High formwork monitoring and early warning value determining and updating method fusing data and model

Abstract

The invention relates to a high-formwork monitoring and early warning value determining and updating method fusing data and a model, which adopts a visual displacement monitoring system to monitor displacement response data of monitoring nodes in real time, replaces the situation that an existing contact type sensor needs to be climbed and installed by a worker, greatly reduces safety accidents, and meanwhile, improves the accuracy of the monitoring and early warning values of the high-formwork monitoring and early warning values of the high-formwork monitoring and early warning values of the high-formwork monitoring and early warning values. According to the method, the finite element model is established to perform buckling failure analysis on the high-supported formwork, the early warning value when buckling failure occurs is obtained, the effect of automatically monitoring the displacement of the high-supported formwork can be achieved by comparing the early warning value with the displacement response data, and the displacement of the high-supported formwork can be automatically monitored along with continuous proceeding of the construction stage and massive accumulation of measured data. According to the method, the finite element model is updated by performing sensitivity analysis on the high-formwork design parameter set, and the monitoring efficiency and accuracy are improved by continuously iteratively updating the early warning value.

Description

Technical Field

[0001] The present invention relates to the technical field of safety monitoring of tall formwork support structures in engineering practice, and in particular to a method for determining and updating a high-support formwork monitoring and early warning value by integrating data and a model. Background Art

[0002] In recent years, my country's construction industry has developed towards the trend of large spans and large spaces, and high formwork support systems (hereinafter referred to as high formwork) have been widely used; high formwork systems refer to the construction site of the construction project where the concrete component formwork support height reaches or exceeds 8m, or the span exceeds 18m, or the total construction load is greater than 15kN / m 2 , or formwork support systems with concentrated line loads > 20kN / m. Due to the high height and poor stability of high-support formwork structures, their safety is difficult to guarantee, resulting in frequent collapse accidents. Improper high-support formwork design and insufficient understanding of the working status of the formwork support system during concrete pouring are the main causes of collapse. At present, many cities have explicitly required an increase in the coverage of safety monitoring of high-support formwork structures. However, there is still no unified conclusion on the determination of warning values ​​in current monitoring practice. Therefore, it is necessary to conduct in-depth research on scientific and reasonable warning value determination and updating methods.

[0003] In recent years, domestic and foreign scholars have focused their research on high formwork on ultimate bearing capacity, semi-rigidity of nodes, stress deformation, etc. Yu et al. studied the instability mechanism and failure mode of the structure through static failure tests on full-scale formwork frames; Xie Nan et al. studied the stable bearing capacity of formwork frames and proposed a simplified calculation method; Guo Yan et al. conducted experimental research on the nodes of fastener-type formwork frames and concluded that the vertical and horizontal bar connection nodes belong to semi-rigid connections. In terms of overall structural safety, real-time monitoring of high formwork is an important means to ensure construction safety. Most of the existing IoT perception and early warning systems are based on contact sensors. For example, Chen et al. introduced an automatic monitoring system for high formwork. The design and implementation of the system involve a variety of sensors, which have the advantages of high automation and low cost. However, such sensors require manual climbing operations in the installation, detection, maintenance, and disassembly stages, which poses a greater risk to operational safety. Therefore, it is necessary to develop a remote, non-contact monitoring and early warning system suitable for complex construction sites.

[0004] Computer vision technology, as a typical non-contact monitoring method, is widely used in the field of civil engineering. For example, Zhou Ying et al. used consumer-grade cameras as acquisition equipment and adopted optical flow technology to track the motion of the target, which can accurately identify the dynamic characteristics of the structure. The results show that it has high measurement accuracy in the frequency domain; Fang et al. proposed a new method for identifying construction site hazards that combines computer vision and ontology models, which can automatically and accurately identify hazards while complying with safety regulations. For high-support formwork structures, Chi Changzheng et al. established a set of intelligent real-time monitoring methods for construction based on computer vision and finite elements, realizing remote, real-time, and multi-point monitoring of supporting structures; Li Hangyu et al. proposed a high-support formwork structure displacement monitoring method based on online cameras, which solved the problem of light path occlusion caused by complex environments in on-site monitoring and has been successfully applied to actual formwork projects. Some scholars have also proposed corresponding solutions and verification methods to improve monitoring efficiency, accuracy, and automation level.

