Multi-unit post-fire concrete box girder bridge damage repairing structure

Abstract

The utility model relates to the field of concrete bridge damage repair, and provides a multi-unit post-fire concrete box girder bridge damage repair structure. A fire damage area exists on a main box girder of the concrete box girder bridge, the repairing structure is applied to repairing the fire damage area, and the repairing structure comprises an ultra-high performance concrete-steel bar repairing unit, a carbon fiber repairing unit, an epoxy cement mortar repairing unit and a coating repairing unit which are connected in sequence. The repairing structure has the advantages that different repairing units are adopted for repairing concrete box girder areas with different fire damage degrees, and compared with repairing structures such as single pasting steel plates, carbon fiber cloth and outer wrapped concrete reinforcement, the repairing structure can effectively improve the bearing capacity and rigidity of the damaged main body box girder, and the repairing structure is simple in structure and convenient to use. And the secondary damage risk caused by reinforcing construction to the beam body can be greatly reduced, the use amount of maintenance materials is reduced, and the reinforcing cost is reduced. The repairing structure is reliable, effective, high in pertinence and good in applicability.

Description

Technical Field

[0001] The utility model relates to the field of concrete bridge maintenance and reinforcement, and more specifically to a multi-unit post-fire concrete box beam bridge damage repair structure. Background Art

[0002] The literature "Post-fire Damage Assessment and Reinforcement Design of a PC Beam Bridge" (Railway Construction, 2015, (11): 27-29.) and the literature "Post-fire Detection and Reinforcement Design of a Prestressed Concrete Box Beam Bridge" (Fujian Transportation Science and Technology, 2020, (04): 151-153.) combined the concrete box beam damage detection and assessment results and proposed reinforcement and repair measures such as gluing steel plates, carbon fiber cloth or adding prestressed carbon fiber plates, but did not give specific structural settings and repair methods, making it difficult to directly apply them in practice. Patent CN115897427 A, a fire damage reinforcement structure and repair method for a concrete bridge, discloses a fire damage reinforcement structure and repair method using steel strips, repair mortar, anchor screws and pressure grouting. The patent does not specify the repair and treatment methods for different fire damage areas. The single steel plate reinforcement treatment method is not only lacking in specificity and increasing costs, but also its large number of holes for anchoring steel plates will cause different degrees of secondary damage to the damaged beam. In addition, the thickness of the steel plate pasted by this reinforcement method is limited, and it is difficult to effectively restore the stiffness of the box beam with severe concrete spalling and large-area exposed steel bars due to the fire. Therefore, its reinforcement effect is relatively poor. Therefore, in view of the large and wide-ranging damage area of ​​the concrete box beam after the fire, the concrete spalling and exposed steel bars in different areas are not exactly the same, and the existing reinforcement methods are limited, a targeted, reliable and practical reinforcement structure is proposed, which has important engineering application value. Utility Model Content

[0003] The utility model aims to overcome at least one defect (shortcoming) of the above-mentioned prior art and provide a multi-unit post-fire concrete box girder bridge damage repair structure to carry out targeted repairs on areas of the concrete box girder with different degrees of damage after the fire.

[0004] The utility model provides a multi-unit post-fire concrete box girder bridge damage repair structure, the concrete box girder bridge comprises a main box girder, the main box girder has a fire damaged area, the repair structure is used to repair the fire damaged area of ​​the concrete box girder bridge, the repair structure comprises an ultra-high performance concrete-steel repair unit, a carbon fiber repair unit, an epoxy cement mortar repair unit and a coating repair unit connected in sequence.

[0005] In this technical solution, the ultra-high performance concrete-rebar repair unit is a structural unit that repairs the damaged area through ultra-high performance concrete and steel bars; the carbon fiber repair unit is a structural unit that repairs the damaged area through carbon fiber materials, the epoxy cement mortar repair unit is a structural unit that repairs the damaged area through epoxy cement mortar, and the coating repair unit is a structural unit that repairs and beautifies the damaged area through beautifying and protective materials.

