Segmental prefabricated steel pin diaphragm UHPC box girder and construction method thereof

Abstract

This invention discloses a segmental precast steel pin diaphragm UHPC box girder and its construction method. The girder includes a UHPC box-shaped outer shell, within which are arranged multiple longitudinal structural steel bars extending along the beam length and spaced apart. Inside the UHPC box-shaped outer shell are multiple steel transverse diaphragms arranged at intervals along the beam length. The edges of the steel transverse diaphragms are fitted against the inner wall of the UHPC box-shaped outer shell. Multiple steel pin structures are connected to the steel transverse diaphragms to form steel pin-type diaphragms. Each steel pin structure is arranged at intervals along the edge of the steel transverse diaphragm and is embedded in the UHPC box-shaped outer shell, engaging with it. This segmental precast steel pin diaphragm UHPC box girder has the advantages of simple structure, low steel consumption, and low cost.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering technology, specifically to a segmental precast steel pin diaphragm UHPC box girder and its construction method. Background Technology

[0002] In the field of bridge engineering technology, with the widespread application of ultra-high performance concrete (hereinafter referred to as UHPC) in bridge engineering, in addition to traditional concrete box girders, steel box girders and conventional composite structure bridges, bridge structures based on UHPC have also been widely used.

[0003] Regarding the construction of box girders for bridges, patent document CN102352597B proposes a unidirectional prestressed concrete box girder made entirely of UHPC material. To ensure the stress requirements of the box girder, a large number of UHPC diaphragms are set up. Due to the high requirements for UHPC casting, a large number of complex steel formworks are needed to erect the inner formwork, which makes the formwork erection process complicated and the demolding process inconvenient. Patent document CN114737462A proposes two forms of UHPC box girders: all-steel inner core and semi-steel inner core. The all-steel inner core UHPC box girder integrates the steel inner mold directly into the box girder, connecting the inner mold steel plates to the UHPC box girder shell via shear studs to form a composite structure. The inner mold contains frame-type diaphragms welded to each inner mold steel plate. However, this bridge structure significantly increases steel consumption, resulting in poor economic efficiency, and the steel inner mold is difficult to manufacture and requires a large amount of processing work. The semi-steel inner core UHPC box girder retains only the upper part of the steel inner mold, replacing the frame-type diaphragms with semi-diaphragms. However, this semi-diaphragm form eliminates the traditional frame-type diaphragms in box girder structures, which is inconsistent with engineering application practices. Its stress characteristics require specific design research for different projects, hindering its widespread application. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a segmental prefabricated steel pin diaphragm UHPC box girder with simple structure, low steel consumption and low cost and its construction method.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A segmental precast steel pin diaphragm UHPC box girder includes a UHPC box-shaped shell. The UHPC box-shaped shell contains multiple longitudinal structural steel bars extending along the beam's length and arranged at intervals. Inside the UHPC box-shaped shell are multiple steel transverse diaphragms arranged at intervals along the beam's length. The edges of the steel transverse diaphragms are fitted against the inner wall of the UHPC box-shaped shell. Multiple steel pin structures are connected to the steel transverse diaphragms to form steel pin-type diaphragms. Each steel pin structure is arranged at intervals along the edge of the steel transverse diaphragm and is embedded in the UHPC box-shaped shell, engaging with it.

[0007] As a further improvement to the above technical solution:

[0008] The longitudinal structural steel bars are arranged on opposite sides of each steel pin structure.

[0009] The steel pin structure is a protruding structure with a smooth transition at the corners, and the protruding structure extends outward along the edge of the steel diaphragm.

[0010] The protruding structure includes a first curved edge composed of a concave arc and a convex arc, and a second curved edge symmetrically arranged with respect to the first curved edge. The longitudinal structural steel bars are arranged at the junction of the concave arc and the convex arc.

[0011] The diameter (mm) of the longitudinal structural steel bar is equal to 2 times the radius of the concave arc (mm) - 20.

[0012] The steel pin-type partition is cut from a single plate in one go.

