A monitoring method for disc-type support frame in building construction

Abstract

The invention discloses a monitoring method for a disc-shaped support frame for building construction. The modified finite element model of the template support frame can better reflect the actual state of the template support frame, and the obtained response surface model can better replace the finite element model for calculation, and the calculation accuracy is good and the result is reliable; compared with the requirements of "Technical Specifications for Temporary Support Structures in Building Construction" JGJ / T 300-2013, a monitoring method for load can be provided; the early warning value and alarm value used in the monitoring parameters can better reflect the characteristics of real-time monitoring.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, and in particular to a monitoring method for a disc-shaped support frame for building construction. Background Art

[0002] Formwork support frames are common temporary structures in construction, usually with the characteristics of large span, high height, wide range, and high danger. After years of research and practice, the construction measures and various management methods for the safety of formwork support frames have been greatly improved. However, formwork support frame collapse accidents continue to occur, causing mass deaths and injuries, and are one of the major sources of danger in the construction process. Formwork support frame safety accidents often occur during the installation, dismantling and concrete pouring process. During the concrete pouring process, the support frame is subjected to complex load types and large time-varying loads. The loads it bears include the weight of steel bars, concrete, pouring equipment, construction workers, and the effects of dynamic loads such as concrete impact and vibration equipment.

[0003] Through real-time monitoring of the formwork support frame, a safety warning can be given to the formwork support frame. At present, the real-time monitoring of the formwork support frame mainly monitors the horizontal displacement of the key parts or weak parts of the formwork support frame, the formwork settlement, the axial force of the vertical pole and the inclination of the pole. There are still the following two problems:

[0004] (1) Due to factors such as material defects and erection quality, there is often a certain deviation between the calculation and analysis results of the formwork support frame in the design stage and the actual measurement results. In addition, factors such as changes in the construction plan and an imperfect safety supervision mechanism during the construction stage lead to deviations in the monitoring data;

[0005] (2) The lack of real-time monitoring of the formwork support frame load makes it difficult to evaluate the real-time status of the support frame and make early safety forecasts.

[0006] In view of the above problems, the present invention improves and optimizes the existing monitoring method and designs a monitoring method for a disc-type support frame in building construction. Summary of the invention

[0007] In view of this, the present invention provides a method for monitoring a disc-type support frame for construction, which reduces the error between the frequency value calculated by the finite element model and the measured value, and the corrected model parameters can reflect the actual situation; it can also realize the load identification of the formwork support frame.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A method for monitoring a disc-type support frame for building construction, comprising:

[0010] Step 1. Establish a finite element model of the formwork support frame according to the design drawing of the formwork support frame;

[0011] Step 2. Using the finite element model, calculate and analyze the monitoring parameters under load conditions at different construction stages to determine the key parts and weak parts of the support frame;

[0012] Step 3. Set up the formwork support frame and arrange the measuring points on the formwork support frame;

[0013] Step 4. The longitudinal and lateral acceleration signal monitoring data of the template support frame are processed by Fourier analysis to obtain the natural frequency of the structure, and the finite element model established in step 1 is corrected by response surface method to generate a corrected finite element model;

[0014] Step 5. Determine the warning value and alarm value of the formwork support frame load parameters, and use the modified finite element model to obtain the critical value of the monitoring parameter under the warning value and alarm value of the load parameter respectively, compare the critical value of the monitoring parameter with the theoretical warning value and theoretical alarm value of the monitoring parameter, and take the minimum value as the actual warning value and alarm value.

[0015] Preferably, the monitoring parameters in step 2 and step 5 include: horizontal displacement, template settlement, pole axial force and pole inclination angle.

[0016] Preferably, the arranging of measuring points on the formwork support frame in step 2 includes: densely arranging measuring points at key locations and weak locations of the formwork support frame, and non-densely arranging measuring points at non-key locations and weak locations of the formwork support frame.

[0017] Preferably, the measurement points in step 2 are arranged using wireless pressure sensors, wireless displacement sensors, wireless inclination sensors, wireless acceleration sensors and wireless sound and light alarms.