[0006] The degree of damage to the concrete bridge repaired in sequence by the ultra-high performance concrete-rebar repair unit, the carbon fiber repair unit, the epoxy cement mortar repair unit and the coating repair unit gradually decreases, that is, the ultra-high performance concrete-rebar repair unit repairs the most severely damaged area of ​​the bridge, and the coating repair unit repairs the least damaged area of ​​the bridge. The individual repair units are connected in sequence, which means that the individual repair units are connected by side connections, rather than stacked connections, and the connection direction between the individual repair units can be a longitudinal connection along the extension direction of the bridge, or a transverse connection perpendicular to the longitudinal direction.

[0007] This technical solution uses different repair units to repair the areas with different degrees of damage to the concrete box girder after the fire, which is highly targeted and has a good repair effect. If the same materials are used, the areas with the greatest damage and the areas with the least damage will use the same repair materials, which will cause waste of repair materials. Therefore, the repair structure of this solution is conducive to cost savings. In addition, compared with the method of using a large number of anchored steel plates and steel bars for repair, this solution causes less secondary damage to the bridge and is more reliable. The reinforcement structure is highly targeted, has good applicability, and has a reliable reinforcement effect.

[0008] Furthermore, the fire damage area includes a severely damaged level V area, a relatively severely damaged level IV area, a moderately damaged level III area, a slightly damaged level II area and a slightly damaged level I area which are connected in sequence.

[0009] In the present technical solution, the severely damaged Grade V area is the area where large-scale concrete peeling occurs and the longitudinal and transverse steel bars are exposed; the relatively severely damaged Grade IV area is the area where large-scale concrete peeling occurs and stirrups and longitudinal steel bars are partially exposed; the moderately damaged Grade III area is the area where local concrete peeling occurs; the slightly damaged Grade II area is the area where the concrete surface is blackened and slightly peeling occurs; the slightly damaged Grade I area is the area that is not burned and has a basically intact appearance.

[0010] The regions are connected in sequence means that the regions are connected through the sides, and the connection direction between the regions can be a longitudinal connection along the extension direction of the bridge, or a transverse connection perpendicular to the longitudinal direction.

[0011] Furthermore, the ultra-high performance concrete-rebar repair unit includes an anti-cracking steel mesh, which is formed by connecting transverse steel bars and longitudinal steel bars. The anti-cracking steel mesh is connected to the severely damaged Grade V area through threaded steel bars, and ultra-high performance concrete is filled between the anti-cracking steel mesh and the severely damaged Grade V area.

[0012] In this technical solution, ultra-high performance concrete has the advantages of high strength, good durability and low maintenance cost. It is combined with steel bars to repair the most damaged areas of the bridge, thus providing effective reinforcement.

[0013] Furthermore, the spacing between two adjacent transverse steel bars is 140-160 mm, the spacing between two adjacent longitudinal steel bars is 140-160 mm, the compressive strength of the ultra-high performance concrete is greater than 150 MPa, the cubic flexural strength of the ultra-high performance concrete is greater than 22 MPa, the cubic tensile strength of the ultra-high performance concrete is greater than 8 MPa, and the cubic elastic modulus of the ultra-high performance concrete is greater than 40 Gpa.

[0014] Furthermore, the carbon fiber repair unit includes: an epoxy fine stone concrete layer, which is arranged on the surface of the more serious IV area; a bottom resin layer, which is arranged on the surface of the epoxy fine stone concrete layer; a carbon fiber cloth layer, which is bonded to the surface of the bottom resin layer through an impregnated resin layer; and a beautification protective layer, which is arranged on the surface of the carbon fiber cloth layer.

[0015] Furthermore, the surface of the bottom resin layer is bonded with two layers of carbon fiber cloth through an impregnated resin layer, the thickness of the epoxy fine stone concrete layer is between 30 and 60 mm, the thickness of the bottom resin layer is between 0.2 and 0.3 mm, and the thickness of the impregnated resin layer is between 0.5 and 1.0 mm.

[0016] Furthermore, the epoxy cement mortar repair unit includes: an epoxy cement mortar layer, which is arranged on the surface of the moderate grade III area; and a beautification and protective layer, which is arranged on the surface of the epoxy cement mortar layer.

[0017] Furthermore, the coating repair unit includes: a curing adhesive layer, which is arranged on the surface of the light grade II area and the slight grade I area; and a beautifying protective layer, which is arranged on the surface of the curing adhesive layer.

[0018] Furthermore, the cured bonding layer is an epoxy putty layer.

