Monitoring system and method for global temperature and humidity of main cable of suspension bridge

Abstract

Disclosed in the present invention are a monitoring system and method for the global temperature and humidity of a main cable of a suspension bridge. The monitoring system for the global temperature and humidity of a main cable of a suspension bridge comprises a demodulation module, a data processing module and a plurality of measurement cable strands. It is only necessary to provide a small number of measurement cable strands in an original main cable to implement global state monitoring of the main cable. Mass temperature and humidity data acquired by means of the monitoring system can provide real data support for state assessment of the main cable. Temperature grating array sensing optical fibers and humidity grating array sensing optical fibers, which are arranged in the measurement cable strands, are small in terms of size and have high measurement precision, are resistant to electromagnetic interference, do not require a power supply, can be directly installed in place as the cable strands are being pulled, and have a good economical performance.

Description

A suspension bridge main cable global temperature and humidity monitoring system and monitoring method Technical Field

[0001] The present invention relates to the technical field of bridge health monitoring, and more specifically, to a system and method for monitoring the global temperature and humidity of a main cable of a suspension bridge. Background Art

[0002] As a key load-bearing component of a suspension bridge, the main cable of a suspension bridge features significant characteristics such as long length, large cross-section, high strength, and non-replaceability. Currently, the main cable's safety is primarily ensured through a multi-layered protection system, including improvements in steel wire strength, corrosion resistance and wear resistance of the steel wire coating, wire wrapping sealing, coating wrapping sealing durability, and the addition of active dry air dehumidification systems. However, there has been no effective monitoring method for the critical temperature and humidity data that affect the corrosion of the main cable's steel wires, meaning that integrated "measurement and control" maintenance of the main cable has not been achieved. Existing technologies monitor the temperature or humidity of the main cable primarily through the installation of independent temperature or humidity sensors along the cable. The number of monitoring points is relatively small compared to the length of the main cable, resulting in low monitoring accuracy. With the increasing number of existing suspension bridges and the continuous expansion of their spans, the demand for intelligent maintenance of suspension bridge main cables has become increasingly prominent. Therefore, it is necessary to develop a monitoring system that can monitor the temperature and humidity of the main cable over the entire area and at all times to understand its true condition. Summary of the Invention

[0003] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0004] Another object of the present invention is to provide a system and method for monitoring the global temperature and relative humidity of a main cable of a suspension bridge, so as to solve the technical problem in the prior art that the global temperature and relative humidity of the main cable of a suspension bridge cannot be fully monitored.

[0005] In order to achieve these purposes and other advantages according to the present invention, on the one hand, the present invention provides a full-area temperature and humidity monitoring system for the main cable of a suspension bridge, including a demodulation module, a data processing module, and multiple measuring strands. The measuring strands are arranged in the main cable with equal length. The measuring strands are made of measuring steel wire and multiple ordinary steel wires. All ordinary steel wires are evenly and symmetrically distributed on the periphery of the measuring steel wire. The measuring steel wire is hinged from a measuring steel pipe and multiple skeleton steel wires. A temperature grating array sensing fiber and a humidity grating array sensing fiber are inserted into the measuring steel pipe. The temperature grating array sensing fiber and the humidity grating array sensing fiber are respectively connected to the demodulation module at the anchor end through optical fiber jumpers, and the demodulation module is connected to the data processing module.

[0006] Preferably, the measuring strands are evenly distributed over the cross section of the main cable.

[0007] Preferably, seven measuring strands are provided on the main cable, one of which is located at the center of the circle, and the other six are symmetrically distributed in the direction of the vertex angles of a regular hexagon relative to the center of the circle.

[0008] Preferably, on the temperature grating array sensing optical fiber and the humidity grating array sensing optical fiber, the gratings are arranged at an interval of 1 m, the grating reflectivity is 0.6‰, and the optical fiber length is more than 4.0‰ longer than the measuring cable strand.

