Prefabricating and mounting method of assembly type fragmented bent cap

Abstract

The invention discloses a prefabrication and installation method of an assembly type fragmented cover beam, which comprises a series of measures and processes such as fragmented cover beam steel bar modular manufacturing, overall matching prefabrication, entity pre-assembly correction, stand column reserved long steel bar guiding and positioning, cover beam post bedding, UHPC wet joint connection, longitudinal and transverse prestress tension and the like. And light weight, standardization and rapid construction of the assembly type fragmented bent cap are achieved. The method for prefabricating and installing the assembly type fragmented bent cap has the advantages that the bent cap is light in fragmentation (multiple in fragmentation), light in self weight, good in manufacturing quality, high in installation precision, few in on-site procedures, convenient to operate and the like, the manufacturing and hoisting difficulty of the bent cap is remarkably reduced, temporary supports are not needed for installation, ground traffic is not occupied, the influence on the surrounding environment is small, and the method is suitable for popularization and application. The construction is fast and convenient.

Description

Technical Field

[0001] This invention relates to the field of bridge prefabrication and assembly construction technology, specifically to a method for the prefabrication and installation of prefabricated segmented cap beams. Background Technology

[0002] In recent years, elevated bridges have played an increasingly important role in transportation, leading to a surge in new elevated bridge projects. Compared to the traditional on-site casting construction method for elevated bridges, prefabrication and assembly have emerged as the main construction method for urban bridges in Shanghai due to their advantages such as high efficiency, environmental friendliness, and minimal impact on the surrounding environment. However, with the rapid pace of urban development, prefabrication and assembly construction is gradually becoming insufficient to meet construction demands. The construction environment is becoming increasingly complex, with more and more important surrounding structures, necessitating the segmented and sectioned installation of ultra-long and ultra-heavy prefabricated components, with cap beams being the most prominent example. In the construction of elevated bridges, cap beams constitute a significant proportion of ultra-long and ultra-heavy components. Conventional ultra-heavy cap beams are constructed in sections along the bridge direction, using two methods: wet-joint cap beams and dry-joint cap beams. 1. Wet-joint cap beam construction requires the erection of temporary supports and a wet joint connection process; 2. Dry-joint cap beams use epoxy resin and prestressed steel strands for temporary fixing.

[0003] Through extensive research and engineering practice, prefabrication plants have developed advanced manufacturing processes and equipment, and on-site joint connection technology has become increasingly mature. Based on this, reducing the weight of prefabricated components in various parts of the bridge and simplifying on-site installation procedures have become the focus of research on bridge prefabrication and assembly technology.

[0004] In existing technologies, such as patent (CN111206492A): segmenting the cap beam along the transverse direction of the bridge results in a relatively large weight for each segment, requiring high-performance transportation and hoisting equipment, and is not economically viable; segmental connections rely on pre-embedded steel lap joints and temporary prestressing tendon fixation, making construction steps cumbersome and temporary fixation costs high; the reinforcement of wet joints requires on-site welding, which is labor-intensive and difficult to guarantee welding quality. Patent (CN115233541A): although segmenting along the longitudinal direction of the bridge reduces the weight of each segment, segment positioning relies solely on hoisting equipment operation, lacking a dedicated guiding and positioning structure, resulting in insufficient installation accuracy; the traditional synchronous grouting method easily leads to misalignment between segmented cap beams and deviation of prestressing hole positions; the wet joint formwork lacks a dedicated fixing structure, resulting in a large workload for on-site formwork and a tendency for grout leakage; the coordination between wet joints and prestressing tensioning is insufficient, making it difficult to fully guarantee the overall structural integrity.

