Comprehensive evaluation method for health state of concrete-filled steel tube arch bridge

Abstract

The invention discloses a comprehensive evaluation method for the health state of concrete filled steel tubes. According to the method, a multilevel evaluation index system for the health state of the concrete-filled steel tube structure is constructed, and factors influencing the health of the structure are divided into a plurality of key indexes including the ultimate bearing capacity, the overall stability performance, the anti-seismic performance and the like. The method comprises the following steps: firstly, quantifying each index by using a membership function in fuzzy mathematics, and constructing a membership matrix; secondly, determining the weight of each index according to the influence of each index on the whole bridge; then, the health state of the concrete filled steel tube is evaluated through the fuzzy comprehensive evaluation model, the structure health level is generated, an accurate health state evaluation result is provided, and the method is suitable for health monitoring and evaluation of complex concrete filled steel tube structures such as bridges, tunnels and high-rise buildings. The method has the advantages of being high in evaluation precision, wide in application range and easy and convenient to operate, and a scientific basis is provided for safety management and maintenance decision making of the concrete-filled steel tube structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of health status assessment of steel tube concrete arch bridges, and specifically relates to an assessment method including bridge components, parts, bridge deck system, superstructure, substructure and full bridge assessment. The method improves steel tube concrete under current specifications based on fuzzy theory, dynamic assessment and time series data to obtain more accurate assessment results. Background Art

[0002] The bridge structure condition assessment method has developed rapidly in recent years. The domestic and foreign bridge safety assessment methods and research can be summarized as follows: they can be mainly divided into the bridge status comprehensive assessment method and the bridge bearing capacity assessment method. Generally, the overall safety assessment of more complex bridges with larger spans is qualitatively evaluated using the comprehensive assessment method, while the safety assessment of small and medium-sized bridge components with smaller spans is generally quantitatively evaluated using the bearing capacity assessment method. Regarding the bearing capacity of bridges, which is one of the important indicators affecting the safety of bridge structures, Chalko proposed a systematic method based on regular inspections of steel tube concrete arch bridge structures to obtain basic information of the structure or components in real time, and to evaluate the bearing capacity of bridge structures based on this. The finite element model is mainly modified based on the test results, and finally the bridge structure bearing capacity is evaluated based on the modified model; for bridge stability indicators, Leveraging concepts from fuzzy set theory, a seismic recovery function and matrix for bridge seismic resilience assessment were proposed. Fuzzy knowledge representation theory was used to define basic seismic parameters, and the bridge recovery process was modeled using fuzzy functions. Furthermore, seismic resistance indicators were determined using concepts from fuzzy metric theory. Therefore, by studying and analyzing the aforementioned existing work, this study, building on the relevant research foundation on the key structural states of bridges, will propose a structural health indicator system that can comprehensively and accurately assess the health of concrete-filled steel tube arch bridges. This will lay a solid foundation for the development of structural health assessment standards for concrete-filled steel tube arch bridges.

[0003] Numerous bridge technical condition assessment methods and systems have been proposed based on current standards or other theoretical approaches. However, each of these theoretical approaches has limitations, and the reliability of the results cannot be guaranteed by simply applying a single method. With the emergence of bridge health monitoring systems, faced with numerous monitoring indicators and a vast amount of data, the question of how to comprehensively assess the health of a bridge at a given moment has become a pressing issue. Summary of the Invention

[0004] The present invention provides a comprehensive health status assessment method for steel tube concrete arch bridges under disease conditions such as debonding and voiding, which solves the technical problems of low efficiency and poor accuracy in technical status assessment of highway bridges in the prior art.

[0005] The present invention adopts the following technical solutions:

[0006] The present invention provides a comprehensive health status assessment method for a steel tube concrete arch bridge, comprising the following steps:

[0007] S1. Using ANSYS finite element software, a finite element model of a CFST arch bridge was constructed. The model was treated for defects and subjected to nonlinear analysis to obtain the state parameters of the CFST arch bridge, including its bearing capacity, stability, dynamic performance, and toughness.

[0008] S2. Establish a health status indicator system for CFST arch bridges, including load-bearing capacity, stability, dynamic performance, and toughness indicators. Based on these indicators, evaluate the health status of CFST arch bridges, with the evaluation levels divided into four categories: "intact," "good," "poor," and "dangerous."

