A highway pile-slab structure connecting joint based on iron-based shape memory alloy

Abstract

The utility model discloses a highway stake board structure connecting joint based on iron base shape memory alloy, including prefabricated concrete slab, prefabricated PRC pipe pile, set between the rubber washer, and the Fe -SMA prestressed reinforcement material of vertical in -order penetration connection in the prefabricated concrete slab, rubber washer and prefabricated PRC pipe pile, the inside of prefabricated PRC pipe pile is provided with pipe pile reinforcement cage, and the pipe pile reinforcement cage is composed of the longitudinal ordinary reinforcement that a plurality of along the circumferential direction is alternately distributed, longitudinal ordinary prestressed reinforcement, longitudinal Fe -SMA prestressed reinforcement and annular spiral hoop reinforcement and Fe -SMA prestressed strip. The utility model node structure adopts longitudinal Fe -SMA prestressed reinforcement and annular Fe -SMA prestressed strip, realizes the delay structure cracking, and need not use additional reinforcing material and construction equipment, simplifies the repair procedure, and repairs high -efficient, reduces the repair cost.

Description

Technical Field

[0001] This utility model relates to a prefabricated highway pile-slab structure connection node, specifically a highway pile-slab structure connection node based on iron-based shape memory alloy, belonging to the technical field of prefabricated pile-slab roadbed structure. Background Technology

[0002] Prefabricated highway pile-slab structures offer advantages such as saving land resources, shortening construction time, reducing project costs, and minimizing subgrade settlement. However, in recent years, due to various reasons, these structures have experienced issues such as cracks in the exposed pipe piles above ground and cracking or damage at the joints between the pipe piles and precast slabs. These problems not only affect the structural appearance but also pose potential safety hazards. Furthermore, the pile-slab connection area is a region with complex stress distribution, making it highly susceptible to cracking and damage to the pile head concrete or yielding of the reinforcing steel under seismic loads. This can lead to weak points in the structure's seismic resistance, thus requiring further improvement in its seismic performance.

[0003] Currently, for problems such as pile body cracks that have appeared in prefabricated pile-slab structures, existing technologies mostly rely on traditional grouting, steel plate wrapping, or carbon fiber cloth reinforcement and repair techniques. These reinforcement and repair methods are not only complex and time-consuming, but also require additional reinforcement materials and equipment, resulting in high maintenance costs. Furthermore, regarding the seismic design of pile-slab joints in prefabricated pile-slab structures, existing technologies have developed semi-rigid seismic joint structures based on ductile design principles. For improving the seismic performance of joints, there are also self-resetting technologies for pile-slab joints based on existing prestressed tendons, such as the Chinese invention patent with authorization announcement number CN114808928B. However, these technologies still require replacing relevant components and re-performing prestressing and other corresponding construction procedures, making the repair process cumbersome and increasing maintenance costs and labor.

[0004] Therefore, there is an urgent need to design a highway pile-slab connection node structure that does not require additional equipment and materials and can solve the problems of exposed pile cracks and pile-slab joint damage through self-healing function. Utility Model Content