[0009] Preferably, the diameters of the measuring steel pipe and the skeleton steel wire are the same, and the measuring steel wire is formed by hingedly forming one measuring steel pipe and six skeleton steel wires.

[0010] On the other hand, the present invention also provides a method for monitoring the temperature and humidity of the entire main cable of a suspension bridge, comprising the following steps:

[0011] S1. Producing the temperature grating array sensing optical fiber and the humidity grating array sensing optical fiber, inserting the temperature grating array sensing optical fiber and the humidity grating array sensing optical fiber into the measuring steel pipe at the same time, and hinge the measuring steel pipe and the skeleton steel wire to form the measuring steel wire;

[0012] S2. braiding the measuring steel wire and a plurality of the ordinary steel wires into an anchor to form the measuring rope strand;

[0013] S3. Installing the measuring cable strands and the common cable strands in sequence at the project site to form the main cable;

[0014] S4, connecting the temperature grating array sensing optical fiber and the humidity grating array sensing optical fiber of all the measuring cables at the anchor head end to the demodulation module through the optical fiber jumper;

[0015] S5. Connect the demodulation module to the data processing module, and convert the optical fiber wavelength demodulated by the demodulation module each time into temperature and relative humidity data of the entire main cable through the data processing module.

[0016] Preferably, in step S5, the data processing module uses the following mathematical model to obtain the temperature value and the humidity value: i =(X i -O i )*K i H i =[G i -T i -(X i -O i )]*R i

[0017] In the above formula, W iThe temperature value of the i-th temperature grating measuring point of a measuring strand of the main cable, X i The wavelength monitoring value of the temperature grating measuring point i of a certain measuring strand of the main cable, O i The initial value of the wavelength corresponding to the reference temperature of the i-th temperature grating measuring point of a measuring strand of the main cable, K i The temperature sensitivity coefficient of the i-th temperature grating measuring point of a measuring strand of the main cable, H i The humidity value of the i-th humidity grating measuring point of a measuring strand of the main cable, G i is the wavelength monitoring value of the i-th humidity grating measurement point of a certain measuring strand of the main cable, T i The initial value of the wavelength corresponding to the reference humidity of the i-th humidity grating measurement point of a certain measuring strand of the main cable, R i The humidity sensitivity coefficient of the i-th humidity grating measuring point of a measuring strand of the main cable.

[0018] The present invention includes at least the following beneficial effects: the global temperature and humidity monitoring system and monitoring method for the main cable of a suspension bridge of the present invention, the global temperature and humidity monitoring system for the main cable of a suspension bridge includes a demodulation module, a data processing module, and multiple measuring strands. Only a small number of measuring strands need to be set in the original main cable to realize the global status monitoring of the main cable. The massive temperature and humidity data obtained by the monitoring system can provide real data support for the main cable status evaluation. The temperature grating array sensor fiber and the humidity grating array sensor fiber set in the measuring strand are small in size, high in measurement accuracy, anti-electromagnetic interference, and do not require power supply. They can be directly installed in place as the cable strands are pulled, and are economical.

[0019] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a schematic structural diagram of a suspension bridge main cable global temperature and humidity monitoring system arranged outside the suspension bridge according to the present invention;

[0021] FIG2 is a cross-sectional structural diagram of the main cable of the present invention;

[0022] FIG3 is a cross-sectional structural diagram of a measuring cable strand of the present invention;

[0023] FIG4 is a cross-sectional structural diagram of the measuring wire of the present invention;

[0024] Figure numerals in the specification: 1. main cable, 2. anchor, 3. optical fiber jumper, 4. demodulation module, 5. data processing module, 6. measuring cable strand, 7. ordinary cable strand, 8. ordinary steel wire, 9. measuring steel wire, 10. measuring steel pipe, 11. temperature grating array sensing optical fiber, 12. humidity grating array sensing optical fiber. DETAILED DESCRIPTION

