Monitoring device for embedded reinforced concrete column of optical fiber sensing network

Abstract

The utility model belongs to the field of civil engineering structure monitoring, and provides a monitoring device for an embedded reinforced concrete column of an optical fiber sensing network, which comprises the optical fiber sensing network fixedly integrated with a reinforcement cage frame and arranged in a spiral-longitudinal crossed manner, a junction box and demodulation equipment, the optical fiber sensing network comprises a plurality of spiral optical fiber networks which are spirally wound on a reinforcement cage frame, the spiral optical fiber networks are provided with fixing assemblies, the reinforcement cage frame is further provided with a plurality of vertical reference optical fibers, and the spiral optical fiber networks and the vertical reference optical fibers are connected with a plurality of groups of FBG sensors in series; according to the utility model, the stress and deformation conditions of the reinforced concrete column in different directions and positions can be comprehensively monitored through the optical fiber sensing network which is arranged in a spiral-longitudinal crossed manner, the spiral optical fiber network can effectively monitor the strain distribution in the circumferential direction of the concrete column, and the vertical reference optical fiber can accurately reflect the stress change in the axial direction of the column body; and all-directional monitoring of the concrete column is realized.

Description

Technical Field

[0001] This utility model belongs to the field of civil engineering structure monitoring, specifically a monitoring device for reinforced concrete columns with an embedded fiber optic sensor network. Background Technology

[0002] In building structural systems, reinforced concrete columns are critical load-bearing components, and their structural health plays a decisive role in the safety and stability of the entire building. Traditional monitoring often uses sensors such as resistance strain gauges and displacement gauges, which are installed on the surface of the concrete column or at a limited number of locations.

[0003] However, the adhesion of resistance strain gauges is easily affected by human factors, such as poor adhesion or inaccurate positioning, which can lead to measurement errors. Furthermore, their measurement range is limited, making it impossible to accurately measure strain values ​​when the concrete column undergoes significant deformation. Displacement gauges are mainly used to measure the macroscopic displacement of concrete columns, but they have low sensitivity to minute deformations and stress changes within the column, making it difficult to provide comprehensive and accurate structural condition information. Moreover, traditional monitoring methods often install sensors on the surface of the concrete column or at limited locations, making it difficult to comprehensively monitor the entire cross-section and different directions of the column. For example, the stress on the internal steel reinforcement is difficult for traditional sensors to detect under the concrete enclosure; and accurate data on internal concrete deformation cannot be obtained due to the lack of internal monitoring points. In reality, the failure of reinforced concrete columns often develops gradually from microscopic changes such as internal steel corrosion and the development of internal cracks in the concrete. If these internal structural changes are not monitored in time, safety hazards cannot be detected early, potentially leading to serious building safety accidents. Utility Model Content

[0004] To address the aforementioned technical problems, this utility model provides a monitoring device for reinforced concrete columns embedded with an optical fiber sensor network, which solves the problems of traditional resistance strain gauges and displacement gauges being attached to the surface of reinforced concrete columns, making it difficult to conduct comprehensive monitoring and easily overlooking internal hidden dangers.

[0005] A monitoring device for a fiber optic sensor network embedded in a reinforced concrete column includes a helical-longitudinal crisscross fiber optic sensor network fixedly integrated with a reinforcing cage, a junction box, and a demodulation device.

[0006] The fiber optic sensing network includes several spiral fiber optic networks spirally wound on a steel cage frame. Fixed components are provided on the spiral fiber optic networks. Several vertical reference fibers are also provided on the steel cage frame. Several groups of FBG sensors are connected in series on both the spiral fiber optic networks and the vertical reference fibers.

[0007] Preferably, the fixing component includes a protective sleeve sleeved on the outside of the spiral optical fiber network, a positioning sleeve provided on the outside of the protective sleeve, the positioning sleeve being sleeved on the corresponding vertical reference optical fiber, and a fixing strap provided on the inside of the protective sleeve.

[0008] Preferably, several groups of the FBG sensors are connected in parallel through a common optical fiber, and the ends of the common optical fiber, the spiral optical fiber network and the vertical reference optical fiber all extend into the junction box, and a demodulation device is connected to the junction box.

[0009] Preferably, the demodulation device includes an optical fiber demodulator, which is transmitted and connected to an optical fiber splitter. The optical fiber splitter is transmitted and connected to a plurality of optical fiber circulators. The plurality of spiral optical fiber networks and the plurality of vertical reference optical fibers are transmitted and connected to the corresponding optical fiber circulators.

