An aging test apparatus for FRP bar-concrete pull-out specimens

Abstract

This invention relates to an aging test apparatus for FRP bar-concrete pull-out specimens, comprising two wet-dry circulation tanks, a circulation pipe, and a test fixture. One wet-dry circulation tank contains a solution, and the two tanks are connected by the circulation pipe. Each tank is equipped with a test fixture, which includes a mounting plate, a manual screw force application component, a tension sensor, and a limiting cylinder. The manual screw force application component is positioned above the mounting plate, and the tension sensor is located between the component and the plate. One end of the FRP bar in the pull-out specimen is connected upwards to the manual screw force application component. A limiting cylinder is positioned between the mounting plate and the concrete component, covering the FRP bar, and the solution immerses the concrete component. This invention enables precise adjustment and stable, continuous application of load force and can simulate wet-dry cycle conditions, allowing for the study of the long-term bond performance between FRP bars and concrete under wet-dry conditions.

Description

Technical Field

[0001] This utility model relates to the field of adhesion testing technology between materials, and in particular to an aging test device for FRP bar-concrete pull-out specimens. Background Technology

[0002] FRP bars are fiber-reinforced reinforcing bars with advantages such as light weight, high tensile strength, strong corrosion resistance, good fatigue performance, and high design flexibility. In actual engineering, FRP bars bear continuous loads during their service life. When studying the bond performance between FRP bars and concrete, FRP bars and concrete are cast together to form pull-out specimens, in which the two ends of the FRP bars extend out of the concrete member.

[0003] Conventional methods use jacks to apply continuous loads to FRP bars. However, the operational precision of the jacks needs improvement, and it is difficult to accurately monitor the real-time changes in the applied load during the test. Moreover, the test environment is relatively simple and does not take into account the influence of the natural environment, so it cannot effectively simulate the harsh environments that the pull-out specimens may be in, such as marine or humid environments. In other words, it is impossible to study the bonding performance of pull-out specimens under different natural environments. Summary of the Invention

[0004] To address the issues of insufficient operational precision and limited testing environments associated with conventional loading tools, this invention provides an aging test device for FRP bar-concrete pull-out specimens. The device utilizes a manual screw operation to continuously provide precise load force, incorporates wet-dry cycles to simulate tidal environments, and employs a tensile sensor to monitor force changes in real time during the test. This allows for the study of the long-term bond performance between FRP bars and concrete under wet-dry cycles and continuous load coupling conditions.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows: An aging test apparatus for FRP bar-concrete pull-out specimens includes two spaced-apart dry-wet circulation tanks, a circulation pipe equipped with a water pump, and a test fixture on which pull-out specimens are mounted. One of the dry-wet circulation tanks contains a solution, and the two dry-wet circulation tanks are connected by two circulation pipes to facilitate the circulation of the solution in the two dry-wet circulation tanks. Each of the aforementioned wet-dry circulation tanks is equipped with at least one test fixture, which includes a mounting plate, a manual screw force application component, a tension sensor, and a limiting cylinder. The mounting plate is detachably connected to the wet-dry circulation tank, facilitating the assembly and disassembly of the test fixture from the wet-dry circulation tank. The manual screw force application component is located above the mounting plate to facilitate the application of a continuous pulling force to the specimen. The tension sensor is located between the manual screw force application component and the mounting plate to facilitate the monitoring of real-time changes in the pulling force. One end of the FRP bar in the pull-out specimen passes upward through the mounting plate and is connected to the manual screw force application component. The manual screw force application component pulls the FRP bar upward. The limiting cylinder is set between the mounting plate and the concrete component of the pull-out specimen. The limiting cylinder is sleeved outside the FRP bar, and the solution immerses the concrete component.

[0006] Furthermore, a movable base frame is provided between the two dry and wet circulation tanks. The movable base frame is a steel structure plate frame with a certain strength to support the dry and wet circulation tanks. The movable base frame is provided with moving wheels and adjusting feet. The water pump on the circulation pipe is installed on the movable base frame. After the circulation pipe is connected to the dry and wet circulation tanks, the solution circulates in the two dry and wet circulation tanks.