[0005] Therefore, to address the problems of existing technologies, a method is needed that differs from conventional wet-joint segmented cap beams, significantly reducing the weight of precast cap beam segments by approximately 50%, while maintaining self-balance during installation, thus greatly reducing transportation and hoisting difficulties. Each precast component possesses its own independent prestressing system and continuous ordinary steel reinforcement system, exhibiting good load-bearing performance and durability. Furthermore, the construction method offers advantages such as requiring only temporary road closures at night for cap beam installation, eliminating the need for temporary scaffolding, and minimizing environmental impact. Summary of the Invention

[0006] This invention aims to provide a method for the prefabrication and installation of prefabricated segmented cap beams. Using this method to construct prefabricated segmented cap beams achieves two advantages: firstly, lightweight cap beams (multiple segments); and secondly, high precision in the matching prefabrication of segmented cap beams, significantly reducing on-site adjustment work and meeting the needs of rapid on-site construction. Simultaneously, only a few on-site procedures, such as wet joint connections, are required, eliminating the need for temporary scaffolding and a large labor input. This is a green and environmentally friendly construction technology that can be widely applied in complex environments such as urban areas and rail transit protection zones.

[0007] To achieve the above objectives, the technical solution of the present invention is: a prefabrication and installation method for prefabricated segmented cap beams, which involves modular fabrication of segmented cap beam reinforcement, overall matching prefabrication, physical pre-assembly and correction, pre-reserved long reinforcement bars for column guidance and positioning, post-grouting of the cap beam, and UHPC. The prefabrication and installation of precast segmented cap beams are achieved through wet joint connection and longitudinal and transverse prestressing tensioning processes. The specific steps include: Step 1: Fabricating the reinforcing bars for the segmented cap beams, hoisting each piece onto the integral prefabrication jig, and pouring the concrete for the segmented cap beams in one go; Step 2: Fine-tuning the prestressing tensioning locations and quantities for a batch, and pre-assembling the segmented cap beams before delivery to correct fabrication deviations; Step 3: Pre-reserving long and short reinforcing bars at the top of the columns, with long guide bars in the inner ring and short bars in the outer ring; Step 4: Installing the segmented cap beams in sequence, first installing the middle segment, then the side segments, precisely adjusting their relative positions and elevations; Step 5: Installing the embedded grout baffle at the bottom of the cap beam, and grouting from top to bottom using long guide bar sleeves; Step 6: Installing the longitudinal prestressed UHPC of the segmented cap beams. Step 7: Construction of longitudinal wet joint reinforcement and concrete at the top of the segmented cap beam; Step 8: Prestressing tensioning of the wet joint of the segmented cap beam, tensioning of longitudinal precision rolled threaded steel bars.

[0008] Furthermore, in step 1, the segmented cap beam reinforcement is manufactured in a modular fashion, and when the whole is poured in one go, a removable inner core mold is used for segmented isolation. The removable inner core mold is compatible with the integral prefabricated frame, and the segmented cap beam concrete structure is not damaged after disassembly.

[0009] Furthermore, in step 2, the first batch of prestressed tensioning adopts an anti-eccentric arrangement. After the tensioning is completed, the segmented cap beams are hoisted to the integral prefabricated jig for secondary pre-assembly to correct the structural deviation after prestressing tensioning.

[0010] Furthermore, in step 2, the batch of prestressed tendons are arranged uniformly and symmetrically along the cross-section of the segmented cap beam to avoid lateral bending deformation after tensioning.

[0011] Furthermore, in step 3, the column reserves long guide steel bars between each segment of the cap beam for guiding the alignment and positioning of the cap beam. The long guide steel bars are fitted with steel sleeves, which extend to the top of the cap beam to form a post-grouting channel.

[0012] Furthermore, the outer sleeve of the reinforcing bar is a grouting sleeve or a grouting corrugated pipe.

[0013] Furthermore, in step 4, the installation sequence of the segmented cap beam is determined according to the segment size of the cap beam, the prestressing arrangement, and the lap splicing form of the wet joint reinforcement. The relative position deviation is monitored in real time during the installation process.

[0014] Furthermore, in step 5, after the cap beam is hoisted, a post-grouting method is used instead of the traditional synchronous grouting. First, a special grout-blocking template is installed and embedded between the segmented cap beams. Grouting material is injected from top to bottom through the outer sleeve of the long guide steel bar, and the gap between the cap beams is observed to determine the fullness of the grouting.

