Semi-prefabricated segment assembled semi-cast-in-place large cantilever prestressed concrete cover beam

Abstract

The utility model discloses a semi-prefabricated section assembled semi-cast-in-place large cantilever prestressed concrete cover beam which comprises a shell prefabricated part, a main beam prefabricated part and an ultra-high performance concrete connecting layer, the shell prefabricated part is formed by assembling three sections, the main beam prefabricated part is formed by assembling three sections, and the ultra-high performance concrete connecting layer is formed by assembling three sections. Splicing seams of the three sections of main beam prefabricated parts and splicing seams of the three sections of shell prefabricated parts are arranged in a staggered mode, corrugated pipes are arranged in the spliced main beam prefabricated parts, and prestressed steel strands penetrate through the corrugated pipes; an ultra-high-performance concrete connecting layer is formed in a cavity between the shell prefabricated part and the main beam prefabricated part through cast-in-place construction, and a steel reinforcement framework is further arranged in the ultra-high-performance concrete connecting layer. The structure is simple, the design is reasonable, the construction is convenient, and the comprehensive economic benefit is improved.

Description

Technical Field

[0001] This utility model relates to the field of bridge precast segmental assembly and construction technology, specifically to a semi-precast segmental assembly and semi-cast-in-place large cantilever prestressed concrete cap beam and its construction method. Background Technology

[0002] With the development of my country's transportation industry, large-scale ring roads mainly adopt elevated bridge construction technology to form cross-type municipal roads. To ensure sufficient driving width on the elevated bridge while also providing ample space and good visibility underneath, the concept of "large cantilever prestressed cap beams" has emerged. However, the cap beams of urban elevated bridges are large in size. If the construction method of casting concrete entirely on-site is adopted, it requires formwork and in-situ casting, which also faces disadvantages such as long traffic interruptions, a large amount of high-altitude work, and a long construction period. If a prefabrication scheme is adopted, the prefabricated cap beams have a large self-weight, placing high demands on lifting equipment and transportation machinery, and resulting in poor construction adaptability. Therefore, for large cantilever prestressed concrete cap beam structures, segmented prefabrication and assembly prestressed concrete cap beam technology is an effective solution to the transportation and hoisting problems of integral cast-in-place cap beams, and has been successfully applied in numerous projects. However, the design of large cantilever prestressed concrete cap beam structures faces key issues such as the division of prefabricated and assembled segments, segment connections, and segment-to-pier connections, which must be combined with the actual project to ensure the rationality and feasibility of the design. Meanwhile, because the longitudinal reinforcement of the segmental precast cap beam is cut off, it may lead to discontinuous force transmission and water seepage at the joints, which is a key factor affecting the stress performance of the segmental precast cap beam.

[0003] For example, Chinese patent document CN202321099700.1 describes a segmental prefabricated cap beam, comprising an intermediate segment placed at the top of a pier and cantilever segments spliced ​​to the left and right ends of the intermediate segment. U-shaped stirrups of the pier pass through grooves in the intermediate segment for positioning, and fixing steel pipes of the cantilever segments pass horizontally through the U-shaped stirrups until they are inserted into fixing holes in the intermediate segment, allowing the prefabricated pier, intermediate segment, and cantilever segments to be assembled together. The three segments facilitate hoisting and installation. However, the overall mechanical performance of this technology is poor, especially since the three segments cannot form a complete unit. Utility Model Content

[0004] In view of the shortcomings of the existing technology, the technical problem to be solved by this utility model is to provide a semi-precast segmental assembly semi-cast-in-place large cantilever prestressed concrete cap beam and construction method, which can greatly reduce the number of construction supports and formwork and the amount of work for fully cast-in-place concrete cap beams, and avoid the adverse effects caused by the weak mechanical properties at the segment joints of fully precast segmental assembly cap beams.

