Reinforcing method of steel bridge deck slab

Abstract

The invention relates to the technical field of steel bridge deck reinforcement, and particularly discloses a method for reinforcing a steel bridge deck through combination of an acrylic plate and HPFRCC. Comprising the following steps: (1) chiseling away a damaged concrete surface layer of a to-be-reinforced part of a bridge deck; (2) concrete is removed, impurities generated by removal are removed, and leveling is completed through HPFRCC; (3) studs are implanted into the to-be-reinforced part at equal intervals in the longitudinal and transverse directions of the bridge deck slab; (4) paving a middle layer by using an acrylic plate; and (5) formwork erecting is conducted on the periphery of the to-be-reinforced part, HPFRCC is poured to the height of the bridge deck slab, and formwork dismounting is conducted after maintenance. According to the reinforcing method, after the middle layer of the acrylic plate and the HPFRCC are poured, the reinforcing layer and the original structure are integrally stressed together, permanent deformation caused by stress concentration is reduced, panel warping is reduced, the thickness of the panel is reduced, the overall weight of the bridge panel is reduced, the reinforcing method is simple, the early forming strength is high, the influence on traffic is small, and the service life of the bridge panel is prolonged. And social and economic benefits are high.

Description

Technical Field

[0001] The present invention relates to the technical field of steel bridge deck reinforcement, and specifically discloses a method for reinforcing a steel bridge deck by using an acrylic plate in combination with HPFRCC. Background Art

[0002] A steel bridge is a type of bridge whose span structure is constructed with steel. It has the characteristics of high strength and great rigidity. Compared with traditional concrete bridges, it can reduce the beam height and deadweight. Due to the isotropy, uniform texture and large elastic modulus of steel, the working conditions of the bridge are more consistent with the assumptions in the calculation diagrams. In addition, steel bridges can generally be prefabricated in factories and spliced on site, so the construction period is shorter, the processing is convenient and it is not affected by the season.

[0003] As the core component of a steel bridge, the steel bridge deck bears direct localized loads from vehicles, resulting in a short stress influence line. Passing vehicles induce multiple stress cycles, which, combined with stress concentrations at welded joints and inevitable weld defects, makes the steel bridge deck susceptible to fatigue cracking and damage. Given the increasing traffic volume and vehicle loads, the original bridge deck's stiffness and bearing capacity are clearly insufficient. Considering the project site conditions and the significant cost of removing and replacing damaged bridge decks, repair and reinforcement are the best option for extending the bridge's service life.

[0004] At present, common bridge reinforcement methods include increasing cross-section, gluing steel plates, gluing carbon fiber, external prestressing, and the later developed UHPC thin-layer embedded rebar reinforcement technology. These traditional reinforcement technologies are generally complex to construct, have long construction cycles, large weight increases, and high costs. Therefore, it is necessary to develop a steel bridge deck reinforcement method with simple construction methods, short construction cycles, and low costs. Summary of the Invention

[0005] The object of the present invention is to provide a steel bridge deck reinforcement method with simple construction method, short cycle and low cost.

[0006] In order to achieve the above object, the present invention provides a new method for reinforcing a steel bridge deck, which specifically comprises the following steps:

[0007] (1) Chisel away the concrete surface layer of the bridge deck that is damaged or loose due to freeze-thaw or other reasons at the part to be reinforced; the thickness of the concrete to be chiseled away from the bridge deck is determined according to the damaged part; if it is not damaged, it can be cleaned without chiseling;

[0008] (2) Remove impurities generated by the removal of bridge deck concrete and use high-performance fiber-reinforced cementitious composite materials (HPFRCC) to complete the leveling;

[0009] (3) Bolts are implanted at equal intervals along the longitudinal and transverse directions of the bridge deck;

[0010] (4) Make holes in the acrylic sheet. The hole diameter is determined according to the size of the bolt head, and the middle layer of the acrylic sheet is laid;

[0011] (5) Support the formwork and pour HPFRCC into the reinforced part. After curing, remove the formwork. Set the middle layer of acrylic board by implanting studs and pour HPFRCC so that the reinforcement layer and the original structure become a whole.

