Fiber grating rebar stress meter and method of use

Abstract

The application relates to the technical field of intelligent sensors, and discloses a fiber grating steel bar stress meter and a use method thereof. In order to solve the problems that the fiber grating on the outer side of the ribbed steel bar is not easy to install and position, two positioning clamps with positioning grooves are installed on the outer side of the ribbed steel bar, the cross ribs are correspondingly positioned in the positioning grooves, after the positioning clamps are installed and fastened, the fiber grating can only be installed on the longitudinal rib of the ribbed steel bar, the longitudinal rib is a plane and is relatively parallel to the central axis of the ribbed steel bar, therefore, the fiber grating is limited on the longitudinal rib by the positioning clamps, surface contact installation between the fiber grating and the longitudinal rib can be realized while the fiber grating is fastened and connected on the outer side of the ribbed steel bar.

Description

Technical Field

[0001] This invention relates to the field of intelligent sensor technology, and in particular to a fiber optic grating rebar stress gauge and its usage method. Background Technology

[0002] In smart sensor applications, fiber optic grating rebar stress sensors have become a core tool in the field of rebar stress monitoring due to their high sensitivity, strong anti-interference, and corrosion resistance. This technology uses the Bragg wavelength shift principle of fiber optic gratings to sense the micro-strain of rebar caused by stress or temperature changes in real time. Combined with a distributed fiber optic sensor network, it can cover the entire life cycle monitoring of rebar stress in large structures such as bridges, dams, and tunnels.

[0003] A search revealed that publication number CN221123333U proposes a sleeve-type fiber optic grating rebar gauge, which includes: using spring force to drive the fiber optic grating rebar gauge against the rebar body, thus avoiding the phenomenon of gaps between the rebar body and the sleeve-type fiber optic grating rebar gauge.

[0004] In principle, using spring force can indeed push the fiber Bragg grating against the outside of the reinforcing steel, thus achieving the purpose of positioning and securing the fiber Bragg grating. However, in actual implementation, the applicant found that the existing technology of directly pushing the fiber Bragg grating with a spring is mainly suitable for round steel bars. Round steel bars are characterized by their smooth, curved outer surfaces, allowing the spring-driven fiber Bragg grating to easily and directly reach the outside of the steel bar. However, in practical applications, such as high-rise building frames and bridge piers that need to withstand vertical loads and horizontal seismic forces, ribbed steel bars are typically used. Unlike round steel bars, ribbed steel bars have periodic raised ribs on their surface. This ribbed structure, through mechanical interlocking with the concrete, significantly enhances the bond between the two, effectively preventing slippage.

[0005] Because of the ribs on the sides of the ribbed steel bar, when the fiber grating is pushed against the side of the ribbed steel bar by the spring, the contact point tends to be concentrated on the protruding parts of the transverse ribs, forming point contact rather than surface contact. This contact method leads to uneven actual strain transmission. The local high strain at the transverse ribs may be over-amplified, while the low strain in other areas may be ignored, ultimately causing the measured value to deviate from the true value. More seriously, excessive stress concentration may cause the fiber grating to bear loads beyond its design range, leading to problems such as fiber breakage. Summary of the Invention

[0006] This invention proposes a fiber optic grating rebar stress gauge and its usage method, which has the characteristics of fiber optic grating surface contact installation and self-limiting, in order to solve the problem of difficult installation and positioning of fiber optic gratings on the outer side of ribbed rebars mentioned in the background art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a fiber optic grating rebar stress gauge, comprising: a ribbed rebar with transverse ribs and longitudinal ribs on its side; a positioning clamp with a positioning groove corresponding to the transverse ribs on its inner side. After the positioning clamp is installed on the side of the ribbed rebar, it is positioned / limited according to the transverse ribs and the positioning groove, so that the limiting groove on the top of the positioning clamp restricts the fiber optic grating to the longitudinal ribs.