[0018] Preferably, the arrangement of measuring points in step 2 includes:

[0019] The wireless pressure sensor is installed between the U-shaped top support of the pole and the template to directly monitor the axial force of the pole;

[0020] The wireless inclination sensor is installed on the pole to directly monitor the tilt deformation of the pole;

[0021] The wireless displacement sensor is connected to the template through a hanging wire to directly measure the deformation of the template;

[0022] Two wireless acceleration sensors are arranged on a vertical pole far away from the wall connection member to collect the longitudinal and transverse acceleration signals of the formwork support frame respectively;

[0023] Wireless sound and light alarms can be installed anywhere on site.

[0024] Preferably, the step 4 comprises:

[0025] S300: Determine correction parameters and value ranges;

[0026] S400: Conduct experimental design and generate sample data;

[0027] S500: Selecting correction parameters that are significant for the characteristic quantity and performing response surface fitting on the sample data;

[0028] S600: Check whether the accuracy of the response surface model meets the preset value, if yes, proceed to step S500; if no, proceed to step S300;

[0029] S700: Substitute the frequency value of the no-load condition into the response surface model, and optimize the correction value of the correction parameter obtained by calculation.

[0030] Preferably, S400 includes: performing experimental design on the support frame using a D-optimal design method to obtain a number of experimental data, substituting each set of experimental data into a finite element model to calculate the first 5 frequency values ​​as target output, and generating sample data.

[0031] Preferably, the S400 includes:

[0032] (a) calling the correction parameters and parameter ranges selected in S300;

[0033] (b) Select the response feature, i.e., the objective function;

[0034] (c) Use D-optimal design method for experimental design;

[0035] (d) generating each group of test data;

[0036] (e) Substitute each set of test data into the finite element model of the support frame to obtain the sample value.

[0037] Preferably, the S500 includes:

[0038] (a) Select the response surface format;

[0039] (b) Parameter significance test: The F test method was used to analyze the significance of the selected parameters to the characteristic frequency, and the significance level P value of the statistical characteristic quantity of each parameter was calculated. When the P value was greater than 0.05, the parameter was not significant, otherwise, it was significant;

[0040] (c) Response surface function fitting: After selecting the correction parameters that are significant for the characteristic quantity, regression analysis technology is used to fit the response surface function to the sample data.

[0041] Preferably, step five includes: determining the warning value and alarm value of the load parameters of the formwork support frame in combination with the "Safety Technical Standard for Socket-Type Disc-Type Steel Pipe Scaffolding in Construction" JGJ / T 231-2021, and using the revised finite element model of the formwork support frame to respectively obtain the horizontal displacement, formwork settlement, vertical pole axial force and rod inclination under the warning value and alarm value of the load parameters, and comparing the above calculation results with the "Technical Specifications for Temporary Support Structures in Construction" JGJ / T 300-2013. The warning value and alarm value of horizontal displacement, formwork settlement, vertical pole axial force and rod inclination are required, and the minimum value is taken as the warning value and alarm value actually used.

[0042] It can be seen from the above technical solutions that the construction disc-type support frame monitoring method provided by the present invention can obtain the following beneficial effects after the model correction of the present invention:

[0043] (1) The modified finite element model of the formwork support frame can better reflect the actual state of the formwork support frame, and the obtained response surface model can better replace the finite element model for calculation, with good calculation accuracy and reliable results;

[0044] (2) Provide a load monitoring method based on the revised model;

[0045] (3) The early warning values ​​and alarm values ​​used in monitoring parameters can better reflect the characteristics of real-time monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0047] Figure 1 A flow chart of a method for monitoring a disc-type support frame for construction provided by an embodiment of the present invention;

[0048] Figure 2 A schematic diagram of a node structure of a disc-type support frame provided in an embodiment of the present invention;

[0049] Figure 3 A flowchart of the finite element model correction of the disc-type support frame provided in an embodiment of the present invention;

[0050] Figure 4 A design diagram of a test model of a disc-type support frame provided in an embodiment of the present invention;

[0051] Figure 5 A finite element model diagram of a disc-type support frame provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] The embodiment of the present invention provides a method for monitoring a disc-type support frame for construction, comprising:

[0054] Step 1. Establish a finite element model of the formwork support frame according to the design drawing of the formwork support frame.

