Prefabricated block type concrete cover beam and construction method thereof

Abstract

The invention relates to the technical field of bridge construction, in particular to a prefabricated block type concrete cover beam which is used for connection of a pier column and a bridge floor and comprises an upper cast-in-place component and a lower prefabricated assembly component, and the lower prefabricated assembly component comprises a column cap prefabricated block and a cantilever type prefabricated block. A tenon is arranged on the top of the column cap prefabricated block, a groove is formed in the bottom of the middle of the cantilever type prefabricated block, and the tenon and the groove are connected in an engaged mode through a fixing piece. The method is used for solving the problems that a cast-in-place cover beam is long in construction period, a prefabricated cover beam is difficult to transport and hoist, and the construction purposes of light weight, convenient construction and reasonable stress are difficult to achieve. Through the modular block design formed by the upper cast-in-place components and the lower prefabricated assembly components, the advantages of light weight and efficient construction are achieved; the through cover beam keeps section type stress balance between the bridge floor and the pier column; the tenons and the grooves are connected in an engaged mode to form a continuously-stressed combined section, and the strength and the shear resistance of the component are enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge construction, and more particularly to a prefabricated block-type concrete cap beam and a construction method thereof. Background Art

[0002] In the field of bridge engineering, the cap beam is a key component connecting the upper structure and the lower piers. Its design and construction directly affect the overall safety and economy of the bridge. Traditional cap beams are mostly made of cast-in-place concrete or integrally prefabricated, which have the following technical defects: the construction period of cast-in-place concrete cap beams is long, and on-site formwork, steel bar tying and maintenance are required, which are greatly affected by environmental factors; the erection of high-altitude scaffolding is difficult and risky, and foundation settlement or load calculation deviations may cause collapse accidents; on-site casting is prone to honeycomb defects, and quality is difficult to accurately control; on-site wet operations generate noise pollution and construction waste, and the rental cost of scaffolding is high; although integrally prefabricated concrete cap beams can reduce the noise caused by on-site wet operations and omit the erection and rental costs of scaffolding, the integrally prefabricated cap beams are difficult to transport and hoist due to their heavy weight, especially for long-span bridges, which require large-tonnage lifting equipment, and the risk increases when the construction site is narrow; the integrally prefabricated cap beams are prone to become weak links at the cast-in-place joints with the piers, and the connection parts may crack or have durability problems under long-term loads; when the on-site geological conditions of the integrally prefabricated cap beams change, there is little room for adjustment, and the investment cost of prefabrication is high.

[0003] The above-mentioned integral prefabricated cap beam still has the problems of difficult maintenance, insufficient flexibility and limited mechanical properties. Prefabricating and assembling the integral prefabricated cap beam in sections can not only overcome the problem of difficulty in lifting and transporting the integral prefabricated structure, but also allow the prefabricated assembly blocks of each section to be cast on site. It can not only make up for the problem of weak nodes at the joints between the integral prefabricated cap beam and the pier columns, but also can form a more flexible and adaptable cast-in-place-prefabricated structure according to the on-site geological conditions and different stress needs, thereby reducing the initial investment cost of prefabrication while meeting the mechanical properties of the structure in different sections, different joints and different geological conditions.

[0004] Therefore, there is an urgent need for a cap beam structure and construction method that is lightweight, easy to construct, and has reasonable stress response to meet the engineering requirements of large-span bridges. Summary of the Invention

[0005] The present invention aims to overcome at least one defect (shortcoming) of the above-mentioned prior art and provide a prefabricated block concrete cap beam and a construction method thereof, which are used to solve the problems of long construction period of cast-in-place cap beams, difficulty in transportation and hoisting of prefabricated cap beams, and difficulty in achieving the construction goals of lightweight, convenient construction and reasonable force for long-span bridges through a simple mixed scheme of cast-in-place and prefabrication.

[0006] The technical solution adopted by the present invention is to provide a prefabricated block-type concrete cap beam for connecting piers and bridge decks, wherein the piers are respectively arranged in the middle and on both sides along the width of the bridge deck, wherein the upper cast-in-place components and the lower prefabricated assembled components are included, and the lower prefabricated assembled components include a column cap prefabricated block arranged above the middle pier and a cantilevered prefabricated block spanning above the piers on both sides, the top of the column cap prefabricated block is provided with a tenon, and the middle bottom of the cantilevered prefabricated block is provided with a groove, and the tenon and the groove are engaged with each other through fixing parts.

