Optical fiber grating sensor intelligent tendon and intelligent cable

Abstract

This utility model discloses a smart rib and smart cable for a fiber Bragg grating sensor. The smart rib is installed in the gap of the prestressed tendon on the outer ring of the cable. The smart rib includes a rib material with a built-in fiber Bragg grating sensor, two anchoring structures for anchoring both ends of the rib material, and a sheath sleeve sleeved on the outside of the rib material between the two anchoring structures. The anchoring structure includes a metal tube sleeved on the outside of the rib material, a binding filler located inside the metal tube, and centering rings installed at both ends inside the metal tube. The centering rings have through holes adapted to the outer diameter of the rib material. The smart rib and smart cable for a fiber Bragg grating sensor disclosed in this utility model can avoid reducing tensile strength, improve monitoring accuracy, and improve the effective protection of the sensor.

Description

Technical Field

[0001] This utility model relates to the field of bridge cable technology, and in particular to a fiber optic grating sensor smart rib and smart cable. Background Technology

[0002] Cable tension is a core indicator of a structure's load-bearing capacity. Abnormal changes in cable tension can lead to stress redistribution, increasing the risk of structural instability. Furthermore, cables are exposed to complex environments throughout their service life, making them susceptible to corrosion. Temperature and humidity changes can trigger material corrosion and time-varying stress effects. Monitoring cable tension, temperature, and humidity provides a scientific benchmark for ensuring structural safety and extending service life, and is crucial for assessing structural safety status and preventing hidden damage. In the field of cable tension monitoring, methods such as pressure sensors, magnetic flux sensors, and hydraulic sensors are insufficient for long-term cable tension monitoring due to limitations in durability, survivability, and stability. In recent years, fiber optic grating sensors have been widely used in cable tension monitoring due to their superior sensing performance.

[0003] In existing technologies, smart cables are mostly made by replacing conventional reinforcing bars with smart reinforcing bars of the same diameter. There are two main types of smart reinforcing bars: one is a reinforcing bar grooved with a fiber Bragg grating sensor, and the other is a fiber composite material coupled with a fiber Bragg grating sensor. For example, Chinese patent CN220789426U discloses a parallel steel wire cable with an embedded array of fiber Bragg grating sensors, including a shaped steel wire and several high-strength steel wires. An array of temperature fiber Bragg grating sensors and an array of strain fiber Bragg grating sensors are encapsulated along the length of the shaped steel wire. Two optical fibers are led out from the ends of the shaped steel wire and connected to the pigtail in a junction box set in the anchor cup. The sidewall of the shaped steel wire has a pair of concave groove channels, each containing a steel tube and an epoxy resin layer. The steel tube and epoxy resin layer are used to encapsulate the array of temperature fiber Bragg grating sensors and the array of strain fiber Bragg grating sensors, respectively. A protective sleeve is provided on the outside of the shaped steel wire, and its diameter is equal to that of the high-strength steel wire. Chinese patent CN109958056A discloses a smart cable, a method for manufacturing a smart cable, and a method for detecting the safety status of a smart cable. The cable includes a sheath and tension bars within the sheath. At least one tension bar within the sheath is replaced with a fiber-reinforced optical fiber tension bar. The fiber-reinforced optical fiber tension bar includes a multi-core optical fiber and a fiber-reinforced plastic reinforcement bar surrounding the multi-core optical fiber. The multi-core optical fiber is inserted into the center of the reinforcement bar along its length. The fiber-reinforced optical fiber tension bar is manufactured using a pultrusion process. During the smart cable manufacturing process, the fiber-reinforced optical fiber tension bar replaces at least one tension bar in the cable. A sheath is then placed over the cable, and anchors are installed, thus creating a smart cable based on multi-core optical fiber sensing.

[0004] The aforementioned smart reinforcing bars require replacing one or more conventional reinforcing wires within the cable. However, due to changes in their cross-sectional shape and material type, their load-bearing capacity is often not considered in cable design, thus reducing the cable's design tensile strength. Furthermore, optical fiber materials are affected by their own temperature-sensitive characteristics; to improve the accuracy of measurement results, temperature compensation correction needs to be further considered. Utility Model Content

[0005] To address the aforementioned issues, this utility model provides a smart fiber optic grating sensor and a smart cable, aiming to solve problems such as reduced tensile strength due to groove coupling on existing prestressed tendons or replacement of prestressed tendons with smart tendons in the prior art; and increased processing difficulty and cost due to further consideration of temperature compensation correction.

