A tensioning system, monitoring device and monitoring method

Abstract

This application discloses a tensioning system, a monitoring device, and a monitoring method. The tensioning system includes a coil, a connecting rod, and an electric wire. Both the coil and the connecting rod are made of shape memory alloy. The tensioning end of the connecting rod is connected to the material under test. The coil is wound around the connecting rod, and both ends of the coil are connected to the connecting rod. An insulating layer is provided on the outer surface of the coil. One end of the electric wire is connected to the coil, and the other end of the electric wire is connected to the connecting rod to form a circuit. A switching component is provided on the circuit. Long-term monitoring of the prestress of the material under test is achieved by changing the resistance of the coil. The coil or the connecting rod can be directionally excited, achieving controllable excitation mode and convenient operation. The monitoring device using this tensioning system is convenient to operate for monitoring the prestress of the material under test, and the monitoring method using this tensioning system can monitor the material under test in real time.

Description

Technical Field

[0001] This application relates to the field of materials monitoring technology, and in particular to a tensioning system, monitoring device, and monitoring method. Background Technology

[0002] Currently, the main function of a typical prestressed FRP (fiber reinforced composite) tensioning system is to provide prestress to the FRP in one go and fix the prestressed FRP after tensioning. After the jacks are removed and the excessively long screws are cut off, the high-strength screws that bear the force transmission are clamped between the wedge-shaped anchor and the anchor base at the tensioning end. Under long-term human disturbance and environmental influence, the high-strength screws resist the tension of the prestressed FRP through their own strength, thereby preventing the loss of prestress in the FRP.

[0003] However, when using only ordinary prestressed FRP tensioning systems, the deformation of high-strength bolts is difficult to identify visually. Combining current mainstream monitoring methods such as monitoring instruments, lidar, photogrammetry, and GPS measurement presents challenges due to high costs, operational difficulties, and high labor costs for training operators. Furthermore, since the deformation of high-strength bolts is irreversible, when the prestressed FRP shrinks after long-term service, it causes the high-strength bolts to elongate, reducing their cross-section and making compensatory tensioning impossible. Re-tensioning the prestressed FRP would incur significant construction costs. Summary of the Invention

[0004] The purpose of this application is to at least solve one of the technical problems existing in the prior art, and to provide a tensioning system, a monitoring device and a monitoring method, wherein the tensioning system can realize compensated tensioning, the monitoring device using the tensioning system can monitor the prestress of the tested material, the operation is convenient, and the monitoring method using the tensioning system can monitor the tested material in real time.

[0005] The technical solution adopted by this application to solve its technical problem is:

[0006] A tensioning system includes a coil, a connecting rod, and an electric wire. The coil and the connecting rod are both made of shape memory alloy. The tensioning end of the connecting rod is connected to the material to be measured. The coil is wound around the connecting rod, and both ends of the coil are connected to the connecting rod. An insulating layer is provided on the outer surface of the coil. One end of the electric wire is connected to the coil, and the other end of the electric wire is connected to the connecting rod to form a circuit. A switching assembly is provided on the circuit.

[0007] In some embodiments of this application, a first wiring portion is provided at the welding point between one end of the coil and the connecting rod, and a second wiring portion is provided at the welding point between the other end of the coil and the connecting rod.

[0008] In some embodiments of this application, the switch assembly is disposed between the first wiring portion and the wire. The switch assembly includes a rotating rod and an insulating sleeve. The wire extends into the insulating sleeve. The rotating rod is connected to the first wiring portion. A first connector is provided on the outer periphery of the rotating rod. Rotating the rotating rod can connect or disconnect the first connector from the wire.

[0009] In some embodiments of this application, the insulating sleeve is provided with a third wiring portion, one end of which is connected to the wire, and the other end forms a second connector on the inner circumference of the insulating sleeve. Rotating the rotating rod can connect or disconnect the first connector from the second connector. A connection portion is provided between the third wiring portion and the coil.

[0010] In some embodiments of this application, the rotating rod is provided with an insulating contact, and rotating the rotating rod can connect the first connector to the insulating contact.

[0011] In some embodiments of this application, the second connector includes a metal contact and a reaction spring, the reaction spring being disposed inside the metal contact.

