Railway bridge performance evaluation method

Abstract

The application discloses a railway bridge performance evaluation method, comprising the following steps: S1, photographing a bridge surface to obtain a bridge apparent image; S2, combining discrete bridge apparent images into a bridge overall image; S3, obtaining disease occurrence positions, disease characteristics and disease degree data through image recognition on the bridge overall image; S4, respectively calculating bridge static evaluation indexes and bridge dynamic evaluation indexes according to the disease occurrence positions, the disease characteristics and the disease degree data; S5, correcting the bridge static evaluation indexes through the bridge dynamic evaluation indexes to obtain a corrected bridge fusion evaluation result; and S6, grading the corrected bridge fusion evaluation result. The application fuses inspection, detection and structural response monitoring indexes for evaluation, and solves the limitation problem of a traditional bridge safety detection monitoring evaluation system.

Description

Technical Field

[0001] This invention relates to the field of bridge data analysis or management, and in particular to a method for evaluating the performance of railway bridges. Background Technology

[0002] Concrete T-beams are a widely used beam structure in railways, highways, and municipal roads both domestically and internationally. This structural form leverages the excellent material properties of concrete and the load-bearing capacity of the beam structure, achieving long-term reliable load-bearing performance. In my country, railway bridges are primarily prestressed concrete beam bridges, characterized by clearly defined stress distribution, simple construction, and the ability to provide the stiffness and stability required for train operation. Among these, prestressed concrete T-beams offer advantages such as high load-bearing capacity, low material consumption, light weight, and convenient construction and erection, making them a typical beam structure in bridge construction and widely used in both conventional and heavy-haul railway bridges.

[0003] Bridge safety assessment has been developing for many years, initially relying primarily on manual methods and regular bridge inspections. These inspections mainly focused on assessing the apparent condition of the bridge structure, with more in-depth assessments, such as structural calculations and load tests, only conducted when unreliable conditions were found. In China, the technical condition inspection of highway bridges combines visual inspection with instrumental methods. The assessment employs a tiered comprehensive evaluation combined with control of five categories of individual bridge indicators. This approach incorporates the structural characteristics of domestic highway bridges and draws on the ideas and experiences of relevant international standards. The technical condition assessment of highway bridges includes evaluation of bridge components, sub-components, deck systems, superstructure, substructure, and the entire bridge. The process begins with the evaluation of individual bridge components, followed by evaluation of individual sub-components, then evaluation of the deck system, superstructure, and substructure, and finally, an overall assessment of the bridge's technical condition.

[0004] Domestic railway bridges have also developed a series of deterioration assessment standards for different parts, such as steel beams, concrete beams, supports, and piers. Deterioration levels are AA, A1, B, C, and D, corresponding to five levels: extremely severe, severe, relatively severe, moderate, and slight deterioration. The "Repair Rules for High-Speed ​​Railway Bridges and Tunnels" and the "Repair Rules for Conventional Railway Bridges and Tunnels" also provide key points and specific assessment standards for bridge evaluation. However, railway bridge evaluation currently mainly focuses on classifying single defects and does not employ the analytic hierarchy process (AHP) or other comprehensive assessment methods.

[0005] With the rapid development of sensors, data transmission, computer hardware and software, signal analysis, and artificial intelligence, researchers have begun to study computer-based automated, continuous, and even real-time bridge structural health monitoring systems, as well as novel non-destructive testing technologies based on intelligent equipment. The former focuses on modeling and analyzing the response of bridge structures under load, while the latter provides mobile, quantitative images and analytical data. In the research of safe, objective, and reliable bridge safety inspection and monitoring technologies and evaluation systems, traditional bridge safety inspection and monitoring assessment systems (model correction methods, dynamic fingerprint analysis evaluation techniques, etc.) have encountered difficulties or limitations due to the complexity of bridge structures, and tend to focus on evaluation from a single perspective or data source.

[0006] Therefore, a performance evaluation method for railway bridges is needed to solve the above problems. Summary of the Invention

[0007] This invention addresses the challenges and limitations of traditional bridge safety inspection and monitoring systems in researching safe, objective, and reliable technologies and evaluation systems. These limitations stem from the complexity of bridge structures and the tendency to rely on evaluations from a single perspective or data source. The invention provides a railway bridge performance evaluation method that integrates inspection, testing, and structural response monitoring indicators to solve these problems.

