Method and system for analyzing temperature effect of large-span railway cable-stayed bridge

Abstract

The invention discloses a method and system for analyzing the temperature effect of a large-span railway cable-stayed bridge, and the method comprises the following steps: constructing a three-dimensional refined finite element model suitable for temperature field analysis; determining key parameters; calculating solar radiation intensity, and determining a corresponding solar radiation absorption coefficient; calculating temperature field distribution of the main beam section and the bridge tower, calculating an effect field based on thermal-mechanical coupling, generating a temperature field and effect field cloud picture, and forming a junction temperature field and temperature effect change rule report; the method comprises the following steps: acquiring original data of a bridge health monitoring system, decoding and classifying the original data to form effective data for analysis, and preprocessing the effective data; the temperature effect is comprehensively analyzed, and the change rules of long-term and short-term time histories are mainly researched; performing long-term and short-term correlation analysis on the temperature; the system comprises a theoretical numerical simulation analysis module and a measured data rule research module. According to the invention, comprehensive analysis of the temperature field and the temperature effect of the long-span bridge can be realized.

Description

Technical Field

[0001] This invention relates to the field of bridge health monitoring data analysis, specifically to a method and system for analyzing the temperature effect of long-span railway cable-stayed bridges. Background Technology

[0002] Bridge health monitoring systems can analyze structural change patterns, assess bridge load-bearing capacity and service status, and provide long-term early warnings for bridge structural safety. However, existing bridge health monitoring systems are mostly applied to highway bridges, with less research on railway bridges. There are differences in monitoring indicators between railway and highway bridges. Railway bridges have very strict requirements for beam end displacement smoothness and track alignment smoothness, and their temperature field and temperature effect analysis modules are insufficient. A comprehensive method and system for analyzing the temperature field and temperature effects of long-span railway bridges is lacking. A temperature effect analysis method and system can monitor bridge temperature changes in real time, summarize the structural response patterns of bridges under temperature-induced effects, and ensure the safe operation of bridges.

[0003] Railway bridges have stringent requirements regarding alignment, and temperature significantly impacts bridge alignment. As bridge spans increase, the temperature effect becomes more pronounced, sometimes exceeding the bridge response caused by vehicle loads. The temperature effect on long-span railway bridges cannot be ignored, necessitating timely and comprehensive monitoring and analysis. Since the 1950s, many scholars have begun researching the temperature field and temperature effects of bridges. Temperature field analysis includes calculations of solar radiation and finite element simulations. Existing research primarily focuses on highway bridges, with fewer studies on railway bridges. While existing research has conducted in-depth studies on the temperature variation patterns and correlations of different highway bridge structures and materials, railway bridges, with even stricter alignment requirements, require a systematic analysis of the temperature field of long-span railway bridges. Temperature effect analysis mainly focuses on highway bridges, with less research on railway bridges. Existing studies often rely on data collected by health monitoring systems, analyzing single indicators and lacking time-history and correlation analysis at the entire bridge level. The temperature field and temperature effects of long-span railway bridges are currently a research hotspot. Summary of the Invention

[0004] This invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a method and system for analyzing the temperature effect of long-span railway cable-stayed bridges.

