A multi-wedge connection joint for concrete structure FRP tendon and a manufacturing method thereof

Abstract

The application relates to the field of civil engineering, and provides a multi-wedge connecting joint for FRP bars of concrete structures and a manufacturing method thereof, to solve the problem that the shear strength between the structure of the existing multi-wedge connecting joint for FRP bars of concrete structures and the FRP bars is small, and when the multi-wedge connecting joint is used to connect FRP bars with large diameters, the length of the connecting joint needs to be greatly extended, thereby causing the connecting joint to be not conducive to the arrangement of the FRP bars in the concrete structure. The multi-wedge connecting joint comprises an inner pipe body and a sleeve pipe, the sleeve pipe is fixedly sleeved on the inner pipe body, a plurality of first wedge-shaped grooves are arranged on the outer surface of the inner pipe body and are matched with the inner surface of the sleeve pipe for connection, and a plurality of second wedge-shaped grooves are arranged on the inner surface of the sleeve pipe and are matched with the outer surface of the inner pipe body for connection.

Description

Technical Field

[0001] This application relates to the field of civil engineering, and more specifically, to a multi-wedge joint for FRP reinforcement in concrete structures and a method for manufacturing the same. Background Technology

[0002] In recent years, in civil engineering fields such as ports, bridges and offshore wind farms, the reinforced concrete structures used are prone to corrosion in the service environment. Using FRP bars instead of steel bars as reinforcement materials for concrete structures can effectively solve this problem. Therefore, the application of FRP bars in concrete structures in the above fields is increasing.

[0003] Currently, the common method for connecting FRP bars in civil engineering involves injecting a filler material (e.g., expansive cement or resin) into a metal pipe connector, and then inserting two FRP bars into the filler material within the connector. The filler material in the connector quickly cures, allowing for rapid connection of the two FRP bars. The connection principle is as follows: the tensile load on the FRP bar is transferred to the metal pipe connector through the shear force between the filler material and the FRP bar. The connection capacity of the metal pipe connector for connecting FRP bars (the tensile force on the metal pipe connector) is equal to the shear force between the filler material and the FRP bar. This shear force is equal to the product of the contact area between the filler material and the FRP bar and the shear stress (shear strength). Therefore, increasing the contact area between the filler material and the FRP bar or improving the shear strength can enhance the connection capacity of the metal pipe connector for FRP bars.

[0004] To ensure sufficient connection capacity for FRP (fiberglass reinforced plastic) reinforcement bars, existing metal pipe joints typically increase the contact area between the filler material and the FRP bars by extending their length. While this approach may not be as problematic when connecting smaller diameter FRP bars, it becomes increasingly necessary for connecting larger diameter FRP bars. Larger diameter FRP bars have a higher strength-to-surface-area ratio, requiring significantly longer joints. For example, a 10cm joint might be sufficient for smaller diameter bars, while a 30cm joint might be needed for larger diameter bars. This not only increases the weight of the joints but also, in concrete structures, the concentration of excessively long joints can affect the arrangement and positioning accuracy of the FRP bars.

[0005] When the contact area between the filler material and the FRP reinforcement cannot be increased further (i.e., further increases would affect the arrangement of the FRP reinforcement in the concrete structure), in order to further improve the connection capacity of the metal pipe joint for connecting FRP reinforcement, from the perspective of improving shear strength, the existing metal pipe joint is set as a single wedge joint composed of a wedge-shaped component and an anti-wedge sleeve. The above structure increases shear strength through lateral pressure. Specifically, when the FRP reinforcement is subjected to tension, the outer surface of the wedge-shaped component abuts against the inner surface of the anti-wedge sleeve, thereby generating mutual compression. This causes compressive stress to be generated inside the wedge-shaped component and transmitted to the FRP reinforcement connected to it, thereby improving shear strength. However, the compressive stress it provides is still too small, that is, its contribution to improving the connection capacity of the metal pipe joint for connecting FRP reinforcement is too small. As a result, it is still impossible to design a joint with a short length that meets the connection capacity required for FRP reinforcement with a large diameter.

[0006] Therefore, the problem to be solved in this application is how to design a short connection joint that can be used to connect FRP bars with larger or larger diameters, from the perspective of improving shear strength. Summary of the Invention

[0007] The purpose of this application is to provide a multi-wedge connection joint for FRP bars in concrete structures and its manufacturing method, so as to solve the problem that the existing multi-wedge connection joints for FRP bars in concrete structures have low shear strength between the structure and the FRP bars, and require a large extension of the connection joint length when used to connect FRP bars with larger diameters, which makes the connection joint unfavorable for the arrangement of FRP bars in concrete structures.

[0008] To achieve the above objectives, the technical solution adopted in the first aspect of the embodiments of this application is as follows:

[0009] A multi-wedge joint for FRP reinforcement in concrete structures includes an inner tube body and a sleeve.

