A loading frame for FRP bar and concrete material bonding slip test

Abstract

The utility model relates to FRP test equipment technical field, concretely relates to a kind of loading frame for FRP tendon and concrete material bonding slip test, the loading frame includes at least two layers of frame plate, frame plate has placement position, topmost layer frame plate has perforation, to make FRP tendon connect upper clamp, the lower side of lowermost layer frame plate has connecting assembly;Through-hole that is also provided in at least one layer of frame plate is passed through plate thickness, displacement meter is arranged in the through-hole, and displacement meter is used for fixedly connecting the FRP tendon;Displacement meter completes displacement measurement in the process of following FRP movement, and displacement meter only moves along through-hole in whole process, and there is no any contact between displacement meter and frame plate, fully avoid the interference caused by the mutual contact of both, reduce the possibility of measurement data fluctuation, can as far as possible truly reflect the slip condition under the ideal state of no friction, solve the technical problem that displacement meter and frame are connected in the prior art, resulting in that measurement result cannot truly reflect slip condition.

Description

Technical Field

[0001] This utility model relates to the technical field of FRP bar testing equipment, specifically to a loading frame for bond slip test between FRP bars and concrete materials. Background Technology

[0002] Fiber-reinforced polymers (FRPs) are materials composed of fiber reinforcements (such as glass fiber, carbon fiber, basalt fiber, aramid fiber, etc.) and matrix materials (such as epoxy resin, vinyl ester, polyester, etc.) through a series of processes. In recent years, FRPs have been increasingly used in structural reinforcement and new construction due to their advantages such as lightweight, high strength, and corrosion resistance. FRP bars can replace steel bars to reinforce concrete, thus effectively solving the problem of steel corrosion, and have broad application prospects in fields such as building engineering, water conservancy engineering, tunnel engineering, and marine engineering. Good synergistic performance between FRP bars and concrete is a prerequisite for leveraging the advantages of each material. Bond-slip performance is an important indicator of the joint performance of the reinforcement and concrete. If bond degradation or failure occurs between the two, it may lead to excessive deformation of the component.

[0003] To ensure the safety and reliability of FRP reinforcement in structural applications, studying its bond behavior with concrete is crucial. Bond performance is a key factor in realizing the superior performance of FRP reinforcement, determining the transfer of mechanical properties between the FRP reinforcement layer and the concrete matrix, and directly affecting the durability and service life of the structure. For example, patent application CN108037072A discloses a device and method for measuring the bond performance between FRP reinforcement and concrete. The device includes a test chamber, a specimen, a loading section, and a heating section. The test chamber has a clamping end on its top surface and a through hole on its bottom surface. The heating section encloses the specimen. The FRP reinforcement of the specimen passes through the through hole. The loading section simultaneously clamps the clamping end and the FRP reinforcement. The loading section includes a displacement gauge, a loading frame, and a loading control system. The displacement gauge is installed on the bottom surface of the test chamber. The loading control system is electrically connected to the loading frame and the displacement gauge.

[0004] In practical use, the above-mentioned measuring device still has certain shortcomings: Since the two displacement gauges are directly connected to the lower end of the test chamber (hereinafter referred to as the frame), and the bottom plate of the test chamber is generally made of steel, the surface of the steel plate is not absolutely flat, and there are minor defects such as bumps and undulations. During the measurement process, with the slight movement of the specimen or slight external disturbance, the contact point between the displacement gauge and the steel plate may change, leading to instability of the measurement reference and thus fluctuations in the measurement data, making it impossible to accurately reflect the true slip amount. Even if the steel plate has good overall rigidity, the clamping force directly applied by the displacement gauge to the steel plate will generate friction between the two. When measuring the slip amount, the friction will hinder or have an additional effect on the displacement gauge measurement, making the measurement results unable to truly reflect the slip situation under the ideal frictionless condition. Utility Model Content

[0005] This invention provides a loading frame for bond slip test between FRP bars and concrete materials, to solve the technical problem in the prior art where the displacement gauge is connected to the frame, resulting in the measurement results not accurately reflecting the slip situation.