[0005] The technical solution of this invention is: a method for analyzing the temperature effect of long-span railway cable-stayed bridges, comprising the following steps: A. In the theoretical numerical simulation analysis module, a three-dimensional refined finite element model suitable for temperature field analysis is constructed based on the geometric dimensions and material parameters provided by the design. B. Based on the bridge's geographical location and meteorological data, determine the key parameters, namely solar tilt angle, solar altitude angle, and day number; calculate the solar radiation intensity and determine the corresponding solar radiation absorption coefficient; C. Based on the refined finite element model and solar radiation, apply thermal boundary conditions, set appropriate convective heat transfer coefficients, calculate the temperature field distribution of the main beam segments and bridge towers, and then calculate the effect field based on thermal coupling, generate temperature field and effect field cloud maps, and form a report on the variation law of junction temperature field and temperature effect. D. In the module for studying the patterns of measured data, the raw data from the bridge health monitoring system is acquired, decoded, and classified to form effective data for analysis, and then preprocessed. E. Based on multiple indicators across the entire bridge, a comprehensive analysis of the temperature effect is conducted, focusing on the variation patterns of long-term and short-term time histories. The measured temperature effect at the actual points is compared and analyzed with the theoretical effect field to verify the effectiveness of the finite element model. F. Combining measured temperatures with various indicators, conduct long-term and short-term correlation analysis of temperature. After verifying the effectiveness of the model, conduct a detailed analysis of the temperature field and temperature effect at different orientations, heights, and locations of the entire bridge, and compile a summary report on the temperature effect law and a bridge temperature-induced response assessment report.

[0006] Furthermore, in step A, within the theoretical numerical simulation analysis module, a refined three-dimensional finite element model suitable for temperature field analysis is constructed based on the geometric dimensions and material parameters provided by the design. The specific process is as follows: First, the three-dimensional refined finite element model includes the solid finite element model of the main beam segment and the solid finite element model of the bridge tower. Then, the model building is performed based on the Ansys command flow; Then, the construction process includes size division, material property definition, element type selection, and mesh generation; Finally, the theoretical numerical analysis subsystem includes a refined finite element model construction module, a solar radiation calculation module, and a temperature field calculation and result analysis module.

[0007] Furthermore, step B, combining the bridge's geographical location and meteorological data, determines key parameters including solar tilt angle, solar altitude angle, and day number; calculates solar radiation intensity, and determines the corresponding solar radiation absorption coefficient. The specific process is as follows: b1. Calculate the intensity of direct solar radiation: (1); in, It is the value of direct solar radiation. It is the solar constant. It is atmospheric transparency. It is atmospheric optical quality. It is the angle of incidence of the sun; b2. Calculate the sky scattering intensity: (2); in, It is the value of direct solar radiation. It is the solar constant; b3. Calculate the ground reflection intensity: (3); in, It is the surface reflectance. It is the sky scattering value on the horizontal plane; b4. Calculate convection and radiation heat transfer: The total radiative heat transfer of concrete is: (4); in, It is the radiation heat transfer coefficient; the heat transfer by convection is expressed as... ;in It is the heat transfer coefficient. It is the structural temperature. It refers to the ambient temperature.

[0008] Furthermore, step C, based on a refined finite element model and solar radiation, applies thermal boundary conditions, sets appropriate convective heat transfer coefficients, calculates the temperature field distribution of the main beam segments and bridge towers, and then calculates the effect field based on thermo-coupling, generating temperature field and effect field cloud maps, and producing a report on the variation law of the junction temperature field and temperature effect. The specific process is as follows: First, the temperature field calculation includes applying thermodynamic boundary conditions, selecting the time step, setting up the solver, and performing the calculation. Then, the temperature effect calculation includes applying constraint boundary conditions, applying temperature field calculation loads, and solving the solution. Next, the thermo-mechanical coupling calculation includes structural model construction, application of temperature field calculation results, application of boundary constraints, application of loads, and solver setup and calculation; Furthermore, the calculation and extraction of effect fields should be consistent with health monitoring indicators; Finally, the report on temperature field variation patterns includes three parts: analysis of temperature field variation patterns at different times of the day, analysis of temperature field variation patterns in different directions, and analysis of temperature field variation patterns in different seasons.

[0009] Furthermore, in step D, within the module for studying patterns in measured data, the raw data from the bridge health monitoring system is acquired, decoded, and classified to form valid data for analysis. Preprocessing is then performed, as detailed below: First, data decoding includes connecting to the health monitoring platform, data packet transmission, timestamp-based data matching, timestamp-based data decoding, and the output of the decoded data. Then, data preprocessing includes outlier removal, sampling frequency conversion, and data separation; Finally, the subsystem for studying the patterns of measured data includes a data transmission decoding and preprocessing module, a multi-index long and short-term time history pattern analysis module, and a multi-index long and short-term temperature correlation analysis module.

