Fabricated small box girder bridge deck continuous position leveling layer crack prevention and control structure

Abstract

The utility model discloses an assembly type small box girder bridge deck continuous position leveling layer crack prevention structure, belongs to the field of bridge engineering, and solves the problem that a small box girder bridge deck continuous position concrete leveling layer is easy to crack. According to the prevention structure, a box girder top plate is arranged at the top of the small box girder, top plate transverse steel bars and top plate longitudinal steel bars are arranged in the box girder top plate, a notch is reserved in the end of the box girder top plate, the top plate longitudinal steel bars at the notch are bent, and the top plate longitudinal steel bars on the two sides of the notch are bound and connected to form a hinged structure. And the notch and the leveling layer are jointly poured with concrete to form a whole. According to the utility model, the problems of insufficient thickness of the beam end leveling layer and weak bonding between the concrete leveling layer and the beam top are effectively solved, and the tensile strength and rigidity of the structure are enhanced, so that the formation of cracks is prevented, and the service life is prolonged.

Description

Technical Field

[0001] The utility model belongs to the field of bridge engineering, and in particular relates to a structure for preventing and controlling cracks in a continuous position leveling layer of an assembled small box girder bridge deck. Background Art

[0002] Prefabricated prestressed concrete simply supported small box girders are widely used in highway and municipal bridges due to their favorable economic performance, rapid construction, controlled quality, and wide applicability. These bridges often feature an 8cm to 15cm thick concrete leveling layer between the box girder and the deck pavement. This layer serves as a link between the upper and lower levels, supporting the deck pavement above and the prefabricated box girder below. This layer not only adjusts and controls the deck elevation, but also improves bridge stability and safety. It also provides waterproofing and corrosion resistance, a key factor influencing bridge stress and durability.

[0003] An investigation of the concrete leveling layers of highway and municipal bridges revealed widespread cracking in the concrete leveling layers at continuous locations (beam ends) on the bridge deck of prefabricated prestressed concrete simply supported small box girder systems. Cracks can be categorized by type as transverse, longitudinal, and reticular cracks. 60% of these cracks are less than 0.5 mm wide, and 40% are irregular cracks greater than 0.5 mm wide. These cracks are generally long and expand and grow over time, eventually forming macrocracks. Because these cracks are located below the pavement, they are difficult to detect during routine bridge inspections. If repaired promptly, further expansion can lead to structural degradation or even failure. Therefore, preventing and controlling cracks in the beam end leveling layer is crucial to improving bridge reliability and durability.

[0004] The causes of this type of cracks are complex and mainly include the following aspects.

[0005] 1) Insufficient leveling layer thickness at beam ends. When prefabricating small box girders, longitudinal slope and elevation factors were not considered. The leveling layer required vertical curve fitting, resulting in uneven thickness. This can easily create weak areas at beam ends located on concave or convex curves, or at slope change points. In extreme cases, the thickness of the leveling layer reinforcement cover may not meet specifications. Concrete shrinkage generates tensile stress, which can easily cause irregular cracks at these locations.

[0006] 2) Weak bonding between the concrete leveling layer and the beam top. Construction companies need to groove or roughen the beam top during the leveling process. Due to differences in construction quality, laitance or oil stains are likely to form on the beam ends. This poor bonding between the new and old concrete compromises the integrity of the concrete, making it susceptible to cracks from the impact loads of wheels.

[0007] 3) The concrete leveling layer at the supports is subjected to negative bending moments. Although the main beam is a simply supported structure, the bridge deck is a continuous structure. Under the action of load, the beam body undergoes flexural deformation, causing the concrete leveling layer at the bridge deck supports to be subjected to negative bending moments, thereby causing cracking of the concrete leveling layer.

[0008] Cracking in the concrete leveling layer at continuous locations on bridge decks has long been a common problem, yet it has received little attention. If left unchecked, these cracks in the concrete leveling layer can gradually reflect into the pavement during bridge operation, causing cracks in the pavement. This increases maintenance costs and further impacts the load-bearing capacity of the main beams. Therefore, implementing optimization measures during the design phase can effectively reduce operating costs and extend the service life of the bridge deck. Utility Model Content

[0009] The utility model aims to provide a structure for preventing and controlling cracks in a continuous leveling layer of an assembled small box girder bridge deck, so as to solve the problem that the continuous concrete leveling layer of the small box girder bridge deck is prone to cracking.

