Steel trestle deformation monitoring method based on non-contact full-field measurement technology DIC

Abstract

This invention discloses a method for monitoring the deformation of steel trestle bridges based on non-contact full-field measurement technology (DIC), comprising the following steps: 1. Developing a DIC monitoring scheme based on actual working conditions; 2. Erecting scaffolding beside the monitored area of ​​the monitoring points determined by the DIC monitoring scheme; 3. Installing monitoring equipment on the scaffolding, with the monitoring equipment facing the monitored area; 4. Creating a DIC speckle pattern on the surface of the monitored area of ​​the steel trestle bridge; 5. Installing displacement sensors beside the monitored area of ​​the steel trestle bridge; 6. Developing an automatic DIC monitoring algorithm and conducting internal testing of the algorithm; 7. Officially running the automatic DIC monitoring algorithm. This invention relates to the field of construction trestle bridge health monitoring technology, and can solve the problems of existing steel trestle bridge deformation monitoring methods that require contact with the object being measured, only measure single-point data, have low data acquisition efficiency, complex installation and maintenance, high cost, and low automation.

Description

Technical Field

[0001] This invention relates to the field of health monitoring technology for construction trestle bridges, and in particular to a method for monitoring the deformation of steel trestle bridges based on the non-contact full-field measurement technology DIC (Digital Image Correlation). Background Technology

[0002] In civil engineering, trestle bridges are temporary bridge facilities used to transport materials, equipment, and personnel. Steel trestle bridges, due to their high load-bearing capacity, can assist in the horizontal transport of materials to the optimal location on site, thereby reducing site occupation and the need for secondary handling. They also offer advantages such as convenient construction and easy dismantling. The temporary and reusable nature of trestle bridges is their significant characteristic, leading to their widespread application in my country's construction industry.

[0003] For construction projects with large foundation pit areas and tight schedules, a steel trestle bridge is typically designed and constructed to facilitate the movement of construction vehicles, thus shortening the construction period. In this context, deformation monitoring of the steel trestle bridge is particularly important. First, steel trestle bridges deform when bearing the weight of vehicles and heavy equipment; timely monitoring of these deformations can prevent potential structural damage and safety accidents. Second, deformation monitoring ensures the stability of the steel trestle bridge during construction and use, thereby guaranteeing construction quality. Finally, deformation monitoring of the steel trestle bridge helps to promptly identify and repair structural problems, extending its service life and reducing maintenance costs.

[0004] Current deformation monitoring technologies for steel trestle bridges still have several limitations. For example, while total stations offer high accuracy, they require manual operation and periodic calibration, have slow data acquisition speeds, and struggle to achieve real-time monitoring. Levels and displacement gauges typically measure displacement at specific points, failing to provide comprehensive deformation information; moreover, manual reading and recording are cumbersome and prone to human error. Strain gauges can only measure localized deformation, offering limited coverage; a large number of sensors are needed to obtain comprehensive data, and installation and maintenance are complex. Fiber optic sensors, while highly accurate, are expensive, have demanding installation requirements, are sensitive to environmental conditions, and are complex to use, hindering large-scale application. Inclinometers can only measure tilt angles, are ineffective for other types of deformation, and have low data acquisition frequencies, making them unsuitable for dynamic monitoring. Furthermore, almost all of these technologies require physical contact with the object being measured to acquire data, increasing the complexity and inconvenience of practical operation.

[0005] Therefore, there is a need to provide a deformation monitoring method for steel trestle bridges based on the non-contact full-field measurement technology DIC, which can solve the problems of existing steel trestle bridge deformation monitoring methods that require contact with the object being measured, only measure single-point data, have low data acquisition efficiency, complex installation and maintenance, high cost, and low degree of automation. Summary of the Invention

[0006] The purpose of this invention is to provide a method for monitoring the deformation of steel trestle bridges based on the non-contact full-field measurement technology DIC, which can solve the problems of existing steel trestle bridge deformation monitoring methods that require contact with the object being measured, only measure single-point data, have low data acquisition efficiency, complex installation and maintenance, high cost, and low degree of automation.