[0005] The purpose of this invention is to overcome the problem that existing prefabricated pile-slab structures require additional reinforcement materials and equipment for repairing exposed pile cracks and pile-slab joint damage, resulting in complex and time-consuming repair procedures. This invention provides a highway pile-slab structure connection node based on iron-based shape memory alloy, employing longitudinal Fe-SMA prestressed tendons and circumferential Fe-SMA prestressed strips, and using electric heating for prestress compensation to achieve intelligent structural repair without the need for additional reinforcement materials and construction equipment. This simplifies the repair process, increases repair efficiency, and reduces repair costs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a highway pile-slab structure connection node based on iron-based shape memory alloy, including a precast concrete slab located above, a precast PRC pipe pile at the bottom, a rubber gasket set between the two, and Fe-SMA prestressed tendons that vertically and sequentially connect the precast concrete slab, the rubber gasket and the precast PRC pipe pile. The precast PRC pipe pile has multiple reserved pipes evenly distributed along the circumferential direction in the axial direction. The precast concrete slab and rubber gasket are respectively provided with reserved pipes and reserved holes for vertically penetrating and connecting Fe-SMA prestressed tendons at corresponding positions above and below the multiple reserved pipes. The upper end of the Fe-SMA prestressed tendon is anchored in the reserved groove at the top of the precast concrete slab and is fixedly connected to the precast concrete slab by mortar pouring. Its lower end is anchored on the outer surface of the precast PRC pipe pile. At the connection point between the precast concrete slab and the pile head of the precast PRC pipe pile, a precast slab extended steel cage is provided, extending out of the slab. The upper end of the precast slab extended steel cage is tied or welded to the inner steel cage of the precast concrete slab to form an integral steel skeleton, and the lower end extends into the inner hole of the precast PRC pipe pile. The outer circumference of the precast slab extended steel cage is also wrapped with an annular columnar rubber pad. The precast PRC pipe pile has a pipe pile reinforcement cage inside. The pipe pile reinforcement cage consists of multiple longitudinal ordinary steel bars, longitudinal ordinary prestressed steel bars, and longitudinal Fe-SMA prestressed tendons that are alternately distributed along the circumference, as well as circumferential spiral stirrups and multiple Fe-SMA prestressed strips arranged in the radial direction. The two ends of the longitudinal Fe-SMA prestressed tendons are anchored to the precast pipe pile end plates at both ends of the precast pipe pile, and Fe-SMA prestressed tendon electro-excitation ports are provided on the precast pipe pile end plates. The Fe-SMA prestressed strips are distributed axially and spaced upward along the outer circumference of the pipe pile reinforcement cage, and Fe-SMA prestressed strip electro-excitation ports located outside the pile body are provided at both ends of each Fe-SMA prestressed strip.

[0007] Furthermore, the length of the precast slab extended reinforcing cage extending into the precast PRC pipe pile is three times the diameter of the precast PRC pipe pile; the precast slab extended reinforcing cage is composed of multiple precast slab extended reinforcing cage longitudinal bars and precast slab extended reinforcing cage stirrups connected to form a cylindrical structure, wherein the precast slab extended reinforcing cage longitudinal bars and precast slab extended reinforcing cage stirrups are all ordinary reinforcing bars.

[0008] Furthermore, the diameter of the cylinder formed by the longitudinal bars of the precast slab's extended reinforcing cage is 120mm, and the spacing between the stirrups of two adjacent precast slab extended reinforcing cages is 80mm.

[0009] Furthermore, the outer diameter of the rubber pad is smaller than the inner diameter of the annular cross-section of the precast PRC pipe pile.

[0010] Furthermore, the reserved pipeline is located on the upper part of the precast PRC pipe pile within a length range of three times the pile diameter from the top of the pipe pile.

[0011] Furthermore, there are 4 longitudinal Fe-SMA prestressing tendons, 8 longitudinal ordinary prestressing tendons, and 12 longitudinal ordinary tendons, and all three are symmetrical about the center of the cross section.

[0012] Furthermore, the circumferential spiral stirrups include a first spiral stirrup and a second spiral stirrup, with the first spiral stirrups provided at both ends near the precast PRC pipe pile and the spacing of the first spiral stirrups being 45mm; and the second spiral stirrups provided at the middle of the precast PRC pipe pile and the spacing of the second spiral stirrups being 80mm.

[0013] Furthermore, both the Fe-SMA prestressing tendons and the longitudinal Fe-SMA prestressing tendons are 20mm Fe-SMA threaded tendons with a pre-tension strain of 6%.

[0014] Furthermore, the Fe-SMA prestressed strip is a 100mm wide and 3mm thick Fe-SMA strip with a pre-tension strain of 4%.