[0008] This invention provides a method for evaluating the performance of railway bridges, comprising the following steps:

[0009] S1. Take pictures of the bridge surface to obtain an image of the bridge's appearance;

[0010] S2. Combine the discrete bridge appearance images into a complete bridge image;

[0011] S3. Obtain data on the location, characteristics, and severity of defects from the overall image of the bridge through image recognition.

[0012] S4. Calculate the bridge static evaluation index Q based on the data of the location, characteristics, and severity of the defects. S and bridge dynamic evaluation index Q D ;

[0013] S5. Through the bridge dynamic evaluation index Q D Static evaluation index Q of bridge S The results were corrected to obtain the corrected bridge fusion evaluation result Q'. S ;

[0014] S6. Evaluation results of the corrected bridge fusion Q' S Conduct a graded evaluation;

[0015] Among them, the static evaluation index Q of the bridge S To take the location and degree of disease deterioration as influencing factors, the sum of the number of diseases for cracking diseases and non-cracking diseases was divided by the total number of diseases.

[0016] Bridge static evaluation index Q S To calculate the ratio of lateral amplitude to the corresponding standard value and the ratio of vertical deflection to the corresponding standard value, the results are summed and averaged.

[0017] The railway bridge performance evaluation method described in this invention, as a preferred embodiment, uses the bridge static evaluation index Q. S Specifically:

[0018]

[0019] Where n and m represent the number of cracks and other types of defects at different parts of the beam surface, i and j represent the ordinal numbers of cracks and other types of defects, li is the length of the main crack, h is the beam height, d is the segment length between the two transverse diaphragms of the beam, Si is the defect area, α is the location coefficient, and β is the damage coefficient.

[0020] The railway bridge performance evaluation method described in this invention, as a preferred embodiment, uses the bridge dynamic evaluation index Q. D Specifically:

[0021]

[0022] Among them, A 10 The typical value of lateral amplitude specified in the bridge operational performance verification standard; A 20 The vertical deflection-to-span ratio is the typical value; A 1t A represents the maximum inferred value or amplitude of the beam's transverse vibration, as measured in the experiment. 2t The vertical deflection-to-span ratio of the beam under static and live load conditions;

[0023] Among them, the maximum inferred value or amplitude A of the measured transverse amplitude of the beam. 1t The specific calculation method is as follows:

[0024] To determine if the number of train trips N at the same speed class is greater than or equal to 20, calculate it using the following formula:

[0025]

[0026] in, This represents the average of the maximum amplitude values ​​when N trains pass by.

[0027] The average of the maximum amplitude when N trains pass. The specific calculation method is as follows:

[0028]

[0029] Where Aimax is the maximum amplitude when the i-th train passes;

[0030] The standard deviation σ is calculated as follows:

[0031]

[0032] If N is less than 20, the maximum estimated value of the transverse amplitude of the beam or the amplitude A1t is taken as the largest value among all the data.

[0033] Vertical deflection-to-span ratio A of beam under static and live loads 2t Take the maximum value among the vertical deflections.

[0034] The railway bridge performance evaluation method described in this invention, as a preferred embodiment, modifies the bridge fusion evaluation result Q'. S The specific calculation method is as follows:

[0035] Q' S =Q S (1+Q D ).

[0036] The railway bridge performance evaluation method of the present invention, as a preferred embodiment, specifically includes step S6 as follows:

[0037] S61. Determine the corrected bridge fusion evaluation result Q' S If the value is greater than 0 and less than or equal to 0.2, then the smaller impact is used as the evaluation result and proceed to step S65; otherwise, proceed to step S62.

[0038] S62. Determine the revised bridge fusion evaluation result Q' S If the value is greater than 0.2 and less than or equal to 0.4, then the continued deterioration will affect the function of the concrete beam. If so, proceed to step S65 after evaluating the result; otherwise, proceed to step S63.

[0039] S63. Determine the revised bridge fusion evaluation result Q' S If the value is greater than 0.4 and less than or equal to 0.8, the degradation will continue and the function of the concrete beam will be severely degraded. Further degradation will endanger driving safety. If the value is positive, proceed to step S65. Otherwise, proceed to step S64.

[0040] S64. The evaluation result is that the concrete beam is severely degraded and endangers traffic safety.

[0041] S65. Output the evaluation results.

[0042] The railway bridge performance evaluation method of the present invention, as a preferred embodiment, includes bridge appearance images including images of both sides of the beam, images of the bottom of the beam, and images of the beam ends.

