Railway special bridge real-time monitoring and evaluation system

Abstract

A track special bridge real-time monitoring and evaluation system is provided with a train positioning system for determining the position of the train at any time on the bridge deck, a finite element real-time calculation system for real-time calculation of finite element calculation values at different positions of the train, a track special bridge monitoring system for collecting bridge operation data, and a real-time monitoring and evaluation system for real-time calculation of the theoretical values of structural deformation, stress and cable force generated by the current train position, comparison with the structural response collected by the track special bridge monitoring system in real time, and consideration of the correlation between the structural response and the train speed, so as to realize accurate evaluation of the bridge structure state under the same working condition.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge monitoring, in particular to a real-time monitoring and evaluation system for track special bridge. BACKGROUND

[0002] With the rapid development of transportation industry, various large bridges are increasingly important in traffic engineering. At present, many bridges have entered the maintenance and repair stage, and the sudden and catastrophic accidents of bridges are increasing, which has caused serious loss to people's life and property. In order to prevent the occurrence of catastrophic events, real-time monitoring of large bridges is needed. The monitoring system uses multiple types of sensors to collect real-time structural response information, and transmits the information to the monitoring center for analysis and processing through modern communication technology, so as to achieve the purpose of real-time monitoring and evaluation of bridge structure state. This system can timely find potential problems, and has early warning function, which can ensure the reliability and safety of the bridge.

[0003] However, due to the coupling effect of train load, temperature, wind and other factors on the bridge, it is impossible to real-time strip the structural response generated by each load, and most of the threshold values are calculated by finite element analysis under the most unfavorable load condition. However, the probability of multiple trains appearing at the most unfavorable position at the same time is extremely low, resulting in that the measured value of structural response is much smaller than the threshold value, and the real-time state of the structure cannot be accurately evaluated. Therefore, for track special bridge, how to realize real-time and accurate evaluation of bridge state under the condition of multiple trains running at high speed is a technical problem to be solved in the industry. SUMMARY

[0004] The present application proposes a real-time monitoring and evaluation system for track special bridge, which integrates laser displacement meters in fixed intervals and collects and identifies the real-time position of trains, and then calculates the theoretical values of structural deformation, stress and cable force generated by the current train position through MIDAS API in real time, and compares them with the structural responses collected by the monitoring system in real time. At the same time, the correlation between structural response and train speed is considered, so as to realize accurate evaluation of the state of bridge structure under the same working condition. The specific technical scheme is as follows:

[0005] A real-time monitoring and evaluation system for track special bridge is provided with a train positioning system for determining the position of the train at any time on the bridge deck;

[0006] A finite element real-time calculation system is provided for real-time calculation of finite element calculation values at different positions of the train;

[0007] A track special bridge monitoring system is provided for collecting bridge operation data;

[0008] The real-time monitoring and evaluation system is arranged to calculate the structural deformation, stress and theoretical value of cable force generated by the current train position in real time, and compare the structural response collected by the track special bridge monitoring system in real time, and meanwhile, the correlation between the structural response and train speed is considered, so as to realize the accurate evaluation of the bridge structure state under the same working condition.

[0009] As preferred, the train positioning system is provided with laser displacement meters which are arranged equidistantly on the bridge deck, and the distance between the train and the laser displacement meter is accurately measured by emitting laser beams and measuring the time of laser return.

[0010] As preferred, the distance calculation method of the laser displacement meter is specifically:

[0011] The laser displacement meter measures the distance of the target surface by laser beams, and determines the relative position of the target based on the phase change of light, and when the laser beams irradiate the surface of the train running on the bridge structure, the laser displacement meter can measure the distance of the structure surface.

[0012] The calculation formula of the laser displacement meter is:

[0013]

[0014] Wherein,

[0015] X is the distance from the light source to the train;

[0016] C is the propagation speed of laser in air;

[0017] T is the 2 times difference of laser to the target;

[0018] Considering the change of train speed, continuous update of position and correction of error, the position update algorithm is introduced, which firstly collects the laser return time data by the laser displacement meter, then calculates the instantaneous speed of the train in each time step by using these data, updates the position of the train by the speed calculation and position update formula, and considers the error correction to improve the accuracy, the whole process is supported by the real-time monitoring system, the train position is continuously updated by iteration to ensure that the system can respond to abnormal situations in time and provide accurate position information for bridge monitoring.