[0015] Furthermore, in step 6, a stepped groove is reserved between the segmented cap beams, the UHPC wet joint template is inserted into the stepped groove and fixed, and the UHPC pouring adopts a layered pouring method.

[0016] Furthermore, in step 7, the longitudinal wet joint reinforcement bars at the top of the segmented cap beam are arranged in an alternating lap joint; in step 8, the longitudinal fine-rolled threaded steel bars are tensioned using a simultaneous tensioning method at both ends, with the tensioning sequence being the middle first and then the two sides, and the deformation of the segmented cap beam is monitored in real time during the tensioning process.

[0017] Compared with the prior art, the present invention has the following significant advantages:

[0018] 1. By dividing the cap beam into multiple sections along the longitudinal direction of the bridge, the prefabrication weight of each cap beam is significantly reduced, greatly reducing the difficulty of transportation and hoisting, and adapting to the construction needs in complex environments.

[0019] 2. The cap beams are prefabricated as a whole, resulting in good forming quality, high prefabrication precision, reduced on-site adjustment workload, and significantly improved construction efficiency.

[0020] 3. The installation posture of the cap beam is adjusted by pre-reserving long steel bars in the column. The long steel bar sleeve also serves as the grouting channel after the cap beam is installed, which takes into account both construction speed and quality control, achieving two goals at once.

[0021] 4. The use of post-grouting solves the problems of misalignment between segmented cap beams, misaligned prestressed holes, and tilting of baffle plates that are easily caused by synchronous grouting of segmented cap beams, thus solving the problem of grouting segmented cap beams.

[0022] 5. The pre-reserved embedded slot solves the problem of fixing the longitudinal prestressed UHPC joint filling template between segmented cap beams, making it simple and quick.

[0023] 6. It has enabled lightweight, precise, rapid, and low-impact operation of segmented girder construction, promoting the leapfrog development of segmented girder technology and enabling its widespread application.

[0024] In summary, the present invention, through the above-mentioned construction method, has many advantages such as lightweight segmented (multiple segments) cap beams, light weight, high manufacturing precision, fewer on-site procedures, and convenient operation. It significantly reduces the difficulty of transporting and hoisting cap beams, does not require temporary supports for installation, does not occupy ground traffic, has little impact on the surrounding environment, and is quick and convenient to construct. Attached Figure Description

[0025] Figure 1 Elevation view of the prefabricated segmented cap beam; Figure 2 This is a cross-sectional view of the prefabricated segmented cap beam; Figure 3 This is a schematic diagram of the prestressing arrangement for a prefabricated segmented cap beam. Figure 4 A schematic diagram of prefabricated modular segmented cap beams; Figure 5 Schematic diagram for pre-reserved reinforcement bars for prefabricated segmented cap beam columns Figure 1 ; Figure 6 Schematic diagram for pre-reserved reinforcement bars for prefabricated segmented cap beam columns Figure 2 ; Figure 7 Schematic diagram of prefabricated segmented cap beam installation Figure 1 ; Figure 8 Schematic diagram of prefabricated segmented cap beam installation Figure 2 ; Figure 9 This is a schematic diagram of the UHPC (Unified High-Pressure Cap) construction method for prefabricated segmented cap Figure 10 A schematic diagram of the construction of wet joints in prefabricated segmented cap beams; Figure 11 Schematic diagram of transverse prestressed installation of prefabricated segmented cap beam; Figure 12Diagram of the stepped slot of the UHPC prefabricated segmented cap beam; Figure 13 Diagram of the grout baffle plate for the prefabricated segmented cap beam; In the diagram: 1. Foundation; 2. Column; 3. Segmented cap beam; 4. Wet joint of cap beam; 5. UHPC; 6. Longitudinal prestressing (fine-rolled threaded steel); 7. Wet joint reinforcement of cap beam; 8. Prestressing of first batch of cap beams (tensioned before leaving the factory); 9. Prestressing of remaining batches of cap beams (tensioned after installation); 10. Integral precast jig; 11. Removable inner core mold; 12. Column pre-reserved reinforcing bar (conventional); 13. Column pre-reserved reinforcing bar (long reinforcing bar); 14. Embedded grout baffle. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and examples.