[0055] S100: Node simulation of disc-type steel pipe formwork support frame. Figure 2 As shown in the figure, when simulating the disc-type node, the horizontal rod and the vertical rod nodes are overlapped, only the vertical rotation of the node between the horizontal rod and the vertical rod is considered, and the degrees of freedom in the remaining directions are rigidly coupled. At this time, the length of the spring simulating the semi-rigid characteristics of the node is zero.

[0056] S200: Simplifications and assumptions in establishing the finite element model of the disc-type steel pipe formwork support frame.

[0057] When analyzing and studying the finite element model of the disc-type formwork support frame, the model makes the following assumptions and simplifications:

[0058] (1) Assume that the vertical poles are rigidly connected and the vertical poles intersect with the horizontal poles at one point;

[0059] (2) The influence of initial defects of components is not considered;

[0060] (3) The connection between the uprights and the formwork structure is assumed to be hinged, and the connection between the uprights and the foundation is assumed to be hinged;

[0061] (4) The nonlinear characteristics of semi-rigid nodes are not considered;

[0062] (5) Ignore the secondary flutes and equate their weight to the template.

[0063] Note: The secondary ribs are densely arranged and there are more of them. They mainly transfer the template force and deformation to the primary ribs. When the weight of the secondary ribs is equivalent to the template, the sum of the mass of the secondary ribs and the template is divided by the projection area of ​​the support frame (not the template area, because the template usually extends out). (m secondary ribs + m templates) / projection area of ​​the support frame.

[0064] Step 2. Use the finite element model to calculate and analyze the horizontal displacement, formwork settlement, pole axial force and pole inclination under load conditions at different construction stages to determine the key and weak parts of the support frame.

[0065] Step 3. Set up the formwork support frame, densely arrange measuring points at key and weak locations, and non-densely arrange measuring points at non-key and weak locations, and use wireless pressure sensors, wireless displacement sensors, wireless inclination sensors, wireless acceleration sensors and wireless sound and light alarms for deployment (the wireless pressure sensor is installed between the U-shaped top support of the vertical pole and the formwork to directly monitor the axial force of the vertical pole; the wireless inclination sensor is installed on the vertical pole to directly monitor the inclination deformation of the pole body; the wireless displacement sensor is connected to the formwork through a hanging wire to directly measure the deformation of the formwork; two wireless acceleration sensors are arranged on a vertical pole away from the wall connection to collect the longitudinal and lateral acceleration signals of the formwork support frame respectively; the wireless sound and light alarm can be installed anywhere on site).

[0066] Step 4. Use Fourier analysis (FFT) to process the longitudinal and lateral acceleration signal monitoring data of the formwork support frame to obtain the natural frequency of the structure, and use the response surface method to correct the finite element model of the formwork support frame to generate a corrected finite element model.

[0067] S300: Select correction parameters by empirical method and sensitivity method (i.e., based on some main parameters of the support frame design, determine the parameter range based on experience, and then perform sensitivity calculation and selection). The sensitivity can be calculated according to formula (1):

[0068]

[0069] Calculate, where: s i is the sensitivity, λ i is the eigenvalue, p i Considering that different correction parameters have different value ranges, in order to make a better comparison, △λ i is the rate of change of available eigenvalues ​​△λ i / λ i Substitution, △p i Available parameter change rate △p i / p i Alternative.

[0070] For the disc-type support frame, the vertical rod wall thickness t1, elastic modulus E1, horizontal rod wall thickness t2, elastic modulus E2, node stiffness k, template equivalent density ρ and other parameters can be used as correction parameters. After calculation, E1, E2, ρ with higher sensitivity are selected as the parameters to be corrected.

[0071] S400: Experimental design. The D-optimal design method is used to design the test of the support frame to obtain a number of test data. Each group of test data is substituted into the finite element model to calculate the first 5 frequency values ​​as the target output.

[0072] illustrate:

[0073] (1) Experimental design (DOE) method refers to the method of selecting appropriate experimental points in the system parameter variable space, generally using methods such as central composite method, D-optimal design method, full factorial experimental design, orthogonal design, uniform design, etc.

[0074] (2) Generally, Design Expert is used to input the design parameters and objective functions into the system to generate a data table.