[0019] The train position update calculation formula is:

[0020] P = P0 + v · dt (2)

[0021] Wherein,

[0022] P is the real-time position of the train, and at this time P will be P0 of the next time step;

[0023] P0 is the set initial position;

[0024] v - speed of the train;

[0025] dt - time step.

[0026] As preferred: the finite element real-time calculation system is specifically a finite element real-time calculation system based on MIDAS API, which solves the problems existing in the MCT file import mode, including covering the original data and being limited to the modeling stage, connects the server through MIDAS API, and uses the HTTP methods of PUT, POST, GET, and DELETE to send requests to perform various operations, including defining materials, creating nodes, performing calculations, and extracting internal forces. Finally, the user can specify the node number in the request Body to extract the corresponding internal force data.

[0027] As preferred: the track special bridge monitoring system, wherein the load and environment monitoring includes ship collision, environmental temperature, environmental humidity, wind speed and direction, rainfall, and water level monitoring; the overall static and dynamic response monitoring of the structure includes main beam vibration, main tower vibration, main beam vertical deformation, main beam spatial deformation GNSS, main tower spatial deformation GNSS, bridge pier horizontal displacement, expansion joint displacement, and rotation displacement monitoring; the local response monitoring of the structure includes main beam stress, main tower stress, stay cable force, and steel structure fatigue monitoring.

[0028] As preferred: the real-time monitoring and evaluation system, which can evaluate the state of the bridge structure in real time by comparing with the actual measurement data in the track special bridge monitoring system, judge whether there is abnormal deformation, excessive stress, or uneven distribution of cable force, and avoid the situation that the threshold value obtained by using the most unfavorable load for finite element analysis and calculation is much larger than the measured value, so as to take maintenance and maintenance measures in time, and ensure the reliability and safety of the track bridge;

[0029] Error calculation is also introduced to quantify the difference between the monitoring value and the calculated value, and the error calculation formula is:

[0030]

[0031] wherein,

[0032] W - the difference between the monitoring value and the calculated value;

[0033] X 监测 , i is the i-th monitoring value;

[0034] X 计算 , i is the i-th calculated value;

[0035] n - the total number of data.

[0036] In order to more intuitively understand the difference, the relative error is standardized to measure the size of the monitoring value, so that it can be more easily compared in the case of different dimensions and ranges, and the calculation formula of the relative error is:

[0037]

[0038] Wherein, the error represents the difference between the monitoring value and the calculated value, the average monitoring value is the average value of the monitoring value, the larger the value of the relative error, the larger the difference between the monitoring value and the calculated value, which is an indication that the system is inaccurate or the model parameters need to be further adjusted, by monitoring the change of the relative error, further correction strategy can be guided to improve the performance of the model or monitoring system;

[0039] High-speed trains can excite different resonance frequencies of the structure, and these frequencies may change with the increase of train speed, the response and speed reduction coefficient takes into account the change of these resonance frequencies, in order to match the actual situation, the transformation between dynamic load and static load is needed to match the static load calculated by the MIDAS finite element model with the measured dynamic load, in order to calculate this transformation, the response and speed reduction coefficient k i In structural dynamics, the velocity reduction effect refers to the fact that when the vibration velocity of a structure is large, the dynamic response may decrease, which is caused by the nonlinear behavior of materials and structures.

[0040] The formula of the response and speed reduction coefficient is:

[0041]

[0042] Wherein,

[0043] k i The response and speed reduction coefficient of the velocity i;

[0044] J i The static load test measured value of the velocity i;

[0045] D i The dynamic load test measured value of the velocity i;

[0046] However, due to the difficulty in obtaining actual load data at each speed, the structure response and train speed relationship formula can be established by the track special bridge load test, which can obtain the structure response value under the condition of train static, 20km / h, 40km / h, 60km / h, 80km / h and 100km / h different driving speed, this transformation and the introduction of the response and speed reduction coefficient help to more accurately reflect the influence of dynamic load on the structure when the train passes, so as to realize more reliable health monitoring and structure evaluation.

