when the designed prestress is reached, screw the coordinated force adjustment nut 9 in the reverse direction until it is completely fitted and fixed with the lower connecting steel plate 12 of the steel pipe, uninstall the jack, and install the lower connecting steel plate fixing nut 10.

[0054] After the bridge reinforcement is completed, according to the later operation status, the lower connecting steel plate fixing nut 10 can be loosened upwards, and the coordinated force adjustment nut 9 can be turned upwards to further adjust the prestressing of the hollow steel pipe, and finally the lower connecting steel plate fixing nut 10 can be tightened to fix it, so as to achieve another reinforcement.

[0055] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A prestressed concrete box girder transverse active reinforcement structure, characterized in that: It includes a prestressed concrete box girder and an upper reinforcement mechanism and a lower reinforcement mechanism; The upper reinforcement mechanism and the lower reinforcement mechanism are connected via a hollow steel pipe (11) and are arranged together in the prestressed concrete box beam to form an active reinforcement structure; The upper reinforcement mechanism comprises a steel pipe upper connecting steel plate (13), a top plate embedded steel plate (14), top plate embedded steel plate fixing bolts (15), a top plate steel base (16), a top plate steel base fixing bolts (17), an arched connecting steel plate (18), an arched connecting steel plate fixing bolts (19), and an upper steel plate connecting bolt (20); The top plate embedded steel plate (14) is connected to the box beam top plate (1) via embedded steel plate fixing bolts (15), and the top plate steel base (16) is connected to the top plate embedded steel plate (14) via top plate steel base fixing bolts (17); The arched connecting steel plate (18) is connected to the top plate steel base (16) via arched connecting steel plate fixing bolts (19); The upper connecting steel plate (13) of the steel pipe and the arch connecting steel plate (18) are connected via upper steel plate connecting bolts (20); The lower reinforcement mechanism comprises a UHPC base (5), a bottom plate embedded steel plate (6), a lower connecting screw (7), a lower connecting screw fixing nut (8), a coordinated force adjustment nut (9), a lower connecting steel plate fixing nut (10), and a steel pipe lower connecting steel plate (12), wherein: The UHPC base (5) is embedded with steel bars and cast at the chamfers of the concrete box girder bottom plate (2) and the web plate (3); The bottom plate embedded steel plate (6) and the lower connecting screw (7) are embedded in the UHPC base (5), and the lower connecting screw fixing nut (8) ensures that the lower connecting screw (7) and the bottom plate embedded steel plate (6) are relatively fixed, and the bolt holes of the steel plate are designed at the corners of the steel plate; The steel pipe lower connecting steel plate (12) and the box beam bottom plate (2) are connected via a lower connecting screw (7), a lower connecting screw fixing nut (8), a coordinated force adjustment nut (9), and a lower connecting steel plate fixing nut (10); The hollow steel pipe (11) is welded to the lower connecting steel plate (12) of the steel pipe and the upper connecting steel plate (13) of the steel pipe.

2. The construction method of a prestressed concrete box girder transverse active reinforcement structure according to claim 1, characterized in that: The specific construction method is as follows: Step 1: Determine the range that needs to be reinforced along the longitudinal position according to the condition of the bridge disease, and perform concrete roughening, reinforcing bar planting, UHPC base (5) formwork installation, bottom plate embedded steel plate (6) installation, and lower connection screw rod (7) installation at a certain interval at the chamfer of the box beam concrete bottom plate (2) and web plate (3), and then perform UHPC pouring; Step 2: according to the scope of reinforcement required, the concrete within a certain range of the longitudinal center line of the top plate in the box is roughened, two rows of expansion bolt holes are drilled at a certain interval, the top plate embedded steel plate fixing bolts (15) are inserted, the top plate embedded steel plate (14) is hung and pre-tightened, and in order to ensure the bonding effect, glue is injected between the steel plate and the concrete and the final bolt tightening is performed; Step 3: After the strength of the structural adhesive between the top plate embedded steel plate (14) and the box beam concrete top plate (1) reaches the design strength, the top plate steel base (16) and the arched connecting steel plate (18) are installed; Step 4: The lower connecting screw fixing nut (8) is screwed until it is tightly attached to the bottom plate embedded steel plate (6), and the coordinated force adjustment nut (9) is screwed to a certain distance from the lower connecting screw fixing nut (8). At this time, the lower connecting screw (7) is inserted into the bolt hole of the lower connecting steel plate (12) of the hollow steel pipe, and the two horizontally symmetrical hollow steel pipes and the arched connecting steel plate (18) are connected to form a whole through the upper steel plate connecting bolts (20); Step 5: Design the required prestressing force of the hollow steel pipe (11) according to the state of the bridge, and use the prestressing force value that closes the longitudinal cracks of the concrete top plate as a control indicator; place a small portable jack between the lower connecting steel plate (12) of the steel pipe and the bottom plate embedded steel plate (6) to apply prestressing force to the hollow steel pipe (11); when the designed prestressing force is reached, reversely screw the coordinated force adjustment nut (9) until it is completely fitted and fixed with the lower connecting steel plate (12) of the steel pipe, remove the jack, and install the lower connecting steel plate fixing nut (10); Step 6: After the bridge reinforcement is completed, according to the later operation status, the lower connecting steel plate fixing nut (10) can be loosened upwards, and the coordinated force adjustment nut (9) can be turned upwards to further adjust the prestressing of the hollow steel pipe, and finally the lower connecting steel plate fixing nut (10) can be tightened to fix it, so as to achieve one-time reinforcement and continuous adjustment.

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