[0075] (3) Steps: (a) Select correction parameters, i.e. design parameters, and determine the parameter range, including minimum value, intermediate value, and maximum value. In this patent, the vertical pole elastic modulus E1, horizontal pole elastic modulus E2, and template equivalent density ρ are selected; (b) Select response characteristics, i.e. objective function, and the first three frequency values ​​are selected in this patent. (c) Use appropriate experimental design methods; (d) Generate each group of test data, i.e., the values ​​of each group of vertical pole elastic modulus E1, horizontal pole elastic modulus E2, and template equivalent density ρ; (e) Substitute each group of test data into the finite element model of the support frame to obtain the sample value.

[0076] S500: Response surface fitting. After parameter screening by F test method, polynomial fitting is used to fit the test data and target of each group of experiments to obtain the response surface model;

[0077] illustrate:

[0078] (1) Response surface fitting requires the following steps: (a) Select the response surface form. This patent recommends selecting a third-order polynomial response surface model, such as:

[0079]

[0080] In the formula, (i∈(1,k)), The design parameters x are i The upper and lower boundaries of the value range, β0, β i , β ii , β iii , β ij , β iij , β ijk are the unknown coefficients.

[0081] In the Design Expert software, you can directly determine which response surface model to use.

[0082] (b) Parameter significance test: The F test method (ANOVA) is used to analyze the significance of the selected parameters to the characteristic frequency, and the significance level P value of the statistical characteristic quantity of each parameter is calculated. When the P value is greater than 0.05, the parameter is not significant, otherwise, it is significant. The calculation formula is as follows:

[0083] Assume that the regression model includes m-1 independent variables x1, x2, x3, …, x m-1 If we add a variable x m To this model, the test statistic F is:

[0084]

[0085] In formula (3), SSE(x1,x1,…,x m-1 ) includes m-1 independent variables x1, x2, x3, …, x m-1 The sum of squared errors of the regression model, SSE(x1,x1,…,x m-1 ,x m ) includes m independent variables x1, x2, x3, ..., x m-1 , x m The sum of squared errors of the regression model, n is the total number of all independent variables in the regression model.

[0086] Given a significant level Pick For a certain sample value, F is calculated by formula (3): j , the test rule is:

[0087] like That is, P≤0.05, the variable has a significant effect on the response; if That is, if P>0.05, the variable has no significant effect on the response.

[0088] Generally, these calculation processes are automatically calculated after being set up in the Design Expert software.

[0089] (c) Response surface function fitting

[0090] After selecting the correction parameters that are significant for the characteristic quantities, regression analysis technology is used to perform response surface fitting on the sample data.

[0091] S600: R 2 The accuracy of the response surface model was tested by the R 2 The closer it is to 1, the more accurately the response surface model can reflect the relationship between the finite element model input parameters and the target output.

[0092] Description: R 2 Inspection method

[0093]

[0094] In the formula, y RS(j) represents the calculated value of the primary response surface model, y(j) represents the corresponding finite element analysis result, y represents the average value of the finite element analysis result, and N represents the number of inspection points in the design space;

[0095] S700: Comparative analysis. The measured frequency is input into the response surface model for optimization calculation to obtain the correction parameters, which are compared and analyzed with the initial values ​​of each correction parameter. If the difference with the initial value is reasonable and can reflect the actual situation to a certain extent, the value can be determined.

[0096] Step 5. Determine the warning value and alarm value of the load parameters of the formwork support frame in combination with the "Safety Technical Standard for Socket-type Disc-type Steel Pipe Scaffolding in Construction" JGJ / T 231-2021, and use the modified finite element model of the formwork support frame to obtain the horizontal displacement, formwork settlement, vertical pole axial force and rod inclination under the warning value and alarm value of the load parameters. Compare the above calculation results with the warning value and alarm value of horizontal displacement, formwork settlement, vertical pole axial force and rod inclination required by the "Technical Specification for Temporary Support Structures in Construction" JGJ / T 300-2013, and take the minimum value as the actual warning value and alarm value.

