Prestressed bidirectionally-assembled prefabricated UHPC-NC box girder bridge efficient connecting structure and construction method thereof

Abstract

The invention relates to the technical field of bridge engineering prefabrication and assembly, and discloses a prestressed bidirectional prefabricated UHPC-NC box girder bridge efficient connecting structure and a construction method thereof. In order to solve the problems of limited span, insufficient strength, poor durability and low construction efficiency of existing prefabricated box girder bridge segments, a combined form of a prefabricated common concrete (NC) top plate and a prefabricated ultra-high performance concrete (UHPC) U-shaped beam is adopted, and high-strength connection of the top plate and the U-shaped beam is realized by matching a connecting piece consisting of a ribbed steel bar and a perforated steel plate with a grouting material; the U-shaped beam is provided with key teeth, and the top plate is provided with U-shaped ribs and chiseling belts, so that reliable connection between U-shaped beam sections and reliable connection between top plate sections are achieved respectively; and meanwhile, top plate and U-shaped beam prestressed ducts are arranged, and the structural integrity is further enhanced by applying prestress. Factory prefabrication and on-site rapid assembly of bridge components are achieved, the connecting strength, durability and construction efficiency of the structure are remarkably improved, and the method is suitable for large-span prefabricated assembly bridge engineering.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of bridge engineering prefabrication and assembly, and particularly relates to a high-efficiency connection structure of a prestressed bidirectional assembly prefabricated UHPC-NC box girder bridge and a construction method thereof, which is suitable for the construction of large-span prefabricated and assembled bridges, and particularly suitable for urban bridges and highway branch bridge projects with high requirements for construction efficiency, structural durability and connection reliability. BACKGROUND

[0002] With the development of industrialization and assembly of bridge engineering becoming the mainstream of the industry, prefabricated and assembled box girder bridges are widely used in medium and small span projects due to their reasonable stress and simple shape. However, the existing technology still has many pain points: in terms of material selection, single ordinary concrete (NC) box girder is prone to cracking due to insufficient durability, full ultra-high performance concrete (UHPC) box girder has high cost and performance waste, and UHPC-NC composite structure often has interface debonding due to lack of adaptive connection structure; in terms of connection structure, the connection between the top plate and the U-shaped beam is prone to slipping, the pull between the top plate segments is insufficient, and the connection defects lead to low reliability; in terms of construction and durability, there are many field wet operations, it is difficult to guarantee the grouting density, and the protective measures are insufficient, which leads to low construction efficiency, the structure is easily eroded by the environment, and high maintenance cost in the later period. These problems are superimposed on each other, and it is difficult to meet the development needs of modern bridge engineering industrialization, high performance, and low cost.

[0003] In summary, the pure NC prefabricated bridge component has a large weight, and the requirements for the lifting tonnage of the bridge erecting machine are extremely high, which makes it difficult to realize the on-site erection of large-span bridges. The existing construction process does not use the lightweight component step-by-step hoisting scheme, which further limits the increase of bridge span. At the same time, the technical defects of the existing prefabricated and assembled box girder bridge in material composite adaptation, connection structure reliability, prestress system synergy, construction efficiency and durability are superimposed on each other, which makes it difficult to meet the comprehensive development needs of bridge engineering industrialization, high performance, large span adaptation and low cost. Therefore, developing a prefabricated box girder bridge structure and a matching construction method that takes into account material economy, connection reliability, construction efficiency, and structural durability, and reduces the lifting requirements of the bridge erecting machine and adapts to large-span erection, has become a technical problem that needs to be solved by the technical personnel in the field. SUMMARY