[0005] In summary, for high-support formwork structures, the existing applications and research have the following shortcomings: 1) There is a lack of research on the method of determining warning values ​​in the market; 2) Most of the existing IoT perception warning systems use contact sensors, which poses a great safety risk when people climb. Summary of the invention

[0006] The technical problem to be solved by the present invention is how to achieve real-time monitoring of high-support formwork and determination and update of warning values ​​during construction. In order to overcome the defects of the above prior art, the present invention provides a method for monitoring high-support formwork and determining and updating warning values ​​by integrating data and models, wherein the high-support formwork is composed of a number of rods constructed at the construction site according to the high-support formwork design parameter set, and the rods include horizontal rods, vertical rods, wall connecting members and diagonal rods. The method for monitoring and updating the warning value of the high-support formwork includes:

[0007] Step 1. Determine the monitoring nodes of the high formwork in the current construction stage, and establish a finite element model according to the high formwork design parameter set and the current construction stage; the high formwork design parameter set includes the design load of the high formwork;

[0008] Step 2. According to the working conditions and load distribution conditions of the diagonal bars in the high formwork, multiple working conditions of the high formwork are defined. The finite element model performs buckling failure analysis on different working conditions respectively to obtain buckling characteristic values ​​under different working conditions; and the buckling loads under different working conditions are obtained by multiplying the buckling characteristic values ​​with the design load; the finite element model calculates the critical displacement values ​​when buckling failure occurs under different working conditions according to the buckling loads under different working conditions, and defines the working condition in which the buckling load is greater than the design load and the critical displacement value is the smallest as the most unfavorable working condition, and uses the critical displacement value corresponding to the most unfavorable working condition as the warning value;

[0009] Step 3. A visual displacement monitoring system is set up for the monitoring nodes on the high formwork at the construction site, wherein the visual displacement monitoring system includes a calibration object for calibrating the monitoring nodes and a monitoring camera for obtaining a real-time displacement monitoring image generated by the monitoring nodes;

[0010] Step 4. The visual displacement monitoring system obtains the displacement response data of the monitoring node;

[0011] Step 5. Determine whether the displacement response data of the monitoring node is greater than the warning value calculated in step 2. If so, issue an alarm signal, carry out manual emergency treatment, and return to step 4; if not, the visual displacement monitoring system continues to monitor the displacement response data at the monitoring node until the current construction stage ends, enters the next construction stage, and enters step 6;

[0012] Step 6. Perform sensitivity analysis on the parameters in the high-support formwork design parameter set, determine the update parameters from the construction design parameter set according to the sensitivity analysis results, update the finite element model by modifying the corresponding update parameters in the finite element model, and then proceed to step 7;

[0013] Step 7. The updated finite element model calculates and updates the warning value according to the building design parameters of the corresponding construction stage according to the content of step 2, and returns to step 4.

[0014] Compared with the prior art, the present application has the following advantages: the present invention adopts the construction of a visual displacement monitoring system to monitor the displacement response data of the monitoring node in real time, replacing the existing contact sensors that require workers to climb and install, greatly reducing the occurrence of safety accidents; at the same time, the present invention establishes a finite element model to perform buckling failure analysis on the high formwork, and obtains a warning value when buckling failure occurs. By comparing the warning value with the displacement response data, the effect of automatically monitoring the displacement of the high formwork can be achieved. As the construction stage continues to advance and a large amount of measured data is accumulated, the present invention updates the finite element model by performing sensitivity analysis on the high formwork design parameter set, and improves the monitoring efficiency and accuracy by continuously iteratively updating the warning value.

[0015] In a possible implementation, the node connection conditions of the high formwork are a rigid connection between the upper and lower uprights, a semi-rigid connection between the uprights and the cross bars, and between the uprights and the diagonal bars, and a rigid connection between the uprights and the ground.

[0016] In a possible implementation, the high formwork design parameter set also includes construction load, rod length, node stiffness, rod density, rod elastic modulus, rod wall thickness, rod yield strength, boundary conditions and rod outer diameter, and the boundary conditions include: the bottom end of the vertical rod simultaneously constrains the displacement in the x, y, and z directions, and releases rotation in all directions; the wall connection member only constrains the displacement in the x and y directions, and releases the z-direction displacement and rotation in all directions.

[0017] In a possible implementation manner, the multiple working conditions of the high-support formwork defined in step 2 according to the working conditions and load distribution conditions of the diagonal bars in the high-support formwork specifically include: working condition 1: the diagonal bars are working and the load is evenly distributed; working condition 2: the diagonal bars are not working and the load is evenly distributed; working condition 3: the diagonal bars are working and the load is unevenly distributed; working condition 4: the diagonal bars are not working and the load is unevenly distributed;

[0018] The finite element model in step 2 performs buckling failure analysis on different working conditions, and the calculation formula of the buckling characteristic value under different working conditions is obtained as follows:

[0019] [K]{U}+[K G ]{U}={P}

[0020] |[K]+λ t [K G ]|=0

[0021] Where [K] is the elastic stiffness matrix of the high-support formwork, [K G ] is the geometric stiffness matrix of the high formwork, {U} is the displacement matrix of the rods on the high formwork; {P} represents the load acting on the high formwork, including the design load and the construction load; λ t represents the buckling eigenvalue corresponding to the tth working condition;

[0022] The calculation formula for the buckling load under different working conditions is obtained by multiplying the buckling eigenvalue by the design load:

[0023] F1λ t =F2

[0024] Where F1 is the design load and F2 is the buckling load.