[0010] Furthermore, step E conducts a comprehensive analysis of the temperature effect based on multiple indicators across the entire bridge, focusing on the variation patterns of long-term and short-term time histories. The measured temperature effect at the measured points is compared with the theoretical effect field to verify the effectiveness of the finite element model. The specific process is as follows: First, the temperature effect analysis indicators were selected from the whole bridge level, including ambient temperature, structural temperature, support displacement, vertical static deflection of the main truss, vertical dynamic deflection of the main truss, lateral deformation of the main truss, modal parameters, and tower top displacement. Then, the temperature effect is divided into two parts based on time: long-term analysis and short-term analysis. Next, the long-term analysis of the temperature effect examines the annual variation patterns at the whole-year level and plots long-term time-history variation curves; Then, the measured data points were compared with the corresponding calculated data points of the finite element model to verify the effectiveness of the finite element model and improve the usability of the finite element model calculation results. Finally, the short-term temperature effect analysis examines the short-term variation patterns from both single-day and three-day perspectives and plots short-term time-history variation curves.

[0011] Furthermore, step F combines measured temperature with various indicators to conduct long-term and short-term correlation analysis of temperature. After verifying the effectiveness of the model, a detailed analysis of the temperature field and temperature effect at different orientations, heights, and locations of the entire bridge is conducted. A summary report on the temperature effect patterns and a bridge temperature-induced response assessment report are then generated. The specific process is as follows: First, temperature-related indicators were selected from the entire bridge level, including ambient temperature, structural temperature, support displacement, vertical static deflection of the main truss, vertical dynamic deflection of the main truss, lateral deformation of the main truss, modal parameters, and tower top displacement. Then, the temperature correlation was divided into two parts: long-term analysis and short-term analysis. Then, the long-term analysis analyzes the annual correlation at the whole year level and draws a scatter plot, while the short-term analysis analyzes the daily correlation and draws a scatter plot. Then, nonlinear fitting was used to study the correlation variation of various indicators on a single day; Next, the correlation of annual variations was studied by fitting monthly averages; Next, a detailed analysis of the temperature field at different orientations, heights, and locations of the entire bridge was conducted. The temperature effect was mainly analyzed in detail on key indicators such as bridge alignment and beam end displacement. Next, a summary report on the temperature effect is conducted, including long-term and short-term time history analysis of indicators such as ambient temperature, structural temperature, support displacement, vertical static deflection of the main truss, vertical dynamic deflection of the main truss, lateral deformation of the main truss, modal parameters, and tower top displacement, as well as correlation analysis with temperature. Finally, the bridge temperature-induced response assessment report includes the annual extreme values ​​of indicators such as ambient temperature, structural temperature, support displacement, main truss vertical static deflection, main truss vertical dynamic deflection, main truss lateral deformation, modal parameters, and tower top displacement, as well as safety limits considering the specifications and design values.

[0012] Furthermore, the system integrating temperature effect analysis methods for long-span railway cable-stayed bridges includes a theoretical numerical simulation analysis module and a measured data pattern research module.

[0013] The beneficial effects of this invention are as follows: The temperature effect analysis method and system of this invention is a key step in ensuring the safe operation of bridges. It can collect bridge temperature and structural response in real time, effectively quantify the degree of influence of temperature on bridge response, analyze the long-term and short-term variation patterns of temperature-induced effects, evaluate the operation of bridges under temperature effects, determine whether there are any over-limit situations, and promptly detect and eliminate potential safety hazards in bridge structures, providing decision-making guidance for bridge maintenance and management.