[0027] like Figures 1 to 13 As shown, the present invention provides a method for installing a modular segmented cover, comprising the following steps: Step 1: Fabricate the reinforcing bars for segmented cap beam 3, hoist them one by one onto the integral precast frame, and pour the concrete of segmented cap beam 3 in one go (using an inner core mold for isolation). The prefabricated multi-section cap beam 3 uses modular steel bars and is prefabricated in a whole-piece matching manner. Each section is isolated by a removable inner core mold 11.

[0028] Step 2: Fine-tune the tensioning points and quantities of the prestressed girder in a batch to prevent the lateral bending of the segmented girder. Before leaving the factory, pre-assemble the segmented girder and correct any manufacturing deviations. The prestressed tendons of the cap beam are arranged to prevent eccentricity. After the tensioning of one batch of prestressed tendons is completed, they are pre-assembled and corrected again on the scaffold.

[0029] Step 3: The top of the column is reserved with a combination of long and short reinforcing bars. The inner ring uses long guide bars (the reinforcing bar sleeve extends to the top of the cap beam) to assist in the positioning of the cap beam. The outer ring uses short reinforcing bars to connect and fix the segmented cap beam. Long guide steel bars need to be reserved between each segment of the cap beam for alignment and positioning guidance of the cap beam. The outer sleeve of the steel bar can be in the form of a grouting sleeve or a grouting corrugated pipe, depending on the situation.

[0030] Step 4: Install the segmented cap beams in sequence, first installing the middle segment, then the side segments, and precisely adjust their relative positions and elevations; The segmented cap beams were hoisted on site in sequence, starting with the middle section and then moving to the sides. This sequence was influenced by the size of the cap beam segments, the arrangement of prestressed concrete, and the lap splicing method of the wet joint reinforcement.

[0031] Step 5: Install the embedded grout baffle plate at the bottom of the cap beam, and complete the grouting from top to bottom through the long guide steel sleeve pre-embedded in the cap beam; After the cap beams are hoisted, a post-grouting method is used instead of the traditional synchronous grouting. First, a special grout-blocking template is installed and embedded between the segmented cap beams. Grout is then injected from top to bottom through the outer sleeve of a long guide steel bar, and the grouting fullness is determined by observing the gaps between the cap beams.

[0032] Step 6: Install the wet joint formwork for the longitudinal prestressed UHPC of the segmented cap beam, and pour the UHPC; UHPC was used to fill the longitudinal prestressed joints, and the formwork was inserted into the stepped slots reserved between the segmented cap beams to complete the UHPC pouring. Step 7: Construction of longitudinal wet joint reinforcement and concrete at the top of the segmented cap beam; Step 8: Prestressing of wet joints of segmented cap beams and tensioning of longitudinal precision-rolled threaded steel bars.

[0033] This construction method has many advantages, such as lightweight segmented cap beams (multiple segments), light weight, high manufacturing precision, fewer on-site procedures, and convenient operation. It significantly reduces the difficulty of transporting and hoisting cap beams, does not require temporary supports for installation, does not occupy ground traffic, has little impact on the surrounding environment, and is quick and convenient to construct.

