Fiber bragg grating-based stiff steel column accurate mounting structure and monitoring method

Abstract

The invention discloses a stiff steel column precise mounting structure based on fiber bragg gratings and a monitoring method, and relates to the technical field of stiff steel column mounting and monitoring. Comprising a stiff steel column, the horizontal section of the stiff steel column is H-shaped, a temporary fixing cable rope is installed on the stiff steel column, and a flexible curvature sensor is installed between the temporary fixing cable rope and the stiff steel column; the flexible curvature sensor comprises a polydimethylsiloxane flexible film, the end part of the polydimethylsiloxane flexible film is provided with an FBG sub-sensor, and the interior of the polydimethylsiloxane flexible film is provided with a tapered optical fiber; a grating array is arranged in the tapered optical fiber; and the sensing ends of the FBG sub-sensors are respectively adhered to a web plate and a flange of the stiff steel column and the temporary fixed mooring rope. According to the invention, the technical problems of complex measurement, installation precision and positioning stability are solved, and installation deviation of the stiff column caused by deviation in the installation process is prevented.

Description

Technical Field

[0001] The present invention belongs to the field of rigid steel column installation and detection technology, and in particular relates to a rigid steel column precision installation structure and monitoring method based on optical fiber grating. Background Art

[0002] Rigid steel columns are commonly used load-bearing structures in high-rise buildings. The installation of rigid steel columns is usually modeled using Tekla software, and the condition of the steel columns is visually checked based on the model. The processes involved in building rigid steel columns include soil preparation, material production, welding, installation, etc. Each stage has many technical details and is relatively difficult. Especially during the installation of rigid columns, a high level of professional ability is required from engineering and technical personnel.

[0003] At present, the application of rigid steel structure in major civil engineering projects has been on the rise in recent years, especially in super high-rise buildings. However, due to the characteristics of cross-operation with civil engineering and the small cross-sectional area of ​​rigid columns, the installation accuracy of rigid steel structure is easily affected by external factors. Whether it is self-deformation during the installation process or the influence of other professions after installation, it will cause the deviation of steel columns. Its installation accuracy is difficult to control, and the later processing of the deviation of rigid columns on site is very difficult. Therefore, it is particularly important to ensure the reasonable matching between steel structure and civil engineering construction processes and control the installation accuracy of steel columns during the construction process.

[0004] On-site installation of rigid columns usually uses cross-composite measurements with multiple theodolites, including control network verification and establishment of steel column construction axis network, positioning of anchor bolt embedded parts, elevation verification. On-site surveyors have high requirements for the accuracy of axis and elevation measurement. Electric welders working at high altitudes are welding. Once the measurement is inaccurate, it may cause the steel column to shift position, beam reinforcement and wall reinforcement to fail to pass, etc., resulting in rework of the steel column, affecting the overall progress of the project and the connection between process steps. In addition, the various subcontracting units of the construction work work at the same time, which will also affect the measurement and layout work. Therefore, measurement work is a major difficulty in steel section welding. Therefore, ensuring the installation accuracy of the steel column is particularly important during construction.

[0005] During the installation process, it is necessary to repeatedly calibrate the installation position and elevation, and ensure the installation accuracy and positioning stability through complex measurements to prevent the installation of the rigid column from deviating due to displacement during the installation process. Therefore, a precise installation structure and monitoring method of a rigid steel column based on fiber Bragg grating as mentioned in the present invention is needed. Summary of the invention

[0006] The purpose of the present invention is to provide a rigid steel column precision installation structure and monitoring method based on fiber grating to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] 1) The flexible curvature sensor uses tapered optical fiber. Compared with ordinary traditional optical fiber, the diameter of the tapered optical fiber working area, that is, the waist area, is close to or even smaller than the wavelength of the transmitted light, and the refractive index difference between the cladding and the core is very large. Therefore, it has many excellent optical and material properties. Fiber optic sensing is widely used in sensing measurement and other aspects due to its unique advantages such as light weight, small size, and immunity to electromagnetic interference.