[0014] This invention enables a comprehensive analysis of temperature fields and temperature effects, providing effective support for improving the analysis of health monitoring data for railway bridges. Attached Figure Description

[0015] Figure 1 This is a flowchart of the method and system for analyzing the temperature field and temperature effect of a long-span railway cable-stayed bridge according to the present invention; Figure 2 This is a system architecture diagram of the temperature field and temperature effect analysis system of the present invention; Figure 3 This is a diagram showing the temperature field analysis of the main beam segment in different orientations according to the present invention; Figure 4 This is a diagram showing the temperature field analysis of the bridge tower from different orientations according to the present invention. Figure 5 This is the short-term time history curve of the support displacement of the present invention; Figure 6 This is the long-term time history curve of the support displacement of the present invention; Figure 7 This is a short-term temperature correlation diagram of the support displacement of the present invention; Figure 8 This is a temperature correlation diagram showing the long-term displacement of the support in this invention. Figure 9 This is the short-term time history curve of the mid-span deflection of the present invention; Figure 10 This is the long-term time history curve of the mid-span deflection of the present invention; Figure 11 This is a short-term temperature correlation diagram of mid-span deflection in this invention; Figure 12 This is a graph showing the long-term temperature correlation of mid-span deflection. Detailed Implementation

[0016] The present invention will now be described in detail with reference to the accompanying drawings and embodiments: like Figures 1 to 12 As shown, a method for analyzing the temperature effect of long-span railway cable-stayed bridges includes the following steps: A. In the theoretical numerical simulation analysis module, a three-dimensional refined finite element model suitable for temperature field analysis is constructed based on the geometric dimensions and material parameters provided by the design. B. Based on the bridge's geographical location and meteorological data, determine the key parameters, namely solar tilt angle, solar altitude angle, and day number; calculate the solar radiation intensity and determine the corresponding solar radiation absorption coefficient; C. Based on the refined finite element model and solar radiation, apply thermal boundary conditions, set appropriate convective heat transfer coefficients, calculate the temperature field distribution of the main beam segments and bridge towers, and then calculate the effect field based on thermal coupling, generate temperature field and effect field cloud maps, and form a report on the variation law of junction temperature field and temperature effect. D. In the module for studying the patterns of measured data, the raw data from the bridge health monitoring system is acquired, decoded, and classified to form effective data for analysis, and then preprocessed. E. Based on multiple indicators across the entire bridge, a comprehensive analysis of the temperature effect is conducted, focusing on the variation patterns of long-term and short-term time histories. The measured temperature effect at the actual points is compared and analyzed with the theoretical effect field to verify the effectiveness of the finite element model. F. Combining measured temperatures with various indicators, conduct long-term and short-term correlation analysis of temperature. After verifying the effectiveness of the model, conduct a detailed analysis of the temperature field and temperature effect at different orientations, heights, and locations of the entire bridge, and compile a summary report on the temperature effect law and a bridge temperature-induced response assessment report.

[0017] Step A: In the theoretical numerical simulation analysis module, based on the geometric dimensions and material parameters provided by the design, a refined three-dimensional finite element model suitable for temperature field analysis is constructed. The specific process is as follows: First, the three-dimensional refined finite element model includes the solid finite element model of the main beam segment and the solid finite element model of the bridge tower. Then, the model building is performed based on the Ansys command flow; Then, the construction process includes size division, material property definition, element type selection, and mesh generation; Finally, the theoretical numerical analysis subsystem includes a refined finite element model construction module, a solar radiation calculation module, and a temperature field calculation and result analysis module.

[0018] Step B, combining the bridge's geographical location and meteorological data, determines the key parameters: solar tilt angle, solar altitude angle, and day number; calculates the solar radiation intensity and determines the corresponding solar radiation absorption coefficient. The specific process is as follows: b1. Calculate the intensity of direct solar radiation: (1); in, It is the value of direct solar radiation. It is the solar constant. It is atmospheric transparency. It is atmospheric optical quality. It is the angle of incidence of the sun; b2. Calculate the sky scattering intensity: (2); in, It is the value of direct solar radiation. It is the solar constant; b3. Calculate the ground reflection intensity: (3); in, It is the surface reflectance. It is the sky scattering value on the horizontal plane; b4. Calculate convection and radiation heat transfer: The total radiative heat transfer of concrete is: (4); in, It is the radiation heat transfer coefficient; the heat transfer by convection is expressed as... ;in It is the heat transfer coefficient. It is the structural temperature. It refers to the ambient temperature.