[0010] The sleeve is fixedly sleeved on the inner tube body. The outer surface of the inner tube body is provided with a plurality of first wedge grooves, which are matched and connected with the inner surface of the sleeve through the first wedge grooves. The inner surface of the sleeve is provided with a plurality of second wedge grooves, which are matched and connected with the outer surface of the inner tube body through the second wedge grooves.

[0011] In one implementation, the inner tube body includes a first inner tube and a second inner tube, which are spaced apart along the axial direction. The multi-wedge-shaped connector further includes an alignment structure, which connects the first inner tube and the second inner tube respectively, and the first inner tube is connected to the second inner tube through the alignment structure.

[0012] In one implementation, the alignment structure includes an alignment part, a first washer ring, and a second washer ring. The alignment part is disposed between the first inner tube and the second inner tube and connects the first inner tube and the second inner tube. The first washer ring is disposed on the end of the first inner tube opposite to the alignment part, and the second washer ring is disposed on the end of the second inner tube opposite to the alignment part. The alignment part is provided with two alignment grooves.

[0013] In one implementation, the thickness of the first washer and the second washer is not less than 10 cm.

[0014] In one implementation, multiple grooves are provided on the inner surfaces of both the first inner tube and the second inner tube.

[0015] In one implementation, both ends of the inner tube body are provided with extensions that extend out of the sleeve.

[0016] The technical solution adopted in the second aspect of the embodiments of this application is:

[0017] A method for manufacturing a multi-wedge connection joint for FRP reinforcement in concrete structures, comprising the following steps:

[0018] A first prepreg tape or a first fiber cloth is wrapped around the outer surface of the first mandrel, and the first prepreg tape or the first fiber cloth is cured to form the inner tube body.

[0019] The outer surface of the inner tube body is cut to generate a first inner tube and a second inner tube with multiple first wedge-shaped grooves on the outer surface;

[0020] An alignment structure is provided between the first inner tube and the second inner tube, and the first inner tube is connected to the second inner tube through the alignment structure to form an inner tube structure;

[0021] A second prepreg tape or a second fiber cloth is wrapped around the outer surface of the inner tube structure, and the second prepreg tape or the second fiber cloth is cured to form a sleeve. The inner surface of the sleeve has a second wedge groove that fits into the first wedge groove. The sleeve is fixed to the first wedge groove of the inner tube body through the second wedge groove to form a multi-wedge joint.

[0022] In one implementation, prior to the step of covering and winding a first prepreg tape or a first fiber cloth onto the outer surface of the first mandrel and curing the first prepreg tape or the first fiber cloth to form the inner tube body, the manufacturing method further includes:

[0023] A winding tape is wound around the outer surface of the pipe body to form a first mandrel with multiple protrusions on the outer surface.

[0024] In one implementation, the step of covering and wrapping the outer surface of the first mandrel with a first prepreg tape or a first fiber cloth, and curing the first prepreg tape or the first fiber cloth to form the inner tube body specifically includes:

[0025] A release agent is sprayed onto the outer surface of the first mandrel and then cured to form a release agent layer.

[0026] A first prepreg tape or a first fiber cloth is wrapped around the outer surface of the release agent layer, and the first prepreg tape or the first fiber cloth is cured to form an inner tube body, wherein the inner surface of the inner tube body has a plurality of grooves that fit into the protrusions.

[0027] The inner tube body is separated from the first mandrel through the release agent layer.

[0028] In one implementation, prior to the step of winding a winding tape around the outer surface of the pipe body and forming a first mandrel with multiple protrusions on the outer surface, the manufacturing method further includes:

[0029] A plastic film is placed over the pipe to form the pipe body.

[0030] This application provides a multi-wedge connection joint for FRP reinforcement in concrete structures and its manufacturing method. Due to the wedge structure formed by the inner tube body, the sleeve, and the first and second wedge grooves between them, the multi-wedge connection joint of this application experiences slippage, i.e., compression, when subjected to tensile force. This compression leads to compressive stress in the wedge structure, which is then transferred to the FRP reinforcement, causing compressive stress on the surface of the FRP reinforcement. This compressive stress increases the shear stress on the surface of the FRP reinforcement, thereby improving the connection strength. Furthermore, the thickness of the wedge structure also affects the magnitude of the compressive stress on the surface of the FRP reinforcement. A higher compressive stress is applied to the FRP reinforcement at the thinner end of the wedge, while a lower compressive stress is applied at the thicker end. In other words, the compressive stress on the surface of the FRP reinforcement is relatively low. The force is distributed from large to small. In this application, multiple first wedge grooves and multiple second wedge grooves between the inner tube body and the sleeve constitute multiple wedge structures. Each wedge structure has a thinner end and a thicker end. That is to say, the multi-wedge connector of this application has multiple thinner ends. Each thinner end of the wedge will generate a large compressive stress on the FRP reinforcement. Furthermore, due to the multiple thicker ends of the wedges in this application, compared with the existing single thicker end, the thicker end of the wedges in this application will be thinner, and thus will provide a greater compressive stress than a single thicker end. This will significantly increase the overall compressive stress on the surface of the FRP reinforcement, thereby fully improving the connection capacity of the connector for connecting FRP reinforcement, and enabling the connection of FRP reinforcement with a shorter length with a larger diameter. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This application provides an internal structural schematic diagram of a multi-wedge-shaped connection joint for FRP bars in concrete structures.