[0008] Furthermore, the longitudinal ribs are parallel to the central axis of the ribbed steel bars, and the surface of the longitudinal ribs is flat.

[0009] Furthermore, the fiber Bragg grating is fixedly installed at the bottom of the protective sleeve, and transmission optical fibers are installed at both ends of the fiber Bragg grating. The transmission optical fibers pass through the protective sleeve and are guided along the fiber optic groove at the top of the protective sleeve before being connected to the control computer.

[0010] Furthermore, the top of the positioning clamp has an internal thread located above the limiting groove. The two positioning clamps fit together to form a complete threaded hole. A bolt is connected to the internal thread of the threaded hole. The end of the bolt is screwed in to press and tighten the protective sleeve. When the bolt is screwed into the internal thread normally, it is determined that the positioning clamp is installed in place.

[0011] Furthermore, the top of the positioning clamp is provided with a guide groove located between the internal thread and the limiting groove. A central shaft is movably installed inside the bolt, and a pressure block fitted with the guide groove is provided at the bottom of the central shaft. A fastening spring is provided between the pressure block and the bolt. A limiting screw seat is fixedly connected in the middle of the central shaft, and a threaded hole is provided at the bottom of the bolt for threaded connection with the limiting screw seat.

[0012] Furthermore, the guide groove is an elliptical groove.

[0013] Furthermore, the pitch of the limiting screw seat is equal to the pitch of the bolt.

[0014] Furthermore, the bottom end of the central shaft is elliptical, and the bottom end of the central shaft is movably installed in the middle of the top of the pressure block. A connecting ring groove is opened at the bottom of the central shaft, and a spring push rod is provided on the pressure block to abut against the connecting ring groove.

[0015] Furthermore, a cutter is movably mounted on the bottom of the pressure block above the transmission optical fiber. The cutter is perpendicular to the central axis of the transmission optical fiber. A spring top rod is fixedly mounted on the side of the cutter, and a top spring is provided between the top of the cutter and the pressure block.

[0016] A method for using a fiber optic grating rebar stress gauge includes the following steps:

[0017] S1. Two positioning clamps are engaged with the side of the ribbed steel bar and limit the protective sleeve. The two internal threads of the positioning clamps are fitted together when they are in place.

[0018] S2. The construction personnel tighten the bolts into the internal threads. As the bolts go deeper, the bolt ends press against the protective sleeve, ensuring that the protective sleeve is tightly pressed against the longitudinal rib and that the fiber optic grating installed on the protective sleeve is always tightly pressed against the plane of the longitudinal rib.

[0019] S3. If the two positioning clamps are not installed in place, and there is a gap between the positioning clamps, the two internal threads cannot form a complete threaded hole, and the bolt cannot be screwed into the internal threads.

[0020] S4. Use bolts to press and tighten the installed protective sleeve, and at the same time check whether the positioning clamp is properly installed. The operator judges whether the positioning clamp is properly installed based on whether the bolts can press and tighten the protective sleeve properly.

[0021] The present invention has the following beneficial effects:

[0022] This invention provides a fiber Bragg grating (FBG) stress gauge for reinforcing bars and its usage method. Two positioning clamps with positioning grooves are installed on the outer side of the ribbed reinforcing bar, with the transverse ribs correspondingly abutting into the positioning grooves. Once the positioning clamps are tightened, they restrict the installation position of the FBG, ensuring that the FBG can only be installed on the longitudinal ribs of the ribbed reinforcing bar. It should be noted that the longitudinal ribs of the ribbed reinforcing bar are planar and relatively parallel to the central axis of the reinforcing bar. By using the positioning clamps to restrict the FBG to the longitudinal ribs, on the one hand, it ensures a tight connection between the FBG and the outer side of the ribbed reinforcing bar, preventing loosening or displacement during use; on the other hand, it achieves surface contact installation between the FBG and the longitudinal ribs. Compared to point contact, this surface contact installation method allows the FBG to more comprehensively and accurately sense the stress changes of the longitudinal ribs, laying the foundation for subsequent precise detection of the stress condition of the ribbed reinforcing bar.