[0015] The beneficial effects of this utility model are: 1) In the node structure of this utility model, a certain number of Fe-SMA prestressing tendons are configured at the joint position of the precast PRC pipe pile and the pile plate. When the structure is in normal use, Fe-SMA can play the role of ordinary steel bars, ordinary prestressing tendons or ordinary stirrups. When the structure cracks or horizontal misalignment occurs between the pile and the plate under seismic action, the recovery characteristics of Fe-SMA can be triggered by electric heating to generate prestress. According to the stress requirements of the structure, the corresponding prestress is applied to realize the reduction of structural cracks, self-closure and self-resetting of horizontal residual deformation of pile plate at the pile plate joint, so that the structure has the functions of self-resetting and intelligent repair.

[0016] 2) In the node structure of this utility model, the longitudinal Fe-SMA prestressed tendons and circumferential Fe-SMA prestressed strips are pre-set inside the lower precast pipe pile. By electrically heating the two types of Fe-SMA prestressed tendons, a certain longitudinal prestress and circumferential constraint force can be applied to the pile body to reduce and delay the generation and extension of longitudinal and circumferential cracks in the pile body.

[0017] 3) In the process of repairing and reinforcing the pile-slab structure and connection nodes based on Fe-SMA in the node structure of this utility model, the additional material reinforcement structure is reduced, and no additional construction equipment is required. Only the Fe-SMA is electrically stimulated, which makes the construction efficient and the repair quick, and can reduce the cost of structural reinforcement, repair and maintenance.

[0018] 4) In the node structure of this utility model, by inserting the precast concrete slab with the extended steel cage and the outer rubber block into the inner hole of the precast pipe pile, the pile-slab node forms a multi-structure energy dissipation mechanism, including the plastic deformation of the precast concrete slab with the extended steel cage under strong earthquakes, the elastic deformation of the outer rubber pad, the reciprocating horizontal misalignment between the pile and the slab, and the high ductility plastic energy dissipation of Fe-SMA, thereby effectively enhancing the seismic performance of the pile-slab structure connection node.

[0019] 5) The pile-slab joint in this utility model adopts a semi-rigid connection design. By setting rubber pads between the piles and slabs, extending the steel cage outside the concrete slab and covering it with rubber pads, the rotation capacity of the pile-slab joint is improved. This can effectively reduce the stress concentration in the pile-slab joint area, reduce cracking of the pile head concrete, and improve the local bearing capacity and durability of the pile-slab connection joint. Attached Figure Description

[0020] Figure 1 This is a structural schematic diagram of the connection node of the pile-slab structure of this utility model; Figure 2 This is a schematic diagram of the reinforcement arrangement at the connection node of the pile-slab structure of this utility model; Figure 3 for Figure 2 Schematic diagram of the reinforcement arrangement in precast concrete slabs; Figure 4 for Figure 2 A structural schematic diagram of the internal reinforcement arrangement of precast PRC pipe piles; Figure 5 for Figure 2 Schematic diagram of the structure of the rubber gasket; Figure 6 for Figure 2 Schematic diagram of the cross-sectional structure at point AA; Figure 7 for Figure 2 A schematic diagram of the cross-sectional structure at point BB.

[0021] In the figure, 1-precast concrete slab, 2-precast slab extended reinforcing cage, 201-longitudinal reinforcement of precast slab extended reinforcing cage, 202-stirrups of precast slab extended reinforcing cage, 3-precast PRC pipe pile, 4-rubber gasket, 401-Fe-SMA hole, 5-inner reinforcing cage of precast PRC pipe pile, 501-longitudinal ordinary reinforcing bar, 502-longitudinal ordinary prestressed reinforcing bar, 503-longitudinal Fe-SMA prestressed tendon, 504-first spiral stirrup, 505-second spiral stirrup, 6-Fe-SMA pipe, 7-Fe-SMA prestressed tendon, 8-rubber block, 9-Fe-SMA prestressed strip, 10-precast PRC pipe pile end plate, 11-Fe-SMA prestressed tendon electro-excitation port, 12-Fe-SMA prestressed strip electro-excitation port. Detailed Implementation

[0022] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0023] Example: Figures 1-3 As shown, this utility model provides a highway pile-slab structure connection node based on iron-based shape memory alloy, including a precast concrete slab 1 located above, a precast PRC pipe pile 3 located below, a rubber gasket 4 set between the two, and Fe-SMA prestressed tendons 7 that are vertically connected to the precast concrete slab 1, the rubber gasket 4 and the precast PRC pipe pile 3.