[0043] The beneficial effects of this invention are as follows:

[0044] (1) Considering the location and importance of structural deterioration, a quantitative analysis of the bridge structure status is conducted to obtain static evaluation indicators that can comprehensively reflect the bridge deterioration status.

[0045] (2) Considering the vibration margin between the measured value and the specified normal value of the beam vibration response under train load, the dynamic evaluation index can reflect the relative level of beam vibration on the same scale.

[0046] (3) A method is proposed to correct the static evaluation results by using dynamic evaluation indicators. This method can take into account the focus of both static and dynamic data. While performing static evaluation, it can also reflect the relative level of beam vibration response, providing a new perspective for the qualitative evaluation of beams to become a comprehensive quantitative evaluation. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of a railway bridge performance evaluation method. Detailed Implementation

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0049] Example 1

[0050] like Figure 1 As shown, a method for evaluating the performance of railway bridges includes the following steps:

[0051] S1. Take pictures of the bridge surface to obtain an image of the bridge's appearance;

[0052] S2. Combine the discrete bridge appearance images into a complete bridge image;

[0053] S3. Obtain data on the location, characteristics, and severity of defects from the overall image of the bridge through image recognition.

[0054] S4. Calculate the bridge static evaluation index Q based on the data of the location, characteristics, and severity of the defects. S and bridge dynamic evaluation index Q D ;

[0055] S5. Through the bridge dynamic evaluation index Q D Static evaluation index Q of bridge SThe results were corrected to obtain the corrected bridge fusion evaluation result Q'. S ;

[0056] S6. Evaluation results of the corrected bridge fusion Q' S Conduct a tiered evaluation.

[0057] In this embodiment, the image acquisition method is as follows:

[0058] Using intelligent equipment such as drones and robots as carriers, a dedicated path is designed according to the structural characteristics of railway bridges to obtain surface image data of the sides, bottom, and ends of simply supported beams. A reconstruction algorithm is used to stitch multiple images of each beam along the designed path to generate an overall image of the side and bottom of the beam. Intelligent algorithms are then used to identify the image data and extract key attribute data such as the location, characteristics, and extent of defects.

[0059] The bridge described in this embodiment is an unsupported beam bridge.

[0060] Intelligent equipment is used to acquire image data of the T-beam structure. Intelligent algorithms are then used to identify the image data and extract key attribute data such as the location, characteristics, and extent of defects. The static evaluation index Q of the T-beam structure is determined. S Taking into account both the location of the diseased area (location coefficient α) and the degree of deterioration (damage coefficient β), the static evaluation results are calculated using the following formula:

[0061]

[0062] In the formula, i and j represent structural cracking and other types of defects (surface damage, honeycombing, pitting, surface looseness, holes, etc.), respectively, and l i The length of the main crack is given by S, where h is the beam height, d is the segment length between the two transverse diaphragms of the T-beam (approximately 4m), and S is the length of the main crack. j The area affected by the disease is divided into units of area.

[0063] The specific deterioration sites of concrete T-beam defects include: upper flange, web, lower flange of the horseshoe-shaped beam, transverse diaphragm, and beam end anchorage area, etc. The deterioration coefficient α is different for each part corresponding to different defects. The deterioration coefficient α values ​​for different parts of commonly used railway prestressed simply supported T-beams are as follows.

[0064] Commonly used values ​​for the degradation coefficient α of prestressed simply supported T-beams in railways

[0065]

[0066]

[0067] The damage coefficient β is determined based on the relevant grading requirements in the deterioration assessment of railway bridge and tunnel structures. The deterioration grading of concrete T-beam structures is divided into four levels: A, B, C, and D. Level A is further divided into two grades: AA and A1. Among them, level D is slight, level C is moderate, level B is relatively severe, level A1 is severe, and level AA is extremely severe. The evaluation of each deterioration level and the corresponding damage coefficient β values ​​are as follows. When level AA is reached, the bridge bearing capacity assessment is carried out directly, and the evaluation results do not need to be calculated according to this method.