[0005] To solve the above-mentioned technical problems, the technical solution of this utility model is as follows:

[0006] A semi-precast segmental assembly semi-cast-in-place large cantilever prestressed concrete cap beam is characterized by comprising a precast outer shell component, a precast main beam component, and an ultra-high performance concrete connecting layer. The precast outer shell component is composed of three assembled segments, with mechanical connections and grout sealing at the joints between adjacent segments. The precast outer shell component is a U-shaped reinforced concrete precast component, and it rests atop the pier. Shear keys are provided on the inner surface of the precast outer shell component, which is then roughened. The precast main beam component is also composed of three assembled segments. The splicing joints of the precast components are staggered from the splicing joints of the three-section shell precast components. The assembled main beam precast components have corrugated pipes. By threading prestressed steel strand bundles through the corrugated pipes, the three main beam precast components are integrated under the tension of the prestressed steel strand bundles. Shear keys and / or roughened surfaces are provided on the surfaces of the shell precast components and / or the main beam precast components. An ultra-high performance concrete connection layer is formed in the cavity between the shell precast components and the main beam precast components through cast-in-place construction. A steel reinforcement skeleton is also provided in the ultra-high performance concrete connection layer.

[0007] The precast outer shell component and / or the precast main beam component are provided with steel bar through holes for connection with the main reinforcement of the pier, and are connected by welding or grouting.

[0008] The joint between the two precast outer shell components is mechanically connected to the adjacent main reinforcement bars by steel sleeves.

[0009] The steel reinforcement cage and shear keys are further fixed by welding or binding.

[0010] The splicing surfaces of the precast main beam components are provided with stepped concave-convex fits.

[0011] Corrugated pipes between adjacent precast main beam components are connected by sleeves.

[0012] The cross-section of the ultra-high performance concrete connecting layer is either a square shape enclosed on four sides or a U shape enclosed on three sides.

[0013] A construction method for a semi-precast segmental assembly and semi-cast-in-place large cantilever prestressed concrete cap beam, characterized by comprising the following steps:

[0014] (1) Based on the specific dimensions of the cap beam and the arrangement of the prestressed steel strand bundles, the cap beam drawings are disassembled and prefabricated drawings of the shell prefabricated components and the main beam prefabricated components are generated.

[0015] (2) Prefabrication of shell prefabricated components and main beam prefabricated components in the prefabrication yard;

[0016] (3) Construct temporary supports and hoist the three prefabricated shell components so that the three prefabricated shell components are placed on the piers and temporary supports. Use steel sleeves to mechanically connect the three prefabricated shell components and use grouting mortar or grouting rubber strips to fill the gaps.

[0017] (4) A steel cage is tied inside the precast outer shell component to form a U-shaped steel skeleton, and a pad is placed at the bottom of the steel skeleton to provide rigid support for the precast main beam component.

[0018] (5) Hoist the precast main beam components in the order of first the middle and then the two sides, and make the splice joints neat. During the alignment process, use the sleeve connection to align the corrugated pipes in the adjacent segments, and use end molds at both ends of the cap beam to seal the pouring space between the precast main beam components and the shell precast components to form the space to be poured.

[0019] (6) Use ultra-high performance concrete to pour into the space to be poured, and use tamping tools to tamp the concrete. After pouring, the cap beam will form a horizontal upper surface.

[0020] (7) After the ultra-high performance concrete has reached the design strength, the prestressed steel strand bundles are tensioned and the anchors are sealed to complete the construction.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This technology employs a semi-precast segmental assembly and semi-cast-in-place large cantilever prestressed concrete cap beam. Its structural form, utilizing precast reinforced concrete components with partial wet connections to ultra-high concrete sections, solves the problems of complex construction and numerous procedures associated with integral cast-in-place large cantilever prestressed concrete cap beams. It also overcomes the difficulties of transporting and hoisting integral precast cap beams and avoids the adverse stress factors associated with the joints of segmental precast cap beams. This enhances the safety of the traditional large cantilever prestressed concrete cap beam construction process, significantly reducing the number and workload of construction supports and formwork required for fully cast-in-place concrete cap beams, while avoiding the adverse effects of segmental joints in fully precast segmental assembly cap beams. This results in significant economic and social benefits. This invention features a simple structure, reasonable design, convenient construction, and improved overall economic efficiency.