[0024] The precast PRC pipe pile 3 has multiple reserved pipes 6 evenly distributed circumferentially in the axial direction. The reserved pipes 6 are located within a length of three times the pile diameter from the top of the precast PRC pipe pile 3. The precast concrete slab 1 and the rubber gasket 4 have reserved pipes 6 and reserved holes 401 at corresponding positions above and below the multiple reserved pipes 6 for vertically penetrating and connecting the Fe-SMA prestressed tendons 7, as shown below. Figure 5 As shown; the upper end of the Fe-SMA prestressed tendon 7 is anchored in the reserved groove on the top of the precast concrete slab 1 and is fixedly connected to the precast concrete slab 1 by mortar pouring, and its lower end is anchored on the outer surface of the precast PRC pipe pile 3; the Fe-SMA prestressed tendon 7 vertically passes through the reserved pipe 6, the reserved hole 11 of the rubber gasket 4 and the reserved pipe 6 at the top of the precast PRC pipe pile 3 in sequence; by electrically heating both ends of the Fe-SMA prestressed tendon 7, prestress can be applied to it to realize the pile-slab joint connection.

[0025] When the seismic load is large, horizontal misalignment will occur between the precast concrete slab 1 and the precast pipe pile 3. However, due to the vertical prestressing effect of the Fe-SMA prestressed tendon 7, there is a tension effect that pulls the horizontally misaligned upper and lower structures back to their original positions. Therefore, the Fe-SMA prestressed tendon 7 plays the role of self-resetting function of the pile-slab joint after the earthquake. After the disaster, when the pile-slab joint undergoes large plastic deformation, the lost prestress can be compensated or the original prestress can be increased by electrically stimulating the Fe-SMA prestressed tendon 7, which plays the role of temporarily reinforcing the pile-slab joint. The construction is convenient, efficient and quick, and no additional materials and equipment are required.

[0026] The inner and outer ring diameters of the rubber washer 4 are the same as the inner and outer diameters of the precast PRC pipe pile 3. The top and bottom surfaces of the washer 4 are in close contact with the top of the precast concrete slab 1 and the precast PRC pipe pile 3 below, respectively, forming a deformation and stress buffer layer to accommodate the relative displacement and stress concentration between the pile and the slab due to the load. It can also absorb some vibration energy and reduce the vibration response of the pile and slab structure.

[0027] like Figure 2 and Figure 3As shown, a precast concrete slab extension steel cage 2 is provided at the connection position between the precast concrete slab 1 and the pile head of the precast PRC pipe pile 3, extending beyond the slab. The upper end of the precast concrete slab extension steel cage 2 is tied or welded to the inner steel cage of the precast concrete slab 1 to form an integral steel skeleton, and the lower end extends into the inner hole of the precast PRC pipe pile 3. The outer circumference of the precast concrete slab extension steel cage 2 is also wrapped with an annular cylindrical rubber pad 8. The outer diameter of the rubber pad 8 is smaller than the inner diameter of the annular section of the precast PRC pipe pile 3, so as to facilitate the hoisting of the upper precast concrete slab 1 during construction, so that the precast concrete slab extension steel cage 2 can be inserted from top to bottom into the inner hole of the corresponding section of the lower precast PRC pipe pile 3. The rubber pad 8 can protect the precast concrete slab extension steel cage 2 from corrosion caused by the external environment, and its elastic deformation can adapt to the relative deformation between the pile and the slab, reducing local stress concentration at the pile-slab joint.

[0028] like Figure 2 As shown, the length of the precast slab extended steel cage 2 extending into the precast PRC pipe pile 3 is three times the diameter of the precast PRC pipe pile 3, ensuring that the pile-slab joint has sufficient lap length.