[0047] The benefits of the present invention are: In bridge monitoring, envelope evaluation method is a traditional way to comprehensively evaluate the overall health status of bridge structure. This method comprehensively considers multiple monitoring parameters such as vibration, displacement and stress, etc. to generate a comprehensive score or index, so that engineers and monitoring personnel can effectively understand the safety and stability of bridge structure. This helps to discover potential problems early to take appropriate maintenance and repair measures to ensure the reliability and long-term use of the bridge. Envelope evaluation method plays a key role in bridge monitoring, improving the safety and maintainability of the bridge.

[0048] However, in the case of multiple trains running at high speed, the theoretical value of the envelope evaluation method is usually calculated according to the most unfavorable load position, while the probability of multiple trains appearing at the most unfavorable position at the same time is very low, resulting in a measured value much smaller than the evaluation threshold, making it difficult to accurately evaluate the structure state. Therefore, in the invention, the method of laser displacement meter is adopted, when the train passes through the laser displacement meter, the laser displacement return time changes, thereby identifying the train position at this time. The laser displacement meter assumes that the train is running at a constant speed, and by calculating the displacement passing through per unit time, the position of the train at any time on the bridge deck can be determined. The train position information is uploaded to the bridge monitoring center through wired connection, so as to more accurately evaluate the health status of the bridge. This method helps to improve the accuracy and reliability of structure evaluation, especially in the case of high-speed multi-train traffic.

[0049] The real-time state monitoring and evaluation system of track special bridge has significant advantages over the traditional envelope evaluation method. First, it uses laser displacement meters to accurately obtain real-time positioning data of trains on the bridge deck, which makes the evaluation of structure state more accurate and reliable compared with the traditional envelope evaluation method. Since the measured data is closer to the actual operation, it can more accurately reflect the behavior of the bridge under actual load.

[0050] Secondly, MIDAS API provides a flexible and comprehensive way to connect to MIDAS server and perform various operations such as defining materials, creating nodes, performing calculations and extracting internal force data using HTTP methods, solving the problem of traditional MCT file import method, no longer limited to the modeling stage, thus realizing more comprehensive functions and data processing, promoting effective interaction between modules of bridge health monitoring system. By integrating MIDAS API into the real-time monitoring system of track special bridge, it is used to calculate the finite element calculation value of different positions of the train in real time, and upload the results to the bridge real-time monitoring center in real time, making it more convenient for monitoring personnel to obtain and analyze data, supporting decision-making and maintenance strategy formulation.

[0051] Furthermore, as the train speed increases, the propagation speed of the vibration waves in the structure can change. High-speed trains can induce higher frequency vibration waves, which can propagate at different speeds. The wavelength of the vibration waves generated by high-speed trains can be different from that of low-speed trains. This change in wavelength can result in a change in the way vibrations propagate in the structure, thus leading to a significant difference in the load on the structure when the train is stationary and when it is moving.

[0052] High-speed trains can excite different resonance frequencies of the structure, and these frequencies can change as the train speed increases. The present invention takes into account this change in resonance frequencies by introducing response and speed reduction factors. These factors take into account the change in resonance frequencies with train speed. By considering the effect of train speed on the resonance frequencies of the structure, the response and speed reduction factors help to adjust the actual train speed more accurately in vibration analysis to better reflect the dynamic response of the structure.

[0053] High-speed trains can excite different resonance frequencies of the structure, and these frequencies can change as the train speed increases. The present invention fully takes into account this change in resonance frequencies by introducing response and speed reduction factors. These factors take into account the change in resonance frequencies with train speed. By considering the effect of train speed on the resonance frequencies of the structure, the response and speed reduction factors help to adjust the actual train speed more accurately in vibration analysis to better reflect the dynamic response of the structure.

[0054] The purpose of introducing response and speed reduction factors is to better adapt to the change in resonance frequencies. This helps to adjust the train speed so that it more accurately simulates the actual response of the structure in vibration analysis. By considering the dynamic load effects of these trains in vibration analysis, the introduction of response and speed reduction factors makes it possible to more accurately and comprehensively compare static and dynamic load data. This method can better understand and evaluate the impact of train speed on the vibration behavior of the structure, thus more effectively guiding relevant engineering design and analysis. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 The system architecture of the present invention is shown.