[0023] Furthermore, when the two positioning clamps are assembled in the normal manner, their internal threads form a complete threaded hole. Construction workers simply need to screw the bolts onto this complete internal thread. As the bolts are gradually screwed in, the bolt ends gradually approach and eventually press the fiber grating, now positioned by the positioning clamps, tightly against the surface of the longitudinal rib. This method further ensures that the fiber grating is tightly and firmly attached to the longitudinal rib, guaranteeing full contact between the fiber grating and the rib. This allows for accurate detection of stress changes in the ribbed steel bars during use, providing reliable data support for quality monitoring of construction projects. Attached Figure Description

[0024] The accompanying drawings, which form part of this specification, illustrate embodiments of the invention and, together with the specification, serve to explain the principles of the invention.

[0025] The invention will be more clearly understood with reference to the accompanying drawings and the following detailed description, wherein:

[0026] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the present invention after assembly;

[0027] Figure 2 This is a schematic diagram of the internal three-dimensional structure of the positioning clamp after the entire assembly of the present invention;

[0028] Figure 3 For the present invention Figure 2 Enlarged structural diagram of section E in the middle;

[0029] Figure 4 This is a schematic diagram of the three-dimensional structure of the positioning clamp of the present invention;

[0030] Figure 5 This is a schematic diagram of the internal three-dimensional structure of the protective sleeve of the present invention;

[0031] Figure 6 This is a schematic diagram showing the installation positions and three-dimensional structure of the various components on the bolt of the present invention;

[0032] Figure 7 This is a schematic diagram showing the state of the bolts of the present invention before installation.

[0033] In the diagram: 1. Ribbed steel bar; 101. Horizontal rib; 102. Longitudinal rib; 2. Protective sleeve; 200. Fiber optic groove; 3. Fiber grating; 300. Transmission fiber; 4. Positioning clamp; 401. Positioning groove; 402. Guide groove; 403. Internal thread; 404. Limiting groove; 5. Bolt; 6. Pressure block; 601. Limiting top rod; 7. Central shaft; 700. Connecting ring groove; 701. Limiting screw seat; 8. Fastening spring; 9. Cutter; 10. Top spring; 11. Spring top rod. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1, please refer to Figure 1 and Figure 2 It can be seen that the reinforcing bars used in this application are mainly ribbed reinforcing bars 1, but the method described in this application still applies to plain round reinforcing bars. Currently, multiple transverse ribs 101 are equidistantly arranged on the side of the ribbed reinforcing bar 1. In this application, the transverse ribs 101 are mainly crescent-shaped, but not limited to this. The shape of the transverse ribs 101 can also be herringbone or spiral, etc. The side of the ribbed reinforcing bar 1 is provided with longitudinal ribs 102 that are relatively parallel to its central axis. The surface of the longitudinal ribs 102 is generally flat.

[0036] Before installing and using the fiber Bragg grating 3, it needs to be protected, such as... Figure 5 As shown, the bottom of the protective sleeve 2 has a groove that can accommodate the fiber Bragg grating 3. The size of the groove is the same as that of the fiber Bragg grating 3. The fiber Bragg grating 3 is fastened to the bottom of the protective sleeve 2 by bolts or adhesive. The top of the protective sleeve 2 has a fiber optic groove 200. Transmission fibers 300 are installed at both ends of the fiber Bragg grating 3. After passing through the fiber optic groove 200, the transmission fibers 300 can output from one end of the protective sleeve 2. The signal generated by the fiber Bragg grating 3 can be transmitted to the control computer through the transmission fibers 300 to calculate the working state of the steel bar measured by the fiber Bragg grating 3.