[0025] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0026] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "horizontal", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0027] As shown in Figures 1-4, the present invention provides a full-area temperature and humidity monitoring system for the main cable of a suspension bridge, including a demodulation module 4, a data processing module 5, and multiple measuring strands 6. The measuring strands 6 are of equal length and are arranged in the main cable 1. The measuring strands 6 are made of a measuring steel wire 9 and multiple ordinary steel wires 8. All ordinary steel wires 8 are evenly and symmetrically distributed around the periphery of the measuring steel wire 9. The measuring steel wire 9 is hinged from a measuring steel pipe 10 and multiple skeleton steel wires. A temperature grating array sensing fiber 11 and a humidity grating array sensing fiber 12 are inserted into the measuring steel pipe 10. The temperature grating array sensing fiber 11 and the humidity grating array sensing fiber 12 are respectively connected to the demodulation module 4 at the anchor end through an optical fiber jumper 3, and the demodulation module 4 is connected to the data processing module 5.

[0028] The main cable 1 consists of a measuring strand 6 and a common strand 7 arranged side by side. The measuring strand 6 is provided with two types of grating array sensing fibers, one for temperature and the other for humidity, along its length. At the anchor 2, the sensing fibers at the anchor ends of these measuring strands 6 are connected to a demodulation module 4 and a data processing module 5 via fiber optic jumpers 3, forming a monitoring system.

[0029] When the monitoring system is operating, a beam of incident light is emitted from the demodulation module 4 to the sensing optical fiber in the measurement cable 6. The incident light passes through the optical fiber jumper 3 and enters the temperature and humidity grating array sensing optical fiber in the measurement cable 6. After propagation, it passes through each grating in sequence and is finally reflected back to the demodulation module 4. The demodulation module 4 converts the optical signal into an electrical signal and stores it. When the temperature or relative humidity changes, the wavelength of the reflected light from the grating in the corresponding sensing optical fiber will change linearly. The data processing module 5 reads the reflected wavelength electrical signal recorded by the demodulation module 4 to generate temperature and relative humidity data, thus completing the monitoring of the temperature and relative humidity of the entire main cable 1.

[0030] Compared with traditional methods, the present invention only requires setting a small number of measuring strands 6 in the original main cable 1 to realize the full-area status monitoring of the main cable 1. The massive temperature and humidity data obtained by the monitoring system can provide real data support for the status evaluation of the main cable 1. In addition, the temperature grating array sensing fiber 11 and the humidity grating array sensing fiber 12 used in the monitoring system are small in size, high in measurement accuracy, resistant to electromagnetic interference, and do not require power supply. They can be directly installed in place as the cable strands are pulled, and are very economical.

[0031] In another technical solution, as shown in Figures 1-4, the measuring strands 6 are symmetrically distributed across the cross-section of the main cable 1. Multiple measuring strands 6 are evenly distributed across the cross-section of the main cable 1 to obtain temperature and relative humidity data at different locations on the main cable 1, providing a more comprehensive understanding of the temperature and relative humidity conditions across the entire cable 1.

[0032] Furthermore, seven measuring strands 6 are provided on the main cable 1 , one of which is located at the center of the circle, and the other six are symmetrically distributed in the direction of the vertex angles of a regular hexagon relative to the center of the circle.

[0033] In another technical solution, as shown in Figures 1-4, the gratings on the temperature grating array sensing optical fiber 11 and the humidity grating array sensing optical fiber 12 are arranged at an interval of 1m, the grating reflectivity is 0.6‰, and the optical fiber length is more than 4.0‰ longer than the measuring rope strand 6.

[0034] In another technical solution, as shown in Figures 1-4, the measuring steel tube 10 and the skeleton wire have the same diameter, and the measuring wire 9 is formed by hingedly hinged one measuring steel tube 10 and six skeleton wires. For example, if the diameters of both the measuring steel tube 10 and the skeleton wires are set to 2 mm, and the measuring steel tube 10 is placed close to the side of the measuring wire 9, humidity measurement efficiency can be improved.