[0007] Furthermore, mounting bolts are provided at the corners of the mounting plate, and the mounting bolts are threadedly connected to the top of the wet-dry circulation tank; The manual screw force application assembly includes a fixed outer cylinder, a lifting inner cylinder, and a screw block. The upper and lower ends of the fixed outer cylinder are open to facilitate the insertion of the lifting inner cylinder. The fixed outer cylinder and the lifting inner cylinder are coaxially arranged with a gap between them. The bottom of the fixed outer cylinder is bolted to the mounting plate. The top of the fixed outer cylinder is threadedly connected to the screw block, which rotates downward to connect with the top of the lifting inner cylinder, facilitating the up-and-down movement of the lifting inner cylinder. The tension sensor is installed between the bottom of the lifting inner cylinder and the mounting plate.

[0008] Furthermore, after the upper end of the FRP bar passes through the mounting plate, it enters the lifting inner cylinder. The upper end of the FRP bar is anchored to a steel pipe. The steel pipe is placed inside the lifting inner cylinder, the bottom of the lifting inner cylinder is closed, and the steel pipe is pressed against the bottom of the lifting inner cylinder. The lifting inner cylinder has a symmetrical two-part structure. The two parts of the lifting inner cylinder are bolted together to form a hollow cylinder, which facilitates the insertion of steel pipes into the lifting inner cylinder.

[0009] Furthermore, the screw block has an inverted "U" shaped cross section, a hand-tightening rod is inserted through the screw block, the lower end of the screw block extends into the top of the lifting inner cylinder, and a horizontal shaft is inserted through the lower end of the screw block; The inner wall of the top of the lifting inner cylinder is provided with a circular rotating groove for accommodating the horizontal shaft, and the two ends of the horizontal shaft are placed in the rotating groove for movement; the top two sides of the lifting inner cylinder are provided with through holes, which are connected to the rotating groove, and the horizontal shaft enters into the rotating groove through the through holes. Each through hole is also threaded with a limit pin to prevent the horizontal shaft from falling out of the rotating groove. The fixed outer cylinder has symmetrical through holes on both sides for the limit pins and the horizontal shaft to pass through and connect with the lifting inner cylinder.

[0010] Furthermore, the two ends of the tension sensor are threadedly connected to the lifting inner cylinder and the mounting plate, respectively, and the tension sensor is electrically connected to a data acquisition device, which is mounted on the mounting plate.

[0011] The beneficial effects of this utility model through the above technical solution are: This utility model has a reasonable structural design. The manual screw force application component in the test fixture can provide a stable and continuous pull-out force through screw rotation. The load application operation is simple; the required load can be adjusted by simply rotating the screw block. The applied pull-out force can act on the pull-out specimen, thereby applying a load to the FRP bar, and the magnitude of the pull-out force can be precisely controlled.

[0012] This utility model features a detachable, manually operated screw-type force application assembly that is easy to assemble and disassemble, facilitating connection with the pull-out specimen and thus securing the specimen to the testing fixture. A tension sensor, in conjunction with a data acquisition instrument, monitors the applied load in real time, accurately reflecting changes in the continuous load applied under wet-dry cycle conditions.

[0013] This invention proposes a wet-dry circulation tank, which allows the solution to circulate between two tanks via pumping. When the test fixture with the pull-out specimen is connected to the wet-dry circulation tank using mounting bolts, the test fixture can be stably and reliably placed on the tank. The concrete component is located inside the tank and submerged in the solution, thus simulating a wet-dry environment and thereby mimicking the degradation of the bond performance between FRP reinforcement and concrete under real-world application conditions.

[0014] This invention allows for the placement of at least one test fixture within a single wet-dry circulation tank. The number of test fixtures can be adjusted according to testing requirements, enabling the placement of multiple sets of test fixtures at once, reducing the number of test repetitions and thus improving testing efficiency. Except for the pull-out specimen, all other components of the entire testing device can be reused, improving the economic efficiency of the test. Attached Figure Description

[0015] Figure 1 This is a front view of an aging test device for FRP bar-concrete pull-out specimens according to this utility model.

