A cavity type prefabricated segment assembled pier top beam and a construction method thereof

Abstract

The application discloses a cavity type prefabricated segment assembled pier top beam and a construction method thereof. The top plate of the pier top beam is divided into a first top plate and a second top plate, the second top plate is located in the middle of the first top plate, the bottom plate is divided into a first bottom plate and a second bottom plate, the second bottom plate is located in the middle of the first bottom plate, the web plate is divided into a first web plate and a second web plate which are mutually attached, the pier top beam structure comprises a shell and an inner cavity part, the shell comprises the first top plate, the first bottom plate, the first web plate and a flange plate, and the shell is a prefabricated reinforced concrete component; the inner cavity part comprises the second top plate, the second bottom plate and the second web plate, and the inner cavity part is a cast-in-situ reinforced concrete structure. The prefabricated shell is light and thin, the prefabricated shell reduces the weight of the prefabricated segment by 30-50% compared with the prefabricated pier top beam, and is convenient for transportation and hoisting; the pier top segment beam has global stability and seismic performance, the wet joint design of the cast-in-situ beam is removed, the installation speed of the segment assembly is ensured, and the longitudinal splicing joint of the beam is reduced, and the safety of the beam is ensured.

Description

Technical Field

[0001] This invention relates to the field of bridge structure construction technology, and in particular to a cavity-type precast segmental assembly pier top crossbeam and its construction method. Background Technology

[0002] With the rapid development of urban construction, urban bridge design and construction schemes are increasingly emphasizing rapid construction, construction quality, and aesthetic appeal. Segmental precast concrete box girder technology offers advantages such as fast construction speed, high construction quality, and minimal impact on existing traffic and the surrounding environment, leading to its increasingly widespread application in concrete bridge structures. Compared to traditional cast-in-place construction methods, segmental precast box girder technology offers significant advantages, including less on-site land use, higher control precision, and less impact on traffic beneath the bridge, making it widely used.

[0003] The segmental precast box girder assembly process involves dividing the bridge superstructure longitudinally into several standard segments. After prefabrication at the prefabrication site, these segments are assembled sequentially on-site using specialized assembly equipment such as bridge erecting machines. Prestress is applied simultaneously to form a unified structure, and the assembly is carried out span by span along a predetermined installation direction. The pier top crossbeam, installed at the top of the pier, is a large cantilevered crossbeam extending transversely from the pier to both sides of the pier. It is a key component in the bridge structure that transmits longitudinal dead and live loads. The pier top crossbeam structure includes a bottom plate, a top plate, web plates, and flange plates. The bottom and top plates are parallel. There are two web plates, located between the bottom and top plates to connect them. The two web plates are inclined outwards between the bottom and top plates. There are two flange plates, located on both sides of the top plate.

[0004] Generally, precast pier top beams are not only large in size but also extremely heavy. Unless there is waterway transportation available, most urban highways cannot transport complete precast pier top beam components. Currently, the main designs and construction methods for pier top beams are as follows: (1) Cast-in-place pier top beam components, where the entire segment is tightly connected to the substructure, but the quality is uncontrollable, the alignment is difficult to control, and wet joint sections need to be set. (2) Precast pier top beam components. To facilitate transportation, precast pier top beams are usually divided into two or more segments for separate precasting, as shown in patent publication number CN115125821A. This reduces the weight of the segmented precast pier top beams, making them easier to transport. Then, the segmented precast pier top beams transported to the site are connected together. The overall integrity of the pier top beams produced by this construction method is poor, and the compressive stress reserve at the top of the beam of the cantilevered component is generally not very large, which may cause the epoxy adhesive to be under tension, resulting in a significant reduction in the service life of the overall bridge. Therefore, there is an urgent need to provide a construction method for precast segmented beam pier top beams. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings in the prior art and provide an internal cavity prefabricated segmental assembly pier top beam and its construction method. The design of the beam adopts a combination of prefabrication and cast-in-place, which facilitates the design and construction of the pier top beam. It avoids the wet joints of the cast-in-place pier top beam and ensures the longitudinal integrity of the beam, so as to achieve the purpose of good construction quality, fast speed and good landscape effect.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A precast segmental pier top beam with an internal cavity is disclosed. The top plate is divided into a first top plate and a second top plate, with the second top plate located in the middle of the first top plate. The bottom plate is divided into a first bottom plate and a second bottom plate, with the second bottom plate located in the middle of the first bottom plate. The web is divided into a first web and a second web that fit together, with the second web located inside the first web. The pier top beam structure includes a shell and an internal cavity. The shell includes the first top plate, the first bottom plate, the first web, and a flange plate, and the shell is a precast reinforced concrete component. The internal cavity includes the second top plate, the second bottom plate, and the second web, and the internal cavity is a cast-in-place reinforced concrete structure.