[0019] Step C, based on a refined finite element model and solar radiation, applies thermal boundary conditions, sets appropriate convective heat transfer coefficients, calculates the temperature field distribution of the main beam segments and bridge towers, and then calculates the effect field based on thermo-coupling, generating temperature field and effect field cloud maps, and producing a report on the variation law of the junction temperature field and temperature effect. The specific process is as follows: First, the temperature field calculation includes applying thermodynamic boundary conditions, selecting the time step, setting up the solver, and performing the calculation. Then, the temperature effect calculation includes applying constraint boundary conditions, applying temperature field calculation loads, and solving the solution. Next, the thermo-mechanical coupling calculation includes structural model construction, application of temperature field calculation results, application of boundary constraints, application of loads, and solver setup and calculation; Furthermore, the calculation and extraction of effect fields should be consistent with health monitoring indicators; Finally, the report on temperature field variation patterns includes three parts: analysis of temperature field variation patterns at different times of the day, analysis of temperature field variation patterns in different directions, and analysis of temperature field variation patterns in different seasons.

[0020] Step D involves acquiring the raw data from the bridge health monitoring system in the measured data pattern research module, decoding and classifying it to form valid data for analysis, and then preprocessing it. The specific process is as follows: First, data decoding includes connecting to the health monitoring platform, data packet transmission, timestamp-based data matching, timestamp-based data decoding, and the output of the decoded data. Then, data preprocessing includes outlier removal, sampling frequency conversion, and data separation; Finally, the subsystem for studying the patterns of measured data includes a data transmission decoding and preprocessing module, a multi-index long and short-term time history pattern analysis module, and a multi-index long and short-term temperature correlation analysis module.

[0021] Step E involves a comprehensive analysis of the temperature effect based on multiple indicators across the entire bridge, focusing on the variation patterns over long and short time periods. The measured temperature effects at different points are compared with the theoretical effect field to verify the effectiveness of the finite element model. The specific process is as follows: First, the temperature effect analysis indicators were selected from the whole bridge level, including ambient temperature, structural temperature, support displacement, vertical static deflection of the main truss, vertical dynamic deflection of the main truss, lateral deformation of the main truss, modal parameters, and tower top displacement. Then, the temperature effect is divided into two parts based on time: long-term analysis and short-term analysis. Next, the long-term analysis of the temperature effect examines the annual variation patterns at the whole-year level and plots long-term time-history variation curves; Then, the measured data points were compared with the corresponding calculated data points of the finite element model to verify the effectiveness of the finite element model and improve the usability of the finite element model calculation results. Finally, the short-term temperature effect analysis examines the short-term variation patterns from both single-day and three-day perspectives and plots short-term time-history variation curves.