[0007] This invention is implemented as follows:

[0008] A method for monitoring the deformation of a steel trestle bridge based on the non-contact full-field measurement technology DIC includes the following steps:

[0009] Step 1: Develop a DIC monitoring plan based on actual working conditions;

[0010] Step 2: Based on the location of the monitoring points determined by the DIC monitoring plan, erect scaffolding next to the monitored area of ​​the monitoring points;

[0011] Step 3: Install monitoring equipment on the scaffolding, ensuring the equipment faces the area to be monitored;

[0012] Step 4: Create a DIC speckle pattern on the surface of the monitored area of ​​the steel trestle;

[0013] Step 5: Install displacement sensors next to the monitored area of ​​the steel trestle bridge;

[0014] Step 6: Develop an automatic DIC monitoring algorithm and conduct internal testing using the algorithm;

[0015] Step 7: Run the DIC automatic monitoring algorithm.

[0016] In step 1, a DIC monitoring plan for the deformation of the steel trestle bridge is formulated based on the construction site conditions, including the monitoring object, the layout of monitoring points, monitoring parameters, monitoring cycle, monitoring method and monitoring equipment.

[0017] In step 2, scaffolding is erected from the ground upwards at the monitoring point location of the steel trestle until the top of the scaffolding reaches the side of the monitored area, ensuring that the scaffolding does not contact the steel trestle.

[0018] In step 3, the line connecting the center of the monitoring device's lens to the center of the monitored area should be a horizontal straight line, and the power cord of the monitoring device should be waterproofed.

[0019] In step 4, DIC speckle patterns are designed using an algorithm and a perforated speckle plate is made using a 3D printer. Then, paint is sprayed through the perforated speckle plate onto the surface of the monitored area of ​​the steel trestle to form a speckle pattern for DIC analysis.

[0020] Step 6 includes the following sub-steps:

[0021] Step 6.1: Based on the open-source algorithm Ncorr, perform secondary development using Matlab to add monitoring functions and automate the DIC monitoring process;

[0022] Step 6.2: For one monitoring point and multiple monitoring points, run the DIC automatic monitoring algorithm to calculate the DIC displacement of the corresponding monitoring points;

[0023] Step 6.3: Perform DIC displacement calculation using the DIC automatic monitoring algorithm for both single and multiple monitoring points;

[0024] Step 6.4: Simultaneously acquire displacement data through displacement sensors at the corresponding monitoring points, and use this displacement data to verify the accuracy of the DIC displacement calculation results.

[0025] In step 6.1, the monitoring functions include: automatic video recording, automatic video downloading, automatic video slicing, automatic DIC calculation, automatic data saving, automatic data visualization, and automatic early warning.

[0026] Step 6.2 includes the following sub-steps:

[0027] Step 6.2.1: The monitoring equipment records video of the monitored area;

[0028] Step 6.2.2: After the video is downloaded from the server, it is sliced ​​into different segments.

[0029] Step 6.2.3: Input the slice images at different times into the Ncorr algorithm, and output the vertical displacement cloud map and the horizontal displacement cloud map of the monitored area through the Ncorr algorithm.

[0030] Step 6.2.3 includes the following sub-steps:

[0031] Step 6.2.3.1: Set the reference image in the Ncorr algorithm, which is the initial image of the monitored area recorded by the monitoring equipment before the structure deforms;

[0032] Step 6.2.3.2: Compare the input slice image with the reference image and use the DIC speckle pattern to determine the deformed image;

[0033] Step 6.2.3.3: Set the area to be monitored;

[0034] Step 6.2.3.4: Set DIC parameters;

[0035] Step 6.2.3.5: Calculate and analyze the deformation image of the monitored area based on the DIC parameters;

[0036] Step 6.2.3.6: Calculate the DIC displacement based on the analysis of the deformed image, including vertical and horizontal displacement, and output the corresponding vertical and horizontal displacement contour maps.

[0037] Step 7 includes the following sub-steps:

[0038] Step 7.1: After the DIC automatic monitoring algorithm passes the test, run the DIC automatic monitoring algorithm on the server to continuously monitor the deformation of the steel trestle.

[0039] Step 7.2: Generate displacement curves using the vertical and lateral displacements of the DIC displacement, respectively, to present the monitoring results in real time.

[0040] Step 7.3: Set the displacement over-limit value. When the vertical or lateral displacement of the DIC displacement at any monitoring point exceeds the displacement over-limit value, a deformation warning will be issued.