[0025] In a possible implementation, the step 3 of building a visual displacement monitoring system for monitoring nodes on the high formwork at the construction site specifically includes:

[0026] Step 301: Determine the image resolution Res of the monitoring camera and the measurement accuracy n of the monitoring nodes in the construction site. r , in mm, and based on the calculation formula Calculate the field of view FOV of the surveillance camera, where n p Indicates the measurement accuracy of the visual displacement monitoring system, in pixels;

[0027] Step 302. Combine the field of view FOV, size and focal length f of the surveillance camera and calculate based on the formula The working distance D of the surveillance camera is calculated, where S is the proportional coefficient for mapping the image collected by the surveillance camera to the coordinates of the construction site:

[0028]

[0029] Where D is the actual distance between the monitoring camera and the monitoring node, and d is the pixel distance of the monitoring camera.

[0030] In a possible implementation manner, the visual displacement monitoring system in step 4 obtains the displacement response data of the rod at the monitoring node, specifically including:

[0031] Step 401. Use a monitoring camera to collect an image of the monitoring node before entering the visual monitoring work as a reference image, use a rectangular search box to mark the position of the monitoring node in the reference image as a feature area, and use the feature area as a predefined template;

[0032] Step 402: Use the same rectangular search box as in step 401 to move pixel by pixel on the image collected during visual monitoring, and calculate the correlation of each pixel in order to find the coordinate position of the feature area in the image;

[0033] Step 403. Perform an inverse transformation on the coordinate positions of the feature areas of the images at different times found in step 402 to determine the coordinate positions of the corresponding monitoring nodes on the high formwork at the construction site.

[0034] In a possible implementation manner, the calculation formula for calculating the correlation of each pixel in step 402 is:

[0035]

[0036] Where c(i, j) represents the correlation coefficient of the pixel point in the i-th row and j-th column (-1<c<1), m and n represent the length and width of the rectangular search box respectively, and f(x, y) represents the pixel information on the predefined template. Represents the average grayscale of the predefined template, g t (x, y) represents the pixel information of the xth row and yth column on the rectangular search box at sampling time t. Represents the average grayscale of the rectangular search box at sampling time t; the area in the image where c(i, j) is closest to 1 is taken as the feature area.

[0037] In a possible implementation, the calculation formula for performing sensitivity analysis on the parameters in the high formwork design parameter set in step 6 is:

[0038]

[0039] In the formula, φ m represents parameter sensitivity, θ m is the parameter in the high formwork design parameter set, Δθ mis the change of parameter value in the high-support formwork design parameter set, Y is the output of the finite element model, and ΔY is the output change of the parameters in the finite element model before and after the change;

[0040] Based on the sensitivity analysis results, the parameter with the largest sensitivity value in the high-support formwork design parameter set is determined as the update parameter, and the corresponding update parameter in the finite element model is modified so that the displacement data of the corresponding monitoring node in the finite element model is consistent with the displacement response data of the rod at the monitoring node obtained by the visual displacement monitoring system in step 4. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the process of the present invention;

[0042] Figure 2 It is a schematic diagram of boundary conditions defined in a specific embodiment of the present invention;

[0043] Figure 3 A visual displacement monitoring system is built for two monitoring nodes at a construction site in a specific embodiment of the present invention;

[0044] Figure 4 This is a real-time monitoring image of displacement collected by a ball camera in a specific embodiment of the present invention;

[0045] Figure 5 It is the vertical displacement of the monitoring node of the ball camera 1 under the design load in the specific embodiment of the present invention;

[0046] Figure 6 It is the vertical displacement of the monitoring node of the ball camera 2 under the design load in the specific embodiment of the present invention;

[0047] Figure 7 It is a time history curve of horizontal displacement monitored by the ball camera 1 in a specific embodiment of the present invention;

[0048] Figure 8 It is a vertical displacement time history curve monitored by the ball camera 1 in a specific embodiment of the present invention;

[0049] Fig. 9 It is a time history curve of horizontal displacement monitored by the ball camera 2 in a specific embodiment of the present invention;

[0050] Fig.10 It is the displacement time history curve of the ball camera 2 in the monitoring direction in the specific embodiment of the present invention;

[0051] Fig.11 It is a comparison diagram of the error in the horizontal direction between the finite element model before and after updating and the measured displacement in a specific embodiment of the present invention;

[0052] Fig.12 It is a comparison diagram of the errors in the vertical direction between the finite element model before and after updating and the measured displacement in a specific embodiment of the present invention;

[0053] Fig.13 The long-term monitoring result of the horizontal displacement of the ball camera 1 in the specific embodiment of the present invention and the comparison of the warning values ​​before and after the finite element model is updated;

[0054] Fig.14 The long-term monitoring result of the horizontal displacement of the ball camera 2 in the specific embodiment of the present invention and the comparison of the warning values ​​before and after the finite element model is updated;

[0055] Fig.15 It is a comparison of the long-term monitoring results of the vertical displacement of the ball camera 1 and the warning values ​​before and after the finite element model is updated in a specific embodiment of the present invention;