[0009] S3. Construct a fuzzy comprehensive evaluation model: Based on fuzzy mathematics theory, a fuzzy comprehensive evaluation model suitable for the health status assessment of steel tube concrete arch bridges is constructed. In this model, a set of evaluation indicators, a set of comments, a set of weights, and fuzzy operation elements are established to convert these fuzzy factors into a specific comprehensive evaluation value;

[0010] S4. Output and comparison of evaluation results: Convert the calculated comprehensive evaluation value into a specific evaluation result and output it in a visual or numerical form.

[0011] Furthermore, the “intact” mentioned in step S2 means that the score is [90, 100], and the CFST arch bridge is in the best condition without any damage or performance degradation;

[0012] The “good” mentioned above refers to the score [75,90). The CFST arch bridge has some defects, which has caused the various indicators of the structure to decline, but it does not affect normal use.

[0013] The “poor” refers to a score of [50,75], indicating that the CFST arch bridge has obvious defects and cannot be put into normal service and must be repaired before it can be put into use again;

[0014] The “dangerous” refers to a score of [0,50], indicating that the CFST arch bridge can no longer be used normally and has structural damage, requiring reinforcement and repair or demolition and reconstruction.

[0015] Furthermore, the specific steps of step S3 are as follows:

[0016] S31. Determine the evaluation objectives: Confirm the health status of the steel tube concrete arch bridge;

[0017] S32. Establish an evaluation index set O based on the key indicators of the steel tube concrete arch bridge, such as bearing capacity, stability, dynamic performance, and toughness;

[0018] S33. Establish an evaluation set P for health status evaluation levels of steel tube concrete arch bridges;

[0019] S34. Determine the weight of each indicator based on the evaluation factors and the logsig fuzzy membership function according to expert experience, and establish a weight set Q;

[0020] S35, determining a comprehensive evaluation matrix R of health status, wherein the comprehensive evaluation matrix R hierarchically establishes a fuzzy relationship between the evaluation index set O and the evaluation set P;

[0021] S36. Perform a comprehensive evaluation of the status of a single indicator according to P=QR=(P1, P2, P3, P4), where P1 is the comprehensive evaluation result of the first evaluation expert, P2 is the comprehensive evaluation result of the second evaluation expert, and P3 is the comprehensive evaluation result of the third evaluation expert. The operation result P is the weight set Q of each indicator and the fuzzy operation of the comprehensive evaluation matrix R to obtain the comprehensive evaluation vector B;

[0022] S37. Calculate the single factor evaluation matrix of the lower level index With the corresponding weight set Obtain comprehensive evaluation vector through fuzzy operation Where i is the level number of the evaluation system, j is the branch number in the i-th level of the evaluation system;

[0023] S38, based on the characteristic of M(.,+) solution model that no information is lost in multiplication and summation operations, the fuzzy comprehensive evaluation vector To solve, in the process of judging from the bottom index to the top index, repeatedly calculate the fuzzy comprehensive evaluation vector Finally, the overall state evaluation vector B of the bridge can be obtained;

[0024] S39. Comprehensive evaluation results: The order of the four subordinate values of the evaluation matrix operation results corresponds to the four health status levels of "intact", "good", "poor" and "dangerous" respectively; the evaluation level of the health status of the steel tube concrete arch bridge is determined by the order of the maximum value of the final fuzzy operation result of the evaluation matrix B.

[0025] Furthermore, in step S32, the process of establishing the evaluation index set O is: defining the top target layer O, the middle target layer O = (O1, O2, O3, O4), and the bottom target layer as the sub-index layer, which are: O1 = (O11, O12, ... O1n), O2 = (O21, O22, ... O2n), O3 = (O31, O32, ... O3n), O4 = (O41, O42, ... O4n).

[0026] Furthermore, in step S33, the health status evaluation levels in the evaluation set P include four evaluation levels: intact, good, poor and dangerous.

[0027] Furthermore, the weight set establishment method of step S34 is as follows:

[0028] S341. Determine the key factors that influence the evaluation system through expert experience and research results in related fields. These factors will form the evaluation index system. Summarize the opinions of experts in related fields through questionnaires, expert interviews, or the Delphi method to select key indicators. Classify the indicators based on actual conditions, including a three-level indicator stratification: top-level indicators, middle-level indicators, and bottom-level indicators, to ensure the scientificity and rationality of the evaluation system.