[0033] Figure 2 This is a schematic diagram of another internal structure of a multi-wedge-shaped connection joint for FRP bars in concrete structures, provided as an embodiment of this application.

[0034] Figure 3 A schematic diagram of an internal structure with an extension provided in a multi-wedge-shaped connection joint for FRP bars in concrete structures, provided as an embodiment of this application;

[0035] Figure 4 A schematic diagram of another internal structure with an extension provided in a multi-wedge-shaped connection joint for FRP bars in concrete structures, provided for an embodiment of this application;

[0036] Figure 5 This is an overall flowchart illustrating a manufacturing method for a multi-wedge connection joint for FRP reinforcement in a concrete structure, as provided in an embodiment of this application.

[0037] The following are the labeling elements in the figure:

[0038] 1. Inner tube body; 11. First inner tube; 12. Second inner tube; 13. First wedge groove; 2. Sleeve; 21. Second wedge groove; 3. Alignment structure; 31. Alignment part; 32. First washer; 33. Second washer; 4. Extension part. Detailed Implementation

[0039] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0040] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it may be directly or indirectly located on that other component. When a component is referred to as "connected to" another component, it may be directly or indirectly connected to that other component. The terms "upper," "lower," "left," "right," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate orientations or positions based on the accompanying drawings, and are for ease of description only, and should not be construed as limiting the technical solution. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. "A plurality" means two or more, unless otherwise explicitly defined.

[0041] In recent years, in civil engineering fields such as ports, bridges and offshore wind farms, the reinforced concrete structures used are prone to corrosion in the service environment. Using FRP bars instead of steel bars as reinforcement materials for concrete structures can effectively solve this problem. Therefore, the application of FRP bars in concrete structures in the above fields is increasing.

[0042] Currently, the common method for connecting FRP bars in civil engineering involves injecting a filler material (e.g., expansive cement or resin) into a metal pipe connector, and then inserting two FRP bars into the filler material within the connector. The filler material in the connector quickly cures, allowing for rapid connection of the two FRP bars. The connection principle is as follows: the tensile load on the FRP bar is transferred to the metal pipe connector through the shear force between the filler material and the FRP bar. The connection capacity of the metal pipe connector for connecting FRP bars (the tensile force on the metal pipe connector) is equal to the shear force between the filler material and the FRP bar. This shear force is equal to the product of the contact area between the filler material and the FRP bar and the shear stress (shear strength). Therefore, increasing the contact area between the filler material and the FRP bar or improving the shear strength can enhance the connection capacity of the metal pipe connector for FRP bars.

[0043] To ensure sufficient connection capacity for FRP (fiberglass reinforced plastic) reinforcement bars, existing metal pipe joints typically increase the contact area between the filler material and the FRP bars by extending their length. While this approach may not be as problematic when connecting smaller diameter FRP bars, it becomes increasingly necessary for connecting larger diameter FRP bars. Larger diameter FRP bars have a higher strength-to-surface-area ratio, requiring significantly longer joints. For example, a 10cm joint might be sufficient for smaller diameter bars, while a 30cm joint might be needed for larger diameter bars. This not only increases the weight of the joints but also, in concrete structures, the concentration of excessively long joints can affect the arrangement and positioning accuracy of the FRP bars.

[0044] When the contact area between the filler material and the FRP reinforcement cannot be increased further (i.e., further increases would affect the arrangement of the FRP reinforcement in the concrete structure), in order to further improve the connection capacity of the metal pipe joint for connecting FRP reinforcement, from the perspective of improving shear strength, the existing method is to set the metal pipe joint as a single wedge joint composed of a wedge-shaped component and an anti-wedge sleeve. This structure increases shear strength through lateral pressure. Specifically, when the FRP reinforcement is subjected to tension, the outer surface of the wedge-shaped component abuts against the inner surface of the anti-wedge sleeve, thereby generating mutual compression. This causes compressive stress to be generated inside the wedge-shaped component and transmitted to the connected FRP reinforcement, thus improving shear strength. However, the compressive stress it provides... The stress is still too low because the single wedge joint only has one wedge. When the wedge component and the anti-wedge sleeve are squeezed against each other, only the thinner end of the wedge can provide a large compressive stress at the interface between the FRP bar and the metal pipe joint (wedge component). The area near the thicker end of the wedge can only provide a small compressive stress at the interface between the FRP bar and the metal pipe joint. The thicker end of the wedge contributes very little to improving the shear performance between the FRP bar and the metal pipe joint. In other words, its contribution to improving the connection capacity of the metal pipe joint for connecting FRP bars is too small. As a result, it is still impossible to design a short joint that meets the connection capacity required for FRP bars with large diameters.