[0012] In some embodiments of this application, the tension end of the connecting rod is provided with an anchor, which is used to fix the material being tested.

[0013] In some embodiments of this application, the fixed end of the connecting rod is provided with a base, which is used to fix the connecting rod.

[0014] This application also provides a monitoring device, including a device body and the tensioning system in the above embodiments, wherein the fixed end of the material to be tested is connected to the device body.

[0015] This application also provides a monitoring method using the tensioning system described in the above embodiments, characterized by comprising the following steps:

[0016] Step 1: Disconnect the switching assembly, energize the coil, and measure the resistance of the coil;

[0017] Step 2: Close the switch assembly. The heating excitation causes the connecting rod to contract, increasing its cross-section and achieving compensating tension.

[0018] Repeat steps one and two to monitor the change in the difference between the resistances of the coil measured in two consecutive measurements, thereby achieving prestress monitoring of the material being tested.

[0019] One of the above technical solutions has at least one of the following advantages or beneficial effects: When using this tensioning system, a switching assembly is used to control the current flow. Since both the coil and the connecting rod are made of shape memory alloy, the switching assembly is in the open state. At this time, the coil is energized and heated to excite it. Since the two ends of the coil are connected to the connecting rod, the coil and the connecting rod form a series system. Because the outer surface of the coil has an insulating layer, the coil is considered an insulator, and the current only acts on the coil, that is, the coil is excited. After being energized and heated, the coil is tightly wound on the connecting rod and deforms synchronously with the connecting rod. The resistance of the coil before tensioning is measured. Then, the switching assembly is closed, and the wires are connected, connecting the coil and the connecting rod in parallel, that is, the coil and the connecting rod form a parallel system. At this time, the current flow is controlled by the switching assembly. The coil is excited, and since the coil's resistance is much greater than the connecting rod's resistance, the current flows entirely to the connecting rod, generating heat and exciting it. Utilizing the shape memory characteristics of the connecting rod, it contracts, increasing its cross-section to achieve compensating tension. Then, the switch assembly is disconnected, and the resistance of the coil after the connecting rod deforms is measured. The correlation between the resistance value and the prestress value is used to monitor the prestress loss of the tested material (FRP material). This tensioning system achieves long-term monitoring of the prestress of the tested material through changes in coil resistance. It can directionally excite the coil or connecting rod, achieving controllable excitation modes and convenient operation. When applied to the monitoring device, the tensioning system causes minimal disturbance to other structures and virtually no additional damage. Using this tensioning system's monitoring method, the prestress of the tested material can be continuously monitored.

[0020] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0021] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0022] Figure 1 This is a schematic diagram of the structure of one embodiment of the tensioning system in this application;

[0023] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0024] Figure 3 yes Figure 2 Cross-sectional view at point BB;

[0025] Figure 4 yes Figure 3 Cross-sectional view at point C;

[0026] Figure 5 This is a partial structural schematic diagram of one embodiment of the tensioning system in this application. Detailed Implementation

[0027] This section will describe in detail the specific embodiments of this application. Preferred embodiments of this application are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of this application, but they should not be construed as limiting the scope of protection of this application.

[0028] In this application, when directions (up, down, left, right, front, and back) are described, it is only for the purpose of describing the technical solution of this application, and does not indicate or imply that the technical features referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on this application.

[0029] In this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc. are understood to exclude the stated number; "above," "below," "within," etc. are understood to include the stated number. In the description of this application, the terms "first" and "second" are used only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of the indicated technical features.

[0030] In this application, unless otherwise explicitly defined, the terms "setup," "installation," and "connection" should be interpreted broadly. For example, they can refer to direct connection or indirect connection through an intermediate medium; they can refer to fixed connection, detachable connection, or integral molding; they can refer to mechanical connection, electrical connection, or connection capable of mutual communication; they can refer to the internal connection of two components or the interaction between two components. Those skilled in the art can reasonably determine the specific meaning of the above terms in this application based on the specific content of the technical solution.

[0031] in, Figure 1 The reference direction coordinate system of this application embodiment is given below, in conjunction with Figure 1 The directions shown are used to illustrate embodiments of this application.