[0029] S342. Selection of fuzzy membership function: logsig (logarithmic S-type) fuzzy membership function is used to quantify the membership of the evaluation index; the formula of this function is:

[0030]

[0031] Where: x is the index value; a is the adjustment parameter of the steepness of the curve, which is adjusted by fitting test data or expert opinions; b is the midpoint of the curve, that is, the offset of the fuzzy membership function, which takes the average value or expected value of the index and reflects the reference standard of the fuzzy membership function;

[0032] For each observation value x of the evaluation index, the membership degree μ(x) is calculated according to the formula and normalized to the interval [0,1];

[0033] S343. Determine the weight allocation principle. Based on fuzzy comprehensive evaluation theory, use membership function values combined with expert experience to allocate weights. Ask multiple experts to rate the importance of each indicator in the range of [1,10]. Calculate the weight of each indicator:

[0034]

[0035] where s i is the expert score of the i-th indicator, and n is the total number of indicators;

[0036] Combine the membership value μ(x) with the expert score to modify the initial weight:

[0037] q i ′=μ(x i )·q i

[0038] Normalized corrected weights:

[0039]

[0040] Finally, a weight set is established, Q = {q1,q2...,q n}.

[0041] Furthermore, the specific method of step S35 is as follows: define R=(r ij ) n×m ; Let r ij Satisfy the following formula to obtain the normalized result;

[0042]

[0043] Where r ij Impact indicator o i In the evaluation level p i The degree of membership on .

[0044] Furthermore, the specific method of step S38 is as follows: Based on the fuzzy rule, use M(., +) to solve the model pair Solve the problem and obtain the overall bridge state evaluation vector B. The specific fuzzy criteria are as follows: Fuzzy rules are the key to the fuzzy reasoning system. Its design directly affects the accuracy and effectiveness of the output results. Logical rules are expressed through logical expressions: if (premise), then (result). It is common to use if-then statements to construct fuzzy rules. Its expression is shown below:

[0045] if x is A, then y is B

[0046] Among them, x and y represent input and output respectively, while A and B represent the logical language results of input and output respectively, which reflects the binary fuzzy relationship between x and y.

[0047] The health status assessment method of steel tube concrete arch bridge based on fuzzy theory has the following characteristics:

[0048] Comprehensiveness: The present invention constructs a health status index system from different aspects such as static performance, dynamic performance, and toughness, which can more comprehensively evaluate the health status of the bridge.

[0049] Objectivity: The comprehensive evaluation method based on fuzzy theory is adopted to avoid the influence of subjective factors in traditional standards on the evaluation results and improve the objectivity of the evaluation results.

[0050] Flexibility: Based on the ANSYS finite element software, CFST models with different diseases are established according to actual engineering conditions. The evaluation model can evaluate the health status of CFST arch bridges with different diseases based on the finite element software simulation data and actual test data.

[0051] Real-time: Through real-time detection of the health status of the steel tube concrete arch bridge and the data fed back from the site, the health status of the steel tube concrete arch bridge can be evaluated in real time.

[0052] The present invention has the following beneficial effects:

[0053] (1) The present invention evaluates the health status of steel tube concrete based on fuzzy theory and finite element analysis method and combines it with real-time data on site, making the evaluation comprehensive, objective, flexible and real-time.

[0054] (2) The present invention uses finite element software to model defective concrete, selects the double element method, and performs fine modeling on the arch ribs of steel tube concrete arch bridges with void defects. The model is then modeled based on the void disease data of real bridges, making the modeling more in line with the actual situation.

[0055] (3) According to the existing health status evaluation standards and based on the fuzzy theory method, the present invention assigns different weight indicators to the mechanical properties of steel tube concrete arch bridges, establishes a more sophisticated and complete health status evaluation system for steel tube concrete arch bridges, improves the objectivity of the evaluation, and provides more accurate guidance for the maintenance and repair of steel tube concrete arch bridges.