[0013] The steel pin-type partition is arranged perpendicular to the UHPC box-type outer shell. The UHPC box-type outer shell includes a bottom plate, a top plate, and two web plates arranged at intervals between the bottom plate and the top plate. The steel transverse partition is attached to the bottom plate, the top plate, and the two web plates. Each steel pin structure is correspondingly embedded in the bottom plate, the top plate, and the two web plates.

[0014] The steel diaphragm has holes for people to pass through.

[0015] An inner top plate, which serves as a top mold for forming the UHPC box-shaped housing, is attached and fixed to the inner top wall of the housing. A plurality of shear studs for embedding into the UHPC box-shaped housing are connected to the inner top plate. A steel pin-type partition is connected to the side of the inner top plate away from the shear studs.

[0016] As a general inventive concept, another aspect of the present invention provides a construction method for the above-mentioned segmental precast steel pin diaphragm UHPC box girder, comprising the following steps:

[0017] S1: Process steel pin-type partitions, prefabricate steel inner molds for forming UHPC box-type shells, and erect and fix longitudinal structural steel bars to fix the steel pin-type partitions in the predetermined positions.

[0018] S2: Erect the external template for forming the UHPC box-shaped shell, and hoist the steel inner mold, longitudinal structural steel bars, and steel pin-type partitions into the external template of the UHPC box-shaped shell and fix them in place;

[0019] S3: Cast UHPC molded UHPC box-shaped shell to form the segmental prefabricated steel pin partition UHPC box beam, remove the inner and outer templates and carry out high temperature steam curing;

[0020] S4: Transport the segmental precast steel pin partition UHPC box girder to the installation position, and use the beam lifting equipment to erect it or assemble it on site to form the main beam structure of the box girder.

[0021] Compared with existing technologies, the advantages of this invention are as follows: The segmental precast steel pin diaphragm UHPC box girder of this invention includes a UHPC box-shaped shell and steel pin diaphragms. The steel pin diaphragms replace the conventional UHPC diaphragms in a pure UHPC box girder. The steel pin structure is embedded in the UHPC box-shaped shell and engages with it. Multiple longitudinal structural steel bars are set in the UHPC box-shaped shell to ensure load-bearing capacity. While simplifying the connection structure between the steel diaphragm and the UHPC beam and reducing steel consumption, it also ensures that the connection strength between the steel pin diaphragm and the UHPC box-shaped shell meets the requirements. The steel pin diaphragm retains the original function of the transverse diaphragm in transmitting shear flow and uniformly distributing internal forces, and further enhances its resistance to torsion and distortion. This invention directly eliminates the upper, lower, left, and right side steel plates of the steel core, simplifying the structure, reducing self-weight, significantly reducing steel consumption, and lowering costs. Furthermore, the steel pin diaphragm can be processed from ordinary steel plates, making processing and manufacturing simple and convenient for application and promotion. Furthermore, when erecting the internal formwork, there is no need to build templates for forming conventional UHPC diaphragms, significantly reducing the number of templates required during construction. The steel pin-type diaphragms can also have larger manholes, facilitating demolding and making demolding quick and convenient, consistent with engineering application practices. In summary, this invention significantly reduces steel consumption, optimizes the performance of the cast box girder structure, and simplifies processing and construction.

[0022] The construction method of segmental precast steel pin diaphragm UHPC box girder of the present invention avoids the need to set up complicated templates for forming conventional UHPC transverse diaphragms during casting, which can improve construction efficiency, reduce construction difficulty, and the construction method is streamlined and reasonable. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural diagram of the segmental precast steel pin diaphragm UHPC box girder in Example 1.

[0024] Figure 2 This is a schematic diagram of the overall structure of the steel pin-type partition in Example 1.

[0025] Figure 3 for Figure 2 A magnified structural diagram of point A in the middle.

[0026] Figure 4 This is a partial three-dimensional structural schematic diagram of the segmental precast steel pin diaphragm UHPC box girder in Example 2.