[0041] Step 7.4: After the project is officially launched, collect user feedback and promptly debug and optimize the algorithm to address the issues raised.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] 1. Because this invention uses non-contact measurement technology, it will not cause any damage to the surface of the steel trestle. It is highly adaptable to the construction environment and is particularly suitable for construction scenarios that require frequent use and disassembly. It ensures the integrity and safety of the structure, can monitor the deformation dynamics of the steel trestle in various construction environments in real time, and can provide timely warnings of potential structural risks, thus providing a strong guarantee for construction safety. It also provides reliable technical support for the health monitoring of steel trestle and other engineering structures.

[0044] 2. This invention achieves rapid production of DIC speckle patterns by customizing and 3D printing high-precision speckle pattern templates. Compared with traditional manual spraying methods, the DIC speckle pattern production method of this invention significantly reduces speckle production time, lowers production difficulty, and greatly improves work efficiency. At the same time, since the speckle pattern is precisely designed by an algorithm and manufactured with high precision by a 3D printer, the consistency and high quality of the speckles are ensured, unaffected by the level of manual operation, guaranteeing the accuracy and reliability of the data, and saving manpower and time.

[0045] 3. This invention achieves full automation of the monitoring process through a secondary developed automated DIC monitoring algorithm. From video recording and slicing to data analysis and result visualization, the entire process requires no manual intervention, greatly reducing the difficulty of operation and maintenance costs.

[0046] 4. By combining displacement sensors to verify the accuracy of the automated DIC monitoring algorithm, this invention can not only achieve comprehensive monitoring over a wide area, but also perform high-precision verification of deformation at key locations, thereby improving the reliability and richness of the monitoring data.

[0047] 5. The present invention provides an efficient, accurate, comprehensive, convenient, economical, real-time, and automated monitoring process for the deformation of steel trestle bridges. It solves the problems of existing steel trestle bridge deformation monitoring methods, which require contact with the object being measured, only measure single-point data, have low data acquisition efficiency, complex installation and maintenance, high cost, and low degree of automation. Attached Figure Description

[0048] Figure 1 This is a flowchart of the steel trestle bridge deformation monitoring method based on the non-contact full-field measurement technology DIC of the present invention;

[0049] Figure 2 This is a schematic diagram of the operation of the steel trestle bridge deformation monitoring method based on the non-contact full-field measurement technology DIC of the present invention;

[0050] Figure 3 This is a displacement cloud map of the steel trestle bridge deformation monitoring method based on the non-contact full-field measurement technology DIC of this invention;

[0051] Figure 4 This is a displacement curve diagram of the steel trestle bridge deformation monitoring method based on the non-contact full-field measurement technology DIC of this invention. Detailed Implementation

[0052] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0053] Please see the appendix Figure 1 A method for monitoring the deformation of a steel trestle bridge based on the non-contact full-field measurement technology DIC includes the following steps:

[0054] Step 1: Develop a DIC monitoring plan based on the actual working conditions.

[0055] A deformation DIC monitoring plan for the steel trestle bridge will be developed based on the construction site conditions, including the monitoring objects, monitoring point layout, monitoring parameters, monitoring cycle, monitoring methods, and monitoring equipment.

[0056] Step 2: Based on the location of the monitoring point determined by the DIC monitoring plan, erect scaffolding next to the monitored area of ​​the monitoring point.

[0057] Specifically, scaffolding is erected from the ground upwards at the monitoring point location on the steel trestle until the top of the scaffolding reaches the side / nearby of the monitored area, ensuring that the scaffolding does not contact the steel trestle to prevent vibration waves from the steel trestle from affecting the monitoring equipment on the scaffolding and thus impacting the accuracy of DIC monitoring.

[0058] Step 3: Install surveillance cameras and other monitoring equipment on the scaffolding, ensuring that the monitoring equipment faces the area to be monitored.

[0059] Specifically, select appropriate monitoring equipment according to monitoring needs, then install it on top of the scaffolding and align it with the area to be monitored on the steel trestle. Ensure that the line connecting the center of the monitoring equipment lens to the center of the monitored area is horizontal and straight. In addition, ensure that the power cord of the monitoring equipment is waterproof.

[0060] Step 4: Create a DIC speckle pattern on the surface of the monitored area of ​​the steel trestle.