[0007] The modular block design formed by the upper cast-in-situ components and the lower prefabricated assembled components reduces the risk of lifting, and combines the lightweight and efficient construction advantages of the cast-in-situ and prefabricated hybrid scheme; the column cap prefabricated blocks and cantilever prefabricated blocks maintain segmented force balance between the bridge deck and the pier columns, thereby enhancing the coordinated force performance of the cap beam; the interlocking connection of the tenon and groove forms a continuously stressed combined section, thereby enhancing the strength and shear resistance of the component.

[0008] Furthermore, the top of the column cap prefabricated block is planar, the tenon is a first shear key protruding from the plane, the groove is arranged along the length direction of the cantilever prefabricated block, and the first shear key is arranged perpendicular to the groove.

[0009] By protruding the tenon above the plane, the plane of the column cap prefabricated block is engaged with the groove of the cantilever prefabricated block to avoid horizontal shear slippage on the contact surface, which may lead to separation of the contact surface; by the direction of the first shear key being perpendicular to the direction of the groove, the tensioning of the contact surface along the length direction of the groove is limited, thereby causing the offset of the cantilever prefabricated block.

[0010] Furthermore, the cantilever prefabricated block includes two cantilever blocks of equal length and a second shear key spanning the top surfaces of the two cantilever blocks, forming a connecting seam between the two parallel cantilever blocks. The second shear keys are evenly distributed along a direction perpendicular to the length of the connecting seam, and the parallel width of the two cantilever blocks is consistent with the width of the column cap prefabricated block.

[0011] A connection seam is formed by two parallel cantilever blocks, which provides space for the extrusion deformation of the cantilever prefabricated block in the width direction; the second shear key is arranged perpendicular to the connection seam direction, which limits the tension of the connection seam along the length direction, thereby causing the two cantilever blocks to separate; the parallel width of the two cantilever blocks is consistent with the width of the column cap prefabricated block, so that the first shear key is firmly connected to the bottom surface of the cantilever prefabricated block, and the second shear key is firmly connected to the top surface of the cantilever prefabricated block, thereby forming an integrated force-bearing structure with the upper cast-in-place component and the column cap prefabricated block through the cantilever prefabricated block.

[0012] Furthermore, the cantilever prefabricated block is a hollow structure, in which a cast-in-place strip and a prestressed steel bundle are provided. The cast-in-place strip is of the same length as the hollow cantilever prefabricated block, and the prestressed steel bundle is uniformly extended throughout the entire length of the cast-in-place strip.

[0013] The equal-length cast-in-place strips can enhance the shear and bending resistance of the connection parts of the cantilever prefabricated blocks spanning the three piers, and can also enhance the shear and bending resistance of the connection parts between the cantilever blocks and the upper cast-in-place components, thereby achieving uniform load transfer and avoiding the risk of local damage; the prestressed steel strands running through the entire length are used to evenly diffuse the stress to the cast-in-place strips, thereby avoiding local breakage of the cantilever prefabricated blocks when the prestressed steel strands are tensioned; the synergistic effect of the cast-in-place strips and the prestressed steel strands is formed into an efficient prefabricated-cast-in-place-prestressed structure, which can not only offset the tensile stress of the external load on the cantilever prefabricated blocks along the length direction, but also enhance the node ductility of each connection part on the cantilever prefabricated blocks, thereby improving the seismic performance of the cantilever prefabricated blocks.

[0014] Furthermore, a prestressed steel strand is built into the upper cast-in-place component and runs through the entire length.

[0015] The stress is evenly diffused into the upper cast-in-place components by the prestressed steel strands running through them, thus avoiding localized breakage of the upper cast-in-place components when the prestressed steel strands are tensioned. The synergistic effect of the upper cast-in-place components and the prestressed steel strands forms an integral cast-in-place-prestressed structure, which can offset the tensile stress of the external loads on the upper cast-in-place components along the length direction and improve the seismic performance of the upper cast-in-place components.

[0016] Furthermore, the upper cast-in-place component is arranged directly above the connection seam, and the width of the second shear key is greater than the width of the upper cast-in-place component.