[0068] Evaluation of each deterioration level and the value of the damage coefficient β

[0069]

[0070] For example, a 32m prestressed concrete T-beam with a beam height of 2.8m has the following defects:

[0071] (1) There is a diagonal crack in the web within 4m from the beam end, with a width of 0.3mm and a length of 1.2m;

[0072] (2) There are two areas of surface damage near the mid-span, with exposed reinforcement in some areas, and the total deteriorated area is approximately 0.2m. 2 ;

[0073] According to the relevant grading requirements in the deterioration assessment of railway bridge and tunnel structures, defect (1) is rated as A1 level, with a deterioration coefficient α1 of 0.8 found in Table 1 and a damage coefficient β1 of 1.0 found in Table 2; defect (2) is rated as B level, with a deterioration coefficient α1 of 0.8 found in Table 1 and a damage coefficient β1 of 0.5 found in Table 2; in addition, l i 1.2m, h is 2.8m, d is 4m, S j The value is 0.2; substituting the above value into the static evaluation index Q... S The calculation formula yields the static evaluation index Q. S for:

[0074] Q S = (0.8 × 1.0 × 1.2 / 2.8) + (0.8 × 0.5 × 0.2 / 1) ≈ 0.423

[0075] Static evaluation index Q S When the value is relatively small, it indicates that the structural deterioration of the beam is relatively mild and may not have a significant impact on the overall performance of the beam, but it will have a certain impact on the durability of the concrete structure. When the value increases, it indicates that the degree of structural deterioration has increased and may have a certain impact on the overall performance of the beam, such as a slight decrease in lateral and vertical stiffness and an increase in the dynamic response of the structure under live load. When the value is very large (close to 1), it indicates that the structural deterioration has a significant impact on the overall performance of the beam, and may even affect the bridge's load-bearing capacity and endanger traffic safety, requiring supplementary calculations of the control section and the structural load-bearing capacity.

[0076] Dynamic evaluation index Q of simply supported beam structure D The calculation formula is as follows:

[0077]

[0078] In the formula, A 10 The lateral amplitude is the typical value specified in the bridge operation performance standards for verification, reflecting the lateral stiffness of the beam; A 20 The vertical deflection-to-span ratio is a typical value, reflecting the vertical stiffness of the beam; A 1t A represents the maximum inferred value or amplitude of the beam's transverse vibration, as measured in the experiment. 2t The vertical deflection-to-span ratio of the beam under static live load (converted to design live load).

[0079] A 1t The following method can be used to obtain the data: Collect the lateral amplitude and vertical deflection of the bridge beam when the train passes over it, and directly read the single peak value from the time-domain waveform. For N trains at the same speed level (speed difference not exceeding 10 km / h), when N≥20, calculate the maximum inferred value A of the test data with a 97.5% guarantee rate. t Calculated by the following formula:

[0080]

[0081] In the formula: The average of the maximum amplitude values ​​when N trains pass:

[0082]

[0083] In the formula: A imax This represents the maximum amplitude when the i-th train passes.

[0084] σ is the standard deviation:

[0085]

[0086] When N < 20, A 1t The maximum amplitude value among all data is approximated.

[0087] For example, for a 32m prestressed concrete T-beam, the measured maximum lateral amplitude at mid-span when a freight train passes is 0.8mm, while the standard value is typically 2.54mm. The measured vertical deflection-to-span ratio at mid-span under design live load when a freight train passes is 1 / 4260, while the standard value is typically 1 / 1800. Substituting these results into the above formula yields:

[0088]

[0089] By correcting static evaluation results with dynamic data, a comprehensive evaluation method integrating static and dynamic data is finally obtained. The calculation formula is as follows:

[0090] Q' S =Q S (1+Q D )

[0091] In the formula, Q' S This is the static evaluation result after being corrected by dynamic evaluation indicators.

[0092] The static evaluation index Q S =0.423 and dynamic evaluation index Q D Substituting 0.369 into the formula for calculating the static evaluation result after dynamic data correction, the corrected static evaluation result is obtained as follows:

[0093] Q' S =Q S (1+Q D = 0.423 × (1 + 0.369) ≈ 0.579

[0094] According to the table below and Q' S The calculation results show that the beam condition evaluation result reaches level three.

[0095] Corrected static evaluation result Q' S Grading indicators

[0096]

[0097]

[0098] The method proposed in this invention reflects the following two aspects:

[0099] On the one hand, when using a uniform vehicle type and speed for testing, and given that the current railway T-beam bridge track type is uniformly ballast track, the beam vibration response is directly related to the lateral and vertical stiffness of the structure. The magnitude of the tested structural response can reflect the relative magnitude of the structural stiffness. That is, for the same type of beam, if structural deterioration leads to a decrease in stiffness, the beam vibration response under live load tends to increase relatively. Therefore, the dynamic evaluation index Q is adopted. D It can characterize whether the static stiffness of the beam has a certain tendency to deteriorate.