[0016] Figure 2 This is a top view of an aging test device for FRP bar-concrete pull-out specimens according to this utility model.

[0017] Figure 3 This is a side view of an aging test device for FRP bar-concrete pull-out specimens according to this utility model.

[0018] Figure 4 This is a cross-sectional view of the testing fixture for an aging test device for FRP bar-concrete pull-out specimens according to this utility model.

[0019] Figure 5This utility model relates to an aging test device for FRP bar-concrete pull-out specimens. Figure 4 A schematic diagram showing the disassembly of the outer cylinder, which is not shown in the diagram.

[0020] Figure 6 This is a schematic diagram of the connection between the lifting inner cylinder and the steel pipe of an aging test device for FRP-concrete pull-out specimens according to this utility model.

[0021] Figure 7 This is a schematic diagram of the connection between the screw block and the lifting inner cylinder of an aging test device for FRP-concrete pull-out specimens according to this utility model.

[0022] Figure 8 This utility model relates to an aging test device for FRP bar-concrete pull-out specimens. Figure 7 Sectional view along the AA direction.

[0023] The attached diagram is labeled as follows: 1. Dry-wet circulation tank, 101. Support plate, 102. Reinforcing plate, 103. Flow plate, 2. Circulation pipe, 201. Water pump, 3. Pull-out test specimen, 31. Concrete component, 32. FRP reinforcement, 4. Mounting plate, 5. Manual screw force application component, 51. Fixed outer cylinder, 52. Lifting inner cylinder, 53. Screw block, 6. Tension sensor, 7. Limiting cylinder, 8. Mounting bolt, 9. Hand-tightening rod, 10. Cap, 11. Horizontal shaft, 12. Rotating groove, 13. Through hole, 14. Limiting nail, 15. Through hole, 16. Data acquisition instrument, 17. Steel pipe, 18. Operating platform, 19. Movable base frame, 191. Moving wheel, 192. Adjustable feet. Detailed Implementation

[0024] The specific embodiments of this utility model are described in detail below with reference to the accompanying drawings: like Figures 1-8 As shown, an aging test apparatus for FRP-reinforced concrete pull-out specimens includes two spaced-apart dry-wet circulation tanks 1, a circulation pipe 2 equipped with a water pump 201, and a test fixture on which pull-out specimens 3 are mounted. Using this apparatus, aging tests can be conducted on the pull-out specimens 3 under continuous load.

[0025] The wet-dry circulation tank 1 is a long tank with a "U"-shaped cross-section. The upper two sides of the wet-dry circulation tank 1 are bent inward to form support plates 101. The support plates 101 on both sides are arranged at intervals, and the intervals between the support plates 101 are sufficient to allow the concrete component 31 in the pull-out specimen 3 to pass through. Multiple stiffening plates 102 are provided between each support plate 101 and the wet-dry circulation tank 1 to enhance the structural strength of the support plate 101 and enable it to have a certain load-bearing capacity.

[0026] Water flow plates 103 are installed on both sides of the lower part of the wet-dry circulation tank 1. The cross-section of the water flow plates 103 is "U". After being connected and combined with the wet-dry circulation tank 1, the cross-section of the water flow plates 103 is rectangular, forming water flow channels. The function of the water flow channels on both sides is to allow water to flow into and out of the wet-dry circulation tank 1. In order to ensure that the flow channels are connected to the interior of the wet-dry circulation tank 1, several holes are made on the surface of the water flow plates 103, so that a filter screen structure is formed on the surface of the water flow plates 103. In this way, water can flow in and out, and a certain filtering effect can be achieved.