[0056] Fig.16 It is a comparison of the long-term monitoring results of the vertical displacement of the ball camera 2 and the warning values ​​before and after the finite element model is updated in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0057] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0058] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0059] In the embodiments of the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0060] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0061] See also Figure 1As shown, the present application discloses a method for determining and updating a high-support formwork monitoring and early warning value that integrates data and models. A specific embodiment is applied to a public building. The cantilevered roof panel of the public building needs to be equipped with an ultra-high formwork support system, wherein the roof panel cantilevers 2.25m from the outside of the edge beam. The boundary conditions of the high-support formwork and the architectural design requirement parameter set are determined for the public building, and based on the architectural design requirement parameter set and the boundary conditions, a high-support formwork with a total height of 31.45m is constructed with a height of horizontal bars, vertical bars, wall connecting parts and diagonal bars from -1.95m to 29.5m. The node connection conditions of the high-support formwork are rigid connection between the upper and lower vertical bars, semi-rigid connection between the vertical bars and the horizontal bars, and between the vertical bars and the diagonal bars, and rigid connection between the vertical bars and the ground; wherein the high-support formwork is composed of a set of buildings at the construction site according to the high-support formwork design parameter set; the monitoring and updating method of the high-support formwork early warning value includes:

[0062] Step 1. Determine the monitoring nodes of the high formwork in the current construction stage, and establish a finite element model according to the high formwork design parameter set and the current construction stage; the high formwork design parameter set includes the design load of the monitoring node, the high formwork design parameter set also includes the rod length, node stiffness, rod density, rod elastic modulus, rod wall thickness, rod yield strength, boundary conditions and rod outer diameter; the boundary conditions are as follows: Figure 2 As shown, the bottom end of the vertical rod simultaneously constrains the displacement in the x, v, and z directions, and releases the rotation in all directions; the wall connecting member only constrains the displacement in the x and y directions, and releases the displacement in the z direction and the rotation in all directions; the embodiment of the tool adopts a disc-type steel pipe formwork support, and the rod material and interface information used are shown in Table 1:

[0063] Table 1 Bar material and section information

[0064] Rod Yield strength(MPa) Outer diameter(mm) Wall thickness(mm) Pole 355 48.3 3.2 Crossbar 235 48.3 2.5 Slant 235 33.7 2.3

[0065] At the same time, the design load of the monitoring node includes horizontal load and vertical load. This specific embodiment takes into account the horizontal load and wind load generated by the dead weight of concrete, steel bars, formwork, etc., the stacking load of construction personnel and machinery, pumping and pouring of concrete, etc. After calculation, the vertical load borne by the support system during construction is 4267.68kN, and the horizontal load is 1725.84kN. The high formwork structure has a total of 408 vertical poles. Assuming that each vertical pole is borne by the same load, a single vertical pole bears a vertical load of 10.46kN and a horizontal load of 4.23kN.

[0066] Step 2. According to the working conditions and load distribution conditions of the diagonal bars in the high formwork, multiple working conditions of the high formwork are defined. The finite element model performs buckling failure analysis on different working conditions respectively to obtain buckling characteristic values ​​under different working conditions; and the buckling loads under different working conditions are obtained by multiplying the buckling characteristic values ​​with the design load; the finite element model calculates the critical displacement values ​​when buckling failure occurs under different working conditions according to the buckling loads under different working conditions, and defines the working condition in which the buckling load is greater than the design load and the critical displacement value is the smallest as the most unfavorable working condition, and uses the critical displacement value corresponding to the most unfavorable working condition as the warning value;

[0067] Four types of disclosure are defined in this specific embodiment, specifically including: working condition 1: the inclined rod works and the load is evenly distributed; working condition 2: the inclined rod does not work and the load is evenly distributed; working condition 3: the inclined rod works and the load is unevenly distributed; working condition 4: the inclined rod does not work and the load is unevenly distributed;

[0068] In this specific embodiment, a vertical load of 10.46 kN and a horizontal load of 4.23 kN are input into the finite element model, and the buckling eigenvalue and buckling load obtained are shown in Table 2:

[0069] Table 2 Buckling failure analysis of high formwork structure

[0070]

[0071] The results show that:

[0072] 1) Under the most unfavorable working condition (i.e. the diagonal rod is not working and the load is evenly distributed), the vertical buckling load of the structure is 18.2kN>10.46kN, and the horizontal buckling load is 7.36kN>4.23kN, indicating that the structural safety margin is sufficient;

[0073] 2) When buckling failure occurs, the displacement of the uniform load distribution condition is smaller than that of the uneven load distribution condition, which means that the larger displacement will cause the diagonal brace to enter the work;

[0074] 3) The monitoring and early warning values ​​of the high formwork structure were set according to the most unfavorable working conditions. The vertical values ​​of ball camera 1 were 7.5 mm and the horizontal values ​​were 9.91 mm. The vertical values ​​of ball camera 2 were 4.3 mm and the horizontal values ​​were 3.9 mm. They were all smaller than the upper limit of the pole settlement alarm value of 8 mm and the upper limit of the horizontal displacement of 12 mm. The values ​​were reasonable.