[0061] Specifically, the DIC speckle pattern is designed using an algorithm, and a perforated speckle plate is fabricated using a 3D printer. Then, paint is sprayed through the perforated speckle plate onto the surface of the monitored area of ​​the steel trestle to form a speckle pattern for DIC analysis. The fabrication of the DIC speckle pattern is simple and efficient, and the speckle has high precision, which helps to ensure the accuracy and reliability of the subsequent calculation structure based on speckle displacement and deformation.

[0062] By precisely designing a perforated speckle pattern plate using algorithms and combining it with 3D printing technology to create the speckle pattern, modular manufacturing is possible, ensuring the consistency and high precision of the speckle pattern in subsequent spraying. This method not only improves the reliability of subsequent DIC analysis but also simplifies the speckle pattern creation process, reduces labor costs and production time, making the entire monitoring process more efficient and economical.

[0063] Step 5: Install displacement sensors next to the monitored area of ​​the steel trestle.

[0064] To verify the accuracy of DIC deformation monitoring, displacement sensors need to be installed near the monitored area of ​​the steel trestle, preferably at monitoring points at critical deformation locations. After installation, the displacement sensors should be connected to the power cord and properly adjusted.

[0065] The monitoring equipment is set up facing the monitored area. The DIC speckle pattern is formed on the surface of the monitored area of ​​the steel trestle by spraying. It adopts a non-contact measurement method and will not cause any damage to the surface of the steel trestle. It is particularly suitable for construction scenarios with frequent use and disassembly, ensuring the integrity and safety of the structure.

[0066] Step 6: Develop an automatic DIC monitoring algorithm and conduct internal testing using the algorithm.

[0067] Step 6 includes the following sub-steps:

[0068] Step 6.1: In order to automate the DIC monitoring process, we will use Matlab to perform secondary development on the open source algorithm Ncorr to add monitoring functions.

[0069] The monitoring functions include: automatic video recording, automatic video downloading, automatic video slicing, automatic DIC calculation, automatic data saving, automatic data visualization, and automatic early warning.

[0070] Step 6.2: For one monitoring point and multiple monitoring points, run the DIC automatic monitoring algorithm to calculate the DIC displacement of the corresponding monitoring point.

[0071] Step 6.2 includes the following sub-steps:

[0072] Step 6.2.1: The monitoring equipment records video of the monitored area.

[0073] Step 6.2.2: After the video is downloaded from the server, it is sliced ​​into different moments.

[0074] Step 6.2.3: Input the slice images at different times into the Ncorr algorithm, and output the vertical displacement cloud map and the horizontal displacement cloud map of the monitored area through the Ncorr algorithm.

[0075] Step 6.2.3 includes the following sub-steps:

[0076] Step 6.2.3.1: Set the reference image in the Ncorr algorithm, which is the initial image of the monitored area recorded by the monitoring equipment before the structure deforms.

[0077] Step 6.2.3.2: Compare the input slice image with the reference image and use the DIC speckle pattern to determine the deformed image.

[0078] Step 6.2.3.3: Set the area to be monitored.

[0079] Step 6.2.3.4: Set DIC parameters.

[0080] Step 6.2.3.5: Calculate and analyze the deformation image of the monitored area based on the DIC parameters.

[0081] Step 6.2.3.6: Calculate the DIC displacement based on the analysis of the deformed image, including vertical and horizontal displacement, and output the corresponding vertical and horizontal displacement contour maps.

[0082] Step 6.3: Perform DIC displacement calculation using the DIC automatic monitoring algorithm for one monitoring point and multiple monitoring points respectively.

[0083] Digital Image Correlation (DIC) is an advanced measurement method based on digital image processing and numerical computation, used to measure the displacement, deformation, and morphology of solid materials and structural surfaces. DIC technology obtains deformation and strain data of the measured object's surface by tracking the deformation process of the speckle pattern on the object's surface and calculating the grayscale changes in the speckle domain. The implementation process of DIC technology typically involves creating a speckle pattern, acquiring digital images, performing image correlation analysis, and calculating the displacement and strain fields. DIC technology has advantages such as being non-contact, non-destructive, providing full-field measurement, high accuracy, wide applicability (indoor / outdoor, static / dynamic, large / small scale structures), high automation, and reusability, overcoming many limitations of traditional monitoring methods.

[0084] Step 6.4: Simultaneously acquire displacement data through displacement sensors at the corresponding monitoring points, and use this displacement data to verify the accuracy of the DIC displacement calculation results.