[0006] To solve the above problems, the loading frame for the bond-slip test between FRP bars and concrete materials provided by this utility model adopts the following technical solution: A loading frame for a bond-slip test of FRP bars and concrete-like materials includes at least two parallel frame plates. The frame plates have placement positions for placing concrete specimens with FRP bars. The uppermost frame plate has a through hole for the FRP bars to pass through so that the FRP bars can be connected to an upper clamp. The lowermost frame plate has a connecting assembly on its underside for connecting to a lower clamp. At least one frame plate also has a through hole that penetrates the thickness of the plate, and a displacement gauge is inserted through the through hole to fix the FRP reinforcement.

[0007] The beneficial effects of the loading frame for the bond slip test between FRP bars and concrete materials provided by this utility model are as follows: the displacement gauge does not contact the frame plate, but is fixed to the FRP bar. During the test, the upper clamp can pull the FRP bar to move and detach it from the concrete specimen. The entire loading frame does not move, and the displacement gauge completes the displacement measurement while following the movement of the FRP. Throughout the process, the displacement gauge only moves along the through hole and has no contact with the frame plate, which fully avoids the interference caused by mutual contact between the two, reduces the possibility of fluctuation in measurement data, and can reflect the slip situation under the ideal frictionless state as realistically as possible. This solves the technical problem in the prior art where the displacement gauge is connected to the frame, resulting in the measurement results not being able to accurately reflect the slip situation.

[0008] Furthermore, the number of displacement gauges is two, and the number of through holes on the frame plate matches the number of displacement gauges. Both displacement gauges are used to fix the FRP reinforcement. Taking the average value after measuring with both displacement gauges can further improve the measurement accuracy.

[0009] Furthermore, it also includes a horizontal support, with two displacement gauges fixed at both ends of the horizontal support, and the FRP reinforcement fixed to the middle of the horizontal support. The displacement gauges are connected to the FRP reinforcement through the horizontal support. The horizontal support can fix two displacement gauges at the same time, which facilitates the connection with the FRP reinforcement.

[0010] Furthermore, the frame plate has three layers, with through holes provided on both the upper and middle frame plates to adjust the number of displacement gauges as needed. The number of displacement gauges can be further increased to further improve data accuracy.

[0011] Furthermore, each layer of frame panels is connected by screws and nuts to facilitate adjustment of the distance between each layer of frame panels before testing.

[0012] Furthermore, the placement position is formed between the upper frame plate and the lower frame plate, and pads are arranged on both the upper and lower sides of the concrete test block. The pads are pressed against the upper frame plate and the lower frame plate respectively to improve the stability of the concrete test block.

[0013] Furthermore, both the upper and middle frame slabs have notches or slots on their sides that connect to the perforations, allowing the FRP reinforcement bars of the concrete test block to enter the perforations along the sides. These notches and slots facilitate smoother placement of the FRP reinforcement bars.

[0014] Furthermore, the notch slot can also be detachably connected to a sealing block to ensure the rigidity of the frame plate.

[0015] Furthermore, the two displacement gauges are located between the middle frame plate and the lower frame plate, with their upper ends inserted into through holes in the middle frame plate. The displacement gauges and the concrete test block are located between different frame plates, thus avoiding interference.

[0016] Furthermore, the connecting assembly includes a connecting rod that is detachably mounted on the lowest frame plate, and the lower end of the connecting rod is used to connect to the lower clamp. Attached Figure Description

[0017] The above and other objects, features, and advantages of the present invention will become readily understood by reading the following detailed description of exemplary embodiments with reference to the accompanying drawings. In the drawings, several embodiments of the present invention are shown by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein: Figure 1This is a three-dimensional schematic diagram of the loading frame for the bond-slip test between FRP bars and concrete materials provided by this utility model. Figure 2 for Figure 1 Top view of the upper and middle frame panels; Figure 3 for Figure 2 The main view; Figure 4 This is a schematic diagram of the loading frame used in the bond slip test between FRP bars and concrete materials provided by this utility model during the test.