[0045] Therefore, the first aspect of this application provides a multi-wedge connection joint for FRP reinforcement in concrete structures, see reference. Figure 1 or Figure 2 The multi-wedge connector of this application is used to connect FRP bars in concrete structures. Generally, one multi-wedge connector is used to connect two FRP bars. Specifically, the inner cavity of the multi-wedge connector is filled with a filling material (e.g., expansive cement or resin), and then the two FRP bars are fixedly installed inside the multi-wedge connector. The multi-wedge connector includes an inner tube body 1 and a sleeve 2. The inner tube body 1 is a glass fiber / epoxy resin prepreg tape body, that is, the inner tube body 1 is formed by curing glass fiber / epoxy resin prepreg tape. The sleeve 2 is a carbon fiber / epoxy resin sleeve, that is... It is said that the sleeve 2 is made of carbon fiber / epoxy resin cured. It can be understood that both the inner tube body 1 and the sleeve 2 are tubes and both have an inner cavity. The sleeve 2 is fixedly sleeved on the inner tube body 1 through its inner cavity, and the inner cavity of the inner tube body 1 is used to arrange filling material. In this embodiment, a plurality of first wedge grooves 13 are opened on the outer surface of the inner tube body 1, and the first wedge grooves 13 are matched and connected with the inner surface of the sleeve 2. A plurality of second wedge grooves 21 are opened on the inner surface of the sleeve 2, and the second wedge grooves 21 are matched and connected with the outer surface of the inner tube body 1.

[0046] Because of the wedge-shaped structure formed by the inner tube body 1, the sleeve 2, and the first wedge groove 13 and the second wedge groove 21 between them, when the multi-wedge connection joint of this embodiment is subjected to tension, the inner tube body 1 and the sleeve 2 will slip, that is, squeeze will occur. This squeeze will cause compressive stress in the wedge structure, and this compressive stress will be transmitted to the FRP rib, causing compressive stress on the surface of the FRP rib. This compressive stress will increase the shear stress on the surface of the FRP rib, thereby increasing the connection strength of the FRP rib.

[0047] Based on this, the thickness of the wedge structure also affects the magnitude of the compressive stress on the surface of the FRP rib. The thinner end of the wedge will provide higher compressive stress to the FRP rib, while the thicker end will result in lower compressive stress. In other words, the compressive stress on the surface of the FRP rib follows a distribution from large to small. In this embodiment, multiple first wedge grooves 13 and multiple second wedge grooves 21 between the inner tube body 1 and the sleeve 2 constitute multiple wedge structures. Each wedge structure has a thinner end and a thicker end. That is to say, the multiple wedge structures in this embodiment... The connector has multiple thinner wedge-shaped ends, and each thinner wedge-shaped end generates a large compressive stress on the FRP reinforcement. Furthermore, since this embodiment has multiple thicker wedge-shaped ends, compared to the existing single thicker wedge-shaped ends, the thicker wedge-shaped ends in this embodiment are thinner, thus providing a greater compressive stress than a single thicker wedge-shaped end. This significantly increases the overall compressive stress on the surface of the FRP reinforcement, thereby greatly improving the connector's ability to connect FRP reinforcements. This enables the connection of FRP reinforcements with larger diameters using a shorter connector length.

[0048] In one embodiment, see [reference] Figure 1The inner tube body 1 includes a first inner tube 11 and a second inner tube 12. The multi-wedge-shaped connecting joint further includes an alignment structure 3, which connects the first inner tube 11 and the second inner tube 12 respectively. The first inner tube 11 and the second inner tube 12 are spaced apart axially, and the first inner tube 11 is connected to the second inner tube 12 through the alignment structure 3. It can be understood that the first inner tube 11 and the second inner tube 12 are formed by cutting the inner tube body 1 into two sections: one section is the first inner tube 11, and the other section is the second inner tube 12. Both the outer surfaces of the first inner tube 11 and the second inner tube 12 have multiple first wedge-shaped grooves 13. Due to the presence of multiple first wedge-shaped grooves 13, both the first inner tube 11 and the second inner tube 12 have multiple thinner wedge-shaped ends and multiple thicker wedge-shaped ends. Furthermore, the thicknesses at both ends of the first inner tube 11 and the second inner tube 12 are different. In this embodiment, when the first inner tube 11 is connected to the second inner tube 12 through the alignment structure 3, the thicker wedge-shaped end of the first inner tube 11 is coaxially connected to the thicker wedge-shaped end of the second inner tube 12 through the alignment structure 3.