[0037] Once the fiber grating 3 is prepared, the ribbed steel bar 1 is positioned and secured using positioning clamps 4. The positioning clamps 4 are semi-circular in shape, and two clamps 4 are fastened to the side of the ribbed steel bar 1 using bolts. According to... Figure 4 It can be seen that the positioning clamp 4 has a positioning groove 401 on its side corresponding to the transverse rib 101. When the two positioning clamps 4 are engaged on the outside of the ribbed steel bar 1, the transverse rib 101 is located in the positioning groove 401. After the positioning clamp 4 is properly assembled, the limiting groove 404 on the inner side of the top of the positioning clamp 4 is located on the longitudinal rib 102. In this way, when it is necessary to limit and tighten the protective sleeve 2, the protective sleeve 2 with fiber optic grating 3 is attached to the plane of the longitudinal rib 102, and the two positioning clamps 4 are engaged on the side of the ribbed steel bar 1. At this time, the limiting groove 404 can limit the installation of the protective sleeve 2. Finally, by limiting the installation of the protective sleeve 2, the fiber optic grating 3 is always attached to the plane of the longitudinal rib 102, avoiding the problem of output data distortion caused by gaps between the fiber optic grating 3 and the ribbed steel bar 1. At the same time, by utilizing the cooperation between the positioning groove 401 and the transverse rib 101, on the one hand, it ensures that after the positioning clamp 4 is installed normally, the limiting groove 404 can limit the installation of the protective sleeve 2; on the other hand, based on the limiting between the positioning groove 401 and the transverse rib 101, the positioning clamp 4 is prevented from moving along the axial direction of the ribbed steel bar 1, thereby further enhancing the accuracy of the installation and fastening position of the positioning clamp 4.

[0038] Example 2 is a further improvement on Example 1. Please refer to Example 1. Figures 2-4 It can be seen that the top of the positioning clamp 4 has an internal thread 403 located above the limiting groove 404, and the internal thread 403 on the top of one positioning clamp 4 is a semi-threaded hole. Two positioning clamps 4 need to be attached together before the two attached internal threads 403 can form a complete threaded hole.

[0039] When the protective sleeve 2 needs to be positioned and tightened, two positioning clamps 4 are used to clamp the side of the ribbed steel bar 1 and limit the position of the protective sleeve 2. At this time, the positioning clamps 4, when properly installed, allow the two internal threads 403 to fit together. The construction personnel then tighten the bolt 5 into the internal threads 403. As the bolt 5 goes deeper, its end abuts against the protective sleeve 2, ensuring that the protective sleeve 2 is tightly pressed against the longitudinal rib 102, and ensuring that the fiber optic grating 3 installed on the protective sleeve 2 is always tightly pressed against the plane of the longitudinal rib 102. Conversely, if the two positioning clamps 4 are not properly installed, there will be a gap between the positioning clamps 4, and the two internal threads 403 will not form a complete thread groove, and the bolt 5 will not be able to be screwed into the internal threads 403. It can be seen that the bolt 5 can be used to press and tighten the installed protective sleeve 2 on the one hand, and to check whether the positioning clamps 4 are properly installed on the other hand. Finally, the operator can know whether the positioning clamps 4 are properly installed by checking whether the bolt 5 can properly press and tighten the protective sleeve 2.

[0040] Based on this, in order to ensure that the bolt 5 can apply appropriate resistance force to the protective sleeve 2, avoiding excessive resistance force of the bolt 5 causing the protective sleeve 2 to deform due to pressing against the fiber optic grating 3, or insufficient resistance force of the bolt 5 causing it to fail to securely limit the protective sleeve 2, this embodiment two is based on... Figure 3 , Figure 4 and Figure 6 As shown, the top of the positioning clamp 4 has a guide groove 402 located between the internal thread 403 and the limiting groove 404. The guide groove 402 is elliptical. Simultaneously, a central shaft 7, which reciprocates along its central axis, is movably mounted inside the bolt 5. A pressure block 6, also elliptical, is fitted at the bottom of the central shaft 7 and fits into the guide groove 402. A fastening spring 8 is positioned between the pressure block 6 and the bolt 5, and is normally in a freely extended state. A limiting screw seat 701 is fixedly connected to the middle of the central shaft 7. Correspondingly, the bottom of the bolt 5 has a threaded hole that connects to the limiting screw seat 701. It should be noted that the pitch of the limiting screw seat 701 is equal to the pitch of the bolt 5.