[0056] (4) The present invention can be programmed according to fuzzy theory. The program can analyze the input data autonomously without human intervention. It can adapt to various data types and characteristics and realize automated health status assessment of steel tube concrete arch bridges. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic diagram of the overall process of the comprehensive assessment method for the health status of a steel tube concrete arch bridge of the present invention.

[0058] Figure 2 The present invention is a schematic diagram of the process of constructing a finite element model of a steel tube concrete arch bridge in a hollow state based on ANSYS finite element software.

[0059] Figure 3 This is a steel tube concrete arch bridge model in a hollow state constructed by the present invention based on ANSYS finite element software.

[0060] Figure 4 These are the evaluation indicators and weight values of the comprehensive evaluation method for the health status of steel tube concrete arch bridges of the present invention.

[0061] Figure 5 This is the health status evaluation standard of the comprehensive health status evaluation method for steel tube concrete arch bridges of the present invention.

[0062] Figure 6This is the evaluation process of the comprehensive evaluation method for the health status of a steel tube concrete arch bridge of the present invention.

[0063] Figure 7 It is a structural schematic diagram of the comprehensive assessment device for the health status of a steel tube concrete arch bridge of the present invention.

[0064] Figure 8 It is a structural diagram of the component fuzzy comprehensive evaluation module in the comprehensive evaluation device for the health status of a steel tube concrete arch bridge of the present invention. DETAILED DESCRIPTION

[0065] The present invention will be further described below in detail with reference to the accompanying drawings and embodiments, but these embodiments should not be construed as limiting the present invention.

[0066] join Figure 1 The comprehensive health status assessment method of a steel tube concrete arch bridge of the present invention comprises the following steps:

[0067] The following describes a specific embodiment using a large-span steel tube concrete arch bridge as an example:

[0068] S1. Based on ANSYS finite element software, a finite element model of the large-span steel tube concrete arch bridge was constructed. The model was treated for defects and nonlinear analysis and calculation were performed to obtain the state parameters of the steel tube concrete arch bridge's bearing capacity, stability, dynamic performance, and toughness.

[0069] The bearing capacity includes the bearing capacity of the ultimate limit state and the bearing capacity of the serviceability limit state;

[0070] Stability includes overall stability and local stability;

[0071] Dynamic performance includes natural frequency, natural vibration mode, structural damping ratio and curvature difference;

[0072] Resilience includes the ability of a structure to recover after an earthquake.

[0073] S2. Establish a health status indicator system for concrete-filled steel tube arch bridges:

[0074] Based on the structural characteristics of CFST arch bridges, a health status index system was established, including load-bearing capacity index, stability index, dynamic performance index and toughness index. Based on these indicators, the health status of CFST arch bridges was evaluated, and the evaluation levels were divided into four levels: "intact", "good", "poor" and "dangerous". Among them:

[0075] “Intact” means the score is between [90,100], and the CFST arch bridge is in the best condition without any damage or performance degradation.

[0076] “Good” refers to the score [75,90). The CFST arch bridge has some defects, which leads to a decrease in various indicators of the structure, but does not affect its normal use.

[0077] “Poor” refers to a score of [50,75), indicating that the CFST arch bridge has obvious defects and cannot serve normally. It must be repaired before it can be put into use again.

[0078] “Dangerous” refers to a score of [0,50), indicating that the CFST arch bridge can no longer be used normally and has structural damage, requiring reinforcement and repair or demolition and reconstruction.

[0079] S3. Construct a fuzzy comprehensive evaluation model: Based on fuzzy mathematics theory, a fuzzy comprehensive evaluation model suitable for the health status assessment of steel tube concrete arch bridges is constructed. In this model, a set of evaluation indicators, a set of comments, a set of weights, and fuzzy operation elements are established to convert these fuzzy factors into a specific comprehensive evaluation value. The specific steps are as follows:

[0080] S31. Determine the evaluation objectives and confirm the health status of the steel tube concrete arch bridge;

[0081] S32. Based on the key indicators of the steel tube concrete arch bridge, such as bearing capacity, stability, dynamic performance and toughness, an evaluation index set O is established. The process is as follows:

[0082] Define the top target layer O, the middle target layer O = (O1, O2, O3, O4), and the bottom target layer as the sub-indicator layer, which are: O1 = (O11, O12, ... O1n), O2 = (O21, O22, ... O2n), O3 = (O31, O32, ... O3n), O4 = (O41, O42, ... O4n);