[0019] Furthermore, the beautification and protective layer includes an epoxy closed primer layer, an epoxy micaceous iron intermediate paint layer arranged on the surface of the epoxy closed primer layer, and a polyurethane topcoat layer arranged on the surface of the epoxy micaceous iron intermediate paint layer, and the epoxy micaceous iron intermediate paint layer is on the side away from the fire damage area.

[0020] Furthermore, the thickness of the epoxy sealing primer layer is 35-45 μm, the thickness of the epoxy micaceous iron intermediate paint layer is 180-200 μm, and the thickness of the polyurethane topcoat layer is 70-90 μm.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention adopts different repair units to repair bridge areas with different degrees of damage after fire, which is highly targeted and has good repair effects; and if unified materials are used, the repair materials for the areas with the greatest degree of damage and the areas with the least degree of damage are the same, which will cause waste of repair materials. Therefore, the repair structure of this scheme is conducive to cost savings; in addition, compared with the method of using a large number of anchoring steel plates and steel bars for repair, this scheme causes less secondary damage to the bridge and the method is more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic cross-sectional view of the fire damage area of ​​the concrete bridge of the utility model.

[0023] Figure 2 It is a schematic longitudinal section diagram of the fire damage area of ​​the concrete bridge of the utility model.

[0024] Figure 3 It is a schematic longitudinal section diagram of the repair structure of the utility model.

[0025] Figure 4 It is a schematic diagram of the partial structure of the ultra-high performance concrete-rebar repair unit of the utility model.

[0026] Figure 5 It is a cross-sectional schematic diagram of the ultra-high performance concrete-rebar repair unit of the utility model.

[0027] Figure 6 It is a partial structural schematic diagram of the carbon fiber repair unit of the utility model.

[0028] Figure 7 It is a cross-sectional schematic diagram of the carbon fiber repair unit of the utility model.

[0029] Figure 8 It is a schematic diagram of the partial structure of the epoxy cement mortar repair unit of the utility model.

[0030] Fig. 9 It is a cross-sectional schematic diagram of the epoxy cement mortar repair unit of the utility model.

[0031] Fig.10 It is a partial structural schematic diagram of the coating repair unit of the present utility model.

[0032] Fig.11 It is a cross-sectional schematic diagram of the coating repair unit of the present utility model.

[0033] Figure numerals: main box girder 100, fire damaged area 110, slightly damaged level I area 111, slightly damaged level II area 112, moderately damaged level III area 113, seriously damaged level IV area 114, seriously damaged level V area 115, concrete 120, stirrups 130, longitudinal force-bearing steel bars 140, prestressed steel bars 150, ultra-high performance concrete-steel repair unit 200, anti-cracking steel mesh 210, ultra-high performance concrete layer 220, threaded steel bars 230, beautification and protective layer 240, epoxy closed primer layer 241, epoxy micaceous iron intermediate paint layer 242, polyurethane topcoat layer 243, carbon fiber repair unit 300, epoxy fine stone concrete layer 310, bottom resin layer 320, carbon fiber cloth layer 330, impregnated resin layer 340, epoxy cement mortar repair unit 400, epoxy cement mortar layer 410, coating repair unit 500, cured adhesive layer 510. DETAILED DESCRIPTION

[0034] The drawings of the present invention are only used for illustrative purposes and cannot be construed as limiting the present invention. In order to better illustrate the following embodiments, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0035] Example 1

[0036] refer to Figures 1 to 3 The present embodiment provides a multi-unit post-fire concrete box girder bridge damage repair structure, wherein the concrete bridge comprises a main box girder 100, wherein the main box girder 100 has a fire damaged area 110, and the repair structure is applied to repair the fire damaged area 110 of the concrete bridge, and the repair structure comprises an ultra-high performance concrete-steel repair unit 200, a carbon fiber repair unit 300, an epoxy cement mortar repair unit 400, and a coating repair unit 500 which are laterally connected in sequence.

[0037] Specifically, the main box girder 100 includes concrete 120, stirrups 130, longitudinal force-bearing steel bars 140 and prestressed steel bars 150. The structure on one side of the central symmetry line of the longitudinal section of the fire damage area is shown in FIG. Figure 2 , repair the structure on one side of the central symmetry line of the longitudinal section of the structure. Figure 3 .