[0027] Figure 5 This is a schematic diagram of the overall structure of the steel pin-type partition in Example 2.

[0028] Legend:

[0029] 1. UHPC box-type shell; 11. Longitudinal structural steel bars; 12. Bottom plate; 13. Top plate; 14. Web plate; 2. Steel diaphragm; 21. Holes; 3. Steel pin structure; 31. Concave arc; 32. Convex arc; 4. Inner top plate. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Example 1:

[0032] like Figures 1 to 3As shown, the segmental precast steel pin diaphragm UHPC box girder of this embodiment includes a UHPC box shell 1. The UHPC box shell 1 is provided with multiple longitudinal structural steel bars 11 extending along the beam length direction and arranged at intervals. The UHPC box shell 1 is provided with multiple steel transverse diaphragms 2 arranged at intervals along the beam length direction. The edges of the steel transverse diaphragms 2 are attached to the inner wall of the UHPC box shell 1. Multiple steel pin structures 3 are connected to the steel transverse diaphragms 2 to form steel pin diaphragms. Each steel pin structure 3 is arranged at intervals along the edge of the steel transverse diaphragm 2. Each steel pin structure 3 is embedded in the UHPC box shell 1 and engages with the UHPC box shell 1. This segmental precast steel pin diaphragm UHPC box girder includes a UHPC box-shaped outer shell 1 and steel pin diaphragms. The steel pin diaphragms replace the conventional UHPC diaphragms in a pure UHPC box girder. Steel pin structures 3 are embedded in and interlock with the UHPC box-shaped outer shell 1. Multiple longitudinal structural steel bars 11 are installed in the UHPC box-shaped outer shell 1 to ensure load-bearing capacity. This simplifies the connection structure between the steel diaphragm and the UHPC beam, reduces steel consumption, and ensures the connection strength between the steel pin diaphragm and the UHPC box-shaped outer shell 1 meets requirements. The steel pin diaphragm retains the original function of the transverse diaphragm in transmitting shear flow and uniformly distributing internal forces, while further enhancing torsional and distortion resistance. This invention directly eliminates the upper, lower, left, and right side steel plates of the steel core, simplifying the structure, reducing self-weight, significantly reducing steel consumption, and lowering costs. Furthermore, the steel pin diaphragm can be processed from ordinary steel plates, making manufacturing simple and convenient for application and promotion. Furthermore, when erecting the internal formwork, there is no need to build templates for forming conventional UHPC diaphragms, significantly reducing the number of templates required during construction. The steel pin-type diaphragms can also have larger manholes, facilitating demolding and making demolding quick and convenient, consistent with engineering application practices. In summary, this invention significantly reduces steel consumption, optimizes the performance of the cast box girder structure, and simplifies processing and construction.

[0033] In this embodiment, each longitudinal structural steel bar 11 is arranged on opposite sides of each steel pin structure 3. Arranging the longitudinal structural steel bars 11 on opposite sides of the steel pin structure 3 can ensure the connection strength between the steel pin structure 3 and the UHPC box-type shell 1.

[0034] In this embodiment, the steel pin structure 3 is a protruding structure with a smooth transition at the corners, extending outward along the edge of the steel diaphragm 2. This prevents stress concentration and provides excellent fatigue resistance.

[0035] In this embodiment, the protruding structure includes a first curved edge formed by a combination of an inwardly concave arc 31 and an outwardly convex arc 32, and a second curved edge symmetrically arranged with respect to the first curved edge. The longitudinal structural steel bar 11 is arranged at the junction of the inwardly concave arc 31 and the outwardly convex arc 32. This enhances the connection strength between the steel pin structure 3 and the UHPC box-type outer shell 1. In this embodiment, the diameter of the longitudinal structural steel bar 11 is 12mm, and the radius of the inwardly concave arc 31 of the steel pin structure 3 is 16mm.

[0036] In this embodiment, the diameter (mm) of the longitudinal structural steel bar 11 is equal to twice the radius (mm) of the concave arc 31 - 20. This ensures that the thickness of the protective layer of the UHPC box-type outer shell 1 meets the specified requirements.