[0032] FRP (fiber reinforced plastic) tensioning systems typically consist of tensioning components that provide support and reaction forces, a force-transmitting connecting rod system, and jacks that apply tension. These systems provide prestress to the FRP at the interface of the reinforced structure. After the initial tensioning, the jacks should be removed and any excessively long connecting rods cut off. Therefore, the completed tensioning system consists of the tensioning components and the force-transmitting connecting rod system. Because this system offers advantages in tensioning effect, working method, ease of operation, and cost, it is widely used in structural reinforcement.

[0033] An embodiment of this application provides a tensioning system, see [link to relevant documentation]. Figures 1 to 5 The tensioning system includes a coil 100, a connecting rod 200, and a wire 300. Both the coil 100 and the connecting rod 200 are made of shape memory alloy. The tensioning end of the connecting rod 200 is connected to the material being measured 400. The coil 100 is wound around the connecting rod 200, and both ends of the coil 100 are connected to the connecting rod 200. An insulating layer is provided on the outer surface of the coil 100. One end of the wire 300 is connected to the coil 100, and the other end of the wire 300 is connected to the connecting rod 200, forming a circuit. A switch assembly 500 is provided on the circuit. When using this tensioning system, [the following is a description of the system's operation]... The current flow is controlled by a switching assembly 500. Since both the coil 100 and the connecting rod 200 are made of shape memory alloy, the switching assembly 500 is in the open state. When energized, it heats and excites the coil 100. Because the two ends of the coil 100 are connected to the connecting rod 200, the coil 100 and the connecting rod 200 form a series system. Since the outer surface of the coil 100 has an insulating layer, the coil 100 is considered an insulator, and the current only affects the coil 100; that is, the coil 100 is excited. After being energized and heated, the coil 100 is tightly wound around the connecting rod 200. The coil 100 deforms synchronously with the connecting rod 200, and the resistance of the coil 100 before compensation tension is measured. Then, the switch assembly 500 is closed, at which point the wire 300 is connected, connecting the coil 100 and the connecting rod 200 in parallel, forming a parallel system. When the coil 100 is excited, since its resistance is much greater than that of the connecting rod 200, the current flows entirely to the connecting rod 200, generating heat and exciting it. Utilizing the shape memory characteristic of the connecting rod 200, the connecting rod 200 contracts, increasing its cross-section. The system achieves compensatory tensioning; then the switch assembly 500 is disconnected, and the resistance of the coil 100 after the connecting rod 200 is deformed is measured. The prestress loss of the tested material 400 (FRP material) is monitored by the correlation between the resistance value and the prestress value. This tensioning system achieves long-term monitoring of the prestress of the tested material through the change of the resistance of the coil 100. It can directionally excite the coil 100 or the connecting rod 200, realizes controllable excitation mode, and is easy to operate. When the tensioning system is applied in the monitoring device, it has little disturbance to other structures and basically does not cause additional damage.

[0034] It is understandable that the winding spacing, diameter, and material of coil 100 have an impact on the excitation and monitoring effect. The optimal monitoring and excitation scheme should be proposed based on the degree of influence of these factors on excitation and monitoring.

[0035] One end of the coil 100 is provided with a first terminal 110 at the welding point to the connecting rod 200, and the other end of the coil 100 is provided with a second terminal 120 at the welding point to the connecting rod 200. After the two ends of the coil 100 are welded to the connecting rod 200, they should be ground flat to facilitate the installation of terminals. The terminals are connected to the coil 100, and one end is connected to an electric wire. Both the first terminal 110 and the second terminal 120 are terminals, which are used to conduct electricity for excitation.

[0036] The switch assembly 500 is disposed between the first wiring portion 110 and the wire 300. The switch assembly 500 includes a rotating rod 510 and an insulating sleeve 520. The wire 300 extends into the insulating sleeve 520. The rotating rod 510 is connected to the first wiring portion 110. A first connector 511 is provided on the outer periphery of the rotating rod 510. Rotating the rotating rod 510 can connect or disconnect the first connector 511 from the wire 300. The insulating sleeve 520 is made of rubber material.