[0008] In the technical solution of this invention, the pier top beam is divided into a precast concrete shell and a cast-in-place concrete cavity. The shell and cavity include different parts and are prepared using different construction methods. The shell is prefabricated in the factory and then transported to the site for installation. The precast shell is lightweight and thin, making it easy to transport and hoist. At the same time, matching casting joints are maintained in the pier top segments. Compared with cast-in-place pier top beams, this method can speed up the construction progress and reduce the impact on the surrounding environment of the construction site. Compared with longitudinally segmented precast pier top beams, this method improves the overall stability and seismic performance of the pier top segment beams.

[0009] In a preferred embodiment of the present invention, the connection between the first top plate and the second top plate is a first joint, the connection between the first web plate and the second web plate is a second joint, and the connection between the second bottom plate and the second bottom plate is a third joint. A groove is provided at the second joint. The groove increases the contact area between the precast reinforced concrete shell and the cast-in-place reinforced concrete cavity, increasing the bonding strength and ensuring a tighter connection between the precast concrete shell and the cast-in-place section, thereby increasing the longitudinal and vertical shear resistance of the beam. Furthermore, the groove connection edge at the second joint is chamfered. The chamfer further increases the contact area between the precast reinforced concrete shell and the cast-in-place reinforced concrete cavity, increasing the bonding strength and making the connection between the shell and the cavity (i.e., the first web plate and the second web plate) smoother, preventing stress concentration at right-angle connections.

[0010] In a preferred embodiment of the present invention, the pier top beam further includes a partition plate disposed between the bottom plate and the top plate, the partition plate being located between the two web plates, and the partition plate belonging to the inner cavity. In the above technical solution, the pier top beam is further provided with a partition plate, which is a cast-in-place reinforced concrete structure.

[0011] As a preferred embodiment of the present invention, one partition is provided, and a manhole is provided between the partition and the web for bridge maintenance.

[0012] Another aspect of the present invention provides a construction method for a precast segmental pier top beam with an internal cavity, used to complete the construction of the above-mentioned pier top beam structure. The construction method includes the following steps:

[0013] Step S1: Transport the prefabricated shell to the installation location and install the shell on the bridge pier;

[0014] Step S2: After the shell is installed, the reinforcing bars of the inner cavity are tied, and the concrete of the inner cavity is poured using the shell as a template and then cured.

[0015] Step S3: Tension the prestressed tendons.

[0016] In the construction method of the present invention, the shell is prefabricated in the prefabrication yard and transported to the site. First, the prefabricated shell of the pier top beam is installed on the pier. After the prefabricated shell is erected in place, the steel bars are tied and the prestressed steel strand pipes are installed. The shell can be used as a casting template for the cast-in-place concrete part inside the beam. Then the prestressed strands are tensioned to complete the construction of the pier top beam.

[0017] As a preferred embodiment of the present invention, the pier is a fixed pier. When binding the reinforcing bars in the inner cavity, the pier reinforcing bars are extended into the shell and connected to the reinforcing bars in the second bottom plate. For the fixed pier, the pier reinforcing bars extend into the bottom plate of the pier top beam, so it is not necessary to erect a casting form at the bottom plate. However, it is necessary to take good sealing measures between the bottom plate and the pier beam to prevent grout leakage.

[0018] As a preferred embodiment of the present invention, the bridge pier is a bridge pier with a support, and an installation hole is provided in the second base plate for the installation of the support; when tying the reinforcing bars of the inner cavity in step S2, an installation hole template is provided in the second base plate, and a steel plate for the support is pre-embedded in the second base plate in advance.