[0029] like Figure 3 and Figure 6 As shown, the precast slab extended reinforcing cage 2 is composed of multiple precast slab extended reinforcing cage longitudinal bars 201 and precast slab extended reinforcing cage stirrups 202 connected to form a cylindrical structure. Both the precast slab extended reinforcing cage longitudinal bars 201 and precast slab extended reinforcing cage stirrups 202 are ordinary reinforcing bars. The diameter of the cylinder formed by the multiple precast slab extended reinforcing cage longitudinal bars 201 is 120mm, and the spacing between two adjacent precast slab extended reinforcing cage stirrups 202 is 80mm. When the structure is subjected to a large earthquake, seismic energy is absorbed through the plastic deformation of the precast slab extended reinforcing cage 2, the elastic deformation of the outer rubber pad 8, and the lateral relative horizontal displacement between the pile and the slab, forming a semi-rigid joint design to improve the seismic performance of the structure.

[0030] like Figure 4 and Figure 7 As shown, the precast PRC pipe pile 3 has a pipe pile reinforcement cage 5 inside. The pipe pile reinforcement cage 5 consists of multiple longitudinal ordinary steel bars 501, longitudinal ordinary prestressed steel bars 502, and longitudinal Fe-SMA prestressed tendons 503 that are alternately distributed along the circumference, as well as circumferential spiral stirrups and multiple Fe-SMA prestressed strips 9 installed in the radial direction. For a pipe pile with a diameter of 600mm, there are 4 longitudinal Fe-SMA prestressed tendons 503, 8 longitudinal ordinary prestressed steel bars 502, and 12 longitudinal ordinary steel bars 501, and all three are symmetrical about the cross-section center.

[0031] The longitudinal Fe-SMA prestressing tendons 503 are anchored at both ends to the precast pipe pile end plates 10 at both ends of the precast PRC pipe pile 3, and Fe-SMA prestressing tendon electro-excitation ports 11 are reserved on the precast pipe pile end plates 10; Fe-SMA prestressing strips 9 are distributed axially along the outer circumference of the pipe pile reinforcement cage 5, and Fe-SMA prestressing strip electro-excitation ports 12 located outside the pile body are reserved at both ends of each Fe-SMA prestressing strip 9.

[0032] The circumferential spiral stirrups include a first spiral stirrup 504 and a second spiral stirrup 505. The first spiral stirrup 504 is set at both ends near the precast PRC pipe pile 3, and the spacing of the first spiral stirrup 504 is 45mm. The second spiral stirrup 505 is set at the middle of the precast PRC pipe pile 3, and the spacing of the second spiral stirrup 505 is 80mm.

[0033] Normally, the longitudinal Fe-SMA prestressed tendon 503 can function as ordinary reinforcement without generating prestress, playing the same role as ordinary steel bars. However, if transverse cracks occur in the precast pipe pile body during use, the Fe-SMA prestressed tendon 503 can be electrically stimulated through the Fe-SMA prestressed tendon electrostimulation port 11 to generate compensating prestress, applying longitudinal pressure to the pile body, causing the pile cracks to decrease or close, and also delaying the occurrence and propagation of cracks, thus achieving the self-repair function of transverse cracks in the pipe pile body. The Fe-SMA prestressed strip 9 can also be used as ordinary stirrups, but when longitudinal cracks occur in the pile body, the Fe-SMA prestressed strip 9 can be electrically stimulated through the anchoring Fe-SMA prestressed strip electrostimulation port 20 to generate self-prestress, generating circumferential active constraint on the precast PRC pipe pile 3, thereby causing the longitudinal cracks in the pile body to close, and effectively constraining the generation and propagation of vertical cracks in the pile concrete, thus achieving the self-repair function of longitudinal cracks in the pile body.

[0034] During the prefabrication stage of precast pipe piles, the longitudinal Fe-SMA prestressed tendons 503 and Fe-SMA prestressed strips 9 can be electrically stimulated in advance to generate prestress, which will have a pre-compression and circumferential restraint effect on the pile body in the longitudinal and circumferential directions, thereby actively preventing and slowing down the occurrence and development of pile cracks.