[0018] Explanation of reference numerals in the attached figures: 1. Frame slab; 101. Upper frame slab; 102. Middle frame slab; 103. Lower frame slab; 2. FRP reinforcement; 3. Concrete test block; 4. Perforation; 5. Upper clamp; 6. Lower clamp; 7. Through hole; 8. Displacement gauge; 9. Horizontal support; 10. Screw; 11. Nut; 12. Spacer; 13. Notch / groove; 14. Sealing block; 15. Connecting rod. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Those skilled in the art should understand that the embodiments described below are only some, not all, of the embodiments disclosed. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0020] The principles and spirit of this utility model will be explained in detail below with reference to several representative embodiments.

[0021] An embodiment of the loading frame for bond-slip testing between FRP bars and concrete materials provided by this utility model: like Figures 1 to 4 As shown, a loading frame for a bond-slip test between FRP bars and concrete materials includes three parallel frame plates 1. The frame plates 1 have placement positions for placing concrete test blocks 3 with FRP bars 2. The uppermost frame plate 101 has through holes 4 for the FRP bars 2 to pass through, so that the FRP bars 2 can be connected to the upper clamp 5. The lowermost frame plate 103 has a connecting assembly on its underside for connecting to the lower clamp 6. The upper frame plate 101 and the middle frame plate 102 also have through holes 7 that penetrate the thickness of the plate. Displacement gauges 8 are installed in the through holes 7 and are used to fix the FRP bars 2.

[0022] Specifically, there are two displacement gauges 8, and the number of through holes 7 on the frame plate matches the number of displacement gauges 8. Both displacement gauges 8 are used to fix the FRP reinforcement 2. The average value of the measurements taken by the two displacement gauges 8 can further improve the measurement accuracy.

[0023] Meanwhile, since through holes 7 penetrating the plate thickness are also provided in the upper frame plate 101 and the middle frame plate 102, the number of displacement gauges 8 can be adjusted according to actual needs. The number of displacement gauges 8 can be further increased to further improve the accuracy of the data. In other embodiments, through holes 7 can be provided only in the middle frame plate 102. Of course, in other embodiments, the number of frame plates can also be two layers.

[0024] like Figure 1 and Figure 3 As shown, each layer of frame panels is connected by screws 10 and nuts 11 to facilitate adjustment of the distance between each layer of frame panels before the test. The placement position is formed between the upper frame panel 101 and the lower frame panel 103. Spacers 12 are arranged on both the upper and lower sides of the concrete specimen 3. The spacers 12 are respectively pressed against the upper frame panel 101 and the lower frame panel 103 to improve the stability of the concrete specimen 3.

[0025] To facilitate the placement of concrete test block 3, in this embodiment, as follows: Figures 1 to 4 As shown, both the upper frame plate 101 and the middle frame plate 102 have notches 13 on their sides that connect to the through holes 4, allowing the FRP reinforcement 2 of the concrete test block 3 to enter the through holes 4 along the sides. The notches 13 facilitate smoother placement of the FRP reinforcement 2. Furthermore, to ensure the rigidity of the frame plates, the notches 13 can be detachably connected to sealing blocks 14. After the concrete test block 3 is placed, the notches 13 can be sealed with the sealing blocks 14.

[0026] To avoid interference, two displacement gauges 8 are located between the middle frame plate 102 and the lower frame plate 103, with the upper ends of the two displacement gauges 8 inserted into the through holes 7 of the middle frame plate 102. The displacement gauges 8 and the concrete test block 3 are located between different frame plates, thus avoiding interference.

[0027] Finally, regarding the connecting assembly. The connecting assembly includes a link 15, which is detachably mounted on the lowest frame plate 103, and the lower end of the link 15 is used to connect to the lower clamp 6.