[0085] Specifically, the actual vertical and lateral displacements of the monitored area are obtained through displacement sensors. Using the actual vertical and lateral displacements as reference standards, the actual vertical displacements are compared with the vertical displacements of the DIC displacement to verify the accuracy of the vertical displacement of the DIC displacement. Similarly, the actual lateral displacements are compared with the lateral displacements of the DIC displacement to verify the accuracy of the lateral displacement of the DIC displacement.

[0086] Preferably, an accuracy standard, such as 90%, can be set according to the adaptability of actual working conditions. When the vertical and lateral displacement accuracy of DIC displacement at each monitoring point reaches 90%, the DIC automatic monitoring algorithm is considered effective, passes the test, and can be officially put into operation. If the vertical or lateral displacement accuracy of one monitoring point does not reach 90%, the DIC automatic monitoring algorithm is considered invalid, and the setting parameters of the DIC automatic monitoring algorithm are optimized and adjusted until the DIC displacement accuracy at each monitoring point reaches 90%.

[0087] By combining DIC (Displacement Injection) technology with displacement sensors, not only can DIC technology be used to achieve comprehensive monitoring of large-scale deformations, but displacement sensors can also be used to verify deformations at key locations with high precision. This method not only improves the reliability and accuracy of the data but also enriches the diversity of monitoring information, ensuring the reliable application of DIC monitoring technology in complex construction environments.

[0088] Step 7: Run the DIC automatic monitoring algorithm.

[0089] Step 7 includes the following sub-steps:

[0090] Step 7.1: After the DIC automatic monitoring algorithm passes the test, run the DIC automatic monitoring algorithm on the server to continuously monitor the deformation of the steel trestle.

[0091] Step 7.2: Generate displacement curves using the vertical and lateral displacements of the DIC displacement, respectively, to present the monitoring results in real time.

[0092] Step 7.3: Set the displacement over-limit value. When the vertical or lateral displacement of the DIC displacement at any monitoring point exceeds the displacement over-limit value, a deformation warning will be issued.

[0093] Preferably, early warnings can be sent to the construction technical supervisor via email, push notifications, or other means to ensure the effectiveness of deformation warnings.

[0094] Step 7.4: After the project is officially launched, collect user feedback and promptly debug and optimize the algorithm to address the issues raised.

[0095] Example 1:

[0096] Taking a steel trestle bridge in the foundation pit of a hotel project in Shenzhen as an example, the trestle bridge is 80m long and 6m wide. The main beam is divided into a sloping section and a straight section, which are arranged in a 90° "L" shape when viewed from above. The sloping section consists of 3 groups of 6 Bailey truss beams, 62.58m long in the longitudinal direction and 10m wide in the transverse direction. The straight section consists of 9 groups of 18 Bailey truss beams, 21.00m long in the transverse direction and 18.00m wide in the longitudinal direction. I-beams are laid horizontally on the Bailey truss beams, with a spacing of 30cm between the beams. An 8mm thick steel plate bridge deck is laid on top of the beams. The lower columns of the steel trestle bridge consist of two steel pipe columns with a diameter of 630mm and a thickness of 8mm per row. The center-to-center distance between the two steel pipe piles is 4.0m. The steel pipe piles are connected by channel steel as scissor bracing. I-beams are embedded in the top of each row of steel pipes as crossbeams. Prefabricated Bailey truss main beams are arranged longitudinally on the crossbeams. Two Bailey truss pieces in each group are connected by 90cm wide decorative windows. No. 10 channel steel is used as scissor bracing to connect the groups every 6m to enhance the overall stability of the Bailey truss.

[0097] Step 1: Develop a DIC monitoring plan.

[0098] Based on the construction site conditions, a Deformation and Influence (DIC) monitoring plan for the steel trestle bridge was developed, identifying four node plates of the Bailey truss as the monitoring targets. The monitoring points were determined to be arranged along the longitudinal and transverse directions of the four node plates, as monitoring point 1, monitoring point 2, monitoring point 3, and monitoring point 4, as shown in the attached diagram. Figure 2As shown. The monitoring parameters are defined as the horizontal and vertical displacements of the entire node plate area (i.e., the monitored area). The monitoring period is defined as one month, and the monitoring method is defined as the 2D-DIC automatic monitoring algorithm based on single-camera measurement in a two-dimensional plane. The monitoring equipment is a zoomable, 4G data transmission-based bullet network camera.