[0037] The insulating sleeve 520 has a third wiring part 521 inside. One end of the third wiring part 521 is connected to the wire 300, and the other end forms a second connector 530 on the inner circumference of the insulating sleeve 520. Rotating the rotating rod 510 can connect or disconnect the first connector 511 and the second connector 530. The third wiring part 521 is connected to the coil 100. The connecting part includes a metal piece 522, which can connect the coil 100 and the rotating rod 510. Rotating the insulating sleeve 520 causes the metal contact on the rotating rod 510 to contact the metal contact on the rubber head, and the insulating switch is closed. Rotating the insulating sleeve 520 causes the insulating contact 512 on the rotating rod 510 to contact the metal contact 531, and the insulating switch is opened.

[0038] The rotating rod 510 is provided with an insulating contact 512. Rotating the rotating rod 510 can connect the first connector 511 to the insulating contact 512. When the switch assembly 500 is disconnected, the first connector 511 and the insulating contact 512 can be aligned.

[0039] See Figure 4 The second connector 530 includes a metal contact 531 and a reaction spring 532. The reaction spring 532 is located inside the metal contact 531 and is used to prevent the metal contact 531 from being excessively recessed.

[0040] An anchor 210 is provided at the tensioning end of the connecting rod 200. The anchor 210 is used to fix the material under test 400. The anchor 210 is a wedge-shaped anchor to connect the prestressed FRP and the connecting rod 200.

[0041] The fixed end of the connecting rod 200 is provided with a base 220, which is used to fix the connecting rod 200.

[0042] This application also provides a monitoring device, including a device body and a tensioning system according to any of the above embodiments, wherein the fixed end of the material to be tested 400 is connected to the device body, and the base 220 is disposed on the device body.

[0043] The initial tensioning process of the tested material 400 (FRP) is similar to that of ordinary tensioning. The monitoring device of this application is used for monitoring and compensating tension after the jack is removed and the excessively long connecting rod 200 is cut off. After the jack is removed and the excessively long connecting rod 200 is cut off, the switch assembly 500 should be disconnected and the initial resistance value of the coil 100 should be collected.

[0044] The steps for the initial tensioning of the tested material 400 (FRP) using a monitoring device are as follows: 1. Accurately locate and lay out the positions of the FRP and anchorages;

[0045] 2. Drill holes and grind them at the corresponding locations according to the design requirements;

[0046] 3. Cut grooves along the anchor block layout area at both ends, with a depth of approximately 3cm;

[0047] 4. After the groove is cut, use repair glue to repair it, and sand it smooth after it has completely cured;

[0048] 5. High-strength chemical anchors or high-strength mechanical anchors are inserted into the holes, with the anchor grade not lower than 8.8;

[0049] 6. Place the anchor blocks into the limiting frames at both ends, keeping the center lines of both ends aligned and fixed, to ensure that the anchor blocks at the tensioning end can slide freely within the limiting frames;

[0050] 7. Cut the FRP, leaving 5-10cm at both ends, insert the FRP into the wedge-shaped hole of the anchor, slide the tensioning end anchor block to the starting position, and clamp it with the clamp;

[0051] 8. Install the tensioning system, along with the gasket, nut, baffle, and jack, in sequence at the tensioning end. The end of the connecting rod (screw) passes through the wedge anchor, base, and baffle at the tensioning end. Adjust the jack to the tightened state, with the force direction of the jack coinciding with the central axis of the FRP plate.

[0052] 9. Take protective measures on site and start pre-tensioning. After unloading the pre-tensioned material, apply structural adhesive evenly to the FRP surface. Then, perform formal tensioning in stages. Each stage of tensioning should be held for 3-5 minutes. Record the corresponding tensile force and elongation before proceeding to the next stage of tensioning.

[0053] 10. After tensioning is completed, tighten the nuts, remove the jack, cut off 200mm of the excessively long connecting rod, and install a pressure plate every two meters for fixation, applying slight pressure.

[0054] 11. Finally, apply fire-retardant and anti-corrosion coating to protect the anchorage and FRP.