[0038] The ultra-high performance concrete-rebar repair unit 200 is used to repair areas where the concrete is severely spalled and the longitudinal and transverse steel bars are exposed over a large area, and this area is set as a severe V-level area 115; the carbon fiber repair unit 300 is used to repair areas where the concrete is slightly spalled and the stirrups 130 and the longitudinal steel bars are partially exposed, and this area is set as a relatively severe IV-level area 114; the epoxy cement mortar repair unit 400 is used to repair areas where the concrete is slightly spalled locally, and this area is set as a moderate III-level area 113; the coating repair unit 500 is used to repair areas where the concrete surface is blackened, slightly spalled or not burned, and the appearance is basically intact, and the former is set as a mild II-level area 112, and the latter is set as a mild I-level area 111.

[0039] In this embodiment, each area in the fire damage area is distributed along the longitudinal direction of the bridge, and each repair unit is also correspondingly distributed along the longitudinal direction of the bridge. The longitudinal distribution can be understood as the extension direction of the length of the bridge.

[0040] refer to Figure 4 and Figure 5 The ultra-high performance concrete-rebar repair unit 200 includes an anti-crack steel mesh 210, which is formed by connecting transverse steel bars and longitudinal steel bars. The anti-crack steel mesh 210 is connected to the fire damaged area 110 through threaded steel bars 230. Ultra-high performance concrete is filled between the anti-crack steel mesh 210 and the fire damaged area 110 to form an ultra-high performance concrete layer 220, and the thickness of the ultra-high performance concrete layer 220 is 25 to 60 mm, for example, 30 mm, 40 mm or 60 mm. A beautification protective layer 240 is also provided on the surface of the ultra-high performance concrete layer 220. In this way, the repair unit is not affected by the outer shape of the beam body, and can give full play to the advantages of ultra-high performance concrete of light weight, high strength and good weather resistance, can effectively improve the stiffness and strength of the damaged beam body, and has a strong reinforcement and improvement effect on the mechanical property recovery of the area with concrete spalling and exposed steel bars, so that the damaged area of ​​the main beam can be reliably repaired.

[0041] The threaded steel bar 230 is a reinforcement structure implanted in the main box girder 100, and the implantation depth is between 18 and 22 cm, for example, 20 cm. The threaded steel bar 230 and the main box girder 100 are further reinforced by structural adhesive, the tensile strength of the structural adhesive is greater than 60 MPa, the bending strength is greater than 50 MPa, and the bonding strength with concrete is greater than 17 MPa. The threaded steel bars 230 are arranged in an array, and the spacing between two adjacent threaded steel bars 230 is 290 to 300 mm. For example, the arrangement specification of the threaded steel bars 230 is 300 mm × 300 mm. The diameter of the threaded steel bars 230 can be different specifications, for example, the diameter is 10 mm or 12 mm. The spacing between two adjacent transverse steel bars is 140 to 160 mm, and the spacing between two adjacent longitudinal steel bars is 140 to 160 mm. For example, the mesh specification of the anti-cracking steel mesh 210 is 140 mm × 140 mm or 150 mm × 150 mm. The diameters of the longitudinal steel bars and the transverse steel bars may be of different specifications, for example, a diameter of 8 mm or 10 mm.

[0042] The compressive strength of the ultra-high performance concrete is greater than 150 MPa, the flexural strength of the ultra-high performance concrete is greater than 22 MPa, for example, 23 MPa or 30 MPa, etc. The tensile strength of the ultra-high performance concrete is greater than 8 MPa, for example, 9 MPa or 20 MPa, etc., and the elastic modulus of the ultra-high performance concrete is greater than 40 Gpa, for example, 41 Gpa or 60 Gpa, etc.

[0043] refer to Figure 6 and Figure 7 The carbon fiber repair unit 300 includes an epoxy fine stone concrete layer 310, a bottom resin layer 320, an impregnated resin layer 340, a carbon fiber cloth layer 330, an impregnated resin layer 340, a carbon fiber cloth layer 330, an impregnated resin layer 340 and a protective beautification layer 240 which are stacked in sequence, that is, two layers of carbon fiber cloth layers 330 are arranged in the carbon fiber repair unit 300. In this way, the repair unit is not affected by the outer shape of the beam body, and can give full play to the advantages of epoxy fine stone concrete, such as high strength and corrosion resistance, and carbon fiber cloth, such as light weight, high tensile strength, and easy construction, and has a good reinforcement and repair effect.