[0083] S33. Establish an evaluation set P for the health status evaluation level of steel tube concrete arch bridges: P = (intact, good, poor, dangerous);

[0084] S34. Determine the evaluation factors based on expert experience and the logsig fuzzy membership function to determine the weights of each indicator to form a weight set Q. The specific method is as follows:

[0085] Under the requirements of completeness, convenience, relative independence, objectivity and representativeness, the middle-level and bottom-level indicators of the condition assessment of steel tube concrete arch bridges are scored respectively, and the scores are normalized to obtain the weights of each evaluation indicator. The weights are refined according to the logical keys between the parameter indicators and integrated into the weight set Q.

[0086] Specifically, the weight set establishment method is as follows:

[0087] S341. Determine the key factors influencing the evaluation system through expert experience and research results in related fields. These factors will form the evaluation index system. Through questionnaires, expert interviews, or the Delphi method, summarize the opinions of experts in related fields and select key indicators. Based on actual conditions, classify the indicators into three tiers: top-level indicators, middle-level indicators, and bottom-level indicators, to ensure the scientific and rationality of the evaluation system.

[0088] S342. Selection of fuzzy membership function: logsig (logarithmic S-type) fuzzy membership function is used to quantify the membership of the evaluation index. The formula of this function is:

[0089]

[0090] Where: x is the index value; a is the adjustment parameter of the steepness of the curve, which is adjusted by fitting experimental data or expert opinions; b is the midpoint of the curve, that is, the offset of the fuzzy membership function, which takes the average value or expected value of the index to reflect the reference standard of the fuzzy membership function.

[0091] For each observation value x of the evaluation index, the membership degree μ(x) is calculated according to the formula and normalized to the interval [0,1].

[0092] S343. Determine the weight distribution principle. Based on the fuzzy comprehensive evaluation theory, use the membership function value combined with expert experience to assign weights. Ask multiple experts to rate the importance of each indicator in the range of [1,10]. Calculate the weight of each indicator:

[0093]

[0094] where s i is the expert score of the i-th indicator, and n is the total number of indicators.

[0095] Combine the membership value μ(x) with the expert score to modify the initial weight:

[0096] q i ′=μ(x i )·q i

[0097] Normalized corrected weights:

[0098]

[0099] Finally, a weight set is established, Q = {q1,q2...,q n}, the specific weight coefficient results are as follows Figure 4 shown.

[0100] S35. Determine the comprehensive evaluation matrix R of health status. The comprehensive evaluation matrix R hierarchically establishes the fuzzy relationship between the evaluation index set O and the evaluation set P. The specific method is as follows:

[0101] Define R = (r ij ) n×m ; Let r ij The following formula is satisfied to obtain the normalized result.

[0102]

[0103] Where r ij Impact indicator o i In the evaluation level p i The degree of membership on .

[0104] S36. Comprehensively evaluate the status of a single indicator according to P=QR=(P1, P2, P3, P4), where P1 is the comprehensive evaluation result of the first evaluation expert, P2 is the comprehensive evaluation result of the second evaluation expert, and P3 is the comprehensive evaluation result of the third evaluation expert. The calculation result P is the comprehensive evaluation vector B obtained by fuzzy operation of the weight set Q of each indicator and the comprehensive evaluation matrix R.

[0105] S37. Calculate the single factor evaluation matrix of the lower level index With the corresponding weight set Obtain comprehensive evaluation vector through fuzzy operation Among them, i is the level number of the evaluation system, and j is the branch number in the i-th level of the evaluation system.

[0106] S38, using the characteristics of M (., +) solution model in which no information is lost in multiplication and summation operations, the fuzzy comprehensive evaluation vector To solve, in the process of judging from the bottom index to the top index, repeatedly calculate the fuzzy comprehensive evaluation vector From the bottom-level indicators to the top-level indicators, we can finally obtain the evaluation vector B of the overall health status of the bridge.