[0049] In one embodiment, multiple grooves (not shown in the figure) are provided on the inner surfaces of the first inner tube 11 and the second inner tube 12. Since the FRP rib is fixed in the first inner tube 11 or the second inner tube 12 by filling material, by providing multiple grooves on the first inner tube 11 and the second inner tube 12 in this embodiment, the contact area between the filling material and the first inner tube 11 or the second inner tube 12 can be increased, thereby further improving the connection capability of the multi-wedge joint in this embodiment.

[0050] In one embodiment, see [reference] Figure 3 or Figure 4 The alignment structure 3 may include an alignment part 31, a first washer 32, and a second washer 33. The alignment part 31 is disposed between the first inner tube 11 and the second inner tube 12 and connects the first inner tube 11 and the second inner tube 12. The alignment part 31 is provided with two alignment grooves on the side of the first inner tube 11 and the second inner tube 12 respectively. The first washer 32 is disposed on the end of the first inner tube 11 away from the alignment part 31, and the second washer 33 is disposed on the end of the second inner tube 12 away from the alignment part 31. The groove diameters of the two alignment grooves, the inner ring diameters of the first washer 32 and the second washer 33 are equivalent to the outer diameter of the FRP reinforcement, and the axes of the two alignment grooves, the first washer 32 and the second washer 33 are located on the same straight line.

[0051] When using the alignment structure 3 of this embodiment for alignment, firstly, filler material is arranged inside the cavities of the first inner tube 11 and the second inner tube 12. Then, by passing one of the two FRP ribs through the first gasket 32 ​​and extending into the first inner tube 11, the FRP rib will extend into the alignment groove of the alignment part 31 near the first inner tube 11 under the guidance of the first gasket 32, thereby achieving the alignment of the alignment structure 3 in the first inner tube 11; the other rib passes through the second gasket 33 and extends into the second inner tube 12. Under the guidance of the second gasket 33, the FRP rib will extend into the alignment groove of the alignment part 31 near the second inner tube 12, thereby achieving the alignment of the alignment structure 3 in the second inner tube 12.

[0052] Furthermore, the alignment part 31 may include a blocking plate, and positioning grooves are respectively provided on both sides of the blocking plate. The alignment part 31 may also include a blocking plate and two third washer rings, wherein the two third washer rings are respectively disposed on both sides of the blocking plate, and the third washer rings are connected to the blocking plate to form positioning grooves. One side of the blocking plate is close to the first inner tube 11, and the other side is close to the second inner tube 12, and the two sides of the blocking plate are opposite to each other.

[0053] In one embodiment, see [reference] Figure 3 or Figure 4 Both ends of the inner tube body 1 are provided with extension portions 4, which extend out of the sleeve 2. That is, the end of the first inner tube 11 away from the alignment portion 31 is provided with an extension portion 4, wherein the extension portion 4 can be an extension tube. The first gasket 32 ​​is provided on the extension portion 4 of the first inner tube 11, and the end of the second inner tube 12 away from the alignment portion 31 is also provided with an extension portion 4. The second gasket 33 is provided on the extension portion 4 of the second inner tube 12. In this embodiment, by providing the extension portion 4, the first gasket 32 ​​and the second gasket 33 can be provided on the extension portion 4, thereby placing both the first gasket 32 ​​and the second gasket 33 outside the sleeve 2, which facilitates the alignment of the alignment structure 3.

[0054] Furthermore, the thickness of the first washer 32 and the second washer 33 is not less than 10 cm. The thickness of the first washer 32 is the distance from the end face of the first washer 32 near its location in the extension 4 to the end face of the first washer 32 away from its location in the extension 4. The thickness of the second washer 33 is the distance from the end face of the second washer 33 near its location in the extension 4 to the end face of the second washer 33 away from its location in the extension 4. The thickness of the first washer 32 and the second washer 33 in this embodiment can be set according to specific needs. In this embodiment, the greater the thickness of the first washer 32 and the second washer 33, the better the guiding effect of the first washer 32 and the second washer 33. Therefore, the alignment effect of the alignment structure 3 can be improved by appropriately increasing the thickness of the first washer 32 and the second washer 33.

[0055] The second aspect of this application provides a method for manufacturing a multi-wedge joint for FRP reinforcement in concrete structures, see [link to relevant documentation]. Figure 5 The manufacturing method includes:

[0056] S101, a plastic film is applied to the pipe to form the pipe body.

[0057] Specifically, the pipe is a relatively rigid pipe such as stainless steel or aluminum pipe, and the plastic film is a film made of polyvinyl chloride, polyethylene, polypropylene, polystyrene and other resins. The pipe body refers to the pipe whose outer surface is covered with a plastic film, wherein the plastic film is covered on the outer surface of the pipe and is used to separate the pipe from the winding tape.