[0019] In a preferred embodiment of the present invention, the prestressed tendons include shear-resistant prestressed steel tendons for the crossbeams, longitudinal internal tendons for the main beams, transverse steel tendons for the bridge deck, and external longitudinal tendons for the main beams. The shear-resistant prestressed steel tendons for the crossbeams are arranged longitudinally within the bottom slab, the longitudinal internal tendons for the main beams are arranged transversely within the top slab, the transverse steel tendons for the bridge deck are arranged longitudinally within the top slab, and the external longitudinal tendons for the main beams are arranged transversely within the web. The prestressed tendons are tensioned in the following order: shear-resistant prestressed steel tendons for the crossbeams, longitudinal internal tendons for the main beams, transverse steel tendons for the bridge deck, and external longitudinal tendons for the main beams. The shear-resistant prestressed steel tendons for the crossbeams penetrate the precast first bottom slab and the cast-in-place second bottom slab, which increases the connection strength between the shell and the inner cavity to resist the shear effect at the joint between the first and second bottom slabs. A certain distance is maintained between the shear-resistant prestressed steel tendon ducts and the spiral reinforcing bars anchored under the longitudinal prestressed steel tendons to ensure that the concrete can be filled and vibrated.

[0020] As a preferred embodiment of the present invention, the prestressing tendons further include crossbeam bending prestressing tendons. For large cantilever box girders, crossbeam bending prestressing tendons need to be installed within the crossbeam at the pier top to counteract the negative bending moment internal force at the top of the crossbeam support, ensuring that the top slab meets the requirements for Class A prestressed concrete components. Whether to install the crossbeam bending prestressing tendons is determined based on the actual situation. The crossbeam bending prestressing tendons are installed within the top slab and the web, and are tensioned before tensioning the crossbeam shear prestressing tendons.

[0021] As a preferred embodiment of the present invention, a shear key is provided inside the shell, and the shear key is located at the connection between the shell and the inner cavity to ensure that the joint surface between the pier top beam segment and the next box girder assembly segment can withstand and transmit shear force.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. This invention divides the pier top beam into a precast concrete shell and a cast-in-place concrete cavity. The shell and cavity consist of different parts and are prepared using different construction methods. The shell is prefabricated in a factory and then transported to the site for installation. The precast shell is lightweight and thin, reducing the weight of the precast segments by 30-50% compared to the precast pier top beam, which facilitates transportation and hoisting. The pier top segment beam provided by this invention has global stability and seismic performance. Eliminating the wet joint design of the cast-in-place beam ensures the installation speed of segment assembly. Reducing the longitudinal splicing joints of the beam ensures the safety of the beam.

[0024] 2. The construction method of the pier top beam of the present invention first installs the precast shell of the pier top beam onto the pier. After the precast shell is erected in place, the steel bars are tied. The shell can be used as a formwork for the pouring of the concrete in the beam. Then the prestressed tendons are tensioned to complete the construction of the pier top beam. The construction method is simple, the pier top beam has strong integrity, ensures the safety of the load in the later stage, and improves the structural safety and economy of the pier top beam. Attached image description:

[0025] Figure 1 This is a cross-sectional view of the pier top crossbeam of the internal cavity prefabricated segmental assembly in Example 1;

[0026] Figure 2 for Figure 1 Cross-sectional view along direction A;

[0027] Figure 3 for Figure 1 Cross-sectional view along direction B;

[0028] Figure 4 This is a schematic diagram of the reinforcement binding inside the crossbeam at the top of the pier according to the present invention;

[0029] Figure 5 This is a schematic diagram of the installation of the fixed pier and the crossbeam at the top of the pier according to the present invention;

[0030] Figure 6 A schematic diagram showing the installation of the pier and the crossbeam at the top of the pier with supports for this invention;

[0031] Figure 7 This is a schematic diagram showing the arrangement of prestressed tendons within the crossbeam at the pier top of the present invention.

[0032] Figure 8 This is a schematic diagram illustrating the setting of the shear key within the crossbeam at the pier top of the present invention.