[0107] Based on fuzzy rules, use M(.,+) to solve the model Solve the problem and obtain the overall bridge state evaluation vector B. The specific fuzzy criteria are as follows: Fuzzy rules are the key to the fuzzy reasoning system. Its design directly affects the accuracy and effectiveness of the output results. Logical rules are expressed through logical expressions: if (premise), then (result). It is common to use if-then statements to construct fuzzy rules. Its expression is shown below:

[0108] if x is A, then y is B

[0109] Among them, x and y represent input and output respectively, while A and B represent the logical language results of input and output respectively, which reflects the binary fuzzy relationship between x and y.

[0110] S39. Comprehensive evaluation results: The order of the four subordinate values of the evaluation matrix operation results corresponds to the four health status levels of "intact", "good", "poor" and "dangerous" respectively; the evaluation level of the health status of the steel tube concrete arch bridge is determined by the order of the maximum value of the final fuzzy operation result of the evaluation matrix B.

[0111] S4. Output and Application of Evaluation Results: The evaluation results obtained through fuzzy calculations are converted into specific evaluation results, and the results are output in a visual and digitized form. The evaluation results can provide reference and guidance for the reinforcement and repair of defective CFST arch bridges.

[0112] like Figure 7 As shown, the health status assessment device of a steel tube concrete arch bridge based on the fuzzy comprehensive evaluation method of the present invention includes the following parts:

[0113] Constructing a finite element model of a CFST arch bridge: This module includes constructing units for healthy and damaged parts of the CFST arch bridge, applying loads and establishing constraints, performing nonlinear analysis on the CFST finite element model, and extracting the bearing capacity, stability, dynamic performance, and toughness of the CFST arch bridge under different conditions.

[0114] Establish a health status indicator system module for CFST arch bridges: Determine the indicators for evaluating the health status of CFST arch bridges based on the requirements of CFST arch bridge specifications and the specific conditions of actual projects, and evaluate the health status based on the importance of the indicators;

[0115] Constructing a fuzzy comprehensive evaluation model module for health status: Based on the fuzzy mathematical theory model, a fuzzy comprehensive evaluation model for the health status assessment of steel tube concrete arch bridges is constructed. The model includes the following components: an indicator set, an evaluation set, a weight set, and a fuzzy theory calculation module. These modules convert fuzzy factors into a specific comprehensive health status evaluation value.

[0116] Health status evaluation result output and application module: The comprehensive health status evaluation value obtained by fuzzy theory calculation is converted to generate a specific evaluation result, and then the result is visualized and digitized before output.

[0117] The specific method of constructing the health status fuzzy comprehensive evaluation module is as follows: Figure 8 .

[0118] Determine the evaluation indicator set: According to the evaluation objectives, determine the evaluation indicators and construct the evaluation indicator set.

[0119] Determine the comment set: According to the characteristics of different evaluation indicators, set the grades or comments corresponding to the indicator items and form an evaluation set.

[0120] Determine the weight set: According to the importance of each evaluation indicator, assign the corresponding weight coefficient to form a weight set, and use objective or subjective weighting methods to assign weight coefficients to each evaluation indicator.

[0121] Construct a fuzzy evaluation matrix: Through expert scoring, scoring according to national standards and questionnaire surveys, obtain the membership degree of each comment corresponding to different evaluation indicators, and construct a fuzzy evaluation matrix for fuzzy operations.

[0122] Perform fuzzy operations: perform fuzzy theory operations on the fuzzy evaluation matrix and the weight set.

[0123] Output health status evaluation results: Based on the comprehensive evaluation results, output comments and grades corresponding to the evaluation indicators to complete the comprehensive evaluation of the health status.

[0124] The comprehensive health status evaluation results of the steel tube concrete arch bridge of the present invention are shown in Table 1 below. When the void rate is 10%, the scores of various indicators of the arch bridge structure health status calculated by the comprehensive health status evaluation method of the steel tube concrete arch bridge of the present invention are as follows: the bearing capacity score of the ultimate bearing capacity state is 0.72, the bearing capacity score of the normal use limit state is 0.87, the overall stability score is 0.73, the local stability score is 0.90, the natural frequency score is 0.78, the natural vibration mode score is 0.85, the structural damping ratio score is 0.83, the curvature difference score is 0.87, and the structural post-seismic recovery capacity score is 0.84; and the overall structural response score of the arch bridge is 70.20, and the health status level is poor. Compared with the traditional health status assessment, the method proposed in the present invention can conduct in-depth assessment on more structural status indicators, and the assessment results are more accurate. At the same time, based on the refined finite element model or on-site measurement of the arch bridge, it can further carry out effective assessment of the void disease of the steel tube concrete arch bridge, providing an accurate theoretical basis for the subsequent maintenance and safe operation of the steel tube concrete arch bridge.