[0010] The technical solution of the utility model is: a prefabricated small box girder bridge deck continuous position leveling layer crack prevention structure, a box girder top plate is provided on the top of the small box girder, top plate transverse steel bars and top plate longitudinal steel bars are provided in the box girder top plate, a notch is reserved at the end of the box girder top plate, the top plate longitudinal steel bars at the notch are bent and the top plate longitudinal steel bars on both sides of the notch are tied and connected to form a hinged structure, and the notch and the leveling layer are cast into one with concrete together.

[0011] As a further improvement of the present invention, the top plate longitudinal steel bars are provided with two layers, the upper layer of the top plate longitudinal steel bars at the notch are bent upward and the ends are horizontal, and the lower layer of the top plate longitudinal steel bars at the notch are bent downward and the ends are horizontal.

[0012] As a further improvement of the present invention, two layers of upper and lower notch transverse reinforcement are provided at the notch, stirrups are provided around the two layers of notch transverse reinforcement, and the stirrups overlap the horizontal ends of the longitudinal reinforcement of the top plate at the notch.

[0013] As a further improvement of the present invention, a leveling layer steel mesh is provided in the leveling layer.

[0014] As a further improvement of the present invention, a rear cut groove is provided at the center line of the pier of the leveling layer along the transverse direction of the bridge, and the rear cut groove is filled with asphalt paste.

[0015] The beneficial effects of this utility model are as follows: By integrally casting the box girder top plate (notch position) at the continuous position of the bridge deck with the leveling layer, this utility model effectively solves the problems of insufficient leveling layer thickness at the beam ends and weak bonding between the concrete leveling layer and the beam top; the longitudinal reinforcement of the top plate on both sides of the notch is hinged, which facilitates load transfer to the leveling layer; the transverse reinforcement and stirrups within the notch form a reinforcement skeleton, enhancing the tensile strength and rigidity of the structure and effectively resisting the negative bending moment of the leveling layer; and by post-grooving the leveling layer, irregular cracks can be prevented during the setting and hardening of the concrete, and shrinkage cracks in the concrete are induced to form along predetermined gaps, thereby preventing the formation of random cracks. This utility model effectively solves the problems of insufficient leveling layer thickness at the beam ends and weak bonding between the concrete leveling layer and the beam top, enhancing the tensile strength and rigidity of the structure, thereby preventing the formation of cracks and extending the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural diagram of a continuous position leveling layer crack prevention structure for assembled small box girder bridge decks of the utility model;

[0017] Figure 2 It is a structural diagram of the notch in the utility model;

[0018] Figure 3 It is a partial enlarged view of the notch in the utility model;

[0019] Figure 4 yes Figure 1 AA view of the .

[0020] In the figure: 1- horizontal reinforcement of top plate; 2- longitudinal reinforcement of top plate; 3- box girder top plate; 4- notch; 5- leveling layer steel mesh; 6- horizontal reinforcement of notch; 7- stirrups; 8- post-cutting; 9- concrete; 10- small box girder; 11- pier cap beam; 12- leveling layer. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below in conjunction with specific implementation methods.

[0022] like Figure 1-4 As shown, a prefabricated small box girder bridge deck continuous position leveling layer crack prevention structure, the small box girder 10 is set on the pier cap beam 11, the top of the small box girder 10 is provided with a box girder top plate 3, the top plate transverse steel bars 1 and the top plate longitudinal steel bars 2 are provided in the box girder top plate 3, and a notch 4 is reserved at the end of the box girder top plate 3 ( Figure 2 The medium thick line indicates the position of the notch 4). The top plate longitudinal steel bars 2 at the notch 4 are bent and the top plate longitudinal steel bars 2 on both sides of the notch 4 are tied and connected to form a hinged structure. The tying position is located at the center line of the pier. The notch 4 and the leveling layer 12 are cast together with concrete 9 to form a whole.

[0023] The top plate longitudinal steel bars 2 are provided in two layers, the top plate longitudinal steel bars 2 of the upper layer at the notch 4 are bent upward with the ends horizontal, and the top plate longitudinal steel bars 2 of the lower layer at the notch 4 are bent downward with the ends horizontal.

[0024] Two layers of upper and lower notch transverse reinforcement bars 6 are provided at the notch 4 , and stirrups 7 are provided around the two layers of notch transverse reinforcement bars 6 . The stirrups 7 overlap the horizontal ends of the top plate longitudinal reinforcement bars 2 at the notch 4 .

[0025] A leveling layer steel mesh 5 is provided in the leveling layer 12 .

[0026] A rear cut groove 8 is provided at the center line of the pier of the leveling layer 12 along the transverse direction of the bridge, and the rear cut groove 8 is filled with asphalt paste.