[0075] Step 3. A visual displacement monitoring system is set up for the monitoring nodes on the high-support formwork at the construction site. The visual displacement monitoring system includes a calibration object for calibrating the monitoring nodes and a monitoring camera for obtaining real-time displacement monitoring images generated by the monitoring nodes; specifically, it includes:

[0076] Step 301: Determine the image resolution Res of the monitoring camera and the measurement accuracy n of the monitoring nodes in the construction site. r , in mm, and based on the calculation formula Calculate the field of view FOV of the surveillance camera, where n p Indicates the measurement accuracy of the visual displacement monitoring system, in pixels;

[0077] Step 302. Combine the field of view FOV, size and focal length f of the surveillance camera and calculate based on the formula The working distance D of the surveillance camera is calculated, where S is the proportional coefficient for mapping the image collected by the surveillance camera to the coordinates of the construction site:

[0078]

[0079] Where D is the actual distance between the monitoring camera and the monitoring node, and d is the pixel distance of the monitoring camera.

[0080] The surveillance camera of this specific embodiment adopts a ball camera. The image resolution of the real-time capture of the ball camera is 1920×1088. The visual measurement system needs to achieve a measurement accuracy of 1mm. The pixel recognition accuracy of the conservative estimation algorithm is 0.5pixel. It is calculated that the maximum field of view of the ball camera is 3.84m×2.18m. The sensor size of the ball camera is 1 / 2.8 (5.0mm×2.8mm after conversion), and the focal length is variable between 4.8 and 110mm. Combining the above parameters, it is calculated that the appropriate working distance of the ball camera is about 3.7m to 84.0m.

[0081] In this specific embodiment, the facade of the public building to be measured at the construction site is directly opposite to the project department and the straight-line distance is 40m, which is within the reasonable working range of the ball camera. Therefore, the ball camera is installed in the project department for monitoring. Considering the technical results of the finite element model and the on-site monitoring conditions, two elevation points are selected for displacement monitoring. The specific layout is as follows: Figure 3 As shown, select the corner and its adjacent poles on the left and right, such as Figure 4 The rods 1-3 shown in the figure are used as monitoring objects. Two ball cameras are used to monitor the areas separated by 8m in the height direction. According to the horizontal displacement and height difference of the measuring points of the same rod in the monitoring areas 1 and 2, the inclination rate of the corresponding rod can be calculated. Among them, the monitoring node 1 monitored by the ball camera 1 is located between 15.4 and 16.9m. The finite element model of step 2 is used to calculate the rod at the corner (see Figure 4 The vertical displacement of the middle rod 2) here is approximately in the range of 0.953mm-1.756mm. Figure 5 As shown; the monitoring node 2 monitored by the ball camera 2 is located at 7.9m. The finite element model of step 2 is used to calculate that the vertical displacement of the rod at the corner is about 2.299mm. Figure 6 shown.

[0082] Step 4. The visual displacement monitoring system obtains the displacement response data of the monitoring node; specifically includes:

[0083] Step 401. The image of the monitoring node captured by the monitoring camera before entering the visual monitoring work is used as a reference image, and the position of the monitoring node is calibrated in the reference image through a rectangular search box as a feature area, and the feature area is used as a predefined template;

[0084] Step 402. After the visual displacement monitoring system enters the visual monitoring work, the monitoring camera collects monitoring images according to the preset monitoring frequency, and uses the same rectangular search box as step 401 to move pixel by pixel on the image collected during the visual monitoring work, and calculates the correlation of each pixel to find the coordinate position of the feature area in the monitoring image; the calculation formula of the correlation of each pixel is:

[0085]

[0086] Where c(i, j) represents the correlation coefficient of the pixel point in the i-th row and j-th column (-1<c<1), m and n represent the length and width of the rectangular search box respectively, and f(x, y) represents the pixel information on the predefined template. Represents the average grayscale of the predefined template, g t (x, y) represents the pixel information of the xth row and yth column on the rectangular search box at sampling time t. Represents the average grayscale of the rectangular search box at sampling time t; the area in the image where c(i, j) is closest to 1 is taken as the feature area.

[0087] Here, the method of calculating the correlation pixel by pixel using a rectangular search box can only obtain integer pixel coordinates, and the measurement accuracy is limited. For this reason, in this specific embodiment, it is necessary to use sub-pixel technology to further improve the measurement accuracy, and use a double parabola fitting method to make the displacement measurement achieve sub-pixel accuracy. The double parabola fitting method is a prior art and will not be elaborated on here.

[0088] Step 403. Perform an inverse transformation on the coordinate positions of the feature areas of the images at different times found in step 402 to determine the coordinate positions of the corresponding monitoring nodes on the high formwork at the construction site.