[0041] In practical applications, the positioning clamp 4 is installed on the ribbed steel bar 1. The protective sleeve 2 can be attached to the longitudinal rib 102 in advance, and the protective sleeve 2 is installed and limited after the positioning clamp 4 is snapped onto the side of the ribbed steel bar 1; or, the positioning clamp 4 is fixed to the side of the ribbed steel bar 1 first, and then the protective sleeve 2 is inserted into the limiting groove 404. During actual installation, adjustments can be made freely according to actual needs.

[0042] After that, as Figure 7As shown, under normal conditions, the limiting screw seat 701 is relatively far from the threaded hole at the bottom of the bolt 5, and the fastening spring 8 is in a freely extended state. As the bolt 5 drives the pressure block 6 into the guide groove 402, the pressure block 6, passing through the guide groove 402, presses against the protective sleeve 2. The bolt 5 is continuously screwed into the internal thread 403, which shortens the distance between the bolt 5 and the pressure block 6, compressing the fastening spring 8 and further pressing the pressure block 6 tightly against the protective sleeve 2. At this time, the pressure block 6 presses against the top of the protective sleeve 2 and will not squeeze the transmission optical fiber 300 in the optical fiber groove 200.

[0043] As bolt 5 is continuously screwed into the internal thread 403, the threaded hole on bolt 5 also gets closer to the limiting screw seat 701. When the threaded hole and the limiting screw seat 701 mate, the limiting screw seat 701 will also be screwed into the threaded hole at the bottom of bolt 5 during the process of bolt 5 being screwed into the internal thread 403. When the limiting screw seat 701 is screwed to the top of the threaded hole, the limiting screw seat 701 and bolt 5 will no longer be able to rotate relative to each other. Afterwards, as bolt 5 continues to be screwed, bolt 5 will drive the central shaft 7 to rotate synchronously according to the limiting screw seat 701. The central shaft 7 has a tendency to drive the pressure block 6 to rotate, but the pressure block 6 is currently installed in the guide groove 402 and cannot rotate. Finally, when the limiting screw seat 701 reaches the bottom threaded hole of bolt 5, the rotation of bolt 5 will be restricted and it will no longer be able to rotate, thus alerting the operator that the protective sleeve 2 has been tightened in place.

[0044] Example 3 is a further improvement on Example 2. Example 2 can be implemented alone or in combination with Example 3. Please refer to [link / reference]. Figure 6 It can be seen that the bottom end of the central shaft 7, located below the limiting screw seat 701, is elliptical, and the bottom end of the central shaft 7 is movably mounted at the center of the top of the pressure block 6. Regarding the connection between the two, from... Figure 6As can be seen, a connecting ring groove 700 is provided at the bottom of the central shaft 7. Correspondingly, a spring push rod 11 is provided on the pressure block 6, which abuts against the connecting ring groove 700. The spring push rod 11 is mainly a cylindrical push rod pushed out by a spring, and its end abuts against the connecting ring groove 700. The advantage of this design is that when the spring push rod 11 abuts against the connecting ring groove 700, the connection between the central shaft 7 and the pressure block 6 is realized. As mentioned in Embodiment 2, when the limiting screw seat 701 abuts against the threaded hole at the bottom of the bolt 5, the bolt 5 will also be unable to rotate. At this time, the fastening spring 8 is compressed and stores force due to the relative proximity of the bolt 5 and the pressure block 6. Afterwards, if there is an accidental movement between the positioning clamps 4, the two will no longer fit together, which will cause the two positioning clamps 4 to fail to form a complete threaded groove, and thus the bolt 5 can no longer be limited and fastened. The bolt 5, pushed by the elastic force of the fastening spring 8, will be pushed out from the positioning clamp 4, and the connecting ring groove 700 and the spring push rod 11 will also separate. Finally, during inspection, construction personnel can determine whether the protective sleeve 2 is securely installed by checking whether bolt 5 protrudes. Therefore, it is clear that the method described in Embodiment 3 facilitates quick inspection by operators to ensure the protective sleeve 2 is securely installed.