[0022] Step F combines measured temperature with various indicators to conduct long-term and short-term correlation analysis of temperature. After verifying the effectiveness of the model, a detailed analysis of the temperature field and temperature effect at different orientations, heights, and locations of the entire bridge is conducted. A summary report of temperature effect patterns and a bridge temperature-induced response assessment report are then generated. The specific process is as follows: First, temperature-related indicators were selected from the entire bridge level, including ambient temperature, structural temperature, support displacement, vertical static deflection of the main truss, vertical dynamic deflection of the main truss, lateral deformation of the main truss, modal parameters, and tower top displacement. Then, the temperature correlation was divided into two parts: long-term analysis and short-term analysis. Then, the long-term analysis analyzes the annual correlation at the whole year level and draws a scatter plot, while the short-term analysis analyzes the daily correlation and draws a scatter plot. Then, nonlinear fitting was used to study the correlation variation of various indicators on a single day; Next, the correlation of annual variations was studied by fitting monthly averages; Next, a detailed analysis of the temperature field at different orientations, heights, and locations of the entire bridge was conducted. The temperature effect was mainly analyzed in detail on key indicators such as bridge alignment and beam end displacement. Next, a summary report on the temperature effect is conducted, including long-term and short-term time history analysis of indicators such as ambient temperature, structural temperature, support displacement, vertical static deflection of the main truss, vertical dynamic deflection of the main truss, lateral deformation of the main truss, modal parameters, and tower top displacement, as well as correlation analysis with temperature. Finally, the bridge temperature-induced response assessment report includes the annual extreme values ​​of indicators such as ambient temperature, structural temperature, support displacement, main truss vertical static deflection, main truss vertical dynamic deflection, main truss lateral deformation, modal parameters, and tower top displacement, as well as safety limits considering the specifications and design values.

[0023] The system integrating methods for analyzing the temperature effects of long-span railway cable-stayed bridges includes a theoretical numerical simulation analysis module and a module for studying the patterns of measured data.

[0024] Example 1 A method for analyzing the temperature effect of long-span railway cable-stayed bridges includes the following steps: A. In the theoretical numerical simulation analysis module, a three-dimensional refined finite element model suitable for temperature field analysis is constructed based on the geometric dimensions and material parameters provided by the design. B. Based on the bridge's geographical location and meteorological data, determine the key parameters, namely solar tilt angle, solar altitude angle, and day number; calculate the solar radiation intensity and determine the corresponding solar radiation absorption coefficient; C. Based on the refined finite element model and solar radiation, apply thermal boundary conditions, set appropriate convective heat transfer coefficients, calculate the temperature field distribution of the main beam segments and bridge towers, and then calculate the effect field based on thermal coupling, generate temperature field and effect field cloud maps, and form a report on the variation law of junction temperature field and temperature effect. D. In the module for studying the patterns of measured data, the raw data from the bridge health monitoring system is acquired, decoded, and classified to form effective data for analysis, and then preprocessed. E. Based on multiple indicators across the entire bridge, a comprehensive analysis of the temperature effect is conducted, focusing on the variation patterns of long-term and short-term time histories. The measured temperature effect at the actual points is compared and analyzed with the theoretical effect field to verify the effectiveness of the finite element model. F. Combining measured temperatures with various indicators, conduct long-term and short-term correlation analysis of temperature. After verifying the effectiveness of the model, conduct a detailed analysis of the temperature field and temperature effect at different orientations, heights, and locations of the entire bridge, and compile a summary report on the temperature effect law and a bridge temperature-induced response assessment report.

[0025] Specifically, the detailed process of constructing the refined finite element model in step A is as follows: a1. Structural geometric modeling: Based on software such as Ansys, solid elements are used to perform three-dimensional geometric modeling of the target structure according to the design or measured dimensions. At the same time, the modeling process should ensure that the established geometric model has high precision characteristics. Geometric modeling should take into account the actual connection relationship, contact surface, boundary conditions and other factors of each component. a2. Mesh generation: Mesh generation is one of the core steps in finite element analysis. At this stage, appropriate element types and mesh refinement levels should be selected. As a result, the mesh density directly affects computational accuracy and efficiency. Refining the mesh can improve the accuracy of the results, but it also increases the computational load. For regions with boundary effects, a denser mesh is required to improve the computational accuracy in those regions. a3. Material property definition: Based on the mechanical property data of actual materials, define various physical parameters of the materials, including but not limited to elastic modulus, Poisson's ratio, density, coefficient of thermal expansion, etc. Among them, linear materials: For most engineering materials, a linear elastic material model can be used, assuming that the stress and strain of the material have a linear relationship; Nonlinear materials: For materials with plasticity or other nonlinear behavior, it is necessary to define the corresponding nonlinear constitutive model, such as ideal plasticity, hyperbolic constitutive model or hardening model.