[0010] Preferably, the fiber optic demodulator is also connected to a wavelength division multiplexer, which is connected to a common optical fiber.

[0011] Preferably, the junction box is equipped with a temperature compensation module, which includes a reference FBG sensor and a thermocouple, to correct the wavelength drift caused by the heat of hydration of concrete.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. This utility model uses a spiral-longitudinal cross-laid fiber optic sensing network to comprehensively monitor the stress and deformation of reinforced concrete columns in different directions and positions. The spiral fiber optic network can effectively monitor the strain distribution in the circumferential direction of the concrete column, and the vertical reference fiber optic can accurately reflect the axial stress changes of the column. The combination of the two realizes all-round monitoring of the concrete column.

[0014] 2. This utility model connects each FBG sensor in parallel via a common optical fiber and optimizes the signal transmission path using a wavelength division multiplexer and an optical fiber circulator, reducing signal transmission loss and improving monitoring accuracy. At the same time, the temperature compensation module in the junction box, through the coordinated work of the reference FBG sensor and the thermocouple, effectively corrects the wavelength drift caused by the heat of hydration of concrete, further improving measurement accuracy and ensuring that the acquired data can truly reflect the stress state of the reinforced concrete column. Attached Figure Description

[0015] Figure 1 This is a first-view perspective three-dimensional structural diagram of the present invention;

[0016] Figure 2 This is a second-view perspective three-dimensional structural diagram of the present invention;

[0017] Figure 3This is a three-dimensional structural diagram of the fixing component in this utility model;

[0018] Figure 4 This is a schematic diagram of the module connection of this utility model.

[0019] In the picture:

[0020] 1. Junction box; 2. Fiber optic sensor network; 201. Spiral fiber optic network; 202. Vertical reference fiber optic cable; 3. Fixing components; 301. Protective sleeve; 302. Positioning sleeve; 303. Fixing strap; 4. Fiber optic circulator; 5. Fiber optic splitter; 6. Fiber optic demodulator; 7. Wavelength division multiplexer; 8. Reinforcing cage. Detailed Implementation

[0021] The embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of this utility model.

[0022] As attached Figure 1 To be continued Figure 4 As shown: This utility model provides a monitoring device for reinforced concrete columns with embedded fiber optic sensor network, comprising a spiral-longitudinal intersecting fiber optic sensor network 2 fixedly integrated with the concrete reinforcing cage 8, a junction box 1, and a demodulation device, to realize the monitoring of reinforced concrete columns.

[0023] As attached Figure 1 To be continued Figure 3 As shown, the fiber optic sensing network 2 includes a spiral fiber optic network 201 and a vertical reference fiber optic cable 202. The spiral fiber optic network 201 is made of single-mode fiber and is tightly wound in a spiral shape around the main reinforcing bars of the steel cage 8. The pitch of the spiral is designed according to the detection accuracy requirements and the stress characteristics of the concrete column, generally between 5 and 20 centimeters. The length of each segment of the spiral fiber optic network 201 is determined according to the height of the steel cage 8, ensuring coverage of different height positions of the concrete column. The spiral fiber optic network 201 is fixed to the steel cage 8 by a fixing component 3.

[0024] As attached Figure 1 To be continued Figure 3As shown: The vertical reference fiber 202 also uses single-mode fiber and is vertically installed on the reinforcing cage 8, intersecting with the spiral fiber network 201. The number of vertical reference fibers 202 is determined according to the cross-sectional dimensions of the concrete column and the key monitoring areas, and is generally evenly distributed around the reinforcing cage 8. The vertical reference fiber 202 and the spiral fiber network 201 are mutually positioned and fixed by the fixing component 3. The vertical reference fiber 202 can accurately reflect the axial stress changes of the column, and works in conjunction with the spiral fiber network 201 to achieve comprehensive monitoring of the reinforced concrete column. The vertical installation allows it to directly sense the strain of the column in the axial direction, providing key data for a comprehensive understanding of the column's structural state. Several sets of FBG (fiber Bragg grating) sensors are connected in series on both the spiral fiber network 201 and the vertical reference fiber 202, and these FBG sensors are connected in parallel through a common fiber. The Bragg wavelength of the FBG sensor changes linearly with the strain. By aggregating the signals from each FBG sensor through a common optical fiber, subsequent signal transmission and processing are facilitated, improving the efficiency and accuracy of signal acquisition while ensuring the stability of signal transmission between the sensors.