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present utility model;

[0025] Figure 2 This is a schematic elevation view of the prefabricated shell component in an embodiment of the present utility model;

[0026] Figure 3 This is a plan view of the prefabricated shell component in an embodiment of the present utility model;

[0027] Figure 4 This is a schematic elevation view of a rectangular section prestressed concrete member in an embodiment of this utility model;

[0028] Figure 5 This is a plan view of a rectangular cross-section prestressed concrete member in an embodiment of this utility model;

[0029] Figure 6 This is a schematic diagram of the mid-span section of the prefabricated outer shell component in an embodiment of the present invention, showing the effect after filling with ultra-high performance concrete;

[0030] Figure 7 This is a schematic diagram of the mid-span section of the prefabricated outer shell component in an embodiment of the present invention, showing the effect before the ultra-high performance concrete is filled;

[0031] Figure 8 This is a schematic diagram of the cantilever end section of the prefabricated outer shell component in an embodiment of the present invention, showing the effect after filling with ultra-high performance concrete;

[0032] Figure 9 This is a schematic diagram of the cantilever end section of the prefabricated outer shell component in an embodiment of this utility model, showing the effect before filling with ultra-high performance concrete.

[0033] In the picture:

[0034] 10. Precast outer shell component; 11. Base slab; 12. Side slab; 13. Shear key; 14. Short reinforcing bar; 15. Reinforcing bar sleeve; 16. Joint mortar; 101. Mid-span precast outer shell component; 102. Cantilever precast outer shell component; 103. Reinforcing bar perforation.

[0035] 20. Main beam precast component; 21. Corrugated pipe; 22. Insertion sleeve; 23. Stepped lap joint; 24. Reserved insertion hole; 201. Mid-span precast component; 202. End side precast component.

[0036] 30. Ultra-high performance concrete bonding layer; 31. Reinforcing steel skeleton; 32. Spacer blocks.

[0037] 40 temporary supports

[0038] 50 piers, 51 reserved steel bars. Detailed Implementation

[0039] To make the above-mentioned features and advantages of this utility model more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings for detailed explanation.

[0040] like Figures 1 to 9As shown, a semi-precast segmental assembly and semi-cast-in-place large cantilever prestressed concrete cap beam is systematically demonstrated. This cap beam is constructed using a process of ground prefabrication, high-altitude assembly, and localized construction with ultra-high performance concrete. The spatial physical structure of this prestressed concrete cap beam consists of three parts: a precast outer shell component 10, an internal main beam precast component 20 (precast), and an ultra-high performance concrete connecting layer 30 (cast-in-place). The precast outer shell component 10 and the main beam precast component 20 are formed using ordinary reinforced concrete prefabrication technology. This prefabrication process, which involves prefabrication in the factory, segmented manufacturing, and hoisting, can effectively reduce the cost of precast molds and hoisting. By constructing temporary supports 40 on both sides of the pier, and using cranes for hoisting operations, the aforementioned precast outer shell component 10 and main beam precast component 20 are assembled at high altitude. This assembly process is a modular construction, forming a casting mold cavity. In this casting mold cavity, ultra-high performance concrete is poured in place to complete the hardening connection, forming a complete cap beam that combines precast and cast-in-place processes. This cap beam has excellent mechanical properties and possesses the dual advantages of traditional cast-in-place concrete cap beams and prestressed precast cap beams, that is, the advantages of mechanical properties and construction technology are combined. The following structural specification drawings provide a detailed explanation.

[0041] The precast outer shell component 10 is a U-shaped reinforced concrete precast component, named so because its vertical cross-section is U-shaped. Specifically, the precast outer shell component 10 consists of a base plate 11 and two side plates 12. It is a reinforced concrete precast component, with the interior serving as a space for the placement of the main beam precast component. Ideally, the inner surfaces of the precast outer shell component 10 (including the inner surfaces of the base plate 11 and the side plates 12) are roughened to form a roughened surface. Simultaneously, shear keys 13 are precast on the inner surface of the precast outer shell component. These shear keys 13 are shear studs or short reinforcing bars; one part of the shear key is embedded inside the precast outer shell component, while the other part is exposed inside, forming a shear key. The presence of this shear key further improves the bonding strength with the cast-in-place ultra-high performance concrete, especially enhancing the shear resistance of the interface between the two. In this embodiment of the invention, the design of the shear key facilitates a better interface connection with the cast-in-place ultra-high performance concrete.