[0026] Specifically, the calculation of solar radiation in step B is as follows: Heat transfer is essentially a change of energy, manifested as a change in temperature, and mainly occurs in three forms: thermal radiation, thermal convection, and thermal conduction. The heat exchange between a bridge structure and its surroundings primarily occurs through thermal radiation and thermal convection. Thermal radiation includes both solar radiation and environmental radiation. Solar radiation comprises direct radiation, sky scattering, and ground reflection. Direct radiation refers to radiation that passes directly through the atmosphere to reach the structural surface. Sky scattering is solar radiation that reaches the structural surface after being refracted by the atmosphere. Ground reflection is solar radiation that reaches the structural surface after being reflected by the ground. Environmental radiation refers to the radiative heat exchange between the bridge and the surrounding environment.

[0027] Based on the above, the intensity of direct solar radiation can be expressed by the following formula: (1); in, It is the value of direct solar radiation. It is the solar constant. It is atmospheric transparency. It is atmospheric optical quality. It is the angle of incidence of the sun, the angle between the direction of the sun's rays and the direction of the outward normal of the sunlit surface of the structure.

[0028] The solar constant is the energy of solar radiation received per unit area of ​​atmosphere per second, which is related to the Earth-Sun distance and is calculated as follows: (5); in, The day number; atmospheric transparency refers to the ratio of transmitted light to incident light in the atmosphere. This value is related to many factors such as air composition and altitude, and its calculation formula is: (6); in, It is the relative atmospheric pressure. The Linke chaos coefficient can be obtained by the following formula: (7); (8); in, , These are two key parameters of the Linke chaos coefficient under different atmospheric conditions. Atmospheric optical quality refers to the mass of gas absorbed or scattered by solar radiation after passing through the atmosphere. It is a parameter that measures the residual radiation, and its value is the ratio of the radiation path to the vertical distance of the atmosphere, as shown in the following formula: (9); (10); in, It refers to geographical latitude, which is within ±90°. It is the solar tilt angle, the angle between the line connecting the Sun and the Earth and the plane of the Earth's equator; It is the solar hour angle, the angle between the meridian connecting the Sun and the Earth and the meridian containing a specific location on Earth. It is the angle between the surface normal vector and the due south direction, where due south is 0°. It is the solar altitude angle, the angle between the line connecting the structure to the sun and the Earth's surface; it is 0° at sunrise and sunset. It is the angle of inclination of the structure's surface relative to the horizontal plane, ranging from 0° to 180°. A value greater than 90° indicates that the surface is facing downwards.

[0029] The calculation formula for the above content is as follows: ; in, Beijing time is based on the 120° East meridian. It is the time difference between the area where the structure is located and Beijing. This is the time difference between the area where the structure is located and Beijing, which can be calculated using the following formula: (14); When sunlight passes through the atmosphere, it is scattered by molecules in the atmosphere. The portion that changes direction is called sky scattering. The intensity of sky scattering at any angle can be determined by the following formula: (2); in, It is the value of direct solar radiation. It is the solar constant. After sunlight passes through the atmosphere, it reaches the ground and undergoes diffuse reflection. The portion that enters the structure is reflected by the ground. The intensity of ground reflection can be determined by the following formula: (3); in, It is the surface reflectance. The sky scattering value on the horizontal plane is calculated using the following formula: (15); The solar radiation received by the structure's surface includes direct radiation, sky scattering, and surface reflection. This is subtracted based on the material's absorptivity, resulting in the amount of solar radiation absorbed by the structure itself, which can be calculated using the following formula: (16); in, It is the shortwave radiation absorptivity.