[0033] The markings in the diagram are: 1-shell, 11-first top plate, 12-first web plate, 13-first bottom plate, 14-flange plate, 15-groove, 16-chamfer, 2-inner cavity, 21-second top plate, 22-second web plate, 23-second bottom plate, 24-partition, 25-manhole, 3-pier, 41-shear prestressed tendon of the crossbeam, 42-longitudinal internal tendon of the main beam, 43-transverse tendon of the bridge deck, 44-longitudinal external tendon of the main beam, 45-bending prestressed tendon of the crossbeam, 46-shear key. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to experimental examples and specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0035] Example 1

[0036] The pier top crossbeam, installed at the top of the pier, is a large cantilevered crossbeam extending transversely to both sides of the pier. It is a key component in the bridge structure for transmitting longitudinal dead and live loads. The pier top crossbeam structure includes a bottom plate, a top plate, web plates, and flange plates. The bottom and top plates are arranged in parallel. There are two web plates, located between the bottom and top plates to connect them. The two web plates are inclined outwards between the bottom and top plates. There are two flange plates, located on either side of the top plate. To address the problems of large size and heavy weight of prefabricated pier top crossbeams, making them difficult to transport, and the poor overall integrity of segmented prefabricated pier top crossbeams, an internal cavity-type prefabricated segmental assembly pier top crossbeam is provided.

[0037] A precast segmental pier top beam with an internal cavity is disclosed. The top plate is divided into a first top plate 11 and a second top plate 21, with the second top plate 21 located in the middle of the first top plate 11. The bottom plate is divided into a first bottom plate 13 and a second bottom plate 23, with the second bottom plate 23 located in the middle of the first bottom plate 13. The web is divided into a first web 12 and a second web 22 that fit together, with the second web 22 located inside the first web 12. The pier top beam structure includes a shell 1 and an internal cavity 2. The shell 1 includes the first top plate 11, the first bottom plate 13, the first web 12, and a flange plate 14. The shell 1 is a precast reinforced concrete component. The internal cavity 2 includes the second top plate 21, the second bottom plate 23, and the second web 22. The internal cavity 2 is a cast-in-place reinforced concrete structure.

[0038] like Figure 1 As shown, the main structure of the pier top beam includes a shell and an inner cavity. The shell 1 is a precast reinforced concrete component, and the inner cavity 2 is a cast-in-place reinforced concrete structure. Figure 1 , Figure 2 , Figure 3As shown, in the vertical direction, the top plate is divided into a first top plate 11 and a second top plate 21 that fit together. The first top plate 11 is located outside the second top plate 21, and the second top plate 21 is located in the middle of the first top plate 11. For the shell 1, this is equivalent to setting a groove in the middle of the first top plate 11 to facilitate the secondary on-site casting of the inner cavity 2. Similarly, in the vertical direction, the bottom plate is divided into a first bottom plate 13 and a second bottom plate 23 that fit together. The second bottom plate 23 is located in the middle of the first bottom plate 13. The web is divided into a first web 12 and a second web 22 that fit together. The second web 22 is located inside the first web 12. The thickness of the top plate of the pier top beam is determined according to the stress condition during the hoisting of the shell 1. Generally, during the hoisting of the pier top beam shell 1, the first top plate 11 bears the shear force transmitted by the entire hoisting weight. In this embodiment, the thickness of the top plate is twice that of the top plate of a conventional box girder. The thickness of the bottom plate of the pier top beam is determined by comprehensively considering the stress condition of shell 1 when it is stored in the prefabrication plant and the height of the compression zone of the bottom plate of the pier top beam after the bridge construction is completed. Generally, the bottom plate needs to be appropriately thickened according to the calculation.

[0039] In some embodiments, the pier top crossbeam further includes a partition 24, which is disposed between the bottom plate and the top plate, located between the two web plates, and belongs to the inner cavity 2. In the above technical solution, the pier top crossbeam also includes a partition 24, which is a cast-in-place reinforced concrete structure. Specifically, one partition 24 is provided, and a manhole 25 is provided between the partition 24 and the web plate for bridge maintenance, such as... Figure 1 As shown. The manhole 25 is set in the transverse direction of the bridge, passing through the crossbeam at the top of the pier. There are two manholes 25. The number of manholes 25 varies depending on the project and is not specifically limited here.