[0056] Figure 2 The laser displacement meter arrangement in the present invention is shown.

[0057] Figure 3 The MIDAS API operation in the present invention is shown.

[0058] Figure 4 The flowchart of the present invention is shown. DETAILED DESCRIPTION

[0059] The advantages and features of the present application will be more readily understood from the detailed description that follows, taken in conjunction with the accompanying drawings, in which the preferred embodiments of the present application are shown by way of illustration.

[0060] As Figure 1 , Figure 2 , Figure 3 and Figure 4 indicated: a track-specific bridge real-time monitoring and evaluation system is provided with a train positioning system for determining the position of the train at any time on the bridge deck;

[0061] The step of positioning the train position using a laser displacement meter is: laser displacement meter deployment - laser displacement meter data acquisition - initial position setting - algorithm calculation - error correction - real-time monitoring system;

[0062] The process of positioning the train position by laser displacement meter begins with the deployment of laser displacement meters along the bridge deck at specified intervals, every 10 meters, to ensure that the entire bridge deck is covered by laser beams. These laser displacement meters periodically emit laser beams and record the time of laser return, and the collected data is transmitted to the bridge monitoring center as the basis for further analysis. Before the system is running, the initial position of the train needs to be set, and the accuracy of this step is crucial for subsequent position calculation;

[0063] Subsequently, by processing the laser return time data, the speed calculation algorithm is used to calculate the displacement of the train in unit time. This algorithm covers the accurate processing of laser return time, the calculation of speed, and the steps of obtaining the change of train position by integration or other numerical methods, to ensure the accuracy and stability of position calculation. Considering the possible errors in laser propagation, such as atmospheric humidity, temperature and other factors, the system introduces an error correction mechanism to real-time correct the laser return time through environmental sensor data, to improve the accuracy of measurement;

[0064] The laser displacement meter measures the distance of the target surface using laser beams, and determines the relative position of the target based on the phase change of light. When the laser beam is irradiated onto the surface of the train driving on the bridge structure, the laser displacement meter can measure the distance of the structure surface.

[0065] The calculation formula of the laser displacement meter is:

[0066]

[0067] Where,

[0068] X - the distance from the light source to the train;

[0069] C——laser speed in air;

[0070] T——laser to target 2 times the difference in time.

[0071] Considering the speed change of the train, continuous updating of the position and correction of errors, a position updating algorithm is introduced. The position updating algorithm first collects laser return time data through the laser displacement meter, and then uses these data to calculate the instantaneous speed of the train at each time step. Through simple speed calculation and position updating formula, the system updates the position of the train, and considers error correction to improve accuracy. The whole process is supported by real-time monitoring system, which continuously updates the position of the train through iteration, ensuring that the system can respond to abnormal situations in time and provide accurate position information for bridge monitoring.

[0072] The train position updating calculation formula is:

[0073] P=P0+v·dt (2)

[0074] Where,

[0075] P——real-time position of the train, and at this time P will be P0 of the next time step;

[0076] P0——set initial position;

[0077] v——speed of the train;

[0078] dt——time step.

[0079] There is a finite element real-time calculation system for real-time calculation of finite element calculation values at different positions of the train; MIDAS API solves the problems existing in the traditional MCT file import method, including covering the original data and being limited to the modeling stage. By connecting the server through MIDAS API and using PUT, POST, GET, DELETE, etc. HTTP methods to send requests, various operations can be performed, such as defining materials, creating nodes, performing calculations, extracting results, etc. Finally, users can specify node numbers in the request Body to extract corresponding deformation, stress and cable force data. This way of using API allows more flexible control and operation of MIDAS software, achieving more comprehensive functions and data processing, not just limited to the modeling stage;

[0080] The bridge establishes a MIDAS finite element model and integrates MIDAS API to realize system interactive operation. This includes creating a finite element model, integrating API, and then interacting data to realize real-time monitoring and maintenance of the bridge to ensure its safety and performance;

[0081] The MIDAS API can utilize train position data measured by sensors such as laser displacement meters to calculate the deformation, stress, and cable force of the bridge structure in real time.