[0055] This application also provides a monitoring method using the tensioning system in the above embodiments, which includes the following steps:

[0056] After the initial tensioning is completed, the jack is removed, and the excessively long connecting rod 200 is cut off. The connecting rod 200 only passes through the wedge-shaped anchor at the tensioning end and the anchor base, so that the connecting rod 200 and the coil 100 are clamped between the wedge-shaped anchor at the tensioning end and the anchor base.

[0057] Step 1: Disconnect switch assembly 500, activate coil 100, and measure the resistance of coil 100, denoted as Ω1;

[0058] Step 2: Close the switch assembly 500. The heating excitation causes the connecting rod 200 to contract, increasing the cross-section and achieving compensating tension, thus completing one monitoring-excitation-compensation procedure.

[0059] Repeat steps one and two, and record the resistance measured each time as Ωn (n = 1, 2, 3...). Monitor the change in the difference between the resistance of coil 100 measured in two consecutive measurements to realize the prestress monitoring of the material 400 under test, characterize the degree of loss of prestressed FRP in different monitoring time periods, and continuously compensate and tension the prestressed FRP to realize long-term prestress monitoring and compensation tension of prestressed FRP.

[0060] This monitoring method can achieve real-time monitoring, low cost, easy operation, multiple compensation tensioning, quantitative compensation tensioning, and low disturbance in various types of structural health monitoring and reinforcement. It is particularly suitable for prestressed FRP reinforcement of concrete beams and steel beams, and is a prestressed FRP tensioning system worthy of promotion and application.

[0061] In the description of this specification, references to terms such as "example," "embodiment," or "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0062] Of course, the present invention is not limited to the above-described embodiments. Those skilled in the art can make equivalent modifications or substitutions without departing from the spirit of this application, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A tensioning system characterized by: The device includes a coil, a connecting rod, and a wire. Both the coil and the connecting rod are made of shape memory alloy. The tension end of the connecting rod is connected to the material being measured. The coil is wound around the connecting rod, and both ends of the coil are connected to the connecting rod. An insulating layer is provided on the outer surface of the coil. One end of the wire is connected to the coil, and the other end of the wire is connected to the connecting rod, forming a circuit. A switching assembly is provided on the circuit. A first wiring portion is provided at the welding point between one end of the coil and the connecting rod, and a second wiring portion is provided at the welding point between the other end of the coil and the connecting rod. The switching assembly is located between the first wiring portion and the wire. The switching assembly includes a rotating rod and an insulating sleeve. The wire extends into the insulating sleeve. The rotating rod is connected to the first wiring portion, and a first connector is provided on the outer periphery of the rotating rod. Rotating the rotating rod allows the first connector to be connected to or disconnected from the wire.

2. The tensioning system of claim 1, wherein: The insulating sleeve is provided with a third wiring part. One end of the third wiring part is connected to the wire, and the other end forms a second connector on the inner circumference of the insulating sleeve. Rotating the rotating rod can connect or disconnect the first connector and the second connector. A connection part is provided between the third wiring part and the coil.

3. The tensioning system according to claim 2, characterized in that: The rotating rod is equipped with an insulating contact, and rotating the rotating rod can connect the first connector to the insulating contact.

4. The tensioning system according to claim 2, characterized in that: The second connector includes a metal contact and a reaction spring, the reaction spring being disposed inside the metal contact.

5. The tensioning system according to claim 1, characterized in that: The tensioning end of the connecting rod is equipped with an anchor, which is used to fix the material being tested.

6. The tensioning system according to claim 1, characterized in that: The fixed end of the connecting rod is provided with a base, which is used to fix the connecting rod.

7. A monitoring device, characterized in that: It includes a device body and a tensioning system as described in any one of claims 1 to 6, wherein the fixed end of the material being tested is connected to the device body.

8. A monitoring method using the tensioning system according to any one of claims 1 to 6, characterized in that... Includes the following steps: Step 1: Disconnect the switching assembly, energize the coil, and measure the resistance of the coil; Step 2: Close the switch assembly. The heating excitation causes the connecting rod to contract, increasing its cross-section and achieving compensating tension. Repeat steps one and two to monitor the change in the difference between the resistances of the coil measured in two consecutive measurements, thereby achieving prestress monitoring of the material being tested.

Images