[0027] One wet-dry circulation tank 1 contains a solution, while the other wet-dry circulation tank 1 is empty. To facilitate solution circulation between the two tanks 1, two circulation pipes 2 connect them, each corresponding to a water flow plate 103. Two water pumps 201 are installed on the circulation pipes 2, and each pump 201 pumps the solution from one tank 1 to the other, operating in a staggered manner. Valves are also installed on the circulation pipes 2 to control their opening and closing. Each wet-dry circulation tank 1 is also connected to a drain pipe with a valve.

[0028] In this embodiment, each wet-dry circulation tank 1 is equipped with at least one test fixture, on which a pull-out specimen 3 is mounted. The pull-out specimen 3 is placed inside the wet-dry circulation tank 1, and the solution can submerge the pull-out specimen 3. The test fixture is located above the wet-dry circulation tank 1 and is not affected by the solution. Here, two test fixtures are arranged on one wet-dry circulation tank 1. Thus, when one wet-dry circulation tank 1 is filled with solution and the other wet-dry circulation tank 1 is empty, the solution circulates between the two wet-dry circulation tanks 1, which can simulate a certain environment.

[0029] The test fixture includes a mounting plate 4, a manual screw force application component 5, a tension sensor 6, and a limiting cylinder 7. The mounting plate 4 is a rectangular plate and is detachably connected to the wet-dry circulation tank 1. Mounting bolts 8 are provided at the four corners of the mounting plate 4. The mounting plate 4 is fixed to the support plate 101 by threaded connection with the top of the wet-dry circulation tank 1 through the mounting bolts 8. The support plates 101 on both sides cooperate to support the test fixture.

[0030] A manual screw force application assembly 5 is installed above the mounting plate 4. The manual screw force application assembly 5 can apply a continuous load to the pull-out specimen 3. The manual screw force application assembly 5 includes a fixed outer cylinder 51, a lifting inner cylinder 52, and a screw block 53. Both the upper and lower ends of the fixed outer cylinder 51 are open, and the bottom of the fixed outer cylinder 51 is a flange structure. The bottom of the fixed outer cylinder 51 is bolted to the mounting plate 4 and is detachable.

[0031] The fixed outer cylinder 51 and the lifting inner cylinder 52 are arranged coaxially inside and outside the fixed outer cylinder 51, and there is a gap between them. That is, the lifting inner cylinder 52 is arranged coaxially inside the fixed outer cylinder 51, and there is a gap between the outer wall of the lifting inner cylinder 52 and the inner wall of the fixed outer cylinder 51.

[0032] The lifting inner cylinder 52 has a symmetrical two-part structure. The lifting inner cylinder 52 is cut into two symmetrical parts along the two corresponding generatrices. The two parts of the lifting inner cylinder 52 are independent of each other. After the two parts of the lifting inner cylinder 52 are bolted together, they form a hollow cylinder. This is the working state of the lifting inner cylinder 52. In this state, the lower end face of the lifting inner cylinder 52 is annular, that is, the lower end of the lifting inner cylinder 52 is closed, but has a hole.

[0033] The lifting inner cylinder 52 can move up and down. To achieve this function, a screw block 53 is threadedly connected to the top of the fixed outer cylinder 51. The screw block 53 is rotatably connected downward to the top of the lifting inner cylinder 52. By operating the screw block 53 to rotate, the lifting inner cylinder 52 is driven to move up and down. The lifting inner cylinder 52 does not rotate, but a relative rotation occurs between the lifting inner cylinder 52 and the screw block 53.

[0034] To facilitate the turning of the screw block 53, the screw block 53 has an inverted "U" shaped cross-section, and its large-diameter section is threaded to the inner wall of the fixed outer cylinder 51. A hand-tightening rod 9 is threaded through the screw block 53, and a cap 10 is fastened to the screw block 53. The cap 10 is a cylindrical body with a "U" shaped cross-section. The hand-tightening rod 9 passes between the cap 10 and the screw block 53, and the hand-tightening rod 9 has a certain length. Turning the hand-tightening rod 9 can drive the screw block 53 to rotate.