[0045] Furthermore, to make it easier for operators to know whether the protective sleeve 2 is securely installed, operators can also, as needed, install a cutter 9 at the bottom of the pressure block 6, located above the transmission optical fiber 300. The cutter 9 is perpendicular to the central axis of the transmission optical fiber 300. Under normal circumstances, the cutter 9 retracts into the pressure block 6. Figure 6 As shown. The spring top rod 11 is fixedly installed on the side of the cutter 9, and a top spring 10 is provided between the top of the cutter 9 and the pressure block 6. The cutter 9 is pushed by the elastic force of the top spring 10, so that it always tends to move downward.

[0046] As mentioned above, when the positioning clamp 4 becomes loose, the fastening spring 8 will push the bolt 5 upward. At this time, the bolt 5, through the limiting screw seat 701, will drive the central shaft 7 upward, causing the connecting ring groove 700 and the spring push rod 11 to disengage. Simultaneously, when the connecting ring groove 700 and the spring push rod 11 disengage, the movement restriction on the spring push rod 11 will also be released, allowing the cutter 9 to extend from the pressure block 6. Pushed by the elastic force of the top spring 10, the cutter 9 will be pushed downward in the direction of the transmitting optical fiber 300, ultimately cutting the transmitting optical fiber 300. Afterward, the operator only needs to check whether the control computer is receiving the signal from the fiber optic grating 3 to determine if it is securely installed.

[0047] In addition, to ensure that the transmission fiber optic cable 300 can be successfully cut, from Figure 3 and Figure 6It can be seen that a limiting rod 601 can also be provided on the side of the pressure block 6. The structure of the limiting rod 601 is the same as that of the spring rod 11. During the process of the limiting rod 601 passing through the guide groove 402, the inclined surface at the top of the guide groove 402 can be used to retract the limiting rod 601 into the pressure block 6. When the limiting rod 601 moves to the bottom of the guide groove 402, it can prevent the pressure block 6 from moving upward and detaching from the guide groove 402. This ensures that during the process of the cutter 9 cutting the transmission optical fiber 300 downward by the top spring 10, the pressure block 6 cannot move upward and detach from the guide groove 402.

[0048] Finally, to reset the cutter 9 and the central shaft 7, simply push the cutter 9 into the pressure block 6 and compress the top spring 10. Then, unscrew the central shaft 7 from the bolt 5 and insert it into the top of the pressure block 6 until the connecting ring groove 700 and the spring top rod 11 are reconnected. Afterward, using the connection between the spring top rod 11 and the connecting ring groove 700, the central shaft 7 is inserted into the pressure block 6, while the connecting ring groove 700 prevents the cutter 9 from extending outward.