[0009] 2) A flexible curvature sensor is proposed. Traditional single optical fiber sensors are fragile and easy to break, so it is difficult to directly apply them to measure the curvature of various objects. The tapered optical fiber is embedded in polydimethylsiloxane (PDMS) to form a flexible film. With good flexibility, the tapered optical fiber and the PDMS film can bend synchronously. Implanting the optical fiber in certain composite flexible materials and then measuring the curvature becomes a solution for the installation and monitoring of rigid structures.

[0010] 3) The flexible curvature sensor uses multi-point tapered optical fiber and the wavelength division multiplexing characteristics of the fiber Bragg grating. By using FBGs with different central wavelengths and cascading multiple tapered optical fiber curvature sensors, multi-point tapered optical fiber flexible curvature sensing is realized. The flexible curvature sensor can sense the curvature information of multiple points at the same time. The multi-point tapered optical fiber flexible curvature sensing based on FBG also has good anti-crosstalk ability, good data repeatability during measurement, and can measure the curvature of multiple points at the same time, and can obtain more accurate sensing results.

[0011] 4) In view of the problems of complicated manufacturing process and high cost of existing sensors, the fiber Bragg grating reflective tapered flexible curvature sensor is simple to manufacture, compact and flexible in structure, and low in cost, and has potential application value in the field of flexible sensing.

[0012] 5) Among various three-dimensional position measurement methods, the fiber optic sensing method has obvious advantages in real-time monitoring due to its small size, light weight, good flexibility, implantability, easy networking, high sensitivity and no influence from electromagnetic interference.

[0013] in:

[0014] Fiber Bragg grating is a diffraction grating. Through ultraviolet exposure, phase mask, online grating, direct writing and other methods, the probability of refraction in the optical fiber core inside is increased, thereby forming a periodically modulated passive filtering element.

[0015] Optical fiber materials are photosensitivity. Photosensitivity means that when external photons enter the optical fiber, the photons will interact with the ions inside the fiber core, causing the refractive index of the material to change.

[0016] By using flexible fiber grating sensors, flexible materials can obtain greater curvature and torsion, and use FBG sensors for three-dimensional modeling and reconstruction, real-time monitoring and analysis of the reconstruction process, and use flexible fiber optic sensors to detect the position of the rigid column to ensure the installation accuracy of the rigid column.

[0017] Beneficial Effects

[0018] Flexible curvature sensing is achieved by using optical fiber sensing elements. Flexible sensing technology can capture, reconstruct and track small, complex and irregular displacements in the process of installing rigid columns in real time through high-precision and high-sensitivity morphological sensing devices, providing more accurate position monitoring and installation guarantees. Flexible sensing technology can monitor and feedback key information such as the spatial state, position and deformation of the rigid structure in real time, thereby providing more accurate data support and control guarantees for the installation of the rigid structure. The technical solution of the present invention can effectively solve the above problems. The construction method is simple, convenient and efficient, thereby significantly reducing the construction cost and achieving high economic benefits.

[0019] 1) Compared with the traditional level and theodolite measurement methods used in China, the fiber Bragg grating rigid steel column precise installation and monitoring method mentioned in the present invention has real-time monitoring, accurate data, and can more comprehensively grasp the strain characteristics of the rigid column, which is convenient for more effective installation process control;

[0020] 2) The fiber Bragg grating flexible sensing monitoring mentioned in the present invention is a preventive monitoring method, which is more efficient than the traditional pre-installation measurement, installation process verification measurement, and post-installation calibration, and can play a role in early prediction and prevention;

[0021] 3) The present invention provides a fiber Bragg grating flexible curvature sensor, which realizes flexible curvature sensing through optical fiber sensing elements. The sensor has high sensitivity and flexibility in use, and the sensor is simple to manufacture, compact and flexible in structure, and low in cost, and has potential application value in the field of flexible sensing.

[0022] 4) Compared with the previous sensors which can only realize multi-point curve morphology sensing, the flexible curvature sensor mentioned in the present invention can realize multi-point curved surface morphology sensing, thereby realizing complex curved surface shape reconstruction and monitoring.