[0082] The MIDAS API works in coordination with the system of the monitoring center to perform real-time calculations on the theoretical response of the bridge structure by receiving real-time data collected by sensors. This enables the monitoring system to quickly and accurately assess the state of the bridge structure;

[0083] A track-specific bridge monitoring system is provided for collecting bridge operation data.

[0084] The system includes the following content: load and environmental monitoring content includes ship collision, environmental temperature, environmental humidity, wind speed and direction, rainfall, water level monitoring, overall static and dynamic response monitoring of the structure includes main beam vibration, main tower vibration, main beam vertical deformation, main beam spatial deformation (GNSS), main tower spatial deformation (GNSS), bridge pier horizontal displacement, expansion joint displacement, angular displacement monitoring, local response monitoring of the structure includes main beam stress, main tower stress, stay cable force, steel structure fatigue monitoring;

[0085] The bridge health real-time monitoring center is provided with:

[0086] The key module in the bridge health monitoring system is mainly used to establish an analysis model of the bridge structure to receive and process data uploaded from the health monitoring subsystem of each bridge. This module uses the collected data to input the structural model of each bridge, and then calculates the bridge health index parameters of different bridges under the current environmental conditions and stress state, including structural deformation, structural fatigue state, and structural dynamic response. Through the calculation and analysis of these parameters, the system can provide important information about the health status of the bridge to help monitoring personnel take appropriate maintenance and maintenance measures to ensure the safety and maintainability of the bridge.

[0087] The monitoring system includes five parts: sensor module, data acquisition and transmission module, data processing and management module, data analysis and safety warning and evaluation module, system integration and user interface interaction, which work together

[0088] A real-time monitoring and evaluation system is provided for real-time calculation of the theoretical values of structural deformation, stress, and cable force generated by the current train position, and comparison with the structural response collected by the track-specific bridge monitoring system in real time, while considering the correlation between structural response and train speed, thereby achieving accurate evaluation of the state of the bridge structure under the same working conditions.

[0089] This real-time condition monitoring and evaluation system for rail-specific bridges assesses the structural condition of the monitored bridge by comparing the calculated theoretical values from the analysis model with the measured values from the monitoring system, in combination with the bridge design standards and relevant bridge specifications. Through this comprehensive evaluation, the system can provide overall strategies and measures for maintenance and care. This helps to ensure the long-term safety and maintainability of rail-specific bridges to adapt to changing environmental and usage conditions.

[0090] The implementation method for real-time precise positioning of train position is as follows:

[0091] A laser displacement meter is installed every 10 meters on the bridge deck. The working principle of the laser displacement meter is to accurately measure the distance by emitting a laser beam and measuring the time of the laser return. When the train passes through the laser displacement meter, the laser displacement return time changes, thereby identifying the train position at that time. Assuming uniform speed of the train between laser displacement meters, the train position at any time on the bridge deck can be determined by calculating the displacement passing through per unit time. The train position information is uploaded to the bridge monitoring center through wired connection.

[0092] This monitoring method can provide important information, including the position, speed, and running trajectory of the train. This is very helpful for ensuring the safety of the train passing through the bridge and monitoring the carrying capacity and health status of the bridge. This real-time monitoring system can detect potential problems in advance to take appropriate maintenance and repair measures, ensuring the reliability and safety of the rail bridge.

[0093] The comparison method of model calculation theoretical value and measured value for real-time precise positioning of train position is as follows:

[0094] By establishing a MIDAS finite element model and integrating MIDAS API, a comprehensive system operation process is realized. First, laser displacement meters are used to collect and identify real-time train positions, and MIDAS API is used to calculate theoretical values such as structural deformation, stress, and cable force caused by the current train position in real time. Then, these theoretical values are converted through response and speed reduction coefficients to simulate actual conditions under different operating conditions. Finally, by comparing with the actual measured data in the health monitoring system, the state of the bridge structure can be evaluated in real time to determine whether there are problems such as abnormal deformation, excessive stress, or uneven distribution of cable force, avoiding the situation where the threshold value obtained by finite element analysis under the most unfavorable load condition is much larger than the measured value, so that maintenance and care measures can be taken in time to ensure the reliability and safety of the rail bridge. This comprehensive system operation process provides a highly accurate tool for structural health monitoring, which helps to identify problems early and reduce risks;

[0095] The system not only provides a comparison between the monitoring value and the calculated value for early warning, but also introduces some error calculation to quantify the difference between the monitoring value and the calculated value. The error calculation formula is:

[0096]

[0097] wherein,

[0098] W is the difference between the monitoring value and the calculated value;

[0099] X 监测 , i is the ith monitoring value;

[0100] X 计算 , i is the ith calculated value;

[0101] n is the total number of data.