[0017] By the relative position of the upper cast-in-place component and the connection seam, the connection surface of the two is kept in force balance; by the width of the second shear key being greater than the width of the upper cast-in-place component, the contact surface of the upper cast-in-place component and the cantilever prefabricated block during the casting process jointly form an inverted T-shaped concrete block, the upper surface of which contacts the bottom surface of the upper cast-in-place component, and the lower surface completely covers the second shear key and the two cantilever blocks, thereby increasing the contact area between the upper cast-in-place component and the cantilever prefabricated block without increasing the bottom surface area of ​​the upper cast-in-place component, thereby strengthening the coordinated bending and shear resistance of the two, making the load evenly distributed and avoiding local cracking.

[0018] Furthermore, the connecting seam is a wet seam.

[0019] The wet joint reduces the displacement between the two cantilever blocks, enhances the rigidity of the overall structure of the two cantilever blocks, and evenly transfers the prestress of the two adjacent cantilever blocks, thereby strengthening the bearing capacity of the overall structure of the cantilever prefabricated block. Furthermore, the cross-section of the upper cast-in-situ component is in an inverted T-shape or a rectangle.

[0020] The inverted T-shaped cross section facilitates the arrangement of supports and reduces the cantilever length of the bridge deck. The rectangular cross section simplifies the cast-in-place structure and facilitates construction. Different cross-sectional shapes are suitable for different bridge decks above the upper cast-in-place components.

[0021] Furthermore, the fixing member is an adhesive or a bolt.

[0022] A lightweight connection between the cantilever prefabricated block and the column cap prefabricated block is achieved through an adhesive to reduce the impact on stress distribution, and bolts are used to provide fixed support for the bonding of the adhesive.

[0023] A construction method for a prefabricated segmented concrete cap beam is also provided, comprising the aforementioned prefabricated segmented concrete cap beam and the following steps: S1. Tenons are prefabricated in the column cap blocks during the prefabrication process. The blocks are hoisted to the top of the intermediate piers, and their level and elevation are adjusted using temporary supports to ensure accurate installation. S2. Sequentially hoist the two cantilever segments to the tops of the piers on both sides. After precisely aligning the groove at the center bottom of the cantilever segment with the tenon at the top of the precast column cap, clean the contact surface between the tenon and the groove, apply a high-strength adhesive, and temporarily secure them with bolts to ensure a seamless fit between the tenon and the groove. S3. Implement simultaneous tensioning within the cast-in-place zone of the cantilevered precast units. After the concrete in the cast-in-place zone reaches sufficient strength, the prestressed steel tendons are directly tensioned in stages. Grouting and anchoring are then performed after tensioning to enhance the coordinated shear and flexural properties of the cantilevered precast units. S4. Clean and moisten the top surface of the cantilevered precast unit, lay the second shear key, erect the mold for the upper cast-in-place component, pour concrete, vibrate and compact, and cover and cure to ensure that the concrete fully covers the second shear key and joint, ensuring that the cast-in-place concrete fully engages the wet joint and the second shear key.

[0024] Through the above construction steps, the cantilever prefabricated blocks and column cap prefabricated blocks are combined with the upper cast-in-place components to form a cast-in-place-prefabricated hybrid integral structure, thereby improving the mechanical properties of the cap beam between the pier and the bridge deck and extending its service life.

[0025] Compared with the existing technology, the beneficial effects of the present invention are: the modular block design formed by the upper cast-in-situ components and the lower prefabricated assembled components reduces the lifting risk and combines the advantages of lightweight and efficient construction of the cast-in-situ and prefabricated hybrid scheme; the column cap prefabricated blocks and cantilever prefabricated blocks enable the cap beam to maintain segmented force balance between the bridge deck and the pier, thereby enhancing the coordinated force performance of the cap beam; the interlocking connection of the tenon and the groove forms a continuously stressed combined section, thereby enhancing the strength and shear resistance of the component. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structural assembly of the present invention.

[0027] Figure 2 It is a schematic diagram of the structural explosion of the present invention.

[0028] Description of the accompanying drawings: upper cast-in-situ component 1, column cap prefabricated block 2, cantilever prefabricated block 3, cast-in-situ strip 4, prestressed steel strand 5, adhesive 6, second shear key 7, first shear key 8. DETAILED DESCRIPTION

[0029] The accompanying drawings are for illustrative purposes only and are not to be construed as limiting the present invention. To better illustrate the following embodiments, some components in the accompanying drawings may be omitted, enlarged, or reduced in size, and do not represent actual product dimensions. Those skilled in the art will appreciate that some well-known structures and their descriptions may be omitted from the accompanying drawings.