[0125] Table 1 Comprehensive evaluation results of the health status of the steel tube concrete arch bridge of the present invention

[0126]

[0127] In particular, the fuzzy comprehensive evaluation algorithm is highly practical and applicable when dealing with fuzzy and uncertain problems. Furthermore, the algorithm needs to be appropriately adjusted and optimized based on the actual needs and specific circumstances of the bridge health status to achieve the best optimization effect.

[0128] This invention fully considers the impact of various diseases on the health status of steel tube concrete arch bridges when evaluating their health status, and uses multiple indicators for evaluation, ensuring the comprehensiveness and accuracy of the evaluation results, thereby ensuring that the health status of steel tube concrete arch bridges can be accurately evaluated regardless of the disease.

Claims

1. A comprehensive assessment method for the health status of a steel tube concrete arch bridge, characterized in that: The following steps are involved: S1. Using ANSYS finite element software, a finite element model of a CFST arch bridge was constructed. The model was treated for defects and subjected to nonlinear analysis to obtain the state parameters of the CFST arch bridge, including its bearing capacity, stability, dynamic performance, and toughness. S2. Establish a health status indicator system for CFST arch bridges, including load-bearing capacity, stability, dynamic performance, and toughness indicators. Based on these indicators, evaluate the health status of CFST arch bridges, with the evaluation levels divided into four categories: "intact," "good," "poor," and "dangerous." S3. Construct a fuzzy comprehensive evaluation model: Based on fuzzy mathematics theory, a fuzzy comprehensive evaluation model suitable for the health status assessment of steel tube concrete arch bridges is constructed. In this model, a set of evaluation indicators, a set of comments, a set of weights, and fuzzy operation elements are established to convert these fuzzy factors into a specific comprehensive evaluation value; S4. Evaluation result output: Convert the calculated comprehensive evaluation value into a specific evaluation result and output it in a visual or numerical way.

2. A comprehensive assessment method for the health status of a steel tube concrete arch bridge according to claim 1, characterized in that: The "intact" mentioned in step S2 means that the score is [90, 100], and the steel tube concrete arch bridge is in the best condition without any damage or performance degradation; The "good" mentioned above refers to the score [75,90). The steel tube concrete arch bridge has some defects, which has caused the various indicators of the structure to decline, but it does not affect normal use; The "poor" refers to a score of [50,75], indicating that the CFST arch bridge has obvious defects and cannot be put into normal service. It must be repaired before it can be put into use again. The "dangerous" refers to a score of [0,50), indicating that the steel tube concrete arch bridge can no longer be used normally and has structural damage, requiring reinforcement and repair or demolition and reconstruction.

3. A comprehensive assessment method for the health status of a steel tube concrete arch bridge according to claim 1, characterized in that: The specific steps of step S3 are as follows: S31. Determine the evaluation objectives: Confirm the health status of the steel tube concrete arch bridge; S32. Establish an evaluation index set O based on the key indicators of the steel tube concrete arch bridge, such as bearing capacity, stability, dynamic performance, and toughness; S33. Establish an evaluation set P for health status evaluation levels of steel tube concrete arch bridges; S34. Determine the weight of each indicator based on the evaluation factors and the logsig fuzzy membership function according to expert experience, and establish a weight set Q; S35, determining a comprehensive evaluation matrix R of health status, wherein the comprehensive evaluation matrix R hierarchically establishes a fuzzy relationship between the evaluation index set O and the evaluation set P; S36. Perform a comprehensive evaluation of the status of a single indicator according to P=QR=(P1, P2, P3, P4), where P1 is the comprehensive evaluation result of the first evaluation expert, P2 is the comprehensive evaluation result of the second evaluation expert, and P3 is the comprehensive evaluation result of the third evaluation expert. The operation result P is the weight set Q of each indicator and the fuzzy operation of the comprehensive evaluation matrix R to obtain the comprehensive evaluation vector B; S37. Calculate the single factor evaluation matrix of the lower level index With the corresponding weight set Obtain comprehensive evaluation vector through fuzzy operation Where i is the level number of the evaluation system, j is the branch number in the i-th level of the evaluation system; S38, based on the characteristic of M(.,+) solution model that no information is lost in multiplication and summation operations, the fuzzy comprehensive evaluation vector To solve, in the process of judging from the bottom index to the top index, repeatedly calculate the fuzzy comprehensive evaluation vector Finally, the overall state evaluation vector B of the bridge can be obtained; S39. Comprehensive evaluation results: The order of the four numerical values in the evaluation matrix calculation results corresponds to the four health status levels of "intact", "good", "poor", and "dangerous". The evaluation level of the steel tube concrete arch bridge's health status is determined by the order of the maximum value of the final fuzzy calculation result in the evaluation matrix B.