[0099] Step 2: Based on the four monitoring point locations determined by the DIC monitoring plan, erect scaffolding from the ground upwards at the four monitoring point locations on the steel trestle bridge, in the following order: scaffolding 1, scaffolding 2, scaffolding 3, and scaffolding 4, until the top of the scaffolding reaches near the monitored node plate area of ​​the steel trestle bridge. Figure 2 The center heights of the four monitored node plates from the ground are 1.31m, 4.42m, 7.17m, and 8.05m, respectively. It is important to ensure that the scaffolding does not come into contact with the steel trestle to prevent the vibration waves from the steel trestle from affecting the camera on the scaffolding and thus affecting the DIC monitoring accuracy.

[0100] Step 3: Install cameras on the top of the four scaffolds respectively, namely Camera 1, Camera 2, Camera 3 and Camera 4.

[0101] Set the camera so that it faces the area of ​​the monitored node board, and ensure that the line connecting the center of the camera lens to the center of the monitored node board area is horizontal and straight. Also, ensure that the camera power cable is waterproof.

[0102] Step 4: Create a DIC speckle pattern on the surface of the monitored area of ​​the steel trestle.

[0103] The DIC speckle pattern is designed using an algorithm (e.g., a highly efficient speckle generation system and method for 2D-DIC monitoring disclosed in Chinese invention patent application 202311234393.8). Using 3D printing technology, a perforated speckle plate is made based on the DIC speckle pattern using a 3D printer. The perforated speckle plate is placed on the monitored node plate of the steel trestle, and paint is sprayed through the perforated speckle plate onto the monitored node plate of the steel trestle to form a speckle pattern for DIC analysis.

[0104] Step 5: Install displacement sensors near the monitored node plate area of ​​the steel trestle. The displacement sensors can be selected from those that can monitor three-dimensional displacement vibration. After installation, connect the displacement sensors to the power cord and debug them.

[0105] Step 6: Develop an automatic DIC monitoring algorithm and conduct internal testing using the algorithm.

[0106] Step 6 includes the following sub-steps:

[0107] Step 6.1: In order to automate the DIC monitoring process, we will use Matlab to perform secondary development on the open source algorithm Ncorr to add monitoring functions.

[0108] The monitoring functions include: automatic video recording, automatic video downloading, automatic video slicing, automatic DIC calculation, automatic data saving, automatic data visualization, and automatic early warning.

[0109] Step 6.2: For one or multiple measuring points, run the DIC automatic monitoring algorithm to calculate the DIC displacement of the corresponding measuring point.

[0110] Step 6.2 includes the following sub-steps:

[0111] Step 6.2.1: The camera records video of the monitored node board area.

[0112] Step 6.2.2: After the video is downloaded from the server, it is sliced ​​at different times. The time points of the slices can be determined according to the monitoring frequency requirements and the computing power of the equipment. The smaller the interval between the time points, the higher the monitoring accuracy, but the amount of calculation will increase accordingly.

[0113] Step 6.2.3: Input the slice images at different times into the Ncorr algorithm. The Ncorr algorithm outputs the vertical and horizontal displacement contour maps of the monitored node plate area. The vertical and horizontal displacement contour maps of the four monitoring points are attached. Figure 3 As shown in the figure, (a) is the lateral displacement cloud map of monitoring point 1, (b) is the vertical displacement cloud map of monitoring point 1, (c) is the lateral displacement cloud map of monitoring point 2, (d) is the vertical displacement cloud map of monitoring point 2, (e) is the lateral displacement cloud map of monitoring point 3, (f) is the vertical displacement cloud map of monitoring point 3, (g) is the lateral displacement cloud map of monitoring point 4, and (h) is the vertical displacement cloud map of monitoring point 4.

[0114] Step 6.2.3 includes the following sub-steps:

[0115] Step 6.2.3.1: Set the reference image in the Ncorr algorithm, which is the initial image of the monitored node plate area recorded by the camera before the structure deforms.

[0116] Step 6.2.3.2: Compare the input slice image with the reference image, and determine the deformed image by utilizing the displacement and deformation of each speckle in the DIC speckle pattern.

[0117] Step 6.2.3.3: Determine the boundary of the monitored node plate area.

[0118] Step 6.2.3.4: Set DIC parameters.