[0044] The epoxy fine stone concrete used in the epoxy fine stone concrete layer 310 has a splitting tensile strength greater than or equal to 7 MPa, a flexural strength greater than or equal to 12 MPa, a 7-day compressive strength greater than or equal to 40 MPa, and a 28-day compressive strength greater than or equal to 55 MPa.

[0045] The impregnating resin has a tensile strength greater than or equal to 40 MPa, an elastic modulus greater than or equal to 2500 MPa, a flexural strength greater than or equal to 50 MPa, and no brittle failure occurs. The compressive strength is greater than or equal to 70 MPa, the elongation is greater than or equal to 1.5%, and the bonding strength with concrete is greater than or equal to 2.5 MPa, and the failure is cohesive.

[0046] The tensile strength of the bottom layer resin is greater than or equal to 30 MPa, the flexural strength is greater than or equal to 40 MPa, and no brittle failure occurs. The bonding strength with concrete is greater than or equal to 2.5 MPa, and the failure is cohesive.

[0047] The carbon fiber cloth has a standard value of tensile strength greater than or equal to 3400 MPa, an elastic modulus greater than or equal to 24000 MPa, an ultimate elongation greater than or equal to 1.7%, and a bending strength greater than or equal to 700 MPa.

[0048] The thickness of the epoxy fine stone concrete layer 310 is between 30 and 60 mm, the thickness of the bottom resin layer 320 is between 0.2 and 0.3 mm, the thickness of the impregnated resin layer 340 is between 0.5 and 1.0 mm, and the thickness of the carbon fiber cloth of each layer of the carbon fiber cloth layer 330 can be of different specifications, for example, the thickness is 0.167 mm.

[0049] refer to Figure 8 and Fig. 9 The epoxy cement mortar repair unit 400 includes: an epoxy cement mortar layer 410, which is arranged on the surface of the fire damaged area 110; and a beautification protective layer 240, which is arranged on the surface of the epoxy cement mortar layer 410. In this way, the repair unit gives full play to the characteristics of the repair material with high bonding force, high compressive strength and no restriction on the shape of concrete surface peeling, and the repair effect is good.

[0050] The thickness of the epoxy cement mortar layer 410 is between 1 and 30 mm. The epoxy cement mortar used in the epoxy cement mortar layer 410 has a splitting tensile strength greater than or equal to 7 MPa, a flexural strength greater than or equal to 12 MPa, a 7-day compressive strength greater than or equal to 40 MPa, and a 28-day compressive strength greater than or equal to 55 MPa.

[0051] refer to Fig.10 and Fig.11 The coating repair unit 500 includes: a curing adhesive layer 510, which is disposed on the surface of the fire damaged area 110; and a beautifying protective layer 240, which is disposed on the surface of the curing adhesive layer 510. The curing adhesive layer 510 is an epoxy putty layer, and the thickness of the epoxy putty layer is 0.5 mm to 2 mm, for example, 1 mm.

[0052] The beautification protection layer 240 includes an epoxy sealing primer layer 241, an epoxy micaceous iron intermediate paint layer 242 disposed on the surface of the epoxy sealing primer layer 241, and a polyurethane topcoat layer 243 disposed on the surface of the epoxy micaceous iron intermediate paint layer 242, wherein the epoxy micaceous iron intermediate paint layer 242 is on the side away from the fire damage area 110. Such a repair structure is simple and convenient in actual construction, can effectively reduce the reinforcement cost, and beautifies the appearance of the beam after repair.

[0053] The thickness of the epoxy closed primer layer 241 is 35-45 μm, for example, 40 μm; the thickness of the epoxy micaceous iron intermediate paint layer 242 is 180-200 μm, for example, 190 μm; the thickness of the polyurethane topcoat layer 243 is 70-90 μm, for example, 80 μm. Specifically, in actual construction, a 40 μm polyurethane topcoat can be applied first, and then a second 40 μm polyurethane topcoat can be applied.

[0054] The repair structure provided in this embodiment uses different maintenance units to repair concrete box beam areas with different degrees of fire damage. Compared with the single repair structure using steel plates, carbon fiber cloth, and external concrete reinforcement, the repair structure can not only effectively improve the rigidity and bearing capacity of the severely damaged area, avoid secondary damage to the beam body during the reinforcement process, but also reduce the amount of reinforcement materials used in the larger area with slight or mild fire damage, thereby reducing the reinforcement cost. The reinforcement structure is highly targeted, has good applicability, and has a reliable and practical reinforcement effect.