[0034] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above examples; the examples and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for prefabrication and installation of a modular segmented cap beam, characterized in that, The prefabrication and installation of prefabricated segmented cap beams are achieved through modular fabrication of segmented cap beam reinforcement, overall matching prefabrication, physical pre-assembly and correction, pre-reserved long reinforcement for column positioning, post-grouting of cap beams, UHPC wet joint connection, and longitudinal and transverse prestressing tensioning processes. Specifically, the process includes the following steps: Step 1: Fabricate segmented cap beam reinforcement, hoist each segment onto the integral prefabrication jig, and pour the segmented cap beam concrete in one go; Step 2: Fine-tune the prestressing tensioning locations and quantities for a batch, and pre-assemble the segmented cap beams before delivery to correct fabrication deviations; Step 3: Reserve a combination of long and short reinforcing bars at the top of the columns, with long guide bars in the inner ring and short bars in the outer ring; Step 4: Install the segmented cap beams sequentially, first installing the middle segment, then the side segments, precisely adjusting their relative positions and elevations; Step 5: Install the embedded grout baffle at the bottom of the cap beam, and grout from top to bottom using long guide bar sleeves; Step 6: Install the longitudinal prestressed UHPC of the segmented cap beams. Step 7: Construction of longitudinal wet joint reinforcement and concrete at the top of the segmented cap beam; Step 8: Prestressing tensioning of the wet joint of the segmented cap beam, tensioning of longitudinal precision rolled threaded steel bars.

2. The prefabrication and installation method of the assembled segmented cap beam according to claim 1, characterized in that, In step 1, the segmented cap beam reinforcement is manufactured in a modular manner. When the whole is poured at once, a removable inner core mold is used for segmented isolation. The removable inner core mold is compatible with the integral prefabricated frame and does not damage the concrete structure of the segmented cap beam after disassembly.

3. The prefabrication and installation method of the assembled segmented cap beam according to claim 1, characterized in that, In step 2, the first batch of prestressed tensioning adopts an anti-eccentric arrangement. After the tensioning is completed, the segmented cap beams are hoisted to the integral prefabricated jig for secondary pre-assembly to correct the structural deviation after prestressing tensioning.

4. The prefabrication and installation method of the assembled segmented cap beam according to claim 1, characterized in that, In step 2, the batch of prestressed tendons are evenly and symmetrically arranged along the cross-section of the segmented cap beam to avoid lateral bending deformation after tensioning.

5. The prefabrication and installation method of the assembled segmented cap beam according to claim 1, characterized in that, In step 3, the column reserves long guide steel bars between each segment of the cap beam for guiding the alignment and positioning of the cap beam. The long guide steel bars are fitted with steel sleeves, which extend to the top of the cap beam to form a post-grouting channel.

6. The prefabrication and installation method of the assembled segmented cap beam according to claim 5, characterized in that, The outer sleeve of the reinforcing bar is a grouting sleeve or a grouting corrugated pipe.

7. The prefabrication and installation method of the assembled segmented cap beam according to claim 1, characterized in that, In step 4, the installation sequence of the segmented cap beam is determined according to the segment size of the cap beam, the prestressing arrangement and the lap splicing form of the wet joint reinforcement. The relative position deviation is monitored in real time during the installation process.

8. The prefabrication and installation method of the assembled segmented cap beam according to claim 1, characterized in that, In step 5, after the cap beam is hoisted, the post-grouting method is used instead of the traditional synchronous grouting. First, a special grout-blocking template is installed and embedded between the segmented cap beams. Grouting material is injected from top to bottom through the outer sleeve of the long guide steel bar, and the gap between the cap beams is observed to determine the fullness of the grouting.

9. The prefabrication and installation method of the assembled segmented cap beam according to claim 1, characterized in that, In step 6, stepped slots are reserved between the segmented cap beams, and the UHPC wet joint template is inserted into the stepped slots for fixation. The UHPC is poured in layers.

10. The prefabrication and installation method of the assembled segmented cap beam according to claim 1, characterized in that, In step 7, the longitudinal wet joint reinforcement bars at the top of the segmented cap beam are arranged in an alternating lap joint; in step 8, the longitudinal fine-rolled threaded steel bars are tensioned using a simultaneous tensioning method at both ends, with the tensioning sequence being the middle first and then the two sides, and the deformation of the segmented cap beam is monitored in real time during the tensioning process.

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