[0040] The connection between the first top plate 11 and the second top plate 21 is the first joint; the connection between the first web plate 12 and the second web plate 22 is the second joint; and the connection between the second bottom plate 23 and the second bottom plate 23 is the third joint. A groove 15 is provided at the second joint. The groove 15 increases the contact area between the precast reinforced concrete shell 1 and the cast-in-place reinforced concrete inner cavity 2, thereby increasing the bonding strength and making the precast concrete shell 1 and the inner cast-in-place section more tightly connected, thus increasing the longitudinal and vertical shear resistance of the beam. Specifically, the groove 15 at the second joint is concave outwards, such as... Figure 1 As shown.

[0041] Meanwhile, the groove 15 at the second joint is chamfered 16. The chamfer 16 can further increase the contact area between the precast reinforced concrete shell 1 and the cast-in-place reinforced concrete inner cavity 2, increase the bonding strength, and make the connection between the shell 1 and the inner cavity 2, that is, the first web 12 and the second web 22, smoother, and prevent stress concentration at the right angle connection.

[0042] In the technical solution of this invention, the pier top beam is divided into a precast concrete shell 1 and a cast-in-place concrete inner cavity 2. The shell 1 and the inner cavity 2 include different parts and are prepared using different construction methods. The shell 1 is prefabricated in the factory and then transported to the site for installation. The precast shell 1 is lightweight and thin, reducing the weight of the precast segments by 30-50% compared to the precast pier top beam, which facilitates transportation and hoisting. This invention provides the overall stability and seismic performance of the pier top segment beam, eliminates the wet joint design of the cast-in-place beam, and ensures the installation speed of segment assembly; it also reduces the longitudinal splicing joints of the beam, ensuring the safety of the beam.

[0043] Example 2

[0044] This embodiment provides an internal cavity prefabricated segmental assembly pier top crossbeam. The pier top crossbeam structure is similar to that of Embodiment 1. In this embodiment, the pier top crossbeam structure is provided with prestressed tendons. The prestressed tendons include shear prestressed steel tendons of the crossbeam, longitudinal internal tendons of the main beam, transverse steel tendons of the bridge deck, and longitudinal external tendons of the main beam. The shear prestressed steel tendons of the crossbeam are arranged in the bottom slab along the longitudinal direction of the bridge. The longitudinal internal tendons of the main beam are arranged in the top slab along the transverse direction of the bridge. The transverse steel tendons of the bridge deck are arranged in the top slab along the longitudinal direction of the bridge. The longitudinal external tendons of the main beam are arranged in the web along the transverse direction of the bridge.

[0045] Example 3

[0046] This embodiment provides a construction method for a precast segmental pier top beam with an internal cavity, used to complete the construction of the pier top beam structure in Embodiment 1. The construction method includes the following steps:

[0047] Step S1: Transport the prefabricated shell 1 to the installation position and install the shell 1 on the bridge pier 3;

[0048] Step S2: After the shell 1 is installed, the reinforcing bars of the inner cavity 2 are tied, and the concrete of the inner cavity 2 is poured using the shell 1 as a template for curing.

[0049] Step S3: Tension the prestressed tendons.

[0050] When hoisting the shell 1, the hoisting point of the shell 1 is set on the first top plate 11, and a 50mm hole is reserved on the first top plate 11 for hoisting with finely rolled threaded steel bars.

[0051] In step S2, some of the reinforcing bars in the inner cavity 2 are prefabricated in the factory, and some are tied on-site. The reinforcing bars in the inner cavity 2 need to be welded or bolted. The stirrups are partially prefabricated and partially cast in place, and then welded together on-site to form a whole. Figure 4 As shown. When a manhole 25 for maintenance is installed inside the crossbeam at the top of the pier, the formwork for the manhole 25 can be erected when the reinforcing steel is tied at the top of the pier.

[0052] The pier 3 is a fixed pier. When binding the reinforcing bars of the inner cavity 2, the reinforcing bars of the pier 3 are inserted into the shell 1 and connected to the reinforcing bars in the second bottom plate 23, such as... Figure 5 As shown. For the fixed pier, the bottom slab of the pier top beam has the pier 3 steel reinforcement extending into it, so it is not necessary to set up a casting form at the bottom slab. However, it is necessary to take good sealing measures between the bottom slab and the pier beam to prevent grout leakage.