[0058] S102, a winding strip is wound at intervals on the outer surface of the pipe body, forming a mandrel with multiple protrusions on the outer surface.

[0059] Specifically, the multiple protrusions on the mandrel are generated by winding a tape around the tube body. The mandrel is a tube body with a tape wound around its outer surface. The mandrel can be generated by first fixing one end of the tape to the tube body, wherein the tape is set on one side of the tube body, the tape is set on the moving end of the moving device, and the tube body is set on the rotating end of the rotating device. At the same time, the rotating device is driven to rotate and the moving device is moved. The tube body will rotate with the rotating device, thereby driving the tape to continuously wind around the tube body. The moving device will drive the other end of the tape to move and make the tape spirally wound around the tube body to generate a mandrel with multiple protrusions. The mandrel is used to manufacture an inner tube body with multiple grooves on the inner surface that fit into the protrusions.

[0060] S103, spray a release agent onto the outer surface of the mandrel and cure the release agent to form a release agent layer.

[0061] Specifically, before spraying the release agent onto the outer surface of the mandrel, the outer surface of the mandrel needs to be cleaned first. After cleaning, the release agent spray gun containing the release agent is used to spray the outer surface of the mandrel. After spraying, the release agent on the outer surface of the mandrel is dried. When the release agent on the outer surface of the mandrel is dry, it will solidify to form the release agent layer. In this embodiment, by setting the release agent layer, it is mainly used to facilitate the separation of the mandrel from the inner tube body. It is worth noting that the release agent is a general term and there are many types. This embodiment does not limit the specific type of release agent.

[0062] S104, a first prepreg tape or a first fiber cloth is wrapped around the outer surface of the release agent layer, and the first prepreg tape or the first fiber cloth is cured to form an inner tube body, wherein the inner surface of the inner tube body has a plurality of grooves that fit into the protrusions.

[0063] Specifically, the release agent layer is only a thin layer, and since it is sprayed onto the mandrel, it is foreseeable that the outer surface of the release agent layer, like the outer surface of the mandrel, also has multiple protrusions. The inner tube body is formed by covering and wrapping the outer surface of the release agent layer with a first prepreg tape or first fiber cloth and then curing it. To ensure that the first prepreg tape or first fiber cloth can fully cover the outer surface of the release agent layer, the width of the first prepreg tape or first fiber cloth is smaller than the width of the protrusions. The method of covering the release agent layer with the first prepreg tape or first fiber cloth can be the same as the method described above for wrapping the outer surface of the tube body, both of which can be achieved using a rotating device and a moving device. In this embodiment, the mandrel with the release agent layer is fixed to the rotating end of the rotating device, and the first prepreg tape or first fiber cloth is fixed to the moving end of the moving device. Compared to the above method where the wrapping tape is spirally arranged on the mandrel, the release agent layer is applied more efficiently.

[0064] The difference is that this embodiment can reduce the speed of the moving device to ensure that the first prepreg tape or the first fiber cloth completely covers the outer surface (including the raised parts) of the release agent layer. After the first prepreg tape or the first fiber cloth is cured on the outer surface of the release agent layer, an inner tube body with multiple grooves on the inner surface that interlock with the raised parts is generated. The prepreg tape can be a fiber-resin composite prepreg tape, which can be made of fiber and resin. The first fiber cloth is a fiber cloth coated with resin on both sides. The first fiber cloth can be glass fiber or carbon fiber, and the resin can be epoxy resin or other resins. It is worth noting that in actual use, the inner tube body can also be made of short fiber or particle-reinforced polymer material.

[0065] S105, the inner tube body is separated from the mandrel through the release agent layer, the outer surface of the separated inner tube body is cut, and a first inner tube and a second inner tube with multiple first wedge grooves on the outer surface are generated.

[0066] Specifically, separating the inner tube body from the mandrel through the release agent layer involves: first, removing the winding tape from the outer surface of the plastic film, at which point the grooves on the inner surface of the inner tube body become visible due to the removal of the winding tape; then, separating the inner tube body from the release agent layer, thereby separating it from the mandrel; after separating the inner tube body, it can be cut into two equal-length first inner tubes and second inner tubes; then, using wire cutting technology, multiple first wedge-shaped grooves are cut along the circumferential direction of the outer surface of the first and second inner tubes, so that the outer surfaces of both the first and second inner tubes have multiple first wedge-shaped grooves.

[0067] S106, an alignment structure is provided between the first inner tube and the second inner tube, and the first inner tube is connected to the second inner tube through the alignment structure to form an inner tube structure.