[0097] Implementation example of finite element model modification of disc-type formwork support frame:

[0098] 1. Frequency test of different working conditions of disc buckle support frame

[0099] The test model of the disc-type support frame was erected for the components with more than 7 turnover times. The main design dimensions and component dimensions of the test model are shown in Table 1. The design drawings are shown in Figure 4 During the test, a dynamic signal acquisition instrument and two acceleration sensors were used to record the longitudinal and lateral acceleration signals of the pole. The acceleration sensors were arranged Figure 4 .

[0100] Table 1 Main design dimensions and component dimensions of the support frame test model

[0101] Table 1 main design dimensions and component dimensions of disk locksteel tubular scaffold test model

[0102]

[0103] Sandbags were used for loading. Each loading was performed to ensure uniform loading on the template surface and avoid the influence of eccentric loading. After loading, the template was left to stand for 10 minutes. Then, a long rope was used to pull the upper vertical pole of the support frame laterally to make the support frame vibrate longitudinally and transversely. After stopping pulling, the acceleration signal was recorded. The test results of the total weight of the loading under each working condition and the first five frequencies under each working condition are shown in Table 2.i They are the measured values ​​of the first five frequencies. As shown in Table 2, with the increase of the total load, the frequencies of the support frame gradually decrease.

[0104] Table 2 Total weight of pile load and measured values ​​of the first five frequencies of the support frame under various working conditions

[0105] Table 2 measured values ​​and first five frequencies of disk lock steeltubular scaffold under various working conditions

[0106]

[0107] 2. Experimental model design and finite element model

[0108] The elastic modulus of the steel pipe components of the support frame is 2.06×10 5 N / mm 2 , Poisson's ratio is 0.3, and density is 7.85 kg·m -3 The density of square wood is 114.92kg·m -3 , Poisson's ratio is 0.3; template density is 556.73kg·m -3 , Poisson's ratio is 0.3. The value of spring stiffness is based on the "Safety Technical Specifications for Socket-type Disc-type Steel Pipe Supports in Construction" JGJ231-2010 [8] , take 8.6×10 7 N·mm / rad. See the finite element model of the support frame for details. Figure 5 The modal analysis results show that the first five frequencies of the support frame under different total load conditions, f1', f2', f3', f4', f5', and the error between them and the measured values, e i See Table 3.

[0109] Table 3 The finite element calculation results of the first five frequencies of the disc-type support frame and the errors between them and the measured values

[0110] Table 3 finite element calculation results of the first five orderfrequency and the error between them and the measured values

[0111]

[0112] Comparing Table 2 and Table 3, it can be seen that there is a certain error between the frequency value calculated by the finite element model and the measured value. The error between the frequency calculated by the finite element model and the measured value under no-load condition is large, and the error under heap load condition is relatively small. The error between the frequency calculated by the finite element model and the measured value is caused by factors such as the assumption and simplification of the finite element model, the error of material size and material properties, and the actual erection quality. The error decreases when the load is piled, indicating that the total weight of the pile load has a greater impact on the frequency of the support frame, and the simulation of the load by the finite element model is more accurate.

[0113] 3. Determination of correction parameters

[0114] For the disc-type support frame, the vertical rod wall thickness t1, elastic modulus E1, horizontal rod wall thickness t2, elastic modulus E2, node stiffness k, template equivalent density ρ and other parameters can be used as correction parameters. Increase each parameter by 10%, input the support frame finite element model to calculate the change rate of the first 5 frequency values, see Table 4. Take the first 5 frequency change rates as characteristic values, and the change rates of each correction parameter as parameters, and substitute them into formula (1) to calculate the sensitivity. Since the change rate of each correction parameter is 10%, the sensitivity is 10 times the frequency change rate. Therefore, the frequency change rate can be directly used to compare the sensitivity.

[0115]

[0116] Table 4 Change rate of the first 5 frequencies of the support frame when the change rate of each correction parameter is 10%

[0117] Table 4 the first five order frequency change rate of the disk locksteel tubular scaffold when the change rate of each correction parameter is10%

[0118]

[0119] It can be seen from Table 4 that when the change rate of the correction parameters is 10%, the highest change rate of each order frequency is E1, E2, ρ. However, the frequency change rate caused by t1, t2, and k is small, and it is not suitable to be used as a correction parameter at this time. Therefore, E1, E2, and ρ with higher sensitivity are selected as correction parameters, and the value range of the correction parameters is shown in Table 5.