[0004] The present application aims to solve the technical problems of the existing precast assembled box girder bridge, such as the mismatch between material performance and engineering requirements, insufficient segment connection strength, poor prestress system synergy, low construction efficiency, poor durability, and the like, and the problems of the pure NC precast bridge component, such as large weight, high requirement for the lifting tonnage of the bridge erecting machine, and difficulty in realizing the field erection of a large-span bridge, and provides a prestressed bidirectional assembled precast UHPC-NC box girder bridge efficient connection structure and a construction method thereof. Through accurate UHPC-NC material composite design, the problems of single material performance and cost imbalance and poor composite interface adaptability are solved, and the optimal matching between material performance and engineering economy is realized. Through the construction of a connecting piece composed of a ribbed steel bar and a perforated steel plate, a key tooth, a U-shaped rib, and a chiseled strip in a synergistic action, the defects of weak shear and tensile resistance of the existing connection structure and insufficient grouting density are solved, and the connection reliability and structural integrity between segments and components are greatly improved. Through the optimization of the layout of the synergistic prestress duct and the tensioning process, the problems of insufficient prestress system synergy and stress concentration are solved, and the structural crack resistance and overall stress performance are enhanced. Through the process optimization of factory standardization precast and field rapid assembly, the step-by-step assembly scheme of hoisting the lightweight precast UHPC component U-shaped beam for segment assembly to form a stressed structure and then hoisting the top plate of the precast NC component is adopted, the lifting requirement for the bridge erecting machine is greatly reduced, the limitation of the existing technology on the bridge span is broken, the efficient erection of a large-span bridge is realized, the field wet work is reduced, the construction efficiency is improved, the structural durability is enhanced, and the maintenance cost is reduced, and finally a prestressed bidirectional assembled precast UHPC-NC box girder bridge efficient connection structure is provided, which takes into account high performance, high reliability, high efficiency, and low cost, and can adapt to the demand of large-span erection, to meet the development needs of bridge engineering industrialization, high performance, and large-span adaptation.

[0005] To achieve the above-mentioned purposes, the present application adopts the following technical scheme: a prestressed bidirectional assembled precast UHPC-NC box girder bridge efficient connection structure, comprising a top plate, which is a precast ordinary concrete (NC) component; a U-shaped beam, which is a precast ultra-high performance concrete (UHPC) component, the top plate and the U-shaped beam are connected through a connecting piece composed of a ribbed steel bar and a perforated steel plate, and the channel at the connecting part is filled with grouting material for solidification; the side surface of the U-shaped beam is provided with a key tooth for embedded connection with the U-shaped beam of the adjacent segment; the U-shaped beam is internally provided with a U-shaped beam prestress duct, and the top plate is internally provided with a top plate prestress duct for passing and applying prestressed steel bars; the splicing end of the top plate is provided with a chiseled strip and a U-shaped rib, the chiseled strip is used to enhance the bonding performance of the grouting material and the top plate matrix, and the U-shaped rib is used to connect with the top plate of the adjacent segment.

[0006] Preferably, the perforated steel plate is embedded in the bottom of the top plate, the ribbed steel bar penetrates through the hole of the perforated steel plate and is embedded in the inside of the top plate and the top of the U-shaped beam, and the grouting material is injected and filled from the side channel.

[0007] Preferably, the key teeth are arranged along the cross section of the U-shaped beam, and are in the shape of a rectangle or a trapezoid, and the key teeth of adjacent segments of the U-shaped beam are embedded into each other and then filled with grouting material.

[0008] Preferably, the pre-stressed ducts of the U-shaped beam are arranged along the cross section of the U-shaped beam, the pre-stressed ducts of the top plate are arranged along the side of the top plate, and the pre-stressed steel bars are made of steel strands or fine rolled threaded steel bars.

[0009] The application also discloses a construction method of the high-efficiency connecting structure of the pre-stressed bidirectional assembled prefabricated UHPC-NC box girder bridge.

[0010] Step one: factory prefabrication, prefabricating the top plate 1 and the U-shaped beam 2 respectively, manufacturing the top plate 1 in the factory, pre-burying the opening steel plate 5, ensuring that the opening steel plate 5 is reliably bonded with the top plate 1, reserving the pre-stressed duct 8 of the top plate and pre-burying the U-shaped steel bar 10, curing to the design strength and then demolding and storing, manufacturing the U-shaped beam 2, pre-burying the ribbed steel bar 4, reserving the pre-stressed duct 7 of the U-shaped beam, setting the chiseling belt 9 at the splicing end and setting the key tooth 6 at the side, curing to the design strength and then demolding and storing.

[0011] Step two: on-site assembly and pre-stressed application of the U-shaped beam 2, transporting the U-shaped beam 2 segments to the site, positioning through the bridge erecting machine, embedding the key teeth 6 of adjacent segments into each other, temporarily fixing after adjusting the position, coating the epoxy resin glue on the key tooth joint surface, completing the preliminary connection of the U-shaped beam segments after curing, then threading the pre-stressed steel bars in the pre-stressed duct 7 of the U-shaped beam, tensioning and anchoring, and completing the pre-stressed application of the U-shaped beam.

[0012] Step three: top plate hoisting and grouting channel preparation, hoisting the top plate 1 to the top of the U-shaped beam 2 which has completed the pre-stressed application, making the ribbed steel bar 4 penetrate the hole of the opening steel plate 5, completing the temporary fixing after adjusting the position of the top plate, simultaneously butting the adjacent top plate 1 segments, making the U-shaped steel bars 10 overlap each other, and arranging the grouting channel at the connecting part of the top plate and the U-shaped beam.