[0025] As attached Figure 3 As shown: The protective sleeve 301 of the fixing component 3 is made of flexible, corrosion-resistant plastic material. Its inner diameter is slightly larger than the outer diameter of the spiral fiber optic network 201, and it is tightly fitted onto the outside of the spiral fiber optic network 201. During the concrete pouring process, the protective sleeve 301 can effectively protect the spiral fiber optic network 201, preventing it from being damaged by steel bar compression, collisions, etc., ensuring the integrity of the optical fiber, thereby ensuring the stable transmission of monitoring signals. The positioning sleeve 302 is a ring structure, made of the same material as the protective sleeve 301, and integrally formed with the protective sleeve 301. The inner diameter of the positioning sleeve 302 is slightly larger than the outer diameter of the vertical reference fiber optic 202, and the positioning sleeve 302 is fitted onto the outside of the vertical reference fiber optic 202. This achieves cross-positioning of the spiral fiber optic network 201 and the vertical reference fiber optic 202, ensuring the accuracy and stability of the fiber optic sensor network layout, enabling the two to work together to accurately monitor the strain of the column in different directions. The fixing strap 303 is made of iron wire or high-strength, corrosion-resistant fiber material. The fixing strap 303 wraps around the inside of the protective sleeve 301, tightly fixing the spiral optical fiber network 201 to the main reinforcement of the steel cage 8. During concrete pouring and structural stress, the fixing strap 303 ensures the stability of the optical fiber network, preventing displacement or detachment, thus guaranteeing the reliability and consistency of the monitoring data.

[0026] As attached Figure 4As shown: the ends of the common optical fiber, the spiral optical fiber network 201, and the vertical reference optical fiber 202 all extend into the junction box 1. The junction box 1 is made of waterproof and dustproof metal or plastic, and is square or rectangular in shape. It is installed on top of the reinforced concrete column or in an easily accessible location, and is connected to the optical fiber sensing network 2 within the reinforcing cage 8 via pre-embedded pipes or cable trays. Inside the junction box 1, the optical fiber is connected to the external demodulation equipment via optical fiber connectors. The junction box 1 contains a temperature compensation module, including a reference FBG and thermocouples. The reference FBG sensor and thermocouples are installed near the optical fiber connectors to accurately measure the temperature of the environment in which the optical fiber is located. The input end of the reference FBG sensor is connected in series with the common optical fiber, and the output end is connected in series with the wavelength division multiplexer. The thermocouple signal needs to be transmitted to the demodulator via cable. During the concrete hydration process, temperature changes cause wavelength drift in the FBG sensor, affecting measurement accuracy. The temperature compensation module, through the coordinated operation of the reference FBG and thermocouples, effectively corrects the wavelength drift caused by the heat of hydration of concrete, ensuring that the acquired data accurately reflects the stress state of the reinforced concrete column. The helical FBG sensor is assigned to the 1550nm band, the longitudinal FBG sensor to the 1555nm band, and the reference FBG sensor to the 1560nm band.

[0027] As attached Figure 4As shown: The demodulation equipment includes an optical fiber demodulator 6, which is connected to an optical fiber splitter 5. The optical fiber splitter 5 is connected to several optical fiber circulators 4, several spiral optical fiber networks 201, and several vertical reference optical fibers 202, each connected to its corresponding optical fiber circulator 4. The optical fiber demodulator 6 is also connected to a wavelength division multiplexer 7, which is connected to a common optical fiber. The optical fiber demodulator 6 is placed in a monitoring room far from the construction site and is connected to the optical fiber splitter 5 and the wavelength division multiplexer 7 via optical fiber. The optical fiber splitter 5 generally adopts a 1×N structure, with the value of N determined according to the actual number of optical fiber circulators 4 to be connected. It is installed in the monitoring room and splits the broadband optical pulses emitted by the optical fiber demodulator 6 into multiple outputs. Each optical fiber circulator 4 has one input port and two output ports. The input port is connected to the output port of the optical fiber splitter 5, one output port is connected to the corresponding spiral optical fiber network 201 or vertical reference optical fiber 202, and the other output port is used to transmit the reflected optical signal back to the optical fiber demodulator 6, which is installed near the junction box 1. A wavelength division multiplexer 7, installed in the monitoring room, multiplexes optical signals of different wavelengths on a common optical fiber and transmits them to the fiber optic demodulator 6 for demodulation. This internal connection method of the demodulation device optimizes the signal transmission path, reduces signal transmission loss, and improves monitoring accuracy. The wavelength division multiplexer 7 improves the utilization rate of the optical fiber and reduces interference between signals; the fiber optic circulator 4 ensures unidirectional transmission of optical signals between different optical paths, avoids signal reflection and interference, and ensures that the fiber optic demodulator 6 can accurately demodulate the received optical signals, convert the optical signals into electrical signals, and calculate the strain value of the reinforced concrete column based on the wavelength-strain relationship of the FBG sensor.