[0089] In addition, in order to solve the problem of insufficient recognition accuracy and low robustness in adverse scenarios such as incomplete outdoor monitoring markers and blurred images, this specific embodiment uses the YOLOX algorithm to identify occluded markers and the SRGAN network to improve image resolution. At the same time, a non-displacement reference point is selected near the structure, and the relative displacement between the point and the structure is used as the measured displacement to reduce the error in the recognition algorithm. The technical content about the YOLOX algorithm, SRGAN network and non-displacement reference point is prior art and will not be elaborated here.

[0090] This specific embodiment selects the monitoring data of a certain day for analysis, and draws the displacement time history curve of the pole during 7:00-17:00, such as Figure 7-10 As shown, the results show that:

[0091] 1) The displacement of the pole does not change much throughout the day, and basically maintains a small fluctuation around a mean value;

[0092] 2) After a long period of work accumulation, each pole has different long-term deformation, resulting in different displacement means in different directions in different areas;

[0093] 3) During the pouring of upper concrete, the horizontal displacement of ball machine 1 was within 4mm (<9.91mm), the vertical displacement was within 3mm (<7.5mm), and the horizontal displacement of ball machine 2 was within 2.5mm (<3.9mm), and the vertical displacement was within 4mm (<4.3mm). All indicators did not exceed the warning value, indicating that during the concrete pouring process, the high formwork structure was always in a safe working state.

[0094] Step 5. Determine whether the displacement response data of the monitoring node is greater than the warning value calculated in step 2. If so, issue an alarm signal, carry out manual emergency disposal, and return to step 4; if not, the visual displacement monitoring system continues to monitor the displacement response data at the monitoring node until the current construction stage ends, enters the next construction stage, and enters step 6.

[0095] Step 6. Perform sensitivity analysis on the parameters in the high formwork design parameter set, determine the update parameters from the construction design parameter set according to the sensitivity analysis results, update the finite element model by modifying the corresponding update parameters in the finite element model, and then proceed to step 7; wherein, the calculation formula for the sensitivity analysis of the high formwork design parameter set is:

[0096]

[0097] In the formula, φ m represents parameter sensitivity, θ m is the parameter in the high formwork design parameter set, Δθ m is the change of parameter values ​​in the high-support formwork design parameter set, Y is the output of the finite element model, and ΔY is the output change of the parameters in the finite element model before and after the change;

[0098] Based on the sensitivity analysis results, the parameter with the largest sensitivity value in the high-support formwork design parameter set is determined as the update parameter, and the corresponding update parameter in the finite element model is modified so that the displacement data of the corresponding monitoring node in the finite element model is consistent with the displacement response data of the rod at the monitoring node obtained by the visual displacement monitoring system in step 4.

[0099] Before conducting the sensitivity analysis, in order to demonstrate the update process of the warning value, 12 sets of vertical and horizontal maximum displacement data were selected from the six monitoring points during the concrete pouring period and compared with the finite element calculation results, as shown in Table 3:

[0100] Table 3 Comparison of finite element calculated displacement values ​​and measured displacement before updating

[0101]

[0102] The results show that:

[0103] Among them, the relative error between the finite element calculation results and the measured displacement of 7 sets of data is controlled within 20%, and the errors of the other 5 sets are relatively large, including vertical bar 1 (high), bar 2 (high), bar 3 (high), horizontal bar 3 (high), bar 1 (low). The reasons for the large errors of these 5 sets of data may be: 1) The node connection quality of these measuring points may be poor during the construction process; 2) The disc support system has high strength and stiffness, resulting in a small actual displacement, and a small absolute error will cause a large relative error; 3) The vertical pole may be partially damaged after repeated use, resulting in the initial finite element model not being able to reflect the actual structure well.

[0104] The sensitivity analysis results calculated in this specific embodiment are shown in Table 4:

[0105] Table 4 Parameter sensitivity analysis results

[0106] Parameter change rate (10%) Displacement change rate Sensitivity Node stiffness -16.80％ 1.68 Rod density -17.20％ 1.72 Elastic modulus of pole -29.50％ 2.95 Elastic modulus of horizontal rod -10.70％ 1.07 Pole wall thickness -27.10％ 2.71 Horizontal rod wall thickness -15.50％ 1.55

[0107] The results show that:

[0108] When the change rate of each parameter is +10%, the elastic modulus and wall thickness of the vertical pole have the greatest influence on the displacement of the high formwork structure and are determined as the update parameters;

[0109] Step 7. The updated finite element model calculates and updates the warning value according to the building design parameters of the corresponding construction stage according to the content of step 2, and returns to step 4.

[0110] Compare the finite element model before and after the update with the measured displacement error, such as Figure 11-12 As shown, after the update, the relative errors between the finite element calculation results and the measured values ​​of 11 out of the 12 data sets were controlled within 20%, and the RMSE was reduced from 0.784mm to 0.132mm, indicating that the updated model can more truly reflect the actual structure.