[0013] Step four: top plate joint pouring and pre-stressed application of the top plate, first pouring at the joint part of the adjacent top plate 1 segments, then injecting the grouting material 3 into the side channel of the U-shaped beam 2 after the poured body reaches the design strength, and forming the rigid connection of the top plate 1 and the U-shaped beam 2 after curing, then threading the pre-stressed steel bars in the pre-stressed duct 8 of the top plate, tensioning and anchoring, and completing the pre-stressed application of the top plate 1.

[0014] Step five: joint treatment, comprehensively checking and supplementing the grouting of all splicing joints, grouting channels and pouring parts, ensuring that the joint is compact and defect-free, and completing the assembly of the whole bridge.

[0015] This invention addresses the key technical challenges of existing precast box girder bridges in five key areas: lifting and erection, materials, connections, prestressing, construction, and durability, through lightweight, phased lifting design, precise multi-domain composite materials, multi-structure collaborative connection system construction, prestressing system optimization, and innovations in precast assembly processes and durability protection. It offers the following significant advantages:

[0016] 1. Lightweight Design Adaptable to Large Spans. The design employs a segmented composite approach, using UHPC (Ultra-High-Pressure Polymer) U-beams and NC (Non-Concrete Composite) top slabs. Compared to pure NC components, the UHPC U-beams offer significant weight advantages. Combined with a phased installation scheme—first hoisting the UHPC U-beams, then the NC top slabs—this drastically reduces the lifting capacity requirements of the bridge erecting machine. This effectively solves the problems of heavy weight, high lifting difficulty, and difficulty in erecting large-span bridges with pure NC precast bridges, breaking through existing technological limitations on bridge spans and enabling efficient erection of large-span bridges.

[0017] 2. High efficiency in material utilization, balancing economy and performance. Precise application of UHPC and NC in specific areas is achieved. UHPC is adapted to the core load-bearing parts of the U-beam, fully leveraging its high durability and crack resistance; NC is adapted to the top slab, utilizing its low cost and high stiffness, avoiding the waste of performance or durability shortcomings of a single material. This ensures high structural performance while significantly controlling project costs, thus achieving both economic efficiency and cost-effectiveness.

[0018] 3. High connection reliability and strong structural integrity. The connectors formed by bidirectional penetration of the perforated steel plate by double-segment ribbed steel bars, combined with the dense filling effect of side grouting, the mechanical interlocking of the key teeth, the tying effect of the U-shaped bars, and the interface bonding enhancement of the chiseled strip, construct a multi-structure collaborative connection system. This significantly improves the shear and tensile strength between components and segments, effectively avoids interface debonding, slippage, and joint cracking, and strengthens the overall load-bearing performance of the structure.

[0019] 4. Excellent prestressing synergy, crack resistance and stability. Through the coordinated arrangement of prestressing ducts and reasonable tensioning process, uniform prestress is formed throughout the structure, which can effectively offset the tensile stress under load, avoid stress concentration, significantly improve the overall crack resistance and deformation capacity of the structure, and ensure the stability of the structure in long-term service.

[0020] 5. Improved construction efficiency, high durability, and low maintenance costs. Standardized prefabrication in the factory enables precise control of component quality. Rapid on-site assembly and side grouting significantly reduce on-site wet work, improving construction efficiency and shortening the construction cycle. Simultaneously, the protective properties of UHPC, the dense filling of the grout, and the interface reinforcement of the roughened strip effectively block environmental erosion, enhancing the overall durability of the structure and significantly reducing later maintenance costs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the pre-assembly process of the high-efficiency connection structure for the precast UHPC-NC box girder bridge with prestressed bidirectional assembly according to the present invention.

[0022] Figure 2 This is a cross-sectional schematic diagram of the high-efficiency connection structure of the precast UHPC-NC box girder bridge with prestressed bidirectional assembly according to the present invention.

[0023] Figure 3 This is a schematic diagram of the assembled precast UHPC-NC box girder bridge high-efficiency connection structure of the prestressed bidirectional assembly according to the present invention.

[0024] The reference numerals in the attached figures are listed below:

[0025] 1: Top slab (precast NC component), 2: U-beam (precast UHPC component), 3: Grouting material, 4: Through-bar reinforcement, 5: Perforated steel plate, 6: Key teeth, 7: U-beam prestressing duct, 8: Top slab prestressing duct; 9: Roughened strip; 10: U-shaped reinforcement. Detailed Implementation

[0026] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are for illustrative purposes only and do not limit the scope of protection of the present invention.