[0030] Example 1 like Figure 1-2 As shown, this embodiment provides a prefabricated block-type concrete cap beam for connecting piers and bridge decks, wherein the piers are respectively arranged in the middle and on both sides along the width of the bridge deck, wherein the upper cast-in-place component 1 and the lower prefabricated assembly component are included, and the lower prefabricated assembly component includes a column cap prefabricated block 2 arranged above the middle pier and a cantilevered prefabricated block 3 spanning above the piers on both sides, the top of the column cap prefabricated block 2 is provided with a tenon, and the middle bottom of the cantilevered prefabricated block 3 is provided with a groove, and the tenon and the groove are engaged with each other through fixing parts.

[0031] In this embodiment, the piers are located below the bridge deck along the width of the bridge deck. There are three piers, one in the middle and one at each end. The cap beam is located between the bridge deck and the piers, bearing the load from the bridge deck and transferring it to the piers. The length of the cap beam is along the width of the bridge deck and consists of an upper cast-in-place component 1 and a lower prefabricated assembly component. The upper cast-in-place component 1 is cast using on-site formwork, while the lower prefabricated assembly component is prefabricated in a factory. The lower prefabricated assembly components include column cap prefabricated blocks 2 and cantilever prefabricated blocks 3. The column cap prefabricated blocks 2 are equipped with multiple layers of steel mesh or spiral stirrups to resist shear and punching forces. The cross-section of the column cap prefabricated blocks 2 is flared, with a narrow lower end matching the pier column and a wide upper end matching the cantilever prefabricated blocks 3. The cantilever prefabricated blocks 3 are the same length as the upper cast-in-place components 1, and are both arranged across the width direction of the bridge deck. The cantilever prefabricated blocks 3 include multiple ones, which are installed in sections along the length direction of the bridge deck to provide section-type support for long-span bridge decks. The installation of each section requires that the cantilever prefabricated blocks 3 be hoisted on site, the grooves be accurately aligned with the tenons, and then placed above the pier column for fixation.

[0032] The top of the column cap prefabricated block 2 is planar, the tenon is a first shear key 8 protruding from the plane, the groove is arranged along the length direction of the cantilever prefabricated block 3, and the first shear key 8 is arranged perpendicular to the groove.

[0033] In this embodiment, the top of the column cap prefabricated block 2 is planar, and a tenon is provided on the top plane. The middle bottom of the cantilevered prefabricated block 3 is provided with a groove. The length of the groove is equal to the length of the top plane, and the width of the groove is equal to the width of the top plane. When the groove and the top plane are matched and fitted, the tenon further interlocks the fitting contact surface between the two, thereby enhancing the bending and shear resistance of the contact surface. The tenon is a first shear key 8 perpendicular to the length of the groove, and the first shear keys 8 are arranged at equal widths on the top plane of the column cap prefabricated block 2.

[0034] The cantilever prefabricated block 3 includes two cantilever blocks of equal length and a second shear key 7 spanning the top surfaces of the two cantilever blocks. A connecting seam is formed between the two cantilever blocks. The second shear keys 7 are evenly distributed along a direction perpendicular to the length of the connecting seam, and the parallel width of the two cantilever blocks is consistent with the width of the column cap prefabricated block 2.

[0035] In this embodiment, the cantilever prefabricated block 3 is cast and formed in a factory using a high-precision template. The cantilever prefabricated block 3 includes two cantilever blocks of equal length and width. After the two cantilever blocks are placed side by side, the connecting seam in the middle is connected as a whole by laying a plurality of second shear keys 7. The second shear keys 7 can also be prefabricated together with the cantilever blocks. The laying direction of the second shear keys 7 arranged at equal width intervals is perpendicular to the length direction of the connecting seam to reduce the possibility of separation of the two cantilever blocks along the length direction of the connecting seam. After the column cap prefabricated block 2 and the cantilever prefabricated block 3 are assembled, the side edges are neat and free of protrusions, so that the stress bearing distribution of the lower prefabricated assembly component formed after the two are assembled is uniform, avoiding uneven stress distribution and local rupture caused by protrusions.

[0036] The cantilever prefabricated block 3 is a hollow structure, in which a cast-in-place strip 4 and a prestressed steel strand 5 are provided. The cast-in-place strip 4 is of the same length as the hollow cantilever prefabricated block 3 , and the prestressed steel strand 5 evenly runs through the entire length of the cast-in-place strip 4 .