[0028] Working Principle: When a reinforced concrete column deforms under external load, the FBG sensors on the helical fiber optic network 201 tightly wound around the reinforcing cage 8 and the vertically positioned reference fiber optic cable 202 undergo strain accordingly. Because the FBG sensor is extremely sensitive to strain, its Bragg wavelength changes linearly with the applied strain. Therefore, by measuring the change in the Bragg wavelength of the FBG sensor, the strain information of the reinforced concrete column at different locations and directions can be accurately obtained. The helical fiber optic network 201 can sense the strain distribution along the circumference of the column, while the vertical reference fiber optic cable 202 can measure the axial strain of the column, thus achieving comprehensive monitoring and data acquisition of the column.

[0029] The signals from each FBG sensor are converged through a common optical fiber. A wavelength division multiplexer (WDM) 7 multiplexes optical signals of different wavelengths within this common fiber and transmits them to the fiber optic demodulator 6. During transmission, a fiber optic circulator 4 ensures the optical signal travels along the correct path, preventing signal reflection and interference. The fiber optic demodulator 6 demodulates the received optical signal, converting it into an electrical signal, and calculates the strain value of the reinforced concrete column based on the wavelength-strain relationship of the FBG sensors. When processing the signals from the FBG sensors, the fiber optic demodulator 6 corrects the measurement results based on the calculated wavelength drift, thus obtaining an accurate value reflecting the stress and strain of the reinforced concrete column.

[0030] The embodiments of this utility model are given for the purpose of illustration and description. Although embodiments of this utility model have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the utility model. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this utility model.

Claims

1. A monitoring device for reinforced concrete columns embedded in a fiber optic sensor network, characterized in that: Includes a spiral-longitudinal cross-laid fiber optic sensor network (2) fixedly integrated with the steel cage (8), a junction box (1), and a demodulation device; The fiber optic sensing network (2) includes several spiral fiber optic networks (201) spirally wound on the steel cage (8). The spiral fiber optic network (201) is provided with a fixing component (3). The steel cage (8) is also provided with several vertical reference fibers (202). Several groups of FBG sensors are connected in series on both the spiral fiber optic network (201) and the vertical reference fibers (202).

2. The monitoring device for a reinforced concrete column embedded in a fiber optic sensor network as described in claim 1, characterized in that: The fixing component (3) includes a protective sleeve (301) sleeved on the outside of the spiral optical fiber network (201), a positioning sleeve (302) is provided on the outside of the protective sleeve (301), the positioning sleeve (302) is sleeved on the corresponding vertical reference optical fiber (202), and a fixing strap (303) is also provided on the inside of the protective sleeve (301).

3. The monitoring device for a reinforced concrete column embedded in a fiber optic sensor network as described in claim 1, characterized in that: Several groups of the FBG sensors are connected in parallel through a common optical fiber. The ends of the common optical fiber, the spiral optical fiber network (201), and the vertical reference optical fiber (202) all extend into the junction box (1) and are connected to an external demodulation device through the junction box (1).

4. The monitoring device for a reinforced concrete column embedded in a fiber optic sensor network as described in claim 3, characterized in that: The demodulation device includes an optical fiber demodulator (6), which is connected to an optical fiber splitter (5). The optical fiber splitter (5) is connected to several optical fiber circulators (4). Several spiral optical fiber networks (201) and several vertical reference optical fibers (202) are respectively connected to the corresponding optical fiber circulators (4).

5. The monitoring device for a reinforced concrete column embedded in a fiber optic sensor network as described in claim 4, characterized in that: The fiber optic demodulator (6) is also connected to a wavelength division multiplexer (7), which is connected to a common optical fiber.

6. The monitoring device for a reinforced concrete column embedded in a fiber optic sensor network as described in claim 1, characterized in that: The junction box (1) is equipped with a temperature compensation module, which includes a reference FBG sensor and a thermocouple, to correct the wavelength drift caused by the heat of hydration of concrete.

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