[0037] In this embodiment, the steel pin-type partition is cut from a single sheet in one step. That is, the steel pin structure 3 and the steel transverse partition 2 can be directly cut and integrally formed from a single sheet, ensuring the connection strength between the steel pin structure 3 and the steel transverse partition 2, while also reducing processing steps and facilitating manufacturing. Preferably, laser or waterjet cutting is used. In other embodiments, the steel pin-type partition is formed by first cutting and then welding a single sheet. That is, the steel pin structure 3 and the steel transverse partition 2 are first cut into several parts, each containing the steel pin structure 3, and then these parts are welded together. This saves materials and also ensures the connection strength between the steel pin structure 3 and the steel transverse partition 2.

[0038] In this embodiment, the steel pin-type partitions are arranged perpendicular to the UHPC box-shaped outer shell 1. The UHPC box-shaped outer shell 1 includes a bottom plate 12, a top plate 13, and two web plates 14 spaced apart and connected between the bottom plate 12 and the top plate 13. The steel transverse partitions 2 are all in contact with the bottom plate 12, the top plate 13, and the two web plates 14. Each steel pin structure 3 is correspondingly embedded in the bottom plate 12, the top plate 13, and the two web plates 14. That is, the steel pin structures 3 are distributed around the four edges of the steel transverse partitions 2, so that each surface of the edge of the steel transverse partitions 2 is in contact with the UHPC box-shaped outer shell 1. This design not only ensures the effect of the steel pin-type partitions in transmitting shear flow and uniform cross-sectional internal forces to each surface of the UHPC box-shaped outer shell 1, but also ensures the stability of the connection between the steel pin-type partitions and the UHPC box-shaped outer shell 1.

[0039] In this embodiment, the steel diaphragm 2 is provided with holes 21 for people to pass through.

[0040] The construction method of segmental precast steel pin diaphragm UHPC box girder in this embodiment includes the following steps:

[0041] Step S1: Process steel pin-type partitions, prefabricate steel inner molds for forming UHPC box-type outer shell 1, and erect and fix longitudinal structural steel bars 11 to fix the steel pin-type partitions in the predetermined positions.

[0042] Step S2: Erect the external template for forming the UHPC box-type shell 1, and hoist the steel inner mold, longitudinal structural steel bars 11, and steel pin-type partitions into the external template of the UHPC box-type shell 1 and fix them.

[0043] Step S3: Cast UHPC molded UHPC box shell 1 to form segmental prefabricated steel pin partition UHPC box beam, remove inner and outer formwork and carry out high temperature steam curing.

[0044] Step S4: Transport the segmental precast steel pin partition UHPC box girder to the installation position, and use the beam lifting equipment to erect it or assemble it on site to form the main beam structure of the box girder.

[0045] This construction method avoids the need for complex formwork for forming conventional UHPC diaphragms during pouring, thus improving construction efficiency and reducing construction difficulty. The method is streamlined and operates reasonably.

[0046] Example 2:

[0047] The segmental precast steel pin diaphragm UHPC box girder in this embodiment is basically the same as that in Embodiment 1, the main difference being that, Figures 4 to 5 As shown, in this embodiment, an inner top plate 4, serving as the top mold for forming the UHPC box-type shell 1, is attached and fixed to the inner top wall. Multiple shear studs for embedding into the UHPC box-type shell 1 are connected to the inner top plate 4. A steel pin-type partition is connected to the side of the inner top plate 4 away from the shear studs. The inner top plate 4 acts as the top mold and does not need to be removed after casting. It forms a combined structure with the top plate 13 of the cast UHPC box-type shell 1, optimizing stress distribution. This design eliminates the need for templates for forming conventional UHPC cross partitions, reducing the number of templates required during construction. The steel pin-type partition and inner top plate 4 also do not need to be removed after construction, reducing construction difficulty. Furthermore, the left, right, and lower steel plates of the steel inner core are eliminated, with longitudinal prestress replacing the steel core, reducing steel consumption and lowering costs.