[0023] 5) The flexible curvature sensor mentioned in the present invention realizes three-dimensional shape measurement, measures the curvature of the spatial sensing point to establish a three-dimensional coordinate system, converts the curvature information into spatial coordinate information, and then reconstructs the three-dimensional shape of the surface of the measured object by interpolation fitting of the spatial discrete coordinate points. The fiber grating sensing technology is combined with the spatial curve reconstruction algorithm to monitor the surface morphology.

[0024] 6) The present invention is applied to a method for precise installation and monitoring of rigid steel columns based on fiber Bragg gratings. In the past, most of the rigid column installation and positioning methods adopted special monitoring points for monitoring. The entire installation process needs to go through measurement, review, and verification, and it is difficult to find possible problems with the installation of the rigid columns during the process. The monitoring methods and monitoring items are numerous and scattered, making it difficult to achieve comprehensive monitoring of the measured structure and to form a systematic and interrelated monitoring system, and it is impossible to effectively achieve intelligent monitoring and early warning. However, flexible fiber Bragg grating curvature sensing has the advantages of comprehensive and systematic monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 A schematic diagram of the structure of a flexible curvature sensor based on fiber grating of the present invention;

[0027] Figure 2 It is a three-dimensional schematic diagram of the structure of a method for precise installation and monitoring of rigid steel columns based on fiber grating of the present invention;

[0028] Figure 3 It is a schematic diagram of the structural effect of a method for precise installation and monitoring of rigid steel columns based on fiber grating of the present invention;

[0029] In the figure: 1. Grating array; 2. Fiber transition zone; 3. Fiber waist zone; 4. Polydimethylsiloxane flexible membrane; 5. Rigid steel column; 6. FBG sub-sensor; 7. MOI demodulator; 8. Flexible curvature sensor; 9. Temporary fixed cable wind rope; 10. Tapered fiber. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] The application principle of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] See also Figure 1-3As shown, it is an embodiment of the present invention, which provides a rigid steel column precision installation structure based on fiber Bragg grating, including a rigid steel column 5, the horizontal cross section of the rigid steel column 5 is "H" shaped, and a temporary fixed cable wind rope 9 is installed on the rigid steel column 5, and a flexible curvature sensor 8 is installed between the temporary fixed cable wind rope 9 and the rigid steel column 5;

[0034] A rigid steel column precision installation structure based on fiber grating includes a rigid steel column 5, the horizontal cross section of the rigid steel column 5 is "H" shaped, and a temporary fixed cable wind rope 9 is installed on the rigid steel column 5, and a flexible curvature sensor 8 is installed between the temporary fixed cable wind rope 9 and the rigid steel column 5;

[0035] The flexible curvature sensor 8 comprises a polydimethylsiloxane flexible membrane 4, an FBG sub-sensor 5 is installed at the end of the polydimethylsiloxane flexible membrane 4, a tapered optical fiber 10 is installed inside the polydimethylsiloxane flexible membrane 4; and a grating array 1 is arranged inside the tapered optical fiber 10;

[0036] The sensing ends of the FBG sub-sensors 5 are respectively bonded to the web, flange and temporary fixing cable wind rope 9 of the rigid steel column 5 .

[0037] Furthermore, the tapered optical fiber 10 includes tails at both ends and a tapered area in the middle, the tapered area includes a fiber transition area 2 and a fiber waist area 3, the diameter of the fiber waist area 3 is smaller than the diameter of the fiber transition area 2; the grating array 1 is arranged in the middle of the tapered optical fiber 10. The tapered optical fiber 10 is a low-loss optical waveguide, which combines the wave guiding characteristics of the tapered optical fiber 10 with the effects of near-field coupling, nonlinear optics, evanescent wave modulation, quantum optics and photoacoustic interaction. The sensor uses the waist area as the measurement position, and monitors the measurement position according to the bending loss at different positions of the flexible curvature sensor tapered optical fiber 10.

[0038] The flexible curvature sensor 8 further includes a MOI demodulator, which is suitable for being connected to the plurality of groups of tapered optical fibers 10 .