[0053] In some embodiments, the pier 3 is a pier with supports, and mounting holes are provided in the second base plate 23 for the installation of the supports; when tying the reinforcing bars of the inner cavity 2 in step S2, a template for the mounting holes is set in the second base plate 23, and a steel plate for the supports is pre-embedded in the second base plate 23, such as... Figure 6 As shown.

[0054] The prestressed tendons include shear prestressed steel tendons 41 for the crossbeams, longitudinal internal tendons 42 for the main beams, transverse steel tendons 43 for the bridge deck, and external longitudinal tendons 44 for the main beams. The shear prestressed steel tendons 41 for the crossbeams are arranged longitudinally within the bottom slab. The longitudinal internal tendons 42 for the main beams are arranged transversely within the top slab. The transverse steel tendons 43 for the bridge deck are arranged longitudinally within the top slab. The external longitudinal tendons 44 for the main beams are arranged transversely within the web. Figure 7 As shown, the prestressed tendons are tensioned in the following order: shear-resistant prestressed steel tendons 41 of the crossbeam, longitudinal internal tendons 42 of the main beam, transverse steel tendons 43 of the bridge deck, and longitudinal external tendons 44 of the main beam. The shear-resistant prestressed steel tendons 41 of the crossbeam penetrate the precast first base plate 13 and the cast-in-place second base plate 23, which can increase the connection strength between the shell 1 and the inner cavity 2 to resist the shear effect at the joint of the first base plate 13 and the second base plate 23.

[0055] Furthermore, the prestressing tendons also include transverse beam bending prestressing tendons 45. For large cantilever box girders, transverse beam bending prestressing tendons 45 need to be installed within the transverse beam at the pier top to counteract the negative bending moment internal force at the top of the transverse beam support, ensuring that the top slab meets the requirements for Class A prestressed concrete components. Whether to install transverse beam bending prestressing tendons 45 is determined based on the actual situation. The transverse beam bending prestressing tendons 45 are installed within the top slab and the web, maintaining a certain distance between the transverse beam bending prestressing tendon 45 ducts and the longitudinal prestressing tendons 42 to ensure that the concrete can fill and vibrate. The transverse beam bending prestressing tendons 45 are tensioned before the transverse beam shear prestressing tendons 41 are tensioned.

[0056] Furthermore, shear keys 46 are provided in the top plate, bottom plate, and web plate of the shell 1. These shear keys 46 are located at the connection between the shell 1 and the inner cavity 2 to ensure that the joint surface between the pier top beam segment and the next box girder assembly segment can withstand and transmit shear force. Specifically, as shown... Figure 8 As shown, shear keys 46 are installed in the top plate, bottom plate and web plate.

[0057] For the construction of the fixed pier, before the construction of the pier top beam, a steel reinforcement frame is pre-embedded on the top of pier 3, and a beam construction platform is erected. Temporary pads and hydraulic jacks are placed sequentially on the beam construction platform. When hoisting the shell 1, the hoisting equipment can be an integrated bridge erecting machine or a crawler crane, depending on the actual situation. The prefabricated shell 1 is slowly hoisted to the designated position, and the bottom plate of the pier top beam rests on the hydraulic jack support, allowing the steel reinforcement of pier 3 to extend into the shell 1, sealing the gap between the first bottom plate 13 and pier 3. The transverse steel reinforcement inside the inner cavity 2 is tied, a manhole 25 is reserved, and the concrete of the inner cavity 2 is poured to complete the pier top beam construction. The hydraulic jacks and beam construction platform are then removed.