[0035] When the screw block 53 is connected to the lifting inner cylinder 52, the lower end of the screw block 53 extends to the top of the lifting inner cylinder 52, and a horizontal shaft 11 passes through the lower end of the screw block 53, enabling the screw block 53 to drive the horizontal shaft 11 to rotate. Simultaneously, a circular rotating groove 12 is formed on the inner wall of the top of the lifting inner cylinder 52. The thickness of the rotating groove 12 is slightly larger than the diameter of the horizontal shaft 11, allowing the horizontal shaft 11 to move slightly up and down within the rotating groove 12. The diameter of the rotating groove 12 is larger than the length of the horizontal shaft 11. The rotating groove 12 is used to accommodate the horizontal shaft 11. When the screw block 53 drives the horizontal shaft 11 to rotate, both ends of the horizontal shaft 11 can be placed within the rotating groove 12 and rotate, thereby lifting the lifting inner cylinder 52.

[0036] To allow the horizontal shaft 11 to be inserted into the rotating groove 12, through holes 13 are provided on both sides of the top of the lifting inner cylinder 52. The through holes 13 are round holes and communicate with the rotating groove 12. The horizontal shaft 11 enters the rotating groove 12 through the through holes 13 and connects to the screw block 53. A limit pin 14 is also threaded into each through hole 13 to seal the through hole 13 and prevent the horizontal shaft 11 from disengaging from the rotating groove 12.

[0037] Since both the limiting pin 14 and the horizontal shaft 11 are connected to the lifting inner cylinder 52, and the lifting inner cylinder 52 is located inside the fixed outer cylinder 51, through holes 15 are symmetrically provided on both sides of the fixed outer cylinder 51 to facilitate the installation of the limiting pin 14 and the horizontal shaft 11. These through holes allow the limiting pin 14 and the horizontal shaft 11 to pass through and connect to the lifting inner cylinder 52. The diameter of the through holes 15 is larger than that of the limiting pin 14 and the horizontal shaft 11.

[0038] To improve the smooth movement of the horizontal shaft 11 within the rotating groove 12, the two ends of the horizontal shaft 11 can be designed as stepped, with the diameter at both ends being smaller than that at the middle. Bearings are installed at both ends of the horizontal shaft 11, with the outer diameter of the bearings matching the diameter of the horizontal shaft 11. When the horizontal shaft 11 rotates, the bearings move within the rotating groove 12, reducing friction and wear.

[0039] The principle of the manual screw force application component 5 is as follows: the screw block 53 is manually turned, and the horizontal shaft 11 rotates accordingly. The horizontal shaft 11 rotates within the rotating groove 12, while the lifting inner cylinder 52 does not rotate accordingly. The horizontal shaft 11 and the lifting inner cylinder 52 rotate relative to each other. As the horizontal shaft 11 rotates, it rises, which in turn causes the lifting inner cylinder 52 to rise, increasing the distance between the lifting inner cylinder 52 and the mounting plate 4.

[0040] To measure the load force of the manual screw force application assembly 5, a tension sensor 6 is installed between the assembly 5 and the mounting plate 4, specifically between the bottom of the lifting inner cylinder 52 and the mounting plate 4. The tension sensor 6 is threaded to both ends of the lifting inner cylinder 52 and the mounting plate 4, facilitating its installation and removal. When a pull-out force is applied to the FRP reinforcement 32 via the manual screw force application assembly 5, the tension sensor 6 acquires the pull-out force data. The tension sensor 6 is electrically connected to a data acquisition unit 16, which is mounted on the mounting plate 4, to read, display, and store the measurement data from the tension sensor 6 in real time.

[0041] The pull-out specimen 3 is constructed by casting a cubic concrete component 31 and an FRP bar 32 as a single unit, which is existing technology. One end of the FRP bar 32 in the pull-out specimen 3 passes upward through the mounting plate 4 and connects to the manual screw force application component 5. The manual screw force application component 5 is used to pull the FRP bar 32 upward. Specifically, after the upper end of the FRP bar 32 passes through the mounting plate 4, it enters the lifting inner cylinder 52. The upper end of the FRP bar 32 is anchored to a steel pipe 17. The steel pipe 17 can be anchored by epoxy resin bonding, threaded connection, or a combination of both. The steel pipe 17 is placed inside the lifting inner cylinder 52, and the steel pipe 17 is pressed tightly against the bottom of the lifting inner cylinder 52.