[0120] The intermediate value of the correction parameter can refer to the engineering design value of the parameter. The range of the correction parameter value directly affects the accuracy of the response surface. If the range is too small, it cannot contain the actual value of the parameter; if the range is too large, the test points determined during the test design are likely to be far away from the actual value. When determining the range of the correction parameter value, the actual engineering experience and multiple trial calculations can be combined to determine a more reasonable parameter range.

[0121] Table 5 Correction parameter value range

[0122] Table 5 range of correction parameters

[0123]

[0124] 4. Response surface model and model modification

[0125] The finite element model of the support frame was modified according to the no-load condition. The D-optimal design method was used for experimental design, and 30 sets of test data were obtained. The test parameters were normalized to obtain the following table:

[0126]

[0127]

[0128] Substitute it into the finite element model to calculate the first five frequency values. Use the F test method to test the significance of the parameters, and then use the quadratic polynomial to fit the frequency response surface model of the support frame, and the response surface model is shown in formulas (5) to (9).

[0129]

[0130] The response surface model of equations (5) to (9) was tested for accuracy, and the calculated R 2 See Table 6 for values.

[0131] Table 6 Determination coefficient R of the first 5-order frequency regression 2

[0132] Table 6 first five order frequency regression coefficient R 2

[0133]

[0134] From Table 6, we can see that the R 2The value is close to 1, indicating that the response surface model can well reflect the relationship between the correction parameter and the frequency. Substitute the frequency values ​​of the no-load condition G0 in Table 2 into equations (5) to (9), and the values ​​of the correction parameters obtained by optimization calculation are shown in Table 7. The corrected parameters are input into the finite element model to calculate the frequency value of the support frame, and compared with the frequency value calculated by the model before correction. The comparison results are shown in Table 8.

[0135] Table 7 Comparison of correction parameter values ​​before and after correction

[0136] Table 7 Comparison of design parameters before and after correction

[0137]

[0138] Table 8 Comparison of frequency values ​​before and after correction

[0139] Table 8 Comparison of frequency values ​​before and after correction

[0140]

[0141] It can be seen from Tables 7 and 8 that the frequencies calculated by the revised finite element model are close to the measured values. The revised elastic moduli E1 and E2 of the vertical and horizontal rods are both smaller than the initial values, which reflects that the initial defects of the actual support frame, the damage of the components after multiple turnovers, the quality of the erection, the nonlinearity of the node stiffness and other factors have reduced the actual situation of the overall stiffness of the support frame to a certain extent; the revised template equivalent density is greater than the initial value, mainly because the adjustable bracket is simplified when the finite element model is established, and the weight of the adjustable bracket is not considered. The revised equivalent density ρ includes part of the weight of the adjustable bracket. This shows that the revised parameters have certain physical significance.

[0142] 5. Data Comparative Analysis

[0143] The first five frequency values ​​under different total load weights were calculated by the modified finite element model, and the error values ​​obtained by comparing with the measured results are shown in Table 9. i " represents the calculated value of the modified finite element model, e i ' represents the error between the corrected finite element calculated value and the measured value.

[0144] Table 9 The first five frequency values ​​of the finite element model after correction and the errors between them and the measured values

[0145] Table 9 error between the first five order frequency values ​​of thefinite element model and the measured values ​​after correction under various working conditions

[0146]

[0147] Comparing the data in Table 2 with those in Table 8 and Table 9, it can be seen that the errors between the calculated frequency values ​​of the finite element model and the measured frequency values ​​after model correction are reduced compared with those before correction, and the error values ​​are small, which shows the reliability of this correction method.