[0102] To more intuitively understand the size of this difference relative to the monitoring value, a relative error is introduced for standardized measurement, so that it can be more easily compared in the case of different dimensions and ranges. The calculation formula of the relative error is:

[0103]

[0104] wherein, error represents the difference between the monitoring value and the calculated value, and the average monitoring value is the average value of the monitoring value. The larger the value of the relative error, the greater the difference between the monitoring value and the calculated value. This may be an indication that the system is inaccurate or the model parameters need to be further adjusted. By monitoring the change of the relative error, further correction strategies can be guided to improve the performance of the model or monitoring system.

[0105] As the train speed increases, the propagation speed of vibration waves in the structure may change. High-speed trains can cause higher frequency vibration waves, and these waves can propagate at different speeds. The wavelength of the vibration wave generated by the high-speed train may be different from that of the low-speed train. This change in wavelength can cause changes in the way vibrations propagate in the structure, so there is a large gap between the dynamic load generated by the train during operation and the static load when the train is stationary. Dynamic load includes changes caused by vibration and impact force when the train is running;

[0106] High-speed trains can excite different resonance frequencies of the structure, and these frequencies can change as the train speed increases. The response with speed reduction factor takes into account this change in resonance frequency.

[0107] To match the actual situation, the conversion between dynamic and static load is needed to match the static load calculated by MIDAS finite element model with the measured dynamic load. To calculate this conversion, the response-to-velocity reduction factor k i In structural dynamics, the velocity reduction effect refers to the fact that when the vibration velocity of a structure is large, the dynamic response may decrease due to the nonlinear behavior of materials and structures.

[0108] The response-to-velocity reduction factor formula is:

[0109]

[0110] where,

[0111] k i — response-to-velocity reduction factor at velocity i;

[0112] J i — measured value of static load test at velocity i;

[0113] D i — measured value of dynamic load test at velocity i.

[0114] However, due to the difficulty in obtaining actual load data at each velocity, the structure response at different running speeds of the train, such as static, 20 km / h, 40 km / h, 60 km / h, 80 km / h, and 100 km / h, can be obtained through the bridge load test of the track-specific bridge. Thus, the relationship between structure response and train speed is established. This conversion and the introduction of the response-to-velocity reduction factor help to more accurately reflect the impact of dynamic load on the structure when the train passes, thereby achieving more reliable health monitoring and structure evaluation.

[0115] The response of the structure to these dynamic loads when in operation can be more complex, including deformation, vibration, etc. The introduction of the response-to-velocity reduction factor helps to better consider the impact of dynamic loads during train operation in vibration analysis.