4. A comprehensive assessment method for the health status of a steel tube concrete arch bridge according to claim 3, characterized in that: In step S32, the process of establishing the evaluation index set O is: defining the top target layer O, the middle target layer O = (O1, O2, O3, O4), and the bottom target layer as the sub-index layer, which are: O1 = (O11, O12, ... O1n), O2 = (O21, O22, ... O2n), O3 = (O31, O32, ... O3n), O4 = (O41, O42, ... O4n).

5. The comprehensive assessment method for the health status of a steel tube concrete arch bridge according to claim 3 is characterized in that: In step S33, the health status evaluation levels in the evaluation set P include four evaluation levels: intact, good, poor and dangerous.

6. A comprehensive assessment method for the health status of a steel tube concrete arch bridge according to claim 3, characterized in that: The method for establishing the weight set in step S34 is as follows: S341. Determine the key factors that influence the evaluation system through expert experience and research results in related fields. These factors will form the evaluation index system. Summarize the opinions of experts in related fields through questionnaires, expert interviews, or the Delphi method to select key indicators. Classify the indicators based on actual conditions, including a three-level indicator stratification: top-level indicators, middle-level indicators, and bottom-level indicators, to ensure the scientificity and rationality of the evaluation system. S342. Selection of fuzzy membership function: logsig (logarithmic S-type) fuzzy membership function is used to quantify the membership of the evaluation index; the formula of this function is: Where: x is the index value; a is the adjustment parameter of the steepness of the curve, which is adjusted by fitting test data or expert opinions; b is the midpoint of the curve, that is, the offset of the fuzzy membership function, which takes the average value or expected value of the index and reflects the reference standard of the fuzzy membership function; For each observation value x of the evaluation index, the membership degree μ(x) is calculated according to the formula and normalized to the interval [0,1]; S343. Determine the weight allocation principle. Based on fuzzy comprehensive evaluation theory, use membership function values combined with expert experience to allocate weights. Ask multiple experts to rate the importance of each indicator in the range of [1,10]. Calculate the weight of each indicator: where s i is the expert score of the i-th indicator, and n is the total number of indicators; Combine the membership value μ(x) with the expert score to modify the initial weight: q i ′=μ(x i )·q i Normalized corrected weights: Finally, a weight set is established, Q = {q1,q2...,q n }.

7. The comprehensive assessment method for the health status of a steel tube concrete arch bridge according to claim 3 is characterized in that: The specific method of step S35 is as follows: define R=(r ij ) n×m ; Let r ij Satisfy the following formula to obtain the normalized result; Where r ij Impact indicator o i In the evaluation level p i The degree of membership on .

8. The comprehensive assessment method for the health status of a steel tube concrete arch bridge according to claim 3 is characterized in that: The specific method of step S38 is as follows: Based on the fuzzy rule, use M(., +) to solve the model pair Solve the problem and obtain the overall bridge state evaluation vector B. The specific fuzzy criteria are as follows: Fuzzy rules are the key to the fuzzy reasoning system. Its design directly affects the accuracy and effectiveness of the output results. Logical rules are expressed through logical expressions: if (premise), then (result). It is common to use if-then statements to construct fuzzy rules. Its expression is shown as follows: if xis A,then yis B Among them, x and y represent input and output respectively, while A and B represent the logical language results of input and output respectively, which reflects the binary fuzzy relationship between x and y.

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