[0148] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0149] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for monitoring a disc-type support frame for construction, characterized in that: include: Step 1. Establish a finite element model of the formwork support frame according to the design drawing of the formwork support frame; Step 2. Using the finite element model, calculate and analyze the monitoring parameters under load conditions at different construction stages to determine the key parts and weak parts of the support frame; Step 3. Set up the formwork support frame and arrange the measuring points on the formwork support frame; Step 4. The longitudinal and lateral acceleration signal monitoring data of the template support frame are processed by Fourier analysis to obtain the natural frequency of the structure, and the finite element model established in step 1 is corrected by response surface method to generate a corrected finite element model; The step 4 includes: S300: determining the correction parameter and the value range; S400: performing experimental design and generating sample data; S500: selecting the correction parameter with significant characteristic quantity and performing response surface fitting on the sample data; S600: checking whether the accuracy of the response surface model meets the preset value, if so, proceeding to step S500; if not, proceeding to step S300; S700: substituting the frequency value of the no-load condition into the response surface model, and optimizing the correction value of the correction parameter obtained by calculation; Step 5. Determine the warning value and alarm value of the formwork support frame load parameters, and use the modified finite element model to obtain the critical value of the monitoring parameter under the warning value and alarm value of the load parameter respectively, compare the critical value of the monitoring parameter with the theoretical warning value and theoretical alarm value of the monitoring parameter, and take the minimum value as the actual warning value and alarm value.

2. The method for monitoring a disc-type support frame for construction according to claim 1 is characterized in that: The monitoring parameters in step 2 and step 5 include: horizontal displacement, template settlement, vertical pole axial force and pole inclination angle.

3. The method for monitoring a disc-type support frame for construction according to claim 1 is characterized in that: Arranging measuring points on the formwork support frame in the step three includes: densely arranging measuring points at key positions and weak positions of the formwork support frame, and non-densely arranging measuring points at non-key positions and weak positions of the formwork support frame.

4. The method for monitoring a disc-type support frame for construction according to claim 1, characterized in that: The measurement points in step three are arranged using wireless pressure sensors, wireless displacement sensors, wireless inclination sensors, wireless acceleration sensors and wireless sound and light alarms.

5. The method for monitoring a disc-type support frame for construction according to claim 4 is characterized in that: Arranging the measuring points in step 3 includes: The wireless pressure sensor is installed between the U-shaped top support of the pole and the template to directly monitor the axial force of the pole; The wireless inclination sensor is installed on the pole to directly monitor the tilt deformation of the pole; The wireless displacement sensor is connected to the template through a hanging wire to directly measure the deformation of the template; Two wireless acceleration sensors are arranged on a vertical pole far away from the wall connection member to collect the longitudinal and transverse acceleration signals of the formwork support frame respectively; Wireless sound and light alarms can be installed anywhere on site.

6. The method for monitoring a disc-type support frame for construction according to claim 1, characterized in that: The S400 includes: performing test design on the support frame using the D-optimal design method to obtain a number of test data, substituting each group of test data into a finite element model to calculate the first five frequency values ​​as target output, and generating sample data.

7. The method for monitoring a disc-type support frame for construction according to claim 1, characterized in that: The S400 includes: (a) calling the correction parameters and parameter ranges selected in S300; (b) Select the response feature, i.e., the objective function; (c) Use D-optimal design method for experimental design; (d) generating each group of test data; (e) Substitute each set of test data into the finite element model of the support frame to obtain the sample value.

8. The method for monitoring a disc-type support frame for construction according to claim 1, characterized in that: The S500 includes: (a) Select the response surface format; (b) Parameter significance test: The F test method was used to analyze the significance of the selected parameters to the characteristic frequency, and the significance level P value of the statistical characteristic quantity of each parameter was calculated. When the P value was greater than 0.05, the parameter was not significant, otherwise, it was significant; (c) Response surface function fitting: After selecting the correction parameters that are significant for the characteristic quantity, regression analysis technology is used to fit the response surface function to the sample data.

9. The method for monitoring a disc-type support frame for construction according to claim 1, characterized in that: The step five includes: determining the warning value and alarm value of the load parameters of the formwork support frame in combination with the "Safety Technical Standard for Socket-Type Disc-Type Steel Pipe Scaffolding in Building Construction" JGJ / T 231-2021, and using the revised formwork support frame finite element model to respectively obtain the horizontal displacement, formwork settlement, vertical pole axial force and rod inclination under the warning value and alarm value of the load parameters, and comparing the above calculation results with the "Technical Specifications for Temporary Support Structures in Building Construction" JGJ / T 300-2013 The warning value and alarm value of horizontal displacement, formwork settlement, vertical pole axial force and rod inclination are required, and the minimum value is taken as the actual warning value and alarm value.

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