[0111] Reasonable analysis of early warning values

[0112] Re-analyze the buckling failure of the updated finite element model, determine the critical displacement, and then analyze the rationality of the warning value. If the alarm value is set too large, the structure will fail without an alarm, and construction safety cannot be guaranteed. If the alarm value is set too small, frequent false alarms will occur, affecting the construction progress and consuming emergency response resources. Therefore, it is more reasonable that the warning value before the update should be slightly smaller than the buckling failure displacement after the update.

[0113] like Figure 13-16 The figure shows the long-term displacement monitoring results and the comparison of warning values ​​before and after the update. It can be found that with the accumulation of time, the horizontal displacement and vertical settlement of the high-support formwork structure have shown a gradual increase trend. At the same time, after the update, the horizontal critical displacement of ball camera 1 is 11.2mm (>9.91mm), the horizontal critical displacement of ball camera 2 is 7.95mm (>7.5mm), the vertical critical displacement of ball camera 1 is 5.16mm (>3.9mm), and the vertical critical displacement of ball camera 2 is 4.51mm (>4.3mm). The updated warning values ​​are all higher than before the update, indicating that the initial alarm value setting is relatively safe and can effectively prevent the high-support formwork structure from being damaged when the set alarm value is not reached.

[0114] This paper proposes a monitoring and updating method for high-support formwork warning values ​​that integrates data and models. Taking actual projects as examples, a finite element model is established and the warning value is determined. A visual displacement monitoring system is built to achieve real-time perception of response and timely data feedback, laying the foundation for the continuous updating of warning values. The specific conclusions are as follows:

[0115] 1) As time goes by, the horizontal displacement and vertical settlement of the high formwork structure show a trend of gradual increase, and the development trend needs to be paid special attention to during the construction process;

[0116] 2) The buckling failure displacement of the updated finite element model of the present invention is greater than the initial warning value, indicating that the warning value is set to be safe and reasonable;

[0117] 3) The monitoring and early warning values ​​and updating methods proposed in the present invention are a dynamic and continuous improvement process. With the continuous advancement of the construction process and the accumulation of a large amount of measured data, the early warning values ​​need to be continuously iterated and improved to accurately match the actual structural characteristics.

[0118] In the description of the embodiments of the present application, it should be noted that in the description of the present application, terms such as "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is only for the convenience of description, and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present application.

[0119] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0120] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for determining and updating high-rise formwork monitoring and early warning values ​​by integrating data and models, wherein the high-rise formwork is constructed on the construction site by a number of horizontal bars, vertical bars, wall connecting pieces and diagonal bars according to a high-rise formwork design parameter set, characterized in that: The methods for determining and updating high-support formwork monitoring and early warning values ​​include: Step 1. Determine the monitoring nodes of the high formwork in the current construction stage, and establish a finite element model according to the high formwork design parameter set and the current construction stage; the high formwork design parameter set includes the design load of the high formwork; Step 2. According to the working conditions and load distribution conditions of the diagonal bars in the high formwork, multiple working conditions of the high formwork are defined. The finite element model performs buckling failure analysis on different working conditions respectively to obtain buckling characteristic values ​​under different working conditions; and the buckling loads under different working conditions are obtained by multiplying the buckling characteristic values ​​with the design load; the finite element model calculates the critical displacement values ​​when buckling failure occurs under different working conditions according to the buckling loads under different working conditions, and defines the working condition in which the buckling load is greater than the design load and the critical displacement value is the smallest as the most unfavorable working condition, and uses the critical displacement value corresponding to the most unfavorable working condition as the warning value; Step 3. A visual displacement monitoring system is set up for the monitoring nodes on the high formwork at the construction site, wherein the visual displacement monitoring system includes a calibration object for calibrating the monitoring nodes and a monitoring camera for obtaining a real-time displacement monitoring image generated by the monitoring nodes; Step 4. The visual displacement monitoring system obtains the displacement response data of the monitoring node; Step 5. Determine whether the displacement response data of the monitoring node is greater than the warning value calculated in step 2. If so, issue an alarm signal, carry out manual emergency treatment, and return to step 4; if not, the visual displacement monitoring system continues to monitor the displacement response data at the monitoring node until the current construction stage ends, enters the next construction stage, and enters step 6; Step 6. Perform sensitivity analysis on the parameters in the high-support formwork design parameter set, determine the update parameters from the construction design parameter set according to the sensitivity analysis results, update the finite element model by modifying the corresponding update parameters in the finite element model, and then proceed to step 7; Step 7. The updated finite element model calculates and updates the warning value according to the building design parameters of the corresponding construction stage according to the content of step 2, and returns to step 4.

2. The method for determining and updating high-support formwork monitoring and early warning values ​​by integrating data and models according to claim 1, characterized in that: The node connection conditions of the high support formwork are rigid connection between the upper and lower vertical poles, semi-rigid connection between the vertical poles and the cross poles, between the vertical poles and the diagonal poles, and rigid connection between the vertical poles and the ground.