[0068] Specifically, the alignment structure is mainly used to guide the FRP ribs and position them in the middle of the first inner tube and the second inner tube. The alignment structure may include an alignment part, which is positioned between the first inner tube and the second inner tube and connects the first inner tube and the second inner tube. There are many ways in which the alignment part is connected to the first inner tube and the second inner tube, which will not be elaborated on here. In addition to the alignment part, the alignment structure also includes a first washer and a second washer. The first washer is positioned on the end of the first inner tube away from the alignment part, and the second washer is positioned on the end of the second inner tube away from the alignment part. The alignment part, the first inner tube, the second inner tube, the first washer, and the second washer are connected together to form the inner tube structure.

[0069] S107, a second prepreg tape or a second fiber cloth is wrapped around the outer surface of the inner tube structure, and the second prepreg tape or the second fiber cloth is cured to form a sleeve, wherein the inner surface of the sleeve has a second wedge groove that is engaged with the first wedge groove, and the sleeve is fixed to the first wedge groove of the inner tube body through the second wedge groove to form a multi-wedge connection joint.

[0070] Specifically, the sleeve is formed by covering and winding a second prepreg tape or second fiber cloth onto the outer surface of the inner tube structure and then curing it. The method of covering the inner tube structure with the second prepreg tape or second fiber cloth is the same as the method of winding the winding tape onto the outer surface of the tube body, and both can be wound using a rotating device and a moving device. In this embodiment, the inner tube structure is fixed on the rotating end of the rotating device, and the second prepreg tape or second fiber cloth is fixed on the moving end of the moving device. Compared to the above method where the winding tape is spirally arranged on the mandrel, the sleeve is formed by the spacing of the winding tape.

[0071] The difference is that in this embodiment, the moving speed of the moving device can be reduced to ensure that the second prepreg tape or the second fiber cloth completely covers the outer surface of the inner tube structure (including the part of the first wedge groove). After the second prepreg tape or the second fiber cloth is cured on the outer surface of the release agent layer, a sleeve with multiple second wedge grooves on the inner surface that are embedded with the first wedge groove is generated. The sleeve and the inner tube structure can be removed from the rotating device to obtain a multi-wedge joint. The second prepreg tape can be a fiber-resin composite prepreg tape, which can be made of fiber and resin. The second fiber cloth is a fiber cloth coated with resin on both sides. The second fiber cloth can be glass fiber or carbon fiber, and the resin can be epoxy resin or other resins.

[0072] In summary, this application provides a multi-wedge connection joint for FRP reinforcement in concrete structures and its manufacturing method. The multi-wedge connection joint includes an inner tube body 1 and a sleeve 2. Multiple first wedge grooves 13 are formed on the outer surface of the inner tube body 1, and the inner surface of the sleeve 2 is connected to the inner surface of the sleeve 2 through the first wedge grooves 13. Multiple second wedge grooves 21 are formed on the inner surface of the sleeve 2, and the outer surface of the inner tube body 1 is connected to the inner surface of the inner tube body 1 through the second wedge grooves 21. Due to the wedge structure formed by the inner tube body 1, the sleeve 2, and the first and second wedge grooves 13 and 21 between them, the multi-wedge connection joint of this application will slip between the inner tube body 1 and the sleeve 2 when subjected to tensile force, i.e., extrusion. This extrusion will cause compressive stress in the wedge structure, which will be transferred to the FRP reinforcement, causing compressive stress on the surface of the FRP reinforcement. This compressive stress will increase the shear stress on the surface of the FRP reinforcement, thereby increasing the connection strength of the FRP reinforcement. Furthermore, the thickness of the wedge structure will also affect the surface stress of the FRP reinforcement. The compressive stress is higher at the thinner end of the wedge and lower at the thicker end. In other words, the compressive stress on the surface of the FRP rib decreases from large to small. This application uses multiple first wedge grooves 13 and multiple second wedge grooves 21 between the inner tube body 1 and the sleeve 2 to form multiple wedge structures. Each wedge structure has a thinner end and a thicker end. Therefore, the multi-wedge connection joint of this application has multiple thinner ends. Each thinner end of the wedge will generate a large compressive stress on the FRP bar. Furthermore, since this application has multiple thicker wedge ends, the thicker wedge ends of this application are thinner than the existing single thicker wedge ends, thus providing a greater compressive stress than a single thicker wedge end. This significantly increases the overall compressive stress on the surface of the FRP bar, thereby greatly improving the connection capacity of the connector for FRP bars. This enables the connection of FRP bars with larger diameters using a shorter connector length.