[0055] Obviously, the above embodiments of the utility model are only examples for clearly explaining the technical solution of the utility model, and are not intended to limit the specific implementation methods of the utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the claims of the utility model shall be included in the protection scope of the claims of the utility model.

Claims

1. A multi-unit post-fire concrete box girder bridge damage repair structure, the concrete box girder bridge comprises a main box girder, the main box girder has a fire damaged area, the repair structure is used to repair the fire damaged area of ​​the concrete box girder bridge, characterized in that: The repair structure comprises an ultra-high performance concrete-steel repair unit, a carbon fiber repair unit, an epoxy cement mortar repair unit and a coating repair unit which are connected in sequence.

2. The multi-unit post-fire concrete box girder bridge damage repair structure according to claim 1 is characterized in that: The fire damage area includes a severely damaged level V area, a relatively severely damaged level IV area, a moderately damaged level III area, a slightly damaged level II area and a slightly damaged level I area which are connected in sequence.

3. The multi-unit post-fire concrete box girder bridge damage repair structure according to claim 2, characterized in that: The ultra-high performance concrete-rebar repair unit includes an anti-cracking steel mesh, which is formed by connecting transverse steel bars and longitudinal steel bars. The anti-cracking steel mesh is connected to the severely damaged V-level area through threaded steel bars, and ultra-high performance concrete is filled between the anti-cracking steel mesh and the severely damaged V-level area.

4. The multi-unit post-fire concrete box girder bridge damage repair structure according to claim 3 is characterized in that: The spacing between two adjacent transverse steel bars of the anti-cracking steel mesh is 140-160 mm, the spacing between two adjacent longitudinal steel bars is 140-160 mm, the compressive strength of the ultra-high performance concrete is greater than 150 MPa, and the flexural strength of the ultra-high performance concrete is greater than 22 MPa; the tensile strength of the ultra-high performance concrete is greater than 8 MPa, and the elastic modulus of the ultra-high performance concrete is greater than 40 Gpa.

5. The multi-unit post-fire concrete box girder bridge damage repair structure according to claim 2, characterized in that: The carbon fiber repair unit comprises: An epoxy fine stone concrete layer is provided on the surface of the relatively serious damage level IV area; A bottom resin layer is provided on the surface of the epoxy fine stone concrete layer; The carbon fiber cloth layer is bonded to the surface of the bottom resin layer through the impregnation resin layer; The beautifying protective layer is arranged on the surface of the carbon fiber cloth layer.

6. The multi-unit post-fire concrete box girder bridge damage repair structure according to claim 5, characterized in that: The surface of the bottom resin layer is bonded with two carbon fiber cloth layers through an impregnated resin layer, the thickness of the epoxy fine stone concrete layer is between 30 and 60 mm, the thickness of the bottom resin layer is between 0.2 and 0.3 mm, and the thickness of the impregnated resin layer is between 0.5 and 1.0 mm.

7. The multi-unit post-fire concrete box girder bridge damage repair structure according to claim 2, characterized in that: The epoxy cement mortar repair unit comprises: An epoxy cement mortar layer is provided on the surface of the moderately damaged level III area; The beautification and protection layer is arranged on the surface of the epoxy cement mortar layer.

8. The multi-unit post-fire concrete box girder bridge damage repair structure according to claim 2, characterized in that: The coating repair unit comprises: A cured adhesive layer is provided on the surface of the lightly damaged Grade II area and the slight Grade I area; The beautification and protection layer is arranged on the surface of the curing bonding layer.

9. The multi-unit post-fire concrete box girder bridge damage repair structure according to claim 8, characterized in that: The cured bonding layer is an epoxy putty layer.

10. The multi-unit post-fire concrete box girder bridge damage repair structure according to any one of claims 5 to 8, characterized in that: The beautification and protection layer includes an epoxy closed primer layer, an epoxy micaceous iron intermediate paint layer arranged on the surface of the epoxy closed primer layer, and a polyurethane topcoat layer arranged on the surface of the epoxy micaceous iron intermediate paint layer. The epoxy micaceous iron intermediate paint layer is on the side away from the fire damage area.

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