[0027] Combination Figure 1 and Figure 2 As shown, the present invention provides a high-efficiency connection structure for a precast UHPC-NC box girder bridge, comprising a top plate 1, which is a precast ordinary concrete (NC) component; and a U-shaped beam 2, which is a precast ultra-high performance concrete (UHPC) component. The top plate 1 and the U-shaped beam 2 are connected by a connector composed of ribbed steel bars 4 and perforated steel plates 5. The grooves at the connection points are filled with grout 3 and cured. The sides of the U-shaped beam 2 are provided with key teeth 6 for fitting and connecting with adjacent U-shaped beam 2 segments. The U-shaped beam 2 is provided with U-shaped beam prestressing ducts 7, and the top plate 1 is provided with top plate prestressing ducts 8 for passing through prestressing tendons and applying prestress. The splicing ends of the top plate 1 are provided with a roughened strip 9 and U-shaped reinforcement 10. The roughened strip 9 is used to enhance the bonding performance between the grout and the top plate matrix, and the U-shaped reinforcement 10 is used to connect with the top plate 1 of adjacent segments.

[0028] Combination Figure 2 and Figure 3As shown, the perforated steel plate 5 is embedded in the bottom of the top plate 1, and the ribbed steel bar 4 passes through the holes in the perforated steel plate 5 and is embedded in the interior of the top plate 1 and the top of the U-shaped beam 2. Grouting material 3 is injected and filled from the side channel. The key teeth 6 are arranged at intervals along the cross section of the U-shaped beam 2, and are rectangular or trapezoidal in shape. After the key teeth of adjacent U-shaped beam segments are interlocked, epoxy resin is applied to the key tooth joint surface. The prestressing ducts 7 of the U-shaped beam are arranged at intervals along the cross section of the U-shaped beam 2, and the prestressing ducts 8 of the top plate are arranged at intervals along the side of the top plate 1. The prestressing tendons are steel strands or finely rolled threaded steel bars.

[0029] like Figure 3 As shown, this invention also discloses a construction method for a prestressed bidirectional prefabricated UHPC-NC box girder bridge high-efficiency connection structure, comprising the following steps:

[0030] Step 1: Factory prefabrication. Prefabricate the top slab 1 and U-shaped beam 2 separately. Fabricate the top slab 1 in the factory, pre-embed perforated steel plates 5, and ensure reliable bonding between the perforated steel plates 5 and the top slab 1; reserve prestressing ducts 8 in the top slab and pre-embed U-shaped reinforcement 10; demold and store after curing to the design strength; fabricate the U-shaped beam 2, pre-embed ribbed steel bars 4, reserve prestressing ducts 7 in the U-shaped beam, set roughening strips 9 at the splicing ends, and set key teeth 6 on the sides; demold and store after curing to the design strength.

[0031] Step 2: On-site assembly of U-shaped beam 2 and application of prestress. The U-shaped beam 2 segments are transported to the site and positioned by the bridge erecting machine so that the key teeth 6 of adjacent segments interlock. After adjusting the position, they are temporarily fixed. Epoxy resin is applied to the key tooth joint surface and cured to complete the initial connection of the U-shaped beam segments. Then, prestressing tendons are inserted into the prestressing ducts 7 of the U-shaped beam, tensioned and anchored to complete the application of prestress to the U-shaped beam.

[0032] Step 3: Hoisting the top plate 1 and preparing for grouting. Hoist the top plate 1 to the top of the U-shaped beam 2 that has been prestressed, so that the ribbed steel bars 4 pass through the holes in the perforated steel plate 5. After adjusting the position of the top plate, complete the temporary fixation. At the same time, connect the adjacent top plate 1 segments so that the U-shaped bars 10 overlap each other to form the grouting channel at the connection between the top plate and the U-shaped beam.

[0033] Step 4: Top slab joint pouring and top slab prestressing application. First, pour the joint of the adjacent top slab 1 segments. After the poured body reaches the design strength, inject grout 3 into the grouting channel of U-beam 2. After curing, a rigid connection is formed between top slab 1 and U-beam 2. Then, prestressing tendons are inserted into the prestressing ducts 8 of the top slab, tensioned and anchored to complete the prestressing application of top slab 1.

[0034] Step 5: Joint treatment. Conduct a comprehensive inspection and grouting of all splicing joints, grouting channels and pouring areas to ensure that the joints are tight and free of defects, and complete the assembly of the entire bridge.

[0035] Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention shall be included within the scope of protection of this invention.