[0028] The working principle of the loading frame for the bonding and slip test between FRP bars and concrete materials provided by this utility model is as follows: a concrete test block 3 is placed along the notch 13 on the side of the frame plate, the distance between the upper frame plate 101 and the middle frame plate 102 is adjusted, the concrete test block 3 is clamped by the pad block 12, the notch 13 is sealed by the sealing block 14, the upper end of the FRP bar 2 is fixed by the upper clamp 5, the connecting rod 15 of the lower frame plate 103 is fixed by the lower clamp 6, the horizontal bracket 9 with displacement gauge 8 is fixed on the FRP bar 2, and the upper clamp 5 is tested by loading and pulling. The upper clamp 5 can pull the FRP bar 2 to move and detach it from the concrete test block 3. The entire loading frame does not move. The displacement gauge 8 completes the displacement measurement while following the movement of the FRP. During the whole process, the displacement gauge 8 only moves along the through hole 7 and has no contact with the frame plate, which fully avoids the interference caused by mutual contact between the two, reduces the possibility of fluctuation in measurement data, and can reflect the slip situation under the ideal state of no friction as realistically as possible.

Claims

1. A loading frame for bond-slip tests between FRP bars and concrete-like materials, characterized in that, It includes at least two parallel frame plates, each frame plate having a placement position for placing a concrete test block with FRP reinforcement, the uppermost frame plate having a through hole for the FRP reinforcement to pass through so that the FRP reinforcement can be connected to an upper clamp, and the lowermost frame plate having a connecting assembly on its underside for connecting to a lower clamp. At least one frame plate also has a through hole that penetrates the thickness of the plate, and a displacement gauge is inserted through the through hole to fix the FRP reinforcement.

2. The loading frame for the bond-slip test between FRP bars and concrete-like materials according to claim 1, characterized in that: The number of displacement gauges is two, and the number of through holes on the frame plate is matched with the number of displacement gauges. Both displacement gauges are used to fix the FRP reinforcement.

3. The loading frame for the bond-slip test between FRP bars and concrete-like materials according to claim 2, characterized in that: It also includes a horizontal support, with two displacement gauges fixed at both ends of the horizontal support, and the FRP reinforcement fixed in the middle of the horizontal support. The displacement gauges are connected to the FRP reinforcement through the horizontal support.

4. The loading frame for the bond-slip test between FRP bars and concrete-like materials according to any one of claims 1 to 3, characterized in that: The frame plate consists of three layers, with through holes provided on both the upper and middle frame plates to adjust the number of displacement gauges as needed.

5. The loading frame for the bond-slip test between FRP bars and concrete-like materials according to claim 4, characterized in that: Each layer of frame panels is connected by screws and nuts to facilitate adjustment of the distance between each layer of frame panels before testing.

6. The loading frame for the bond-slip test between FRP bars and concrete-like materials according to claim 5, characterized in that: The placement position is formed between the upper frame plate and the lower frame plate. The concrete test block is provided with pads on both the upper and lower sides. The pads are pressed against the upper frame plate and the lower frame plate respectively to improve the stability of the concrete test block.

7. The loading frame for the bond-slip test between FRP bars and concrete materials according to claim 4, characterized in that: Both the upper and middle frame slabs have notches on their sides that connect to the perforations, so that the FRP reinforcement of the concrete test block can enter the perforations along the sides.

8. The loading frame for the bond-slip test between FRP bars and concrete materials according to claim 7, characterized in that: The notch slot can also be detachably connected to a sealing block to ensure the rigidity of the frame plate.

9. The loading frame for the bond-slip test between FRP bars and concrete-like materials according to any one of claims 5 to 8, characterized in that: The two displacement gauges are located between the middle frame plate and the lower frame plate, with the upper ends of the two displacement gauges inserted into the through holes of the middle frame plate.

10. The loading frame for the bond-slip test between FRP bars and concrete materials according to any one of claims 1 to 3, characterized in that: The connecting assembly includes a connecting rod, which is detachably mounted on the lowest frame plate, and the lower end of the connecting rod is used to connect to the lower clamp.

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