[0037] In this embodiment, the cantilevered precast block 3 is precast in the factory before placement, preserving space for the cast-in-place strip 4 and prestressed steel strands 5. After the cantilevered precast block 3 is installed on the pier, the reserved space is roughened or coated with an adhesive, and the side formwork is supported. Before concrete is poured, the base layer is moistened, and micro-expansive concrete is poured in layers. Insertion vibration compaction is then applied to allow the prestressed steel strands 5 and cast-in-place concrete to set, followed by curing. The prestressed steel strands 5 and cast-in-place strips 4 are arranged to extend the entire length of the cantilevered block, enhancing the ductility of the cantilevered precast block 3.

[0038] The upper cast-in-situ component 1 has a built-in prestressed steel strand 5 that runs through the entire length.

[0039] In this embodiment, after the cantilever prefabricated block 3 and the column cap prefabricated block 2 are assembled, the interface on the top of the lower prefabricated assembled component is cleaned and moistened, the prestressed steel bundle 5 built into the upper cast-in-place component 1 is laid, and the mold of the upper cast-in-place component 1 is erected and then concrete is poured, vibrated and compacted, and covered for maintenance to ensure that the concrete fully wraps the second shear key 7. After vibrating and compacting, it is covered with geotextile for maintenance.

[0040] The upper cast-in-place component 1 is arranged directly above the connection joint, and the width of the second shear key 7 is greater than the width of the upper cast-in-place component 1.

[0041] In this embodiment, the two side formworks of the upper cast-in-place component 1 are placed with symmetrical connecting seams, and prestressed steel bundles 5 are tied between the two side formworks. In order to allow the cast-in-place concrete to fully wrap the second shear key 7, two formworks are also required to be laid above the second shear key 7, and the ports of the above formworks are sealed. Then, concrete is poured to cast the upper cast-in-place component 1 and the second shear key 7 into a formed integrated structure.

[0042] The connecting seams are wet seams.

[0043] In this embodiment, the wet joint is a connection portion formed by pouring concrete on site after the two cantilever blocks are spliced ​​together, which enhances the rigidity of the overall structure of the integrated cantilever prefabricated block 3, strengthens the nodes, strengthens the prestressed anchoring area, and can also coordinate the deformation of the two cantilever blocks, resist the negative bending moment during pouring, and extend the life of the overall structure. The cross section of the upper cast-in-situ component 1 is in an inverted T-shape or a rectangle.

[0044] In this embodiment, the upper cast-in-place member 1 with an inverted T-shaped cross section is suitable for wide bridge decks with multiple piers. The inverted T-shape facilitates support arrangement and reduces the cantilever length of the bridge deck. The upper cast-in-place member 1 with a rectangular cross section is suitable for simply supported beam bridges with small and medium spans. The rectangular shape is simple in structure and easy to construct.

[0045] The fixing member is an adhesive 6 or a bolt.

[0046] In this embodiment, the adhesive 6 is applied to the top surface of the column cap prefabricated block 2 and the first shear key 8 protruding therefrom, as well as the groove of the cantilever prefabricated block 3. When the tenon of the column cap prefabricated block 2 and the groove of the cantilever prefabricated block 3 are aligned, the adhesive 6 can strengthen the engagement between the two. The bolts can assist in the engagement of the adhesive 6.

[0047] Example 2 This embodiment also provides a construction method for a prefabricated segmented concrete cap beam, which includes the aforementioned prefabricated segmented concrete cap beam and further includes the following steps: S1. The column cap prefabricated block 2 is prefabricated with a tenon reserved during the prefabrication process. The column cap prefabricated block 2 is hoisted to the top of the middle pier column and the level and elevation are adjusted by temporary support to ensure accurate installation position. S2. Sequentially hoist the two cantilever blocks to the top of the piers on both sides, and precisely align the groove at the bottom of the middle cantilever block with the tenon at the top of the column cap precast block 2. Clean the contact surface between the tenon and the groove, and apply high-strength adhesive 6 on the contact surface. Temporarily secure with bolt connectors to ensure that there is no gap between the tenon and the groove. S3. The cantilever precast block 3 is subjected to synchronous tensioning in the cast-in-place zone 4. After the concrete in the cast-in-place zone 4 reaches strength, the prestressed steel strands 5 are tensioned directly and then anchored by grouting to enhance the shear and bending synergy of the cantilever precast block 3. S4. Clean and moisten the top surface of the cantilevered precast block 3, lay the second shear key 7, erect the mold for the upper cast-in-place component 1, and pour concrete. Compact the concrete by vibrating it tightly and cover it for curing. Ensure that the concrete fully covers the second shear key 7 and the joint, ensuring that the cast-in-place concrete, the wet joint, and the second shear key 7 are fully engaged.