Claims

1. A high-efficiency connection structure for a precast UHPC-NC box girder bridge with prestressed bidirectional assembly, characterized in that, include: The top slab (1) is a precast ordinary concrete (NC) component; The U-shaped beam (2) is a precast ultra-high performance concrete (UHPC) component. The top plate (1) and the U-shaped beam (2) are connected by a connector composed of ribbed steel bars (4) and perforated steel plates (5). The groove of the connection part is filled with grout (3) and cured. The side of the U-shaped beam (2) is provided with key teeth (6) for fitting and connecting with the adjacent U-shaped beam (2) segments. The U-shaped beam (2) is provided with U-shaped beam prestressing ducts (7) inside. The top plate (1) is provided with top plate prestressing ducts (8) inside, for passing through prestressing tendons and applying prestress. The splicing end of the top plate (1) is provided with a roughening strip (9) and U-shaped reinforcement (10). The roughening strip (9) is used to enhance the bonding performance between the grout and the top plate matrix. The U-shaped reinforcement (10) is used to connect with the adjacent top plate (1) segments.

2. The high-efficiency connection structure for precast UHPC-NC box girder bridge with prestressed bidirectional assembly as described in claim 1, characterized in that: The perforated steel plate (5) is embedded in the bottom of the top plate (1), the ribbed steel bar (4) passes through the hole of the perforated steel plate (5) and is embedded in the top of the top plate (1) and the top of the U-shaped beam (2), and the grout (3) is injected and filled from the side channel.

3. The high-efficiency connection structure for precast UHPC-NC box girder bridge with prestressed bidirectional assembly as described in claim 1, characterized in that: The key teeth (6) are arranged at intervals along the cross section of the U-shaped beam (2), and are rectangular or trapezoidal in shape. The key teeth of adjacent U-shaped beam segments are interlocked and then filled with grout.

4. The precast UHPC-NC composite box girder bridge structure according to claim 1, characterized in that: The prestressed ducts (7) of the U-shaped beam are arranged at intervals along the cross section of the U-shaped beam (2), and the prestressed ducts (8) of the top plate are arranged at intervals along the side of the top plate (1). The prestressed tendons are steel strands or finely rolled threaded steel bars.

5. A construction method for a prestressed bidirectional precast UHPC-NC box girder bridge high-efficiency connection structure, characterized in that, Includes the following steps: Step 1: Factory prefabrication. Prefabricate the top slab (1) and U-shaped beam (2) separately. Make the top slab (1) in the factory and embed the perforated steel plate (5) to ensure reliable bonding between the perforated steel plate (5) and the top slab (1). Reserve the prestressing ducts (8) in the top slab and embed the U-shaped reinforcement (10). Demold and store after curing to the design strength. Make the U-shaped beam (2) and embed the ribbed steel bars (4). Reserve the prestressing ducts (7) in the U-shaped beam. Set the roughening strip (9) at the splicing end and set the key teeth (6) on the side. Demold and store after curing to the design strength. Step 2: On-site assembly and prestressing of U-beam (2) The U-beam (2) segments are transported to the site and positioned by the bridge erecting machine so that the key teeth (6) of adjacent segments can be interlocked. After adjusting the position, they are temporarily fixed. Epoxy resin is applied to the joint surface of the key teeth (6) and cured to complete the initial connection of the U-beam (2) segments. Then, prestressing tendons are inserted into the prestressing ducts (7) of the U-beam (2), tensioned and anchored to complete the prestressing of the U-beam (2). Step 3: Hoisting of the top plate (1) and preparation of grouting channels. Hoist the top plate (1) to the top of the U-shaped beam (2) that has been prestressed, so that the ribbed steel bars (4) pass through the holes of the perforated steel plate (5). After adjusting the position of the top plate (1), temporary fixation is completed. At the same time, connect the adjacent top plate (1) segments so that the U-shaped bars (10) overlap each other, and lay out the grouting channels at the connection between the top plate (1) and the U-shaped beam (2). Step 4: Casting of joints in top slab (1) and application of prestress in top slab (1). First, cast the joints of adjacent top slab (1) segments. After the cast body reaches the design strength, inject grout (3) into the side channel of the U-beam (2). After curing, a rigid connection is formed between the top slab (1) and the U-beam (2). Then, prestressing tendons are inserted into the prestressing ducts (8) of the top slab (1), tensioned and anchored to complete the application of prestress in the top slab (1). Step 5: Joint treatment. Conduct a comprehensive inspection and grouting of all splicing joints, grouting channels and pouring areas to ensure that the joints are tight and free of defects, and complete the assembly of the entire bridge.

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