[0035] Southeast University, in collaboration with Liuzhou OVM Machinery Co., Ltd. and Fubai New Materials (Zhejiang) Co., Ltd., has developed and produced products in various specifications, including 15.2mm diameter Fe-SMA prestressed strands, 3mm thick Fe-SMA sheets, 10mm and 20mm diameter Fe-SMA threaded ribs, 100mm wide Fe-SMA strips, and 1.5mm and 5.20mm diameter Fe-SMA wires. Corresponding electro-excitation equipment is also available. The excitation temperature range for Fe-SMA materials is 100°C to 400°C, and the recovery stress that Fe-SMA can generate is approximately 200 to 400 MPa.

[0036] Fe-SMA prestressed reinforcement 7 uses 20mm Fe-SMA threaded reinforcement with a pre-tension strain of 6%, and is electrically heated to 300° to generate vertical prestress constraint.

[0037] The longitudinal Fe-SMA prestressed tendon 503 uses 20mm Fe-SMA threaded steel bar with a pre-tension strain of 6%. It is electrically heated to 300° to generate vertical prestress for passive reinforcement. Without electrical heating, it functions as ordinary longitudinal steel bar and is used in the normal service stage before structural reinforcement when no cracks have occurred.

[0038] Fe-SMA prestressed strip 9 is made of Fe-SMA strip with a width of 100mm and a thickness of 3mm, and is set at a longitudinal spacing of 1m along the precast PRC pipe pile 3. The pre-tension strain is 4%, and it is electrically heated to 300° to generate active circumferential prestress constraint.

[0039] Tables 1 and 2 below provide the electrical excitation parameters for Fe-SMA in concrete, offering a reference for electrical excitation in practical engineering. Appropriate electrical excitation conditions can be selected according to specific needs.

[0040] Table 1 shows the electrical excitation parameters for Fe-SMA prestressed tendons. Table 2 shows the electrical excitation parameters for Fe-SMA prestressed strips. In this utility model, a certain number of Fe-SMA prestressed longitudinal reinforcements are configured at the joint positions of precast PRC pipe piles and pile slabs. When the structure is in normal use, Fe-SMA can function as ordinary steel bars, ordinary prestressed tendons, or ordinary stirrups. When cracks appear in the structure or horizontal misalignment occurs between the piles and slabs under seismic action, the recovery characteristics of Fe-SMA can be triggered by electric heating to generate prestress. According to the stress requirements of the structure, corresponding prestress is applied to achieve the reduction of structural cracks, self-closure, and self-resetting of horizontal residual deformation of the pile slab at the pile-slab joint, so that the structure has self-resetting and intelligent repair functions.

[0041] The above description is only used to illustrate the technical solution of this utility model and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of this utility model, as long as they do not depart from the spirit and scope of the technical solution of this utility model, should be covered within the scope of the claims of this utility model.