[0035] The present invention also provides a method for monitoring the global temperature and humidity of a main cable of a suspension bridge, as shown in Figures 1-4, comprising the following steps:

[0036] S1. Produce the temperature grating array sensing optical fiber 11 and the humidity grating array sensing optical fiber 12, insert the temperature grating array sensing optical fiber 11 and the humidity grating array sensing optical fiber 12 into the measuring steel pipe 10 at the same time, and hinge the measuring steel pipe 10 with the skeleton steel wire to form the measuring steel wire 9.

[0037] A fiber optic temperature grating array sensor 11 with a diameter of 0.25 mm, a grating spacing of 1 m, and a grating reflectivity of 0.6‰, and a fiber optic relative humidity grating array sensor 12 with a diameter of 0.15 mm, a grating spacing of 1 m, and a grating reflectivity of 0.6‰ were produced using a drawing tower process. The fiber lengths were at least 4.0‰ longer than the measuring cable strand 6. Both the fiber optic temperature grating array sensor 11 and the relative humidity grating array sensor 12 were simultaneously placed in a 2 mm diameter measuring steel tube 10 with holes at both ends. The measuring steel tube 10 was then twisted with six 2 mm steel wires to form the measuring wire 9.

[0038] S2. Braiding the measuring steel wire 9 and a plurality of the ordinary steel wires 8 to form the measuring rope strand 6.

[0039] The measuring steel wire 9 and 126 common steel wires 8 are braided and anchored to form a measuring rope strand 6, which is 3000 meters long.

[0040] S3. Install the measuring strands 6 and the common strands 7 in sequence at the project site to form the main cable 1.

[0041] S4. At anchor 2, connect the temperature grating array sensing fibers 11 and the humidity grating array sensing fibers 12 of all measurement cables 6 at the anchor head end to the demodulation module 4 via the fiber jumper 3. Demodulation module 4 has eight channels, each capable of simultaneously acquiring up to 5,000 grating wavelength signals at a frequency of 1 Hz.

[0042] S5 , connecting the demodulation module 4 to the data processing module 5 , and converting the optical fiber wavelength demodulated by the demodulation module 4 each time into temperature and relative humidity data of the entire main cable 1 through the data processing module 5 .

[0043] In another technical solution, as shown in FIG1-4, in step S5, the data processing module 5 uses the following mathematical model to obtain the temperature value and the humidity value: W i =(X i -O i )*K i H i =[G i -T i -(X i -O i )]*R i

[0044] In the above formula, W i is the temperature value of the i-th temperature grating measuring point of a measuring strand 6 of the main cable 1, X i is the wavelength monitoring value of the i-th temperature grating measuring point of a measuring strand 6 of the main cable 1, O iThe initial value of the wavelength corresponding to the reference temperature of the i-th temperature grating measuring point of a measuring strand 6 of the main cable 1, K i The temperature sensitivity coefficient of the i-th temperature grating measuring point of a measuring strand 6 of the main cable 1 is generally 10.6, H i The humidity value of the i-th humidity grating measuring point of a measuring strand 6 of the main cable 1, G i is the wavelength monitoring value of the i-th humidity grating measuring point of a measuring strand 6 of the main cable 1, T i The initial value of the wavelength corresponding to the reference humidity of the i-th humidity grating measuring point of a certain measuring strand 6 of the main cable 1, R i The humidity sensitivity coefficient of the i-th humidity grating measuring point of a certain measuring strand 6 of the main cable 1 is obtained by experimental testing.

[0045] By setting up a temperature grating array sensing optical fiber 11 and a humidity grating array sensing optical fiber 12, the temperature and relative humidity data in the main cable 1 are monitored simultaneously. During the data processing process, the temperature monitoring data and the relative humidity monitoring data are correlated, which can eliminate environmental influencing factors, improve measurement accuracy, and better reflect the true state of the main cable 1.