[0100] On the other hand, the dynamic evaluation index Q D It can characterize the safety margin of structural vibration, when the dynamic evaluation index Q DA relatively small dynamic index (Q) indicates that the beam's vibration response is far from the specified normal value, and the structural stiffness is relatively large. From a dynamic evaluation perspective, the static index still has a certain "deterioration margin." If the dynamic index is close to 1, it means that the beam's response is very close to the specified normal value, the structural stiffness is relatively small, and there is not much "deterioration margin." The beam structure cannot deteriorate further, and the static evaluation index Q needs to be appropriately increased and corrected. S This is to reflect the insufficient "deterioration surplus".

[0101] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for evaluating the performance of railway bridges, characterized in that: Includes the following steps: S1. Take pictures of the bridge surface to obtain an image of the bridge's appearance; S2. Combine the discrete bridge appearance images into a complete bridge image; S3. Obtain data on the location, characteristics, and severity of defects from the overall image of the bridge through image recognition. S4. Calculate the static evaluation index of the bridge based on the data on the location, characteristics, and severity of the defects. and bridge dynamic evaluation indicators ; S5. Using the aforementioned bridge dynamic evaluation indicators The static evaluation index of the bridge The results were corrected to obtain the corrected bridge fusion evaluation results. ; S6. Evaluation results of the modified bridge fusion Conduct a graded evaluation; Among them, the bridge static evaluation index To take the location and degree of disease deterioration as influencing factors, the sum of the number of diseases for cracking diseases and non-cracking diseases was divided by the total number of diseases. The bridge dynamic evaluation indicators To calculate the ratio of lateral amplitude to the corresponding standard value and the ratio of vertical deflection to the corresponding standard value, the results are summed and averaged. The static evaluation indicators of the bridge Specifically: ； Where n and m represent the number of cracks and other types of defects at different parts of the beam surface, i and j represent the ordinal numbers of cracks and other types of defects, li is the length of the main crack; h is the beam height; d is the segment length between the two transverse diaphragms of the beam; Si is the defect area; α is the location coefficient; β is the damage coefficient. The bridge dynamic evaluation indicators Specifically: ； Among them, A 10 The typical value of lateral amplitude specified in the bridge operational performance verification standard; A 20 The vertical deflection-to-span ratio is the typical value; A 1t A represents the maximum inferred value or amplitude of the beam's transverse vibration, as measured in the experiment. 2t The vertical deflection-to-span ratio of the beam under static and live loads; Among them, the measured maximum inferred value or amplitude A of the beam's transverse amplitude. 1t The specific calculation method is as follows: To determine if the number of train trips N at the same speed class is greater than or equal to 20, calculate it using the following formula: ； in, This represents the average of the maximum amplitude values ​​when N trains pass by. The average of the maximum amplitude when the N trains pass. The specific calculation method is as follows: ； Where Aimax is the maximum amplitude when the i-th train passes; Standard deviation The calculation method is as follows: ； If N is less than 20, then the maximum estimated value or amplitude A of the transverse amplitude of the beam is obtained from the actual measurement. 1t Take the largest amplitude value from all data; The vertical deflection-to-span ratio A of the beam under static live load 2t Take the maximum value among the vertical deflections; The revised bridge fusion evaluation results The specific calculation method is as follows: 。 2. The method for evaluating the performance of railway bridges according to claim 1, characterized in that: Step S6 specifically involves: S61. Determine the revised bridge fusion evaluation result. If the value is greater than 0 and less than or equal to 0.2, then the smaller impact is used as the evaluation result and proceed to step S65; otherwise, proceed to step S62. S62. Determine the revised bridge fusion evaluation result. If the value is greater than 0.2 and less than or equal to 0.4, then the continued deterioration will affect the function of the concrete beam. If so, proceed to step S65 after evaluating the result; otherwise, proceed to step S63. S63. Determine the revised bridge fusion evaluation result. If the value is greater than 0.4 and less than or equal to 0.8, the degradation will continue and the function of the concrete beam will be severely degraded. Further degradation will endanger driving safety. If the value is positive, proceed to step S65. Otherwise, proceed to step S64. S64. The evaluation result is that the concrete beam is severely degraded and endangers traffic safety. S65. Output the evaluation results.

3. The method for evaluating the performance of railway bridges according to claim 1, characterized in that: The bridge appearance images include images of both sides of the beam, the bottom of the beam, and the ends of the beam.

Images