[0027] The construction method includes the following steps:

[0028] A. When the assembled small box beam 10 is prefabricated in the factory, a notch 4 is reserved at the end of the box beam top plate 3, and the longitudinal reinforcement 2 of the top plate is extended according to the overlap length;

[0029] B. After the small box girder is erected and the crossbeam and wet joints are cast in place, the longitudinal steel bars 2 of the top plate on both sides of the notch 4 are symmetrically bent and tied. The longitudinal steel bars 2 of the top plate on the upper layer are bent upward with the ends horizontal, and the longitudinal steel bars 2 of the top plate on the lower layer at the notch 4 are bent downward with the ends horizontal. After tying, a hinged structure is formed;

[0030] C. Set two layers of transverse notch reinforcement 6 at the notch 4, set stirrups 7 around the two layers of transverse notch reinforcement 6, and make the stirrups 7 overlap the horizontal ends of the longitudinal reinforcement 2 of the top plate at the notch 4; and simultaneously tie the leveling layer reinforcement mesh 5;

[0031] D. Pour concrete 9 into the notch 4 and the leveling layer 12 together to form an integral whole. After the concrete 9 has initially set, use a cutting machine to cut a 2 cm wide and 1 cm deep post-cut groove 8 along the transverse direction of the bridge at the centerline of the pier of the leveling layer 12. Fill the post-cut groove 8 with asphalt paste, and then cure the concrete 9.

[0032] By integrally casting the box girder top plate 3 (notch 4 position) and the leveling layer 12 at the continuous position of the bridge deck, the problems of insufficient thickness of the leveling layer at the beam end and weak bonding between the concrete leveling layer and the beam top are effectively solved; the top plate longitudinal steel bars 2 on both sides of the notch 4 are hinged, which is beneficial to the load transfer of the leveling layer; the notch transverse steel bars 6 and stirrups 7 in the notch 4 form a steel skeleton, which enhances the tensile strength and rigidity of the structure and can effectively resist the negative bending moment of the leveling layer 12; by cutting the groove 8 after the construction of the leveling layer 12, irregular cracks can be prevented during the setting and hardening process of the concrete, and shrinkage cracks of the concrete can be induced to occur along the predetermined gaps, thereby preventing the formation of random cracks and extending the service life.

[0033] The utility model is easy to implement, simple in structure and low in cost. By optimizing the construction method and local structure, it effectively solves the problem of local cracking of the concrete leveling layer at continuous positions on the bridge deck, thereby achieving the purpose of effectively reducing operating costs and extending the service life of the bridge deck.

Claims

1. A structure for preventing and controlling cracks in a continuous leveling layer of an assembled small box girder bridge deck, wherein a box girder top plate is provided on the top of the small box girder, and transverse and longitudinal top plate steel bars are provided in the box girder top plate, characterized in that: A notch (4) is reserved at the end of the box beam top plate (3), the top plate longitudinal steel bars (2) at the notch (4) are bent, and the top plate longitudinal steel bars (2) on both sides of the notch (4) are tied and connected to form a hinged structure, and the notch (4) and the leveling layer (12) are cast together with concrete (9) to form a whole.

2. The structure for preventing and controlling cracks in the continuous position leveling layer of the assembled small box girder bridge deck according to claim 1 is characterized in that: The top plate longitudinal steel bars (2) are provided in two layers, the upper layer of the top plate longitudinal steel bars (2) at the notch (4) is bent upward with its end portion horizontal, and the lower layer of the top plate longitudinal steel bars (2) at the notch (4) is bent downward with its end portion horizontal.

3. The structure for preventing and controlling cracks in the continuous position leveling layer of the assembled small box girder bridge deck according to claim 2 is characterized in that: Two layers of upper and lower notch transverse reinforcement bars (6) are provided at the notch (4), stirrups (7) are provided around the two layers of notch transverse reinforcement bars (6), and the stirrups (7) overlap the horizontal ends of the top plate longitudinal reinforcement bars (2) at the notch (4).

4. The structure for preventing and controlling cracks in the continuous position leveling layer of the assembled small box girder bridge deck according to claim 3 is characterized in that: A leveling layer steel mesh (5) is provided in the leveling layer (12).

5. The structure for preventing and controlling cracks in the continuous position leveling layer of the assembled small box girder bridge deck according to claim 4 is characterized in that: A rear cut groove (8) is provided at the bridge pier centerline position of the leveling layer (12) along the transverse direction of the bridge, and the rear cut groove (8) is filled with asphalt paste.

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