[0046] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A main cable global temperature and humidity monitoring system for a suspension bridge, characterized in that, It includes a demodulation module, a data processing module, and multiple measuring strands. The measuring strands are of equal length and are arranged in the main cable. The measuring strands are made of measuring steel wire and multiple ordinary steel wires. All ordinary steel wires are evenly and symmetrically distributed on the periphery of the measuring steel wire. The measuring steel wire is hinged from a measuring steel pipe and multiple skeleton steel wires. Temperature grating array sensing optical fiber and humidity grating array sensing optical fiber are inserted into the measuring steel pipe. The temperature grating array sensing optical fiber and the humidity grating array sensing optical fiber are respectively connected to the demodulation module at the anchor end through optical fiber jumpers, and the demodulation module is connected to the data processing module.

2. The main cable global temperature and humidity monitoring system of the suspension bridge according to claim 1, characterized in that The measuring strands are evenly distributed over the cross section of the main cable.

3. The main cable global temperature and humidity monitoring system for suspension bridges according to claim 2, characterized in that, A total of seven measuring strands are arranged on the main cable, one of which is located at the center of the circle, and the other six are symmetrically distributed in the direction of the vertex angles of a regular hexagon relative to the center of the circle.

4. The main cable global temperature and humidity monitoring system of a suspension bridge according to claim 1, characterized in that, On the temperature grating array sensing optical fiber and the humidity grating array sensing optical fiber, the gratings are arranged at intervals of 1 m, the grating reflectivity is 0.6‰, and the optical fiber length is more than 4.0‰ longer than the measuring cable strand.

5. The main cable global temperature and humidity monitoring system of the suspension bridge according to claim 1, characterized in that The diameters of the measuring steel pipe and the skeleton steel wire are the same, and the measuring steel wire is formed by hingedly forming one measuring steel pipe and six skeleton steel wires.

6. The method for monitoring the temperature and humidity of the entire main cable of a suspension bridge according to claim 1, wherein The steps include: S1, producing the temperature grating array sensing optical fiber and the humidity grating array sensing optical fiber, inserting the temperature grating array sensing optical fiber and the humidity grating array sensing optical fiber into the measuring steel pipe at the same time, and the measuring steel pipe and the skeleton steel wire are hinged to form the measuring steel wire; S2, braiding the measuring steel wire and a plurality of the common steel wires to form the measuring rope strand; S3, installing the measuring cable strands and the common cable strands in sequence at the project site to form the main cable; S4, at the anchorage, the temperature grating array sensing optical fiber and the humidity grating array sensing optical fiber of all the measuring cables at the anchor head end are connected to the demodulation module through the optical fiber jumper; S5. Connect the demodulation module to the data processing module, and convert the optical fiber wavelength demodulated by the demodulation module each time into temperature and relative humidity data of the entire main cable through the data processing module.

7. The method for monitoring the temperature and humidity of the entire main cable of a suspension bridge according to claim 6, characterized in that, In step S5, the data processing module uses the following mathematical model to obtain the temperature value and humidity value: Wi = (Xi-Oi)*Ki Hi = [Gi-Ti-(Xi-Oi)]*Ri In the above formula, Wi is the temperature value of the ith temperature grating measuring point of a certain measuring strand of the main cable, Xi is the wavelength monitoring value of the ith temperature grating measuring point of a certain measuring strand of the main cable, Oi is the initial value of the wavelength corresponding to the reference temperature of the ith temperature grating measuring point of a certain measuring strand of the main cable, Ki is the temperature sensitivity coefficient of the ith temperature grating measuring point of a certain measuring strand of the main cable, Hi is the humidity value of the ith humidity grating measuring point of a certain measuring strand of the main cable, Gi is the wavelength monitoring value of the ith humidity grating measuring point of a certain measuring strand of the main cable, Ti is the initial value of the wavelength corresponding to the reference humidity of the ith humidity grating measuring point of a certain measuring strand of the main cable, and Ri is the humidity sensitivity coefficient of the ith humidity grating measuring point of a certain measuring strand of the main cable.

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