[0042] A limiting sleeve 7 is provided between the mounting plate 4 and the concrete component 31 of the pull-out specimen 3. The limiting sleeve 7 is sleeved outside the FRP reinforcement 32 to limit the interval between the mounting plate 4 and the concrete component 31. The solution immerses the concrete component 31.

[0043] To facilitate the movement of the entire experimental setup, a movable base 19 is installed between the two wet-dry circulation tanks 1. The movable base 19 is a steel structure frame, and it is equipped with casters 191 and adjustable feet 192 to enable movement and ensure stability when stopped. The water pump 201 on the circulation pipe 2 is mounted on the movable base 19, which supports the water pump 201. An operating platform 18 is also installed between the two wet-dry circulation tanks 1. The operating platform 18 can be equipped with a start button for the water pump 201 and can also hold tools used in the experiment.

[0044] The principle of this invention is as follows: After the pull-out specimen 3 is cast and cured, a steel pipe 17 is anchored at one end of the FRP reinforcement 32. Then, the pull-out specimen 3 is connected and fixed to the mounting plate 4 and the manual screw force application assembly 5. A tension sensor 6 is installed in the manual screw force application assembly 5, and the tension sensor 6 is connected to the data acquisition instrument 16. Four test fixtures with pull-out specimens 3 are prepared according to the above method. The four test fixtures are arranged in pairs in two dry-wet cycle tanks 1, and the test fixtures are connected and fixed to the dry-wet cycle tanks 1 by mounting bolts 8. Then, an aging test is carried out under the coupled action of continuous load and dry-wet cycle environment.

[0045] Tightening the screw block 53 causes the lifting inner cylinder 52 to move upward, thereby applying a continuous and stable pull-out force to the FRP reinforcement 32. The pull-out force data is measured by the tension sensor 6. With the circulation pipe 2 closed, a solution is manually added to one of the wet and dry circulation tanks 1. Typically, an aqueous solution is used; salt can be added to simulate seawater, or acid can be added to simulate an acidic solution environment, etc. The solution immerses the concrete components 31 of the two pull-out specimens 3, and slightly raises them above the concrete components 31.

[0046] After a certain period of settling, one circulation pipe 2 is opened and the water pump 201 is started to pump the solution into another wet-dry circulation tank 1 until the solution level is above the concrete component 31. Then, the water pump 201 is stopped and the circulation pipe 2 is closed. After a certain period of settling, another circulation pipe 2 is opened and the water pump 201 is started again to guide the solution back into the original wet-dry circulation tank 1 until it is again above the concrete component 31. Then, the water pump 201 is stopped and the circulation pipe 2 is closed. This process is repeated multiple times, ensuring that the concrete component 31 is continuously in a wet-dry cycle environment. During this process, the changes in pull-out force are monitored in real time by observing the data changes on the data acquisition instrument 16, thereby assessing the bond performance between the FRP reinforcement 32 and the concrete.

[0047] The embodiments described above are merely preferred embodiments of this utility model and are not intended to limit the scope of implementation of this utility model. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the patent claims of this utility model should be included within the scope of the patent application of this utility model.

Claims

1. An aging test device for a FRP tendon-concrete pull-out test specimen, characterized by, It includes two spaced-apart wet and dry circulation tanks (1), a circulation pipe (2) equipped with a water pump (201) and a test fixture equipped with a pull-out specimen (3), wherein one of the wet and dry circulation tanks (1) contains a solution and the two wet and dry circulation tanks (1) are connected by two circulation pipes (2). Each of the dry-wet circulation tanks (1) is provided with at least one test fixture, which includes a mounting plate (4), a manual screw force application component (5), a tension sensor (6), and a limiting cylinder (7). The mounting plate (4) is detachably connected to the dry-wet circulation tank (1). The manual screw force application component (5) is provided above the mounting plate (4), and the tension sensor (6) is provided between the manual screw force application component (5) and the mounting plate (4). One end of the FRP bar (32) in the pull-out specimen (3) passes upward through the mounting plate (4) and is connected to the manual screw force application component (5). The manual screw force application component (5) pulls the FRP bar (32) upward. The limiting cylinder (7) is set between the mounting plate (4) and the concrete component (31) of the pull-out specimen (3). The limiting cylinder (7) is sleeved outside the FRP bar (32), and the solution immerses the concrete component (31).