3. The method for determining and updating high-rise formwork monitoring and early warning values ​​by integrating data and models according to claim 1, characterized in that: The high formwork design parameter set also includes rod length, node stiffness, rod density, rod elastic modulus, rod wall thickness, rod yield strength, boundary conditions and rod outer diameter. The boundary conditions include: the bottom end of the vertical rod simultaneously constrains the displacement in the x, y and z directions, and releases rotation in all directions; the wall connection member only constrains the displacement in the x and y directions, and releases the z-direction displacement and rotation in all directions.

4. The method for determining and updating high-rise formwork monitoring and early warning values ​​by integrating data and models according to claim 1, characterized in that: In step 2, the multiple working conditions of the high-support formwork are defined according to the working conditions and load distribution conditions of the diagonal bars in the high-support formwork, specifically including: working condition 1: the diagonal bars are working and the load is evenly distributed; working condition 2: the diagonal bars are not working and the load is evenly distributed; working condition 3: the diagonal bars are working and the load is unevenly distributed; working condition 4: the diagonal bars are not working and the load is unevenly distributed; The finite element model in step 2 performs buckling failure analysis on different working conditions, and the calculation formula of the buckling characteristic value under different working conditions is obtained as follows: [K]{U}+[K G ]{U}={P} |[K]+λ t [K G ]|=0 Where [K] is the elastic stiffness matrix of the high-support formwork, [K G ] is the geometric stiffness matrix of the high formwork, {U} is the displacement matrix of the rods on the high formwork; {P} represents the load acting on the high formwork, including the design load and the construction load; λ t represents the buckling eigenvalue corresponding to the tth working condition; The calculation formula for the buckling load under different working conditions is obtained by multiplying the buckling eigenvalue by the design load: F1λ t =F2 Where F1 is the design load and F2 is the buckling load.

5. The method for determining and updating high-rise formwork monitoring and early warning values ​​by integrating data and models according to claim 1, characterized in that: In step 3, the visual displacement monitoring system is built for the monitoring nodes on the high formwork at the construction site, specifically including: Step 301. Install the calibration object on the pole corresponding to the monitoring node; Step 302: Determine the image resolution Res of the monitoring camera and the measurement accuracy n of the monitoring nodes in the construction site. r , in mm, and based on the calculation formula Calculate the field of view FOV of the surveillance camera, where n p Indicates the measurement accuracy of the visual displacement monitoring system, in pixels; Step 303. Combine the field of view FOV, size and focal length f of the surveillance camera and calculate based on the formula The working distance D of the surveillance camera is calculated, where S is the proportional coefficient for mapping the image collected by the surveillance camera to the coordinates of the construction site: Where D is the actual distance between the monitoring camera and the monitoring node, and d is the pixel distance of the monitoring camera.

6. The method for determining and updating high-rise formwork monitoring and early warning values ​​by integrating data and models according to claim 1, characterized in that: The visual displacement monitoring system in step 4 obtains the displacement response data of the rod at the monitoring node, specifically including: Step 401. Use a monitoring camera to collect an image of the monitoring node before entering the visual monitoring work as a reference image, use a rectangular search box to mark the position of the monitoring node in the reference image as a feature area, and use the feature area as a predefined template; Step 402. Use the same rectangular search box as step 401 to move pixel by pixel on the image collected during the visual monitoring work, and calculate the correlation of each pixel in the hope of finding the coordinate position of the feature area in the image; Step 403. Perform an inverse transformation on the coordinate position of the feature area of ​​the image at different times found in step 402 to determine the coordinate position of the corresponding monitoring node on the high formwork at the construction site.

7. The method for determining and updating high-rise formwork monitoring and early warning values ​​by integrating data and models according to claim 6, characterized in that: The calculation formula for calculating the correlation of each pixel in step 402 is: Wherein, c(i, j) represents the correlation coefficient of the pixel at the i-th row and the j-th column (-1 < c < 1), m and n respectively represent the length and width of the rectangular search window, f(x, y) represents the pixel information on the predefined template, represents the average gray level of the predefined template, g t (x, y) represents the pixel information at the x-th row and the y-th column on the rectangular search window at the sampling time t, represents the average gray level of the rectangular search window at the sampling time t; The area where c(i, j) in the image is closest to 1 is taken as the feature area.

8. The method for determining and updating high-rise formwork monitoring and early warning values ​​by integrating data and models according to claim 1, characterized in that: The calculation formula for performing sensitivity analysis on the parameters in the high-support formwork design parameter set in step 6 is: In the formula, φ m represents parameter sensitivity, θ m is the parameter in the high formwork design parameter set, Δθ m is the change of parameter values ​​in the high-support formwork design parameter set, Y is the output of the finite element model, and ΔY is the output change of the parameters in the finite element model before and after the change; Based on the sensitivity analysis results, the parameter with the largest sensitivity value in the high-support formwork design parameter set is determined as the update parameter, and the corresponding update parameter in the finite element model is modified so that the displacement data of the corresponding monitoring node in the finite element model is consistent with the displacement response data of the rod at the monitoring node obtained by the visual displacement monitoring system in step 4.

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