[0012] As a preferred solution, in order to ensure that the bolts have uniform and sufficient anchoring force, in step (3), the bolts are implanted at equal intervals of 20-30 cm along the longitudinal and transverse directions of the bridge deck, and the anchoring depth is 15-20 cm.

[0013] As a preferred solution, in order to ensure the tightness of the connection between the stud and the HPFRCC and to prevent the vehicle and the stud head from jointly damaging the HPFRCC of the stud head, the assembled stud described in step (3) can use a traditional φ16 cylindrical head stud, and its actual length can be determined comprehensively based on the anchoring depth, the thickness of the middle layer of the acrylic plate and the HPFRCC surface layer; the thickness of the protective layer on the top surface of the stud head described in step (5) is not less than 20 mm.

[0014] As a preferred solution, in order to ensure that the acrylic sheet has sufficient elasticity to dissipate strain, the thickness of the acrylic sheet in step (4) is determined according to the thickness of the upper HPFRCC layer and should not be less than 1 cm. In order to facilitate the rapid installation of the acrylic sheet on the stud, the aperture of the acrylic sheet is 3-5 mm larger than the diameter of the stud head.

[0015] As a preferred solution, in order to improve the fit between the acrylic sheet and the original part to be reinforced so as to achieve stable support for the acrylic sheet, in step (4), the bottom of the acrylic sheet is coated with a HPFRCC layer during installation, and the HPFRCC layer is used to further fit the leveling surface in step (2).

[0016] As a preferred solution, in order to better support the HPFRCC around the studs and further eliminate stress, two semi-annular acrylic plates are arranged between the holes of the acrylic plate and the studs in step (4), so that the strain around the studs can be better dissipated through the acrylic plates.

[0017] As a preferred solution, to improve the reinforcement efficiency and strength of steel bridge decks after reinforcement, the HPFRCC composite material has a compressive strength of at least 120 MPa and a tensile strength of at least 8 MPa, and does not require steam curing. Due to its high strength, the HPFRCC composite material should be cast at a thickness of 10-20 cm. After casting, the HPFRCC composite material is cured at room temperature for 1-3 days. Traffic can be maintained during the reinforcement process without affecting its use.

[0018] Compared with the prior art, the steel bridge deck reinforcement method of the present invention has the following advantages:

[0019] (1) Compared with the traditional method of increasing the cross-section, this technology can reduce the self-weight generated by the reinforcement, which is about one-third of the self-weight generated by the traditional method; secondly, it can increase the space utilization of the structure, and the space occupied is only one-third of the traditional method of increasing the cross-section.

[0020] (2) Compared with the traditional method of gluing steel plates, this method has simple construction steps and a short construction period, saving the cost of anti-corrosion and rust prevention of the steel plates in the later stage. The reinforcement method of the present invention can be constructed under open traffic conditions, reducing the impact of construction on society. After reinforcement, no special curing conditions are required and the steel plates can be formed at room temperature, and the curing time is no more than 3 days.

[0021] (3) Compared with the UHPC thin-layer rebar reinforcement technology, the present invention adds an acrylic plate intermediate layer as a transition layer between the original bridge deck and the HPFRCC surface layer, which can dissipate most of the strain energy, maintain high stiffness and load-bearing capacity, and effectively ensure the overall coordination of the new and old structures. By using HPFRCC as the surface layer material, the occurrence of cracks can be effectively controlled, and a small amount or no anti-crack structural steel bars can be arranged during the surface layer casting. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the arrangement of the studs according to embodiment 1 of the present invention.

[0023] Figure 2 for Figure 1 AA cross-sectional structure diagram.