[0006] The present invention achieves the above objectives by adopting the following technical solution:

[0007] A smart rib for fiber optic grating sensors is disclosed, wherein the smart rib is installed in the gap of the prestressed tendon of the outer ring of a cable; the smart rib includes a rib material, two anchoring structures for anchoring both ends of the rib material, and a sheath sleeve sleeved on the outside of the rib material between the two anchoring structures; the anchoring structure includes a metal tube sleeved on the outside of the rib material, a binding filler located inside the metal tube, and centering rings installed at both ends inside the metal tube, wherein the centering rings are provided with through holes adapted to the outer diameter of the rib material.

[0008] In this technical solution, the metal tube and its internal gripping filler anchor and fix both ends of the reinforcing bar. The smart reinforcing bar can be installed at the same length as the prestressing tendons within the cable body, effectively encapsulating the smart reinforcing bar along its entire length. The direct measurement method of co-deformation between the smart reinforcing bar and the cable body improves the accuracy of cable force monitoring. Simultaneously, the smart reinforcing bar, which encapsulates temperature and stress sensors within the cable body, provides temperature compensation for stress measurement, solving the problem of lacking temperature compensation in existing technologies. By installing the smart reinforcing bar in the gaps of the outer ring of prestressing tendons, the traditional method of slotting and coupling or replacing the original prestressing tendons is avoided, maintaining the original design tensile strength of the cable. Furthermore, the sheath and anchoring structure effectively protect the sensors, preventing damage during production and transportation and improving the sensor survival rate.

[0009] A further technical solution involves using a sheath made of steel pipe, corrugated pipe, or armored pipe. The sheath in this solution possesses a certain radial stiffness and is capable of meeting the twisting requirements during cable making, thus effectively protecting the sensor.

[0010] A further technical solution involves using a reinforcing material made of carbon fiber, glass fiber, or basalt fiber, with a fiber Bragg grating sensor fixed at its center. In this solution, the fiber Bragg grating sensor replaces a portion of the original fiber filaments at the center of the reinforcing material, and is pultruded and bonded together with the fibers.

[0011] A further technical solution involves adding a PE layer to the reinforcing material. This solution provides further effective protection for the sensor.

[0012] A further technical solution is that the smart rib also includes an optical fiber lead, which is fused to the fiber optic grating sensor at the center at the tail end of the rib.

[0013] A smart cable includes at least one of the aforementioned fiber Bragg grating sensor smart ribs.

[0014] A further technical solution includes a fiber splitter plate and an optical fiber protective cover plate. The optical fiber protective cover plate is adapted to the inner diameter of the anchor cup. The outer end face of the optical fiber protective cover plate has an internal hexagonal groove at its center, and the inner end face extends with an external threaded section. The fiber splitter plate has threaded holes that mate with the external threaded section, and also has through holes adapted to the metal tube. The protective cover plate of this technical solution is used to protect the optical fiber lead wire, preventing damage during processes such as cable coiling, transportation, cable spreading, and tensioning.

[0015] The beneficial effects of this utility model are:

[0016] This utility model provides a fiber optic grating sensor with intelligent reinforcement and intelligent cable. The metal tube and its internal gripping filler anchor both ends of the reinforcement. The intelligent reinforcement can be installed along the same length as the prestressing tendons within the cable, effectively encapsulating the intelligent reinforcement along its entire length. The direct measurement method of co-deformation between the intelligent reinforcement and the cable improves the accuracy of cable force monitoring. Simultaneously, the intelligent reinforcement, which encapsulates temperature and stress sensors within the cable, provides temperature compensation for stress measurement, solving the problem of lacking temperature compensation in existing technologies. By installing the intelligent reinforcement in the gaps of the outer ring of prestressing tendons, the traditional method of slotting and coupling or replacing the original prestressing tendons is avoided, maintaining the original design tensile strength of the cable. Furthermore, the sheath and anchoring structure effectively protect the sensor, preventing damage during production and transportation and improving the sensor's survival rate. Attached Figure Description

[0017] Figure 1 Here is a schematic diagram of the structure of the intelligent cable described in this utility model.

[0018] Figure 2 See: A cross-sectional view of the intelligent cable described in this utility model.

[0019] Figure 3See: A schematic diagram of the anchoring structure of the intelligent rib described in this utility model.

[0020] Figure 4 See: A cross-sectional view of the intelligent rib described in this utility model.

[0021] Figure 5 See: A cross-sectional view of the intelligent rib with PE layer described in this utility model.

[0022] Figure 6 Here is a schematic diagram of the structure of the optical fiber protective cover plate of this utility model.