[0119] Step 6.2.3.5: Calculate and analyze the deformation image of the monitored node plate area based on the DIC parameters.

[0120] Step 6.2.3.6: Calculate the DIC displacement based on the analysis of the deformed image, including vertical and horizontal displacement. The deformation of the deformed image relative to the initial image includes the vertical and horizontal deformation of the speckle, i.e., vertical and horizontal displacement. The deformation of the monitored node plate area is characterized by the calculation of vertical and horizontal displacement, respectively.

[0121] Step 6.3: Perform DIC displacement calculation using the DIC automatic monitoring algorithm for one measuring point and multiple measuring points respectively.

[0122] Step 6.4: Simultaneously acquire displacement data using displacement sensors at the corresponding measuring points, and use this displacement data to verify the accuracy of the DIC displacement calculation results.

[0123] Specifically, the actual vertical and lateral displacements of the monitored area are obtained through displacement sensors. Using the actual vertical and lateral displacements as reference standards, the actual vertical displacements are compared with the vertical displacements of the DIC displacement to verify the accuracy of the vertical displacement of the DIC displacement. Similarly, the actual lateral displacements are compared with the lateral displacements of the DIC displacement to verify the accuracy of the lateral displacement of the DIC displacement.

[0124] The number of displacement sensors can be adjusted according to actual needs. At least one and at most four sensors can be installed. The more displacement sensors there are, the more reliable the verification of the accuracy of the DIC displacement calculation results will be.

[0125] Preferably, an accuracy qualification standard can be set according to the adaptability of actual working conditions, such as 90%. When the vertical and lateral displacement accuracy of each measuring point reaches 90%, the DIC automatic monitoring algorithm is considered effective, the test is passed, and it can be officially put into operation; if the vertical or lateral displacement accuracy of one measuring point does not reach 90%, the DIC automatic monitoring algorithm is considered invalid, and the setting parameters of the DIC automatic monitoring algorithm are optimized and adjusted until the DIC displacement accuracy of each measuring point reaches 90%.

[0126] Step 7: Run the DIC automatic monitoring algorithm.

[0127] Step 7 includes the following sub-steps:

[0128] Step 7.1: After the DIC automatic monitoring algorithm passes the test, run the DIC automatic monitoring algorithm on the server to continuously monitor the deformation of the steel trestle.

[0129] Step 7.2: Generate displacement curves using the vertical and lateral displacements of the DIC displacement data to present real-time, visualized monitoring results, as shown in the attached figure. Figure 4 As shown.

[0130] Step 7.3: Set the displacement over-limit value. When the vertical or lateral displacement of the DIC displacement at any measuring point exceeds the displacement over-limit value, a deformation warning will be issued.

[0131] Preferably, early warnings can be sent to the construction technical supervisor via email, push notifications, or other means to ensure the effectiveness of deformation warnings.

[0132] Step 7.4: After the project is officially launched, collect user feedback and promptly debug and optimize the algorithm to address the issues raised.

[0133] During the operation of the DIC automatic monitoring algorithm, the entire process is automated through AutoHotKey control, video preprocessing is performed through FFMpeg, the Ncorr algorithm is executed through Matlab, and data post-processing and automatic sending of warning emails are performed through Matlab. AutoHotKey, FFMpeg, and Matlab are all commonly used control software in this field, realizing the automated operation of the DIC automatic monitoring algorithm.

[0134] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the invention. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for monitoring the deformation of steel trestle bridges based on non-contact full-field measurement technology DIC, characterized by: Includes the following steps: Step 1: Develop a DIC monitoring plan based on actual working conditions; Step 2: Based on the location of the monitoring points determined by the DIC monitoring plan, erect scaffolding next to the monitored area of ​​the monitoring points; Step 3: Install monitoring equipment on the scaffolding, ensuring the equipment faces the area to be monitored; Step 4: Create a DIC speckle pattern on the surface of the monitored area of ​​the steel trestle; Step 5: Install displacement sensors next to the monitored area of ​​the steel trestle bridge; Step 6: Develop an automatic DIC monitoring algorithm and conduct internal testing using the algorithm; Step 6 includes the following sub-steps: Step 6.1: Based on the open-source algorithm Ncorr, perform secondary development using Matlab to add monitoring functions and automate the DIC monitoring process; Step 6.2: For one monitoring point and multiple monitoring points, run the DIC automatic monitoring algorithm to calculate the DIC displacement of the corresponding monitoring points; Step 6.3: Perform DIC displacement calculation using the DIC automatic monitoring algorithm for both single and multiple monitoring points; Step 6.4: Simultaneously acquire displacement data through displacement sensors at the corresponding monitoring points, and use this displacement data to verify the accuracy of the DIC displacement calculation results; Step 7: Run the DIC automatic monitoring algorithm.