[0048] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the technical solutions of the present invention, and are not intended to limit the specific implementation methods of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A prefabricated block concrete cap beam for connecting piers and bridge decks, wherein the piers are respectively arranged in the middle and on both sides along the width of the bridge deck, characterized in that: It includes an upper cast-in-situ component and a lower prefabricated assembly component. The lower prefabricated assembly component includes a column cap prefabricated block located above the middle pier and a cantilevered prefabricated block spanning the piers on both sides. The top of the column cap prefabricated block is provided with a tenon, and the middle bottom of the cantilevered prefabricated block is provided with a groove. The tenon and the groove are engaged with each other through fixing parts.

2. The prefabricated segmented concrete cap beam according to claim 1, characterized in that: The top of the column cap prefabricated block is planar, the tenon is a first shear key protruding from the plane, the groove is arranged along the length direction of the cantilever prefabricated block, and the first shear key is arranged perpendicular to the groove.

3. The prefabricated segmented concrete cap beam according to claim 1, characterized in that: The cantilever prefabricated block includes two cantilever blocks of equal length and a second shear key spanning the top surfaces of the two cantilever blocks. A connecting seam is formed between the two cantilever blocks. The second shear keys are evenly distributed in a direction perpendicular to the length of the connecting seam, and the parallel width of the two cantilever blocks is consistent with the width of the column cap prefabricated block.

4. The prefabricated segmented concrete cap beam according to claim 1, characterized in that: The cantilever prefabricated block is a hollow structure, in which a cast-in-place strip and a prestressed steel bundle are provided. The cast-in-place strip is of the same length as the hollow cantilever prefabricated block, and the prestressed steel bundle evenly runs through the entire length of the cast-in-place strip.

5. The prefabricated segmented concrete cap beam according to claim 1, characterized in that: The upper cast-in-situ component is embedded with a prestressed steel strand that runs through the entire length.

6. The prefabricated segmented concrete cap beam according to claim 3, characterized in that: The upper cast-in-place component is arranged directly above the connection seam, and the width of the second shear key is greater than the width of the upper cast-in-place component.

7. The prefabricated segmented concrete cap beam according to claim 3, characterized in that: The connecting seams are wet seams.

8. The prefabricated segmented concrete cap beam according to any one of claims 1 to 7, characterized in that: The cross section of the upper cast-in-situ component is in an inverted T shape or a rectangle.

9. The prefabricated segmented concrete cap beam according to claim 8, characterized in that: The fixing member is an adhesive or a bolt.

10. A construction method for prefabricated block concrete cap beam, characterized in that: The prefabricated segmented concrete cap beam according to claim 9 further comprises the following steps: S1. Tenons are prefabricated in the column cap blocks during the prefabrication process. The blocks are hoisted to the top of the intermediate piers, and their level and elevation are adjusted using temporary supports to ensure accurate installation. S2. Sequentially hoist the two cantilever segments to the tops of the piers on both sides. After precisely aligning the groove at the center bottom of the cantilever segment with the tenon at the top of the precast column cap, clean the contact surface between the tenon and the groove, apply a high-strength adhesive, and temporarily secure them with bolts to ensure a seamless fit between the tenon and the groove. S3. Implement simultaneous tensioning within the cast-in-place zone of the cantilevered precast units. After the concrete in the cast-in-place zone reaches sufficient strength, the prestressed steel tendons are directly tensioned in stages. Grouting and anchoring are then performed after tensioning to enhance the coordinated shear and flexural properties of the cantilevered precast units. S4. Clean and moisten the top surface of the cantilevered precast unit, lay the second shear key, erect the mold for the upper cast-in-place component, pour concrete, vibrate and compact, and cover and cure to ensure that the concrete fully covers the second shear key and joint, ensuring that the cast-in-place concrete fully engages the wet joint and the second shear key.

Images