[0042] In this embodiment, the precast outer shell component 10 is composed of three sections: left, middle, and right. Depending on their position, they can be divided into a mid-span precast outer shell component 101 and a cantilever precast outer shell component 102. Short reinforcing bars 14 of at least ten centimeters are reserved at the joint surfaces of adjacent precast outer shell components. During the jointing process of the two precast outer shell components, the two short reinforcing bars 14 are mechanically connected using reinforcing bar sleeves 15. Specifically, the reinforcing bar sleeves 15 mechanically fix the exposed connecting short reinforcing bars 14 of the two precast outer shell components 10. Combined with grout mortar 16 or self-expanding sealing strips, the joint is locally filled and sealed to prevent grout leakage at the joint (during the construction of cast-in-place ultra-high performance concrete). After the above construction is completed, the three precast outer shell components form a complete precast outer shell component 10. Furthermore, the three-section design further reduces the difficulty of precast manufacturing, hoisting, and transportation, resulting in higher feasibility.

[0043] Furthermore, the two ends of the aforementioned mid-span precast outer shell component 101 and one end of the cantilever precast outer shell component 102 overlap with the two piers. That is, the two ends of the mid-span precast outer shell component 101 and the cantilever precast outer shell component each occupy half of the overlap position of the pier. Reinforcing bar through-holes 103 are provided on the bottom plate of the precast outer shell component at the overlap or placement position. The presence of these through-holes allows the reserved reinforcing bars 51 at the top of the pier 50 to pass through the through-holes and be inserted into the reserved insertion holes in the internal mid-span main beam precast component. After connection, the pier and the internal mid-section main beam precast component are mechanically or grouted and connected as a single unit. In other words, there is also a rigid connection between the aforementioned mid-section main beam precast component and the reserved reinforcing bars of the pier.

[0044] The main beam precast component 20 is placed inside the internal channel of the outer shell precast component 10. This main beam precast component 20 is a solid reinforced concrete structure with a rectangular cross-section and corrugated pipes installed inside. To reduce the difficulty of hoisting and transporting the main beam precast component, it consists of three sections of precast concrete components (left, middle, and right). Specifically, all three sections are solid reinforced concrete precast components with pre-installed corrugated pipes 21. The corrugated pipes 21 in adjacent sections are interconnected. After installation, the corrugated pipes 21 between adjacent sections are aligned and connected using plug-in sleeves 22 to form a channel that facilitates the construction of prestressed steel strands.

[0045] In this embodiment of the utility model, three precast main beam components 20 are overlapped to form a continuous main beam. For ease of description, they are divided into mid-span precast components 201 and end-side precast components 202. A stepped overlap surface 23 is provided at the overlap surface between the single-side precast components at both ends and the mid-span precast components. The two stepped components cooperate to form a corbel-like connection, which improves the docking speed between the two. This is of positive significance for high-altitude operations.

[0046] In this embodiment of the utility model, the interior of the precast main beam component 20 is a precast corrugated pipe, which also serves as the passage for the subsequent prestressed steel strand bundle 23. Furthermore, during the docking process of the three rectangular cross-section reinforced concrete components, the corresponding corrugated pipes are connected by a socket joint to facilitate smooth installation.

[0047] In this embodiment of the utility model, the segmental joints of the main beam prefabricated component 20 and the segmental joints of the shell prefabricated component 10 cannot be on the same cross-section and must be staggered by a certain distance.

[0048] In this embodiment, the mid-span prefabricated component 201 completely covers the two segmental seams of the outer shell prefabricated component 10, and a reserved insertion hole 24 for mechanical cooperation with the reserved reinforcing bar 51 is provided in the mid-span prefabricated component 201.

[0049] In this embodiment, the precast outer shell component 10 forms four-point support at the pier 50 and the temporary support 40, and the U-shaped structure in the precast outer shell component itself has reliable bending resistance and sufficient stability to bear its own weight and the self-weight of the main beam precast component 20 inside.

[0050] After the aforementioned precast outer shell component 10 is constructed, an outer formwork for casting ultra-high performance concrete is formed. The main beam precast component 20 is placed inside. The three-section main beam precast component is assembled into a whole using a prestressed steel strand construction process. Side formwork is then sealed at both ends to form the casting space for ultra-high performance concrete. Through the solidification of this ultra-high performance concrete, the inner main beam precast component and the outer shell precast component are connected into a whole.