2. The method for monitoring the deformation of steel trestle bridges based on the non-contact full-field measurement technology DIC as described in claim 1, characterized in that: In step 1, a DIC monitoring plan for the deformation of the steel trestle bridge is formulated based on the construction site conditions, including the monitoring object, the layout of monitoring points, monitoring parameters, monitoring cycle, monitoring method and monitoring equipment.

3. The method for monitoring the deformation of steel trestle bridges based on the non-contact full-field measurement technology DIC as described in claim 1, characterized in that: In step 2, scaffolding is erected from the ground upwards at the monitoring point location of the steel trestle until the top of the scaffolding reaches the side of the monitored area, ensuring that the scaffolding does not contact the steel trestle.

4. The method for monitoring the deformation of a steel trestle bridge based on the non-contact full-field measurement technology DIC as described in claim 1, characterized in that: In step 3, the line connecting the center of the monitoring device's lens to the center of the monitored area should be a horizontal straight line, and the power cord of the monitoring device should be waterproofed.

5. The method for monitoring the deformation of steel trestle bridges based on non-contact full-field measurement technology DIC as described in claim 1, characterized in that: In step 4, DIC speckle patterns are designed using an algorithm and a perforated speckle plate is made using a 3D printer. Then, paint is sprayed through the perforated speckle plate onto the surface of the monitored area of ​​the steel trestle to form a speckle pattern for DIC analysis.

6. The method for monitoring the deformation of a steel trestle bridge based on the non-contact full-field measurement technology DIC as described in claim 1, characterized in that: In step 6.1, the monitoring functions include: automatic video recording, automatic video downloading, automatic video slicing, automatic DIC calculation, automatic data saving, automatic data visualization, and automatic early warning.

7. The method for monitoring the deformation of a steel trestle bridge based on the non-contact full-field measurement technology DIC as described in claim 1, characterized in that: Step 6.2 includes the following sub-steps: Step 6.2.1: The monitoring equipment records video of the monitored area; Step 6.2.2: After the video is downloaded from the server, it is sliced ​​into different segments. Step 6.2.3: Input the slice images at different times into the Ncorr algorithm, and output the vertical displacement cloud map and the horizontal displacement cloud map of the monitored area through the Ncorr algorithm.

8. The method for monitoring the deformation of a steel trestle bridge based on the non-contact full-field measurement technology DIC as described in claim 7, characterized in that: Step 6.2.3 includes the following sub-steps: Step 6.2.3.1: Set the reference image in the Ncorr algorithm, which is the initial image of the monitored area recorded by the monitoring equipment before the structure deforms; Step 6.2.3.2: Compare the input slice image with the reference image and use the DIC speckle pattern to determine the deformed image; Step 6.2.3.3: Set the area to be monitored; Step 6.2.3.4: Set DIC parameters; Step 6.2.3.5: Calculate and analyze the deformation image of the monitored area based on the DIC parameters; Step 6.2.3.6: Calculate the DIC displacement based on the analysis of the deformed image, including vertical and horizontal displacement, and output the corresponding vertical and horizontal displacement contour maps.

9. The method for monitoring the deformation of a steel trestle bridge based on the non-contact full-field measurement technology DIC as described in claim 1, characterized in that: Step 7 includes the following sub-steps: Step 7.1: After the DIC automatic monitoring algorithm passes the test, run the DIC automatic monitoring algorithm on the server to continuously monitor the deformation of the steel trestle. Step 7.2: Generate displacement curves using the vertical and lateral displacements of the DIC displacement, respectively, to present the monitoring results in real time. Step 7.3: Set the displacement over-limit value. When the vertical or lateral displacement of the DIC displacement at any monitoring point exceeds the displacement over-limit value, a deformation warning will be issued. Step 7.4: After the project is officially launched, collect user feedback and promptly debug and optimize the algorithm to address the issues raised.

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