Claims

1. A fiber optic grating rebar stress gauge, characterized in that, include: The ribbed steel bar (1) has transverse ribs (101) and longitudinal ribs (102) on its side. The positioning clamp (4) has a positioning groove (401) on its inner side that corresponds to the transverse rib (101). After the positioning clamp (4) is installed on the side of the ribbed steel bar (1), it is positioned / limited according to the transverse rib (101) and the positioning groove (401), so that the limiting groove (404) opened at the top of the positioning clamp (4) limits the fiber optic grating (3) on the longitudinal rib (102). The top of the positioning clamp (4) is provided with an internal thread (403) located above the limiting groove (404). The two positioning clamps (4) fit together to form a complete threaded hole with the two internal threads (403). The threaded hole is connected to a bolt (5). The end of the bolt (5) is screwed in and presses against the protective sleeve (2). When the bolt (5) is screwed into the internal thread (403) normally, it is determined that the positioning clamp (4) is installed in place. The top of the positioning clamp (4) is provided with a guide groove (402) located between the internal thread (403) and the limiting groove (404). The bolt (5) is movably installed with a central shaft (7), and the bottom of the central shaft (7) is provided with a pressure block (6) that fits with the guide groove (402). A fastening spring (8) is provided between the pressure block (6) and the bolt (5). The middle part of the central shaft (7) is fixedly connected with a limiting screw seat (701). The bottom of the bolt (5) is provided with a threaded hole that is threadedly connected to the limiting screw seat (701). The bottom end of the central shaft (7) is elliptical, and the bottom end of the central shaft (7) is movably installed in the middle of the top of the pressure block (6). A connecting ring groove (700) is opened at the bottom of the central shaft (7), and a spring push rod (11) is provided on the pressure block (6) to abut against the connecting ring groove (700). When there is an unexpected movement between the positioning clamps (4), the two will no longer fit together, which will prevent the two positioning clamps (4) from forming a complete thread groove. Therefore, the bolt (5) can no longer be limited and tightened. The bolt (5) pushed by the elastic force of the tightening spring (8) will be pushed out of the positioning clamp (4), and the connecting ring groove (700) and the spring push rod (11) will also separate. When the construction personnel inspect, they can judge whether the protective sleeve (2) is installed firmly by whether the bolt (5) protrudes.

2. The fiber optic grating rebar stress gauge according to claim 1, characterized in that, The longitudinal rib (102) is parallel to the central axis of the ribbed steel bar (1), and the surface of the longitudinal rib (102) is a plane.

3. The fiber optic grating rebar stress gauge according to claim 1, characterized in that, The fiber optic grating (3) is fixedly installed at the bottom of the protective sleeve (2). Transmission optical fibers (300) are installed at both ends of the fiber optic grating (3). The transmission optical fibers (300) pass through the protective sleeve (2) and are guided along the fiber optic groove (200) at the top of the protective sleeve (2) before being connected to the control computer.

4. The fiber optic grating rebar stress gauge according to claim 1, characterized in that, The guide groove (402) is an elliptical groove.

5. The fiber optic grating rebar stress gauge according to claim 1, characterized in that, The pitch of the limiting screw seat (701) is equal to the pitch of the bolt (5).

6. The fiber optic grating rebar stress gauge according to claim 1, characterized in that, A cutter (9) is movably installed at the bottom of the pressure block (6) above the transmission optical fiber (300). The cutter (9) is perpendicular to the central axis of the transmission optical fiber (300). A spring top rod (11) is fixedly installed on the side of the cutter (9), and a top spring (10) is provided between the top of the cutter (9) and the pressure block (6).

7. A method of using the fiber optic grating rebar stress gauge as described in claim 1, characterized in that, Includes the following steps: S1. Two positioning clamps (4) are clamped to the side of the ribbed steel bar (1) and limit the protective sleeve (2). The two internal threads (403) of the positioning clamps (4) are fitted together. S2. The construction personnel screw the bolt (5) into the internal thread (403). As the bolt (5) goes deeper, the end of the bolt (5) abuts against the protective sleeve (2), so that the protective sleeve (2) is pressed tightly against the longitudinal rib (102), ensuring that the fiber optic grating (3) set on the protective sleeve (2) is always pressed tightly against the plane of the longitudinal rib (102). S3. If the two positioning clamps (4) are not installed in place, there will be a gap between the positioning clamps (4), and the two internal threads (403) cannot form a complete threaded hole, and the bolt (5) cannot be screwed into the internal thread (403); S4. Use bolts (5) to press and tighten the installed protective sleeve (2), and at the same time check whether the positioning clamp (4) is properly installed. The operator judges whether the positioning clamp (4) is properly installed based on whether the bolts (5) can press and tighten the protective sleeve (2).

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