[0039] A method for monitoring a rigid steel column 5 precise installation structure based on fiber grating includes the following steps:

[0040] 1) Installation of rigid steel column 5 structure involves the construction points of embedding anchor bolts at the column foot, installation of foundation section, installation of upper structure steel column, welding, and binding of steel column and steel bar. Installation is carried out according to design requirements and installation drawings;

[0041] 2) For monitoring the rigid steel column 5, a flexible curvature sensor 8 is installed;

[0042] The flexible curvature sensor 8 is provided with three groups of working surfaces to produce a multi-point tapered optical fiber 10, and polydimethylsiloxane is used as a base flexible film to encapsulate the tapered optical fiber 10;

[0043] The tapered optical fiber 10 is synchronously bent with the polydimethylsiloxane flexible film 4, and synchronously drives the flexible curvature sensor 8 to obtain greater curvature, position and torsion data;

[0044] 3) FBG sub-sensors 5 with different central wavelengths are cascaded with multiple tapered optical fibers 10, located at the tail end of the tapered optical fiber 10, and the transmission sensing of the tapered optical fiber 10 is changed to reflection sensing, and the optical signal passes through the sensing area twice, thereby realizing multi-point flexible curvature sensing of the tapered optical fiber 10;

[0045] 4) The flexible curvature sensor 8 is adhered to the surface of the rigid column by using adhesive material, and the multi-point optical fiber flexible curvature sensor of the flexible curvature sensor 8 is adhered to the web, flange and temporary fixed cable wind rope 9 of the rigid column respectively to monitor the spatial position offset and torsional deformation caused by welding during the installation of the rigid column;

[0046] 5) The flexible curvature sensor 8 is externally connected to a MOI demodulator. When a load acts on the rigid column, the rigid column will deform and twist, and the central wavelength of the FBG sub-sensor 5 will shift. The MOI demodulator 7 demodulates the information of the FBG sub-sensor 5, and the demodulated information is stored and processed by a computer. The wavelength variation collected is used as characteristic data, and the size and position of the load are monitored according to the characteristic data;

[0047] 6) Adjust the position of the rigid column in time according to the monitoring data to ensure that during the installation of the rigid column, verticality and position deviation errors are avoided, thereby accurately controlling the overall installation of the rigid column.

[0048] The present invention combines a fiber Bragg grating with a flexible material. The flexible curvature sensor has a large specific surface area and can be used for complex flexible curvature measurements. Computer calculation uses an interpolation algorithm to obtain a relationship curve between the FBG central wavelength drift and the curvature of the object being measured. The deformed shape of the object is reconstructed based on the curve and the interpolation algorithm to monitor the overall installation accuracy of the rigid column.

[0049] Four groups of temporary fixed cables 9 are provided, and are respectively connected to the ends of the flanges on both sides of the rigid steel column 5. The three groups of working surfaces of the flexible curvature sensor 8 are not coplanar, and are measured in a three-dimensional state. The curvature of the spatial sensing point is measured in the computer to establish a three-dimensional coordinate system, and the curvature information is converted into spatial coordinate information. Then, the three-dimensional shape of the surface of the measured object is reconstructed by interpolation fitting of the spatial discrete coordinate points. The fiber grating sensing technology is combined with the spatial curve reconstruction algorithm to monitor the surface morphology.

[0050] Among them, a reflective spectrometer is added to the external computer to pass the output light through the 50:50 main coupler and then to another 50:50 coupler, and then pass through the sensor element respectively. After the light carries the sensor information, it is reflected back and then enters the main coupler through the sub-coupler, and finally enters the reflective spectrometer through the main coupler. The spectrometer is used to collect and record data, and the curvature information at the corresponding measured position can be obtained by analyzing the data.

[0051] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0052] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A rigid steel column precision installation structure based on fiber grating, characterized in that: It includes a rigid steel column, the horizontal cross section of which is an "H" shape, and a temporary fixed cable wind rope is installed on the rigid steel column, and a flexible curvature sensor is installed between the temporary fixed cable wind rope and the rigid steel column; The flexible curvature sensor comprises a polydimethylsiloxane flexible membrane, an FBG sub-sensor is installed at the end of the polydimethylsiloxane flexible membrane, a tapered optical fiber is installed inside the polydimethylsiloxane flexible membrane; a grating array is arranged inside the tapered optical fiber; The sensing ends of the FBG sub-sensors are respectively bonded to the web, flange and temporary fixed cable wind rope of the rigid steel column.