[0023] In the picture:

[0024] 1. Intelligent cable; 11. Prestressed tendon; 12. PE sheath; 13. Anchor cup; 14. Wire splitter; 15. Cold-cast filler; 16. Sealing cylinder; 2. Intelligent reinforcement; 21. Reinforcing bar; 211. Sensor; 212. PE layer; 22. Metal pipe; 23. Centering ring; 24. Gathering filler; 25. Sheath tube; 26. Fiber optic lead; 3. Fiber optic protective cover plate; 31. Disc; 32. Internal hexagonal groove; 33. External thread section. Detailed Implementation

[0025] The following is in conjunction with the appendix Figures 1 to 6 The present invention will be described in detail below with specific embodiments. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0026] like Figures 1 to 4 As shown, this embodiment provides a smart rib for a fiber optic grating sensor. The smart rib 2 is installed in the gap of the prestressed tendon 11 on the outer ring of the smart cable 1. The smart rib 2 includes a rib 21, anchoring structures for anchoring both ends of the rib 21, and a sheath tube 25 between the two anchoring structures. The sheath tube 25 is sleeved on the outside of the rib 21. The anchoring structure includes a metal tube 22 sleeved on the outside of the anchoring end of the rib 21, a gripping filler 24 located inside the metal tube 22, and centering rings 23 installed at both ends inside the metal tube 22. The centering rings 23 are provided with through holes that are adapted to the outer diameter of the rib 21. The centering rings 23 can be connected to the inner wall of the metal tube 22 by means of threaded structure, welding, integral molding, etc., without limitation.

[0027] Specifically, the intelligent cable 1 includes prestressed tendons 11, anchor cups 13 located at both ends of the prestressed tendons, cold-cast filler 15 inside the anchor cups 13, a splitting plate 14 inside the anchor cups 13 and anchored to the ends of the prestressed tendons 11, and a nut threaded to the outside of the anchor cups 13. During installation, the reinforcing bar 21 is inserted into the sheath tube 25, cut into raw materials of the same length as the prestressed tendons 11, arranged according to the cable surface design, twisted, wrapped with tape, and then extruded and cooled to form a PE sheath 12, thus preparing the cable body. The sheath tube 25 is specifically a steel pipe with a diameter not exceeding 7mm, having a certain radial stiffness to meet the twisting requirements. The reinforcing bar 21 is specifically glass fiber, with a sensor 211 installed in the center. The fiber optic grating sensor 211 replaces part of the original glass fiber filaments in the center and is pultruded and bonded together with the glass fiber to form the cable body. The PE sheath 21 of the anchor head of the end anchor and the fixed end anchor is made to complete the end treatment of the prestressed tendon 11. Then, the sealing cylinder 16, anchor cup 13, and wire splitting plate 14 are put on the outside of the cable body in sequence. The centering ring 23 is installed at both ends of the metal pipe 22 and put on the outside of the tendon 21 through the through hole of the centering ring 23. The binding filler 24 is poured into the metal pipe 22 to complete the anchoring and fixing of the tendon 21. The binding filler 24 is specifically cold-cast filler. The smart tendon 2 is anchored and fixed by the cold-cast filler 15 poured into the anchor cup 13. After the cold-cast filler is poured, it should be hoisted into the high-temperature curing oven for curing. Among them, the sensor 211 is a fiber optic grating sensor. The fiber optic grating can be one of ordinary fiber optic grating, distributed fiber optic grating and ultra-weak fiber optic grating. The distribution of grating points in the fiber is determined according to the engineering monitoring needs to realize single-point parameter monitoring or distributed parameter monitoring.

[0028] This embodiment improves the accuracy of cable force monitoring by encapsulating the smart rib 2 along the entire length of the cable body and directly measuring the deformation of the smart rib 2 in tandem with the cable body. Furthermore, the sheath tube 25 and the anchoring structure effectively protect and anchor the sensor 211, avoiding damage during production and transportation and improving the sensor's survival rate. The smart rib 2 is arranged in the gaps of the outer prestressing rib 11, avoiding the need for traditional technology to groove and couple or replace the original prestressing ribs, thus maintaining the original design tensile strength of the cable.

[0029] The above embodiments exemplarily illustrate the specific materials of the sheath tube 25 and the reinforcing material 21. In other embodiments or practical applications, corrugated pipes, armored pipes, etc. can also be used as the sheath tube 25, and carbon fiber or basalt fiber can be used as the reinforcing material 21.