[0051] After the cast-in-place ultra-high performance concrete is poured, an ultra-high performance concrete connecting layer 30 is formed covering the four sides of the main beam precast component. The thickness of this ultra-high performance concrete connecting layer 30 should not be less than the wall thickness of the outer shell precast component 10 to provide sufficient transition connection performance. Through the hardening of this ultra-high performance concrete connecting layer 30, the inner main beam precast component 20 and the outer shell precast component are integrated, making the inner and outer parts of the cap beam a whole that shares the load.

[0052] In this embodiment, the cap beam has strong overall performance after construction. The U-shaped precast shell component 10 provides an outer template for the structural construction process. All the prestressed steel strands of the cap beam are laid inside the main beam precast component, and the ends of the prestressed steel strands are buried in the cast-in-place ultra-high performance concrete to form the middle layer of the cap beam.

[0053] Furthermore, in this embodiment of the invention, a steel reinforcement cage 31 is disposed inside the ultra-high performance concrete connecting layer 30. This steel reinforcement cage is disposed in the intermediate layer by on-site binding. The reserved steel reinforcement 51 of the pier is bound or welded to the steel reinforcement cage in the ultra-high performance concrete connecting layer 30, further improving the overall mechanical properties of the cap beam.

[0054] The three precast main beam segments 20 are laid in the middle of the U-shaped shell precast components, and are positioned as centrally as possible. Multiple permanent positioning pads are placed between them to maintain an appropriate distance and create a space sufficient for pouring ultra-high concrete, thus avoiding the impact of compaction on the position.

[0055] In this embodiment of the invention, the excellent mechanical properties of ultra-high performance concrete are utilized to improve the overall mechanical performance of the cap beam.

[0056] A construction method for a semi-precast segmental assembly and semi-cast-in-place large cantilever prestressed concrete cap beam includes the following steps:

[0057] (1) Based on the specific dimensions, weight, and arrangement of the prestressed steel strands of the cap beam, the cap beam is divided into an outer shell precast component, a main beam precast component, and an ultra-high performance concrete connection layer. Drawings are designed and produced. Based on the weight, transportation, and hoisting conditions of the outer shell precast component and the main beam precast component, the outer shell precast component and the main beam precast component are divided into three outer shell precast components, and the main beam precast component is divided into three rectangular cross-section prestressed concrete segments. The segment joints of the outer shell precast component and the segment joints of the rectangular cross-section prestressed concrete component cannot be on the same cross-section and must be staggered by a certain distance, i.e., the splicing joints are staggered.

[0058] (2) According to the drawing requirements, the prefabricated shell components and main beam components are prefabricated in the factory, and the prestressed steel strand bundle channel is reserved in the main beam prefabricated components.

[0059] (3) The precast outer shell component is manufactured, wherein the bottom of the precast outer shell component has a pre-reserved rebar through hole. The rebar through hole is a vertically set hole, the function of which is to allow the reserved rebar at the top of the pier to pass through, that is, to pass through the hole from bottom to top. The main rebar at the segment joint needs to reserve a certain length according to the width of the segment joint to form a short rebar 14 for the connection of the main rebar between segments in the later stage. The inner surface of the precast outer shell component is made into a rough surface and several shear keys are set to facilitate a better interface connection with the cast-in-place ultra-high performance concrete.

[0060] (4) Prefabricated main beam components are manufactured according to the segment dimensions after segmentation. Corrugated pipes are pre-embedded inside the main beam components. Corbel structures are set at the lap surfaces between the main beam components to assist in the rapid docking of the two main beam components during the construction phase.

[0061] (5) After the concrete strength of each precast segment reaches the design strength, the precast U-shaped shell precast component is transported and hoisted on the pier and temporary support at the bottom of the cap beam. The reserved steel bars at the top of the pier need to pass through the reserved holes at the bottom of the shell precast component. The short steel bars 14 between the shell precast components are connected by steel sleeves so that the three U-shaped shell precast components form a mechanical connection. During this process, the three U-shaped shell precast components are kept on the same straight line, and the joints of the two adjacent U-shaped shell precast components are filled with sealing material.