2. The device for aging test of FRP bar-concrete pull-out test specimen according to claim 1, wherein, A movable base frame (19) is provided between the two dry and wet circulation tanks (1). The movable base frame (19) is a steel structure plate frame. The movable base frame (19) is provided with a movable wheel (191) and an adjusting foot cup (192) below it. The water pump (201) on the circulation pipe (2) is installed on the movable base frame (19). After the circulation pipe (2) is connected to the dry and wet circulation tank (1), the solution circulates in the two dry and wet circulation tanks (1).

3. The device for aging test of FRP bar-concrete pull-out test specimen according to claim 1, wherein, The mounting plate (4) is provided with mounting bolts (8) at the corners, and the mounting bolts (8) are threaded to the top of the dry and wet circulation tank (1); The manual screw force application assembly (5) includes a fixed outer cylinder (51), a lifting inner cylinder (52), and a screw block (53). The upper and lower ends of the fixed outer cylinder (51) are open. The fixed outer cylinder (51) and the lifting inner cylinder (52) are coaxially arranged inside and outside and have a gap. The bottom of the fixed outer cylinder (51) is bolted to the mounting plate (4). The top of the fixed outer cylinder (51) is threaded with the screw block (53). The screw block (53) rotates downward to the top of the lifting inner cylinder (52). The tension sensor (6) is set between the bottom of the lifting inner cylinder (52) and the mounting plate (4).

4. The device for aging test of FRP bar-concrete pull-out test specimen according to claim 3, wherein, The upper end of the FRP bar (32) passes through the mounting plate (4) and then enters the lifting inner cylinder (52). The upper end of the FRP bar (32) is anchored to the steel pipe (17). The steel pipe (17) is placed inside the lifting inner cylinder (52). The bottom of the lifting inner cylinder (52) is closed, and the steel pipe (17) is pressed against the bottom of the lifting inner cylinder (52). The lifting inner cylinder (52) is a symmetrical two-lobed structure. The two lifting inner cylinders (52) are bolted together to form a hollow cylindrical body.

5. The device for aging test of FRP bar-concrete pull-out test specimen according to claim 3, wherein The screw block (53) has an inverted "convex" shaped cross section. A hand-twisting rod (9) is inserted through the screw block (53). The lower end of the screw block (53) extends into the top of the lifting inner cylinder (52). A horizontal shaft (11) is inserted through the lower end of the screw block (53). The inner wall of the top of the lifting inner cylinder (52) is provided with a circular rotating groove (12) for accommodating the horizontal shaft (11). The two ends of the horizontal shaft (11) are placed in the rotating groove (12) and move. The top two sides of the lifting inner cylinder (52) are provided with through holes (13). The through holes (13) are connected to the rotating groove (12). The horizontal shaft (11) enters the rotating groove (12) through the through holes (13). Each through hole (13) is also threaded with a limit pin (14) to prevent the horizontal shaft (11) from falling out of the rotating groove (12). The fixed outer cylinder (51) has symmetrical through holes (15) on both sides for the limit pin (14) and the horizontal shaft (11) to pass through and connect with the lifting inner cylinder (52).

6. The device for aging test of FRP bar-concrete pull-out test specimen according to claim 3, wherein The tension sensor (6) is threaded to the lifting inner cylinder (52) and the mounting plate (4) at both ends, and the tension sensor (6) is electrically connected to a data acquisition instrument (16), which is mounted on the mounting plate (4).

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