[0073] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for manufacturing a multi-wedge-shaped connection joint for FRP reinforcement in concrete structures, characterized in that, Multi-wedge joints for FRP reinforcement in concrete structures; A multi-wedge connection joint for FRP reinforcement in concrete structures includes an inner tube body and a sleeve, wherein the sleeve is fixedly sleeved on the inner tube body. The inner tube body is characterized by having a plurality of first wedge grooves on its outer surface, which are connected to the inner surface of the sleeve through the first wedge grooves. The inner surface of the sleeve is provided with a plurality of second wedge grooves, and the second wedge grooves are used to connect with the outer surface of the inner tube body. The inner tube body includes a first inner tube and a second inner tube, which are spaced apart along the axial direction. The multi-wedge-shaped connection joint also includes an alignment structure, which connects the first inner tube and the second inner tube respectively, and the first inner tube is connected to the second inner tube through the alignment structure. The alignment structure includes an alignment part, a first washer ring, and a second washer ring. The alignment part is disposed between the first inner tube and the second inner tube and connects the first inner tube and the second inner tube. The first washer ring is disposed on the end of the first inner tube opposite to the alignment part, and the second washer ring is disposed on the end of the second inner tube opposite to the alignment part. The alignment part is provided with two alignment grooves. The alignment part also includes a baffle plate and two third washers. The two third washers are respectively disposed on the two sides of the baffle plate. After the third washers are connected to the baffle plate, they form a positioning groove. One side of the baffle plate is close to the first inner tube, and the other side is close to the second inner tube. The two sides of the baffle plate are opposite to each other. The manufacturing method includes: A winding tape is wound around the outer surface of the pipe body to form a first mandrel with multiple protrusions on the outer surface. Specifically, one end of the winding tape is first fixed to the pipe body, the winding tape is set on one side of the pipe body, the winding tape is set on the moving end of the moving device, and the pipe body is set on the rotating end of the rotating device. At the same time, the rotating device is driven to rotate and the moving device is moved. The pipe body will rotate with the rotating device, which will then drive the winding tape on it to continuously wind around the pipe body. The moving device will drive the other end of the winding tape to move and make the winding tape spirally wound around the pipe body to generate a first mandrel with multiple protrusions. The first mandrel is used to manufacture an inner pipe body with multiple grooves on the inner surface that fit into the protrusions. A first prepreg tape or a first fiber cloth is wrapped around the outer surface of the first mandrel, and the first prepreg tape or the first fiber cloth is cured to form the inner tube body. The outer surface of the inner tube body is cut to generate a first inner tube and a second inner tube with multiple first wedge-shaped grooves on the outer surface; An alignment structure is provided between the first inner tube and the second inner tube, and the first inner tube is connected to the second inner tube through the alignment structure to form an inner tube structure; A second prepreg tape or a second fiber cloth is wrapped around the outer surface of the inner tube structure, and the second prepreg tape or the second fiber cloth is cured to form a sleeve. The inner surface of the sleeve has a second wedge groove that fits into the first wedge groove. The sleeve is fixed to the first wedge groove of the inner tube body through the second wedge groove to form a multi-wedge joint.

2. The manufacturing method of the multi-wedge connection joint for FRP reinforcement in concrete structures as described in claim 1, characterized in that, The thickness of the first washer and the second washer is not less than 10cm.

3. The manufacturing method of the multi-wedge connection joint for FRP reinforcement in concrete structures as described in claim 1, characterized in that, Multiple grooves are provided on the inner surfaces of both the first inner tube and the second inner tube.

4. The manufacturing method of the multi-wedge connection joint for FRP reinforcement in concrete structures as described in claim 1, characterized in that, Both ends of the inner tube body are provided with extensions, which extend out of the sleeve.

5. The manufacturing method of the multi-wedge connection joint for FRP reinforcement in concrete structures as described in claim 1, characterized in that, Before the step of covering and winding a first prepreg tape or a first fiber cloth onto the outer surface of the first mandrel and curing the first prepreg tape or the first fiber cloth to form the inner tube body, the manufacturing method further includes: A winding tape is wound around the outer surface of the pipe body to form a first mandrel with multiple protrusions on the outer surface.

6. The manufacturing method of the multi-wedge connection joint for FRP reinforcement in concrete structures as described in claim 5, characterized in that, The step of covering and winding a first prepreg tape or a first fiber cloth onto the outer surface of the first mandrel, and curing the first prepreg tape or the first fiber cloth to form the inner tube body specifically includes: A release agent is sprayed onto the outer surface of the first mandrel and then cured to form a release agent layer. A first prepreg tape or a first fiber cloth is wrapped around the outer surface of the release agent layer, and the first prepreg tape or the first fiber cloth is cured to form an inner tube body, wherein the inner surface of the inner tube body has a plurality of grooves that fit into the protrusions. The inner tube body is separated from the first mandrel through the release agent layer.

7. The manufacturing method of the multi-wedge connection joint for FRP reinforcement in concrete structures as described in claim 5, characterized in that, Before the step of winding a winding tape around the outer surface of the pipe body and forming a first mandrel with multiple protrusions on the outer surface, the manufacturing method further includes: covering the pipe with a layer of plastic film to form the pipe body.

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