Claims

1. A real-time monitoring and evaluation system for dedicated track bridges, characterized in that: A train positioning system is installed to determine the position of the train on the bridge at any time. The train positioning system is equipped with laser displacement meters, which are evenly distributed on the bridge surface. The distance between the train and the laser displacement meters is accurately measured by emitting a laser beam and measuring the time it takes for the laser to return. The laser displacement meter distance calculation method is as follows: Laser displacement gauges use laser beams to measure the distance to a target surface and determine the relative position of the target based on the phase change of light. When a laser beam shines on the surface of a train traveling on a bridge structure, the laser displacement gauge can measure the distance to the surface of the structure. The calculation formula for the laser displacement gauge is as follows: （1） in, x — the distance from the light source to the train; c—the speed at which laser light travels through the air; t — twice the time difference between the laser beam and the target object; Considering train speed changes, continuous position updates, and error correction, a position update algorithm is introduced. The position update algorithm first collects laser return time data through a laser displacement meter, then uses this data to calculate the instantaneous speed of the train in each time step. Through speed calculation and position update formula, the system updates the train's position and considers error correction to improve accuracy. The entire process is supported by a real-time monitoring system, and the train's position is continuously updated iteratively to ensure that the system can respond to abnormal situations in a timely manner and provide accurate position information for bridge monitoring. The formula for calculating train position updates is: （2） in, P—the real-time position of the train, and at this time P will be used as P0 for the next time step; P0 — The initial position set; v — the speed of the train; dt — time step; A real-time finite element calculation system is installed to calculate the finite element values ​​at different positions of the train in real time. A dedicated bridge monitoring system for railway tracks is installed to collect bridge operation data; A real-time monitoring and evaluation system is set up to calculate the theoretical values ​​of structural deformation, stress, and cable force generated at the current train position in real time, and compare them with the structural response collected in real time by the track-specific bridge monitoring system. At the same time, the correlation between structural response and train speed is considered, thereby achieving an accurate evaluation of the bridge structural state under the same working conditions. The real-time monitoring and evaluation system specifically compares the actual measurement data with the monitoring data of the dedicated rail bridge to assess the state of the bridge structure in real time, determine whether there are abnormal deformations, excessive stress, or uneven cable force distribution, avoid the situation where the threshold calculated by finite element analysis under the most unfavorable load conditions is greater than the measured value, and thus take maintenance and upkeep measures to ensure the reliability and safety of the rail bridge. Error calculation is also introduced to quantify the difference between the monitored value and the calculated value. The error calculation formula is as follows: （3） in, W—The difference between the monitored value and the calculated value; — is the i-th monitoring value; — is the i-th calculated value; n is the total number of data points; To more intuitively understand this difference relative to the monitored value, a standardized measure of relative error is used, making comparisons easier under different dimensions and ranges. The formula for calculating relative error is: （4） Among them, error represents the difference between the monitored value and the calculated value, and the average monitored value is the average value of the monitored values. The larger the relative error value, the larger the difference between the monitored value and the calculated value. This is an indication that the system is inaccurate or the model parameters need further adjustment. By monitoring the changes in relative error, we can guide further correction strategies to improve the performance of the model or monitoring system. High-speed trains excite different resonant frequencies in the structure, and these resonant frequencies change with increasing train speed. The response and speed reduction factor take into account the changes in resonant frequencies. To match the actual situation, it is necessary to convert between dynamic and static loads, matching the static load calculated by the MIDAS finite element model with the measured dynamic load, and introducing the response and speed reduction factor k. i ; The formulas for response and velocity reduction factors are as follows: （5） in, —Response at velocity i and velocity reduction factor; J i —Measured values ​​from static load tests at speed i; D i —Measured values ​​from dynamic load tests at speed i; However, since it is difficult to obtain actual load data at every speed, load tests on dedicated track bridges can be conducted to obtain structural response values ​​at different travel speeds of 20km / h, 40km / h, 60km / h, 80km / h, and 100km / h. This allows the establishment of a relationship between structural response and train speed. This transformation and the introduction of a speed reduction factor more accurately reflect the impact of dynamic loads on the structure when the train passes, enabling health monitoring and structural assessment.

2. The real-time monitoring and evaluation system for dedicated track bridges according to claim 1, characterized in that: The aforementioned real-time finite element calculation system is specifically a real-time finite element calculation system based on the MIDAS API. The MIDAS API solves the problems existing in the MCT file import method, including overwriting the original data and limitations limited to the modeling stage. By connecting to the server through the MIDAS API, and sending requests using HTTP methods such as PUT, POST, GET, and DELETE, various operations are performed, including defining materials, creating nodes, performing calculations, and extracting deformation, stress, and cable force. Finally, the user specifies the node number in the request body. The node number corresponds to the sensor installation location of the track-specific bridge monitoring system to extract the corresponding deformation, stress, and cable force data.

3. The real-time monitoring and evaluation system for dedicated track bridges according to claim 1, characterized in that: The monitoring system for the dedicated railway bridge includes load and environmental monitoring of ship collision, ambient temperature, ambient humidity, wind speed and direction, rainfall, and water level, as well as overall static monitoring of the structure; and dynamic response monitoring of main beam vibration, main tower vibration, main beam vertical deformation, main beam spatial deformation GNSS, main tower spatial deformation GNSS, pier horizontal displacement, expansion joint displacement, and angular displacement. Structural local response monitoring includes monitoring of main beam stress, main tower stress, cable tension, and steel structure fatigue.

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