[0024] It includes: original concrete layer 1, acrylic board 2, HPFRCC surface layer 3, HPFRCC leveling surface 4, studs 5, and semi-circular acrylic board 6. DETAILED DESCRIPTION

[0025] The following is further described in detail with reference to the accompanying drawings and specific embodiments:

[0026] Example 1

[0027] like Figure 1 and Figure 2 As shown, this embodiment provides a method for reinforcing a steel bridge deck, and the specific steps are as follows:

[0028] (1) Use an impact drill to remove the concrete surface layer that is damaged or loose due to freeze-thaw or other reasons at the part to be reinforced. The thickness of the concrete to be removed is determined according to the damaged part. If it is not damaged, it can be cleaned without removal.

[0029] (2) Clean and remove impurities generated by the bridge deck concrete, blow it clean with high-pressure gas, and then use HPFRCC to complete leveling to obtain HPFRCC leveling surface 4;

[0030] (3) Studs 5 are implanted at equal intervals of 20-30 cm along the longitudinal and transverse directions of the bridge deck at the part to be reinforced. The spacing in this embodiment is 20 cm. The studs 5 are φ16 cylindrical head studs 5. The anchoring depth of the studs 5 in the original concrete layer 1 is generally 15-20 cm. In this embodiment, 15 cm is used. The studs are anchored to the concrete using a resin adhesive, and the verticality of the studs is ensured. After implanting the studs, the stud position deviation and the stud pull-out bearing capacity are inspected before installing the acrylic plate to ensure that they meet the design requirements.

[0031] (4) Select an acrylic plate 2 with a thickness of not less than 1 cm, and make holes in the acrylic plate 2 in the vertical and horizontal directions. The position of the holes matches the distribution of the studs. The hole diameter is 3-5 mm larger than the head of the stud 5. In this embodiment, 3 mm is selected. Then, the middle layer of the acrylic plate 2 is paved. During paving, a layer of HPFRCC is applied on the bottom surface of the acrylic plate 2 to better fit the HPFRCC leveling surface 4 obtained in step (2). The joints between adjacent acrylic plates are required to be no larger than 3 mm, and a semi-circular acrylic plate 6 is used to fill the gaps around the studs.

[0032] (5) Support the formwork and pour the HPFRCC into the reinforced area to obtain the HPFRCC surface layer 3. The HPFRCC has a compressive strength of 120 MPa or more and a tensile strength of 8 MPa. The thickness of the protective layer on the top surface of the stud head 5 is 20 mm. After pouring, the HPFRCC becomes an integral part of the original structure and is cured at room temperature for 1-3 days. In this embodiment, the curing time is 1 day. After pouring the HPFRCC, the thickness of the HPFRCC layer, the thickness of the protective layer on the top surface of the stud head, and the strength of the HPFRCC layer are tested.

[0033] Generally, the thickness of the acrylic board 2 should be less than the thickness of the HPFRCC surface layer 3 , and the height of the head of the stud 5 should not be less than two-thirds of the thickness of the HPFRCC surface layer 3 .

[0034] This embodiment anchors bolts into the existing bridge deck and secures the HPFRCC surface layer to the deck using these bolts. By cleverly adding an acrylic sheet intermediate transition layer between the HPFRCC surface layers, and leveraging the acrylic sheet's high strength, weather resistance, and acid and alkali resistance, this effectively dissipates most strain energy, reduces permanent deformation caused by stress concentration, and reduces deck warping. This not only reduces deck thickness and overall weight while maintaining high stiffness and load-bearing capacity, but also effectively ensures the coordinated operation of the new and old structures. Furthermore, the HPFRCC used in this embodiment does not require high-temperature steam curing after reinforcement, resulting in a short curing time and low cost. It quickly develops strength early on, has minimal impact on traffic, and can be constructed without closing traffic, resulting in high socioeconomic benefits.

[0035] Example 2

[0036] This embodiment provides a method for reinforcing a steel bridge deck, and the specific steps are as follows:

[0037] (1) Use an impact drill to remove the concrete surface layer that is damaged or loose due to freeze-thaw or other reasons at the part to be reinforced. The thickness of the concrete to be removed is determined according to the damaged part. If it is not damaged, it can be cleaned without being removed.