2. According to a rigid steel column precision installation structure based on fiber grating, it is characterized in that: The tapered optical fiber includes tail lines at both ends and a tapered area in the middle, the tapered area includes a fiber transition area and a fiber waist area, the diameter of the fiber waist area is smaller than the diameter of the fiber transition area; the grating array is set in the middle of the tapered optical fiber.

3. According to a rigid steel column precision installation structure based on fiber grating, it is characterized in that: The flexible curvature sensor further includes an MOI demodulator, which is suitable for being connected to the plurality of groups of tapered optical fibers.

4. A method for monitoring a rigid steel column precision installation structure based on fiber grating as claimed in claim 3, characterized in that: The following steps are involved: 1) Installation of rigid steel column structure involves the construction points of embedding anchor bolts at the foot of steel column, installation of foundation section, installation of upper structure steel column, welding, and binding of steel column and steel bar. Installation is carried out according to design requirements and installation drawings; 2) For rigid steel column monitoring, install flexible curvature sensors; The flexible curvature sensor is provided with three groups of working surfaces to produce multi-point tapered optical fibers, and polydimethylsiloxane is used as a base flexible film to encapsulate the tapered optical fibers; The tapered optical fiber and the polydimethylsiloxane flexible film are bent synchronously, and the flexible curvature sensor is driven synchronously to obtain greater curvature, position and torsion data; 3) FBG sub-sensors with different central wavelengths are cascaded with multiple tapered optical fibers and located at the tail end of the tapered optical fiber, and the transmission sensing of the tapered optical fiber is changed to reflection sensing. At the same time, the optical signal passes through the sensing area twice, realizing multi-point tapered optical fiber flexible curvature sensing; 4) The flexible curvature sensor is glued to the surface of the rigid column with sticky material, and the multi-point optical fiber flexible curvature sensor of the flexible curvature sensor is glued to the web, flange and temporary fixed cable wind rope of the rigid column respectively to monitor the spatial position offset and torsional deformation caused by welding during the installation of the rigid column; 5) The flexible curvature sensor is connected to an external MOI demodulator. When the load acts on the rigid column, the rigid column will deform and twist, and the central wavelength of the FBG sub-sensor will shift. The MOI demodulator demodulates the information of the FBG sub-sensor, and the demodulated information is saved and processed by a computer. The collected wavelength change is used as characteristic data, and the size and position of the load are monitored according to the characteristic data; 6) Adjust the position of the rigid column in time according to the monitoring data to ensure that during the installation of the rigid column, verticality and position deviation errors are avoided, thereby accurately controlling the overall installation of the rigid column.

5. The method for monitoring the rigid steel column precision installation structure based on fiber grating according to claim 4 is characterized in that: The computer calculation adopts the interpolation algorithm to obtain the relationship curve between the FBG central wavelength drift and the curvature of the measured object. The deformed shape of the object is reconstructed based on the curve and the interpolation algorithm to monitor the overall installation accuracy of the rigid column.

6. The method for monitoring a rigid steel column precision installation structure based on fiber grating according to claim 4, characterized in that: The temporary fixing cables are provided in four groups and are respectively connected to the ends of the flanges on both sides of the rigid steel column.

7. The method for monitoring a rigid steel column precision installation structure based on fiber grating according to claim 4, characterized in that: The three working surfaces of the flexible curvature sensor are not coplanar and are measured in a three-dimensional state. The curvature of the spatial sensing point is measured in the computer to establish a three-dimensional coordinate system, and the curvature information is converted into spatial coordinate information. The three-dimensional shape of the surface of the object being measured is reconstructed by interpolation fitting of the spatial discrete coordinate points. The fiber grating sensing technology is combined with the spatial curve reconstruction algorithm to monitor the surface morphology.

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