[0048] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and modifications obtained without departing from the inventive concept should also be considered within the scope of protection of the present invention.

Claims

1. A segmental precast steel dowel diaphragm UHPC box girder, comprising a UHPC box shell (1), a plurality of longitudinal structural steel bars (11) are arranged in the UHPC box shell (1) and extend along the length direction of the beam, a plurality of steel transverse diaphragms (2) are arranged in the UHPC box shell (1) and are spaced along the length direction of the beam, characterized in that: The edge of the steel diaphragm (2) is attached to the inner wall of the UHPC box-type shell (1). Multiple steel pin structures (3) are connected to the steel diaphragm (2) to form a steel pin type diaphragm. Each steel pin structure (3) is arranged at intervals along the edge of the steel diaphragm (2). Each steel pin structure (3) is embedded in the UHPC box-type shell (1) and engages with the UHPC box-type shell (1). The steel pin structure (3) is a protruding structure with a smooth transition at the corners, and the protruding structure extends outward along the edge of the steel diaphragm (2). The protruding structure includes a first curved edge composed of an inner concave arc (31) and an outer convex arc (32) and a second curved edge arranged symmetrically with respect to the first curved edge. The longitudinal structural steel bar (11) is arranged at the junction of the inner concave arc (31) and the outer convex arc (32).

2. The segmental precast steel pin diaphragm UHPC box girder according to claim 1, characterized in that: The longitudinal structural steel bars (11) are arranged on opposite sides of each steel pin structure (3).

3. The segmental precast steel pin diaphragm UHPC box girder according to claim 1, characterized in that: The diameter (mm) of the longitudinal structural steel bar (11) is 2 times the radius (mm) of the concave arc (31) - 20.

4. The segmental precast steel pin diaphragm UHPC box girder according to claim 1, characterized in that: The steel pin-type partition is cut from a single plate in one go.

5. The segmental precast steel pin diaphragm UHPC box girder according to claim 1, characterized in that: The steel pin-type partition is arranged perpendicular to the UHPC box-type shell (1). The UHPC box-type shell (1) includes a bottom plate (12), a top plate (13), and two web plates (14) arranged at intervals between the bottom plate (12) and the top plate (13). The steel transverse partition (2) is in contact with the bottom plate (12), the top plate (13), and the two web plates (14). Each steel pin structure (3) is correspondingly embedded in the bottom plate (12), the top plate (13), and the two web plates (14).

6. The segmental precast steel pin diaphragm UHPC box girder according to claim 1, characterized in that: The steel diaphragm (2) is provided with holes (21) for people to pass through.

7. The segmental precast steel pin diaphragm UHPC box girder according to claim 1, characterized in that: An inner top plate (4) for serving as a top mold for forming the UHPC box-type housing (1) is attached and fixed to the inner top wall. A plurality of shear studs for embedding into the UHPC box-type housing (1) are connected to the inner top plate (4). The steel pin partition is connected to the side of the inner top plate (4) away from the shear studs.

8. A construction method for a segmental precast steel pin diaphragm UHPC box girder according to any one of claims 1 to 7, characterized in that: Includes the following steps: S1: Process steel pin-type partitions, prefabricate steel inner molds for forming UHPC box-type shells (1), and erect and fix longitudinal structural steel bars (11) to fix the steel pin-type partitions in the predetermined positions. S2: Erect the external template for forming the UHPC box-type shell (1), and hoist the steel inner mold, longitudinal structural steel bars (11), and steel pin partition into the external template of the UHPC box-type shell (1) and fix them. S3: Cast UHPC molded UHPC box shell (1) to form the segmental prefabricated steel pin partition UHPC box beam, remove the inner and outer templates and carry out high temperature steam curing; S4: Transport the segmental precast steel pin partition UHPC box girder to the installation position, and use the beam lifting equipment to erect it or assemble it on site to form the main beam structure of the box girder.

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