[0038] (2) Clean and remove impurities generated by the bridge deck concrete, blow it clean with high-pressure gas, and then use HPFRCC to complete the leveling.

[0039] (3) Bolts are implanted at equal intervals of 20-30 cm along the longitudinal and transverse directions of the bridge deck at the part to be reinforced. The spacing in this embodiment is 30 cm. The bolts are φ16 cylindrical head bolts. The anchoring depth is generally 15-20 cm. In this embodiment, 20 cm is used. Resin adhesive is used to anchor the bolts to the concrete, and the verticality of the bolts is ensured to avoid large angle inclination.

[0040] (4) Select an acrylic sheet with a thickness of not less than 1 cm, and make holes in the acrylic sheet in the vertical and horizontal directions. The position of the holes matches the distribution of the studs. The hole diameter is 3-5 mm larger than the head of the stud. In this embodiment, 5 mm is selected. Then, the middle layer of the acrylic sheet is paved. During paving, a layer of HPFRCC is applied on the bottom surface of the acrylic sheet to better fit the HPFRCC leveling surface obtained in step (2). The joints between adjacent acrylic sheets are required to be no larger than 3 mm, and semi-circular acrylic sheets are used to fill the gaps around the studs.

[0041] (5) Support the formwork and pour the HPFRCC into the reinforced part. The compressive strength of the HPFRCC is above 120 MPa and the tensile strength is 10 MPa. The thickness of the protective layer on the top surface of the bolt head is 20 mm. After pouring, the HPFRCC becomes an integral part of the original structure and is cured at room temperature for 1-3 days. In this embodiment, 3 days is used.

[0042] The above is only an embodiment of the present invention, and the common knowledge such as the specific technical solutions and / or characteristics known in the solution are not described in detail here. It should be pointed out that for those skilled in the art, several variations and improvements can be made without departing from the technical solution of the present invention. In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. The scope of protection claimed by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for reinforcing a steel bridge deck, characterized in that: The specific steps include: (1) Chisel away the damaged or loose concrete surface layer at the part of the bridge deck to be reinforced; (2) Remove impurities generated by concrete removal and use HPFRCC to complete leveling; (3) Insert studs at equal intervals along the longitudinal and transverse directions of the bridge deck at the part to be reinforced; (4) using acrylic sheets for paving the middle layer, wherein the acrylic sheets are provided with holes for the heads of the bolts to pass through; (5) Formwork is supported around the area to be reinforced and HPFRCC is cast to the height of the bridge deck. After curing, the formwork is removed so that the studs, the middle layer of acrylic board, the cast HPFRCC and the original area to be reinforced become a whole.

2. The method for reinforcing a steel bridge deck according to claim 1, characterized in that: The assembled bolt described in step (3) is a cylindrical head bolt, the bottom of which is anchored in the original concrete layer by adhesive, with an anchoring depth of 15-20 cm.

3. The method for reinforcing a steel bridge deck according to claim 1, characterized in that: The spacing between the pegs in step (3) is 20-30 cm.

4. The method for reinforcing a steel bridge deck according to claim 1, wherein: In the step (3), HPFRCC that does not require steam curing is used, and its compressive strength is not less than 120 MPa and its tensile strength is not less than 8 MPa.

5. The method for reinforcing a steel bridge deck according to claim 4, characterized in that: After pouring, the HPFRCC is cured at room temperature for 1-3 days.

6. The method for reinforcing a steel bridge deck according to claim 1, characterized in that: In step (5), the thickness of the top surface protective layer of the bolt head is not less than 20 mm.

7. The method for reinforcing a steel bridge deck according to claim 1, characterized in that: In the step (4), the bottom of the acrylic board is coated with a HPFRCC layer.

8. The method for reinforcing a steel bridge deck according to claim 1, characterized in that: In the step (4), two semi-annular acrylic plates are arranged between the hole of the acrylic plate and the peg.

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