[0062] (6) According to the specific dimensions, tie the steel reinforcement skeleton of the middle layer of the cap beam. The steel reinforcement skeleton shall at least cover the bottom of the middle layer of the cap beam, and set several permanent positioning pads at the bottom of the middle layer of the cap beam to form auxiliary support for the precast shell component and the rectangular cross-section reinforced concrete component.

[0063] (7) The rectangular cross-section reinforced concrete component is transported and hoisted onto the permanent positioning pad 32, and the reserved steel bars at the top of the pier are fixed to the reserved steel bars on the rectangular cross-section reinforced concrete component. Corrugated pipes are used to connect the pre-embedded corrugated pipes between adjacent segments through a sleeve connection to form a prestressed pipe channel. Steel sleeves are used to connect the main bars between the precast rectangular cross-section reinforced concrete components.

[0064] (8) According to the specific dimensions, tie the steel reinforcement skeleton of the top layer of the cap beam, and use the end formwork to seal the two ends of the three-section U-shaped reinforced concrete shell. Specifically, the end formwork is a U-shaped template, which is fixed at the end for temporary sealing.

[0065] (9) Use ultra-high performance concrete to cast the middle layer and top layer of the cap beam to fill the space and compact it with a vibrator.

[0066] (10) After the ultra-high performance concrete has reached the design strength, the prestressed steel strand bundles are tensioned and anchored, and the curing continues until it is fully hardened to complete the construction.

[0067] The embodiments described above are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Without departing from the spirit of the present utility model, all modifications and improvements to the present utility model by those skilled in the art should fall within the protection scope defined by the claims of the present utility model.

Claims

1. A semi-precast segmental assembly semi-cast-in-place large cantilever prestressed concrete cap beam, characterized in that: The structure includes a precast outer shell component (10), a precast main beam component (20), and an ultra-high performance concrete connecting layer (30). The precast outer shell component (10) is composed of three sections, with mechanical connection and anti-leakage grouting at the joints between adjacent sections. The precast outer shell component is a U-shaped reinforced concrete precast component, and it is placed on top of the pier. The precast main beam component (20) is composed of three sections, and the joints between the three sections of the main beam component and the joints between the three sections of the outer shell component are adjacent to each other. This staggered arrangement, and the corrugated pipe inside the assembled main beam precast component, through which prestressed steel strand bundles are threaded, the three main beam precast components (20) are integrated under the tension of the prestressed steel strand bundles; shear keys and / or roughened surfaces are provided on the surface of the shell precast component and / or the main beam precast component; and an ultra-high performance concrete connection layer (30) is formed in the cavity between the shell precast component and the main beam precast component by cast-in-place construction, and a steel reinforcement skeleton (31) is also provided in the ultra-high performance concrete connection layer.

2. The semi-precast segmental assembly semi-cast-in-place large cantilever prestressed concrete cap beam according to claim 1, characterized in that, The precast outer shell component (10) and / or the precast main beam component (20) are provided with steel bar through holes for connection with the main reinforcement of the pier, and are welded or grouted.

3. The semi-precast segmental assembly semi-cast-in-place large cantilever prestressed concrete cap beam according to claim 1, characterized in that, The joint between the two precast outer shell components is mechanically connected to the adjacent main reinforcement bars by steel sleeves.

4. The semi-precast segmental assembly semi-cast-in-place large cantilever prestressed concrete cap beam according to claim 1, characterized in that: The steel reinforcement cage (31) and the shear key are auxiliaryly fixed by welding or binding.

5. A semi-precast segmental assembly semi-cast-in-place large cantilever prestressed concrete cap beam according to claim 1, characterized in that: The splicing surfaces of the precast main beam components are provided with stepped concave-convex fits.

6. The semi-precast segmental assembly semi-cast-in-place large cantilever prestressed concrete cap beam according to claim 1, characterized in that: Corrugated pipes between adjacent precast main beam components are connected by sleeves.

7. A semi-precast segmental assembly semi-cast-in-place large cantilever prestressed concrete cap beam according to claim 1, characterized in that: The cross-section of the ultra-high performance concrete connecting layer is a square shape enclosed on four sides or a U-shape enclosed on three sides.

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