Claims

1. A highway pile-slab structure connection node based on iron-based shape memory alloy, characterized in that: It includes a precast concrete slab (1) at the top, a precast PRC pipe pile (3) at the bottom, a rubber gasket (4) between the two, and Fe-SMA prestressed tendons (7) that are vertically connected to the precast concrete slab (1), the rubber gasket (4) and the precast PRC pipe pile (3). The precast PRC pipe pile (3) has multiple reserved pipes (6) evenly distributed along the circumferential direction in the axial direction. The precast concrete slab (1) and the rubber gasket (4) are respectively provided with reserved pipes (6) and reserved holes (401) for vertically penetrating and connecting Fe-SMA prestressed tendons (7) at the corresponding positions above and below the multiple reserved pipes (6). The upper end of the Fe-SMA prestressed tendon (7) is anchored in the reserved groove at the top of the precast concrete slab (1) and is fixedly connected to the precast concrete slab (1) by mortar pouring. Its lower end is anchored on the outer surface of the precast PRC pipe pile (3). At the connection point between the precast concrete slab (1) and the pile head of the precast PRC pipe pile (3), a precast slab extended steel cage (2) is provided extending out of the slab. The upper end of the precast slab extended steel cage (2) is tied or welded to the inner steel cage of the precast concrete slab (1) to form an integral steel skeleton, and the lower end extends into the inner hole of the precast PRC pipe pile (3). The outer circumference of the precast slab extended steel cage (2) is also wrapped with an annular columnar rubber pad (8). The precast PRC pipe pile (3) is equipped with a pipe pile reinforcement cage (5). The pipe pile reinforcement cage (5) is composed of multiple longitudinal ordinary steel bars (501), longitudinal ordinary prestressed steel bars (502), longitudinal Fe-SMA prestressed tendons (503) that are alternately distributed along the circumference, as well as circumferential spiral stirrups and multiple Fe-SMA prestressed strips (9) arranged along the radial direction. The two ends of the longitudinal Fe-SMA prestressed tendons (503) are anchored on the precast pipe pile end plates (10) at both ends of the precast PRC pipe pile (3), and Fe-SMA prestressed tendon electro-excitation ports (11) are provided on the precast pipe pile end plates (10). The Fe-SMA prestressed strips (9) are distributed at intervals along the outer circumference of the pipe pile reinforcement cage (5), and Fe-SMA prestressed strip electro-excitation ports (12) located outside the pile body are provided at both ends of each Fe-SMA prestressed strip (9).

2. The highway pile-slab structure connection node based on iron-based shape memory alloy according to claim 1, characterized in that: The length of the precast slab extended steel cage (2) extending into the precast PRC pipe pile (3) is three times the diameter of the precast PRC pipe pile (3); the precast slab extended steel cage (2) is composed of multiple precast slab extended steel cage longitudinal bars (201) and precast slab extended steel cage stirrups (202) connected to form a cylindrical structure, wherein the precast slab extended steel cage longitudinal bars (201) and precast slab extended steel cage stirrups (202) are both ordinary steel bars.

3. A highway pile-slab structure connection node based on iron-based shape memory alloy according to claim 2, characterized in that: The diameter of the cylinder formed by the longitudinal bars (201) of the precast slab extended steel cage is 120mm, and the spacing between two adjacent precast slab extended steel cage stirrups (202) is 80mm.

4. A highway pile-slab structure connection node based on iron-based shape memory alloy according to claim 1, characterized in that: The outer diameter of the rubber pad (8) is smaller than the inner diameter of the annular section of the precast PRC pipe pile (3).

5. A highway pile-slab structure connection node based on iron-based shape memory alloy according to claim 1, characterized in that: The reserved pipe (6) is set on the upper part of the precast PRC pipe pile (3) within a length of three times the pile diameter from the top of the pipe pile.

6. A highway pile-slab structure connection node based on iron-based shape memory alloy according to claim 1, characterized in that: The longitudinal Fe-SMA prestressed tendons (503) are provided in 4 pieces, the longitudinal ordinary prestressed tendons (502) are provided in 8 pieces, and the longitudinal ordinary tendons (501) are provided in 12 pieces, and all three are symmetrical about the center of the cross section.

7. A highway pile-slab structure connection node based on iron-based shape memory alloy according to claim 1, characterized in that: The circumferential spiral stirrups include a first spiral stirrup (504) and a second spiral stirrup (505). The first spiral stirrup (504) is set at both ends near the precast PRC pipe pile (3), and the spacing of the first spiral stirrup (504) is 45mm. The second spiral stirrup (505) is set at the middle of the precast PRC pipe pile (3), and the spacing of the second spiral stirrup (505) is 80mm.

8. A highway pile-slab structure connection node based on iron-based shape memory alloy according to claim 1, characterized in that: The Fe-SMA prestressing tendon (7) and the longitudinal Fe-SMA prestressing tendon (503) are both made of 20mm Fe-SMA threaded tendon with a pre-tension strain of 6%.

9. A highway pile-slab structure connection node based on iron-based shape memory alloy according to claim 1, characterized in that: The Fe-SMA prestressed strip (9) is a 100mm wide and 3mm thick Fe-SMA strip with a pre-tension strain of 4%.

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