[0030] Another implementation method, based on the above implementation method, such as... Figure 5 As shown, the reinforcing bar 21 is also covered with a PE layer 212, which effectively protects the sensor 211.

[0031] In another embodiment, based on the above embodiment, the smart rib 2 also includes an optical fiber lead 26. After the cold-cast filler has solidified, the central fiber optic grating sensor 211 is fused to the optical fiber lead 26 at the tail end of the rib 21.

[0032] The above embodiment shows a structure in which a smart rib 2 is applied to a smart cable 1. The smart rib 2 is used to monitor the cable force. This embodiment provides a smart cable including two smart ribs 2. The other smart rib 2 is used to monitor the temperature of the cable. The two smart ribs 2 are symmetrically distributed in the gaps of the outer prestressing ribs 11, which can provide temperature compensation for stress measurement and solve the problem of lack of temperature compensation in the prior art.

[0033] Another implementation method, based on the above implementation method, such as... Figure 6 As shown, it also includes an optical fiber protective cover plate 3; the optical fiber protective cover plate 3 is adapted to the inner diameter of the anchor cup 13, the optical fiber protective cover plate 3 includes a disc 31, the center of the outer end face of the disc 31 is provided with an internal hexagonal groove 32, and the center of the inner end face extends with an external thread section 33; the fiber splitting plate 14 is provided with a threaded hole that matches the external thread section 33, and the fiber splitting plate 14 is also provided with a through hole that matches the metal tube 22. Through the optical fiber protective cover plate 3 of this embodiment, the optical fiber lead 26 can be protected to prevent damage to it during the processes of cable coiling, transportation, cable spreading, tensioning, etc. The metal tube 22 passes through the through hole of the fiber splitting plate 14, which facilitates the splicing of the optical fiber lead 26.

[0034] This utility model provides a fiber optic grating sensor smart rib and smart cable. The metal tube 22 and its internal gripping filler 24 anchor and fix the two ends of the rib 21. The smart rib 2 can be installed at the same length as the prestressing rib 11 in the cable body, that is, the smart rib 2 can be fully encapsulated in the cable body. The direct measurement method of the smart rib 2 and the cable body deforming together can improve the accuracy of cable force monitoring. At the same time, the smart rib encapsulating temperature and stress sensors in the cable body can provide temperature compensation for stress measurement, solving the problem of lack of temperature compensation in the prior art. By installing the smart rib 2 in the gap of the outer ring prestressing rib 11, the traditional technology of groove coupling or replacing the original prestressing rib is avoided, maintaining the original design tensile strength of the cable. Furthermore, the sheath tube 25 and the anchoring structure effectively protect the sensor 211, avoiding damage during production and transportation, and improving the survival rate of the sensor.

Claims

1. A smart rib for a fiber Bragg grating sensor, characterized in that, The smart reinforcement is installed in the gap of the prestressed tendons on the outer ring of the cable; the smart reinforcement includes a reinforcement material with a built-in fiber optic grating sensor, two anchoring structures for anchoring the two ends of the reinforcement material, and a sheath sleeve sleeved on the outside of the reinforcement material between the two anchoring structures. The anchoring structure includes a metal tube sleeved outside the reinforcing bar, a binding filler located inside the metal tube, and centering rings installed at both ends inside the metal tube. The centering rings are provided with through holes that are adapted to the outer diameter of the reinforcing bar.

2. The smart rib for a fiber Bragg grating sensor according to claim 1, characterized in that, The sheath is one of a steel pipe, a corrugated pipe, or an armored pipe.

3. The smart rib for a fiber Bragg grating sensor according to claim 1, characterized in that, The reinforcing material is one of carbon fiber, glass fiber or basalt fiber, and a fiber optic grating sensor is fixed in the center.

4. The smart rib for a fiber Bragg grating sensor according to claim 3, characterized in that, The reinforcing bar is also fitted with a PE layer.

5. The smart rib for a fiber Bragg grating sensor according to claim 3, characterized in that, The smart rib also includes an optical fiber lead, which is fused to a central fiber optic grating sensor at the tail end of the rib.

6. A smart cable, characterized in that, It includes at least one fiber Bragg grating sensor smart rib as described in claim 1.

7. The intelligent cable according to claim 6, characterized in that, It also includes fiber splitting plates and fiber optic protective covers; The fiber optic protective cover is adapted to the inner diameter of the anchor cup. The outer end face of the fiber optic protective cover has an internal hexagonal groove at its center, and the inner end face extends with an external threaded section. The fiber splitting plate has a threaded hole that matches the external threaded section, and the fiber splitting plate also has a through hole that matches the metal tube.

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