[0058] For the construction of the pier top supports, before the construction of the pier top crossbeam, a steel reinforcement frame is pre-embedded on the top of pier 3, and a crossbeam construction platform is erected. Temporary pads and hydraulic jacks are placed sequentially on the crossbeam construction platform, and permanent pad stones and permanent supports are placed on the pier top. When hoisting the shell 1, the hoisting equipment can be an integrated bridge erecting machine or a crawler crane, depending on the actual situation. The precast shell 1 is slowly hoisted to the designated position, the bottom plate of the pier top crossbeam rests on the hydraulic jack support, the steel reinforcement inside pier 3 extends into the shell 1, a formwork is erected under the bottom plate, the transverse steel reinforcement inside the inner cavity 2 is tied, a manhole 25 is reserved, and the concrete of the inner cavity 2 is poured to complete the construction of the pier top crossbeam.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cavity-type prefabricated segmental assembly pier top crossbeam, characterized in that, The top plate is divided into a first top plate (11) and a second top plate (21), with the second top plate (21) located in the middle of the first top plate (11). The bottom plate is divided into a first bottom plate (13) and a second bottom plate (23), with the second bottom plate (23) located in the middle of the first bottom plate (13). The connection between the first top plate (11) and the second top plate (21) is the first joint. The connection between the first web plate (12) and the second web plate (22) is the second joint. The connection between the second bottom plate (23) and the second bottom plate (23) is the third joint. A groove (15) is provided at the second joint. The web is divided into a first web (12) and a second web (22) that fit together. The second web (22) is located inside the first web (12). The pier top beam structure includes a shell (1) and an inner cavity (2). The shell (1) includes a first top plate (11), a first bottom plate (13), a first web (12), and a flange plate (14). The shell (1) is a precast reinforced concrete component. The inner cavity (2) includes a second top plate (21), a second bottom plate (23), and a second web (22). The inner cavity (2) is a cast-in-place reinforced concrete structure. The thickness of the bottom plate is determined based on the stress condition of the shell when it is stored in the prefabrication plant and the height of the compression zone of the bottom plate of the pier top beam after the bridge construction is completed. The construction method for the pier top crossbeam includes the following steps: Step S1: Transport the prefabricated shell (1) to the installation position and install the shell (1) on the bridge pier (3); Step S2: After the shell (1) is installed, the reinforcing bars of the inner cavity (2) are tied, and the concrete of the inner cavity (2) is poured using the shell (1) as a template for curing. Step S3, tensioning the prestressed tendons; the prestressed tendons include shear prestressed steel tendons (41) of the crossbeam, longitudinal internal tendons (42) of the main beam, transverse steel tendons (43) of the bridge deck, and longitudinal external tendons (44) of the main beam. The shear prestressed steel tendons (41) of the crossbeam are arranged in the bottom slab along the longitudinal direction of the bridge. The longitudinal internal tendons (42) of the main beam are arranged in the top slab along the transverse direction of the bridge. The transverse steel tendons (43) of the bridge deck are arranged in the top slab along the longitudinal direction of the bridge. The longitudinal external tendons (44) of the main beam are arranged in the web along the transverse direction of the bridge. The prestressed tendons are tensioned in the following order: shear prestressed steel tendons (41) of the crossbeam, longitudinal internal tendons (42) of the main beam, transverse steel tendons (43) of the bridge deck, and longitudinal external tendons (44) of the main beam.

2. The cavity-type prefabricated segmental assembly pier top crossbeam according to claim 1, characterized in that, The groove (15) at the second joint has a chamfered edge (16).

3. The cavity-type prefabricated segmental assembly pier top crossbeam according to claim 1, characterized in that, The pier top beam also includes a partition (24), which is disposed between the bottom plate and the top plate. The partition (24) is located between the two web plates and belongs to the inner cavity (2).

4. The cavity-type prefabricated segmental assembly pier top crossbeam according to claim 1, characterized in that, The pier (3) is a fixed pier. When binding the steel bars of the inner cavity (2), the steel bars of the pier (3) are inserted into the shell (1) and connected with the steel bars in the second bottom plate (23).

5. The cavity-type prefabricated segmental assembly pier top crossbeam according to claim 1, characterized in that, The pier (3) is a pier with a support. An installation hole is provided in the second base plate (23) for the installation of the support. When the steel bars of the inner cavity (2) are tied in step S2, an installation hole template is set in the second base plate (23), and a steel plate for the support is pre-embedded in the second base plate (23).

6. The cavity-type prefabricated segmental assembly pier top crossbeam according to claim 1, characterized in that, The prestressed tendons also include the beam bending prestressed tendons (45), which are disposed in the top plate and the web plate. The beam bending prestressed tendons (45) are tensioned before the beam shear prestressed steel tendons (41) are tensioned.

7. The cavity-type prefabricated segmental assembly pier top crossbeam according to claim 1, characterized in that, A shear key (46) is provided inside the shell (1), and the shear key (46) is located at the connection between the shell (1) and the next box girder assembly segment.

Images