[0030] Total radiative heat transfer in concrete represents the difference between the heat absorbed and the heat dissipated by the concrete, including atmospheric radiation and concrete thermal radiation, and can be obtained using the following formula: (4); in, This is the radiative heat transfer coefficient, with units of W / (m²·K⁴), which can be obtained using the following formula: (17); in, This refers to emissivity; for concrete surfaces, it is typically taken as 0.88. It is the Stefan-Boltzmann constant, which is 5.67 × 10⁻⁸ W / (M²·K⁴). It is ambient temperature. This refers to the surface temperature of the structure. In Ansys finite element analysis, thermal radiation between objects can be expressed by the following formula: (18); in, It is heat flux density. It is the shape factor between radiating surfaces. It is the temperature of the first radiating surface. It is the temperature of the second radiating surface.

[0031] Thermal convection is the transfer of heat between different spaces through a flowing medium. This type of heat transfer can only occur in fluids, and convection is usually more pronounced in gases than in liquids. According to Newton's equation of cooling, the formula for thermal convection can be expressed as follows: ; in, It is the heat transfer coefficient. It is the structural temperature. It refers to the ambient temperature.

[0032] The convective heat transfer coefficient is usually determined using an empirical formula. When the wind speed v is less than or equal to 5 m / s, the calculation formula is as follows: (19); When the wind speed v is greater than 5 m / s, the calculation formula is: (20); Heat conduction is the transfer of heat between two objects at different temperatures in contact, or it can be the transfer of heat within an object. According to Fourier's law, the formula for heat conduction can be expressed as follows: (twenty one); in, It is heat flux density. It is the thermal conductivity; The formula for calculating convective heat transfer is: (twenty two); in, It is the convective heat transfer coefficient, with units of W / (m²·K⁴).

[0033] Specifically, step C, temperature field calculation and result analysis, is as follows: c1. Boundary Conditions and Load Application: Define the boundary conditions and load conditions in the finite element model. When solving for the temperature field, the boundary conditions and loads are the ambient temperature and heat transfer coefficient. When solving for temperature effects, the boundary conditions are freedom constraints, and the loads applied include static loads and dynamic loads. c2. Solver settings: Configure the solver to perform numerical calculations of the structural response based on the established mathematical model. Appropriate time steps and analysis types need to be set. c3. Temperature Field Calculation and Result Analysis: After the preliminary solution is completed, a sensitivity analysis is performed to evaluate the impact of different parameters on the analysis results. The temperature field variation report includes three parts: analysis of temperature field variation at different times of the day, analysis of temperature field variation from different orientations, and analysis of temperature field variation in different seasons. Using the bearing displacement of a long-span railway bridge as an example, its long-term and short-term time-history variation patterns are analyzed. Figure 3 and Figure 4 As shown.

[0034] Specifically, the calculation and result analysis of the effect field in step C are as follows: After the temperature field is solved, the effect field is calculated to assess the changes in various indicators under the influence of the temperature field. The calculation of the temperature effect is consistent with the actual monitoring project. First, establish a structural field model; Subsequently, the temperature field calculation results are applied to the structural field, and boundary condition constraints and external loads are applied to the structural model. Finally, set up the solver and perform structural calculations.

[0035] Specifically, the monitoring data decoding and preprocessing in step D are as follows: First, data decoding includes connecting to the health monitoring platform, data packet transmission, timestamp-based data matching, timestamp-based data decoding, and the output of the decoded data. Then, data preprocessing includes outlier removal, acquisition frequency transformation, and data separation. Data separation separates the temperature effect from the effects caused by vehicle load and environmental noise. The methods used include, but are not limited to, EMD, VMD, and wavelet transform.

[0036] Specifically, the multi-indicator long-term and short-term time-series analysis in step E is as follows: Temperature effect analysis indicators were selected from the whole bridge level, including ambient temperature, structural temperature, support displacement, vertical static deflection of the main truss, vertical dynamic deflection of the main truss, lateral deformation of the main truss, modal parameters, tower top displacement, etc. The temperature effect is divided into two parts in terms of time: long-term analysis and short-term analysis. The long-term analysis of the temperature effect analyzes the annual variation pattern at the whole year level and plots the long-term time-course variation curve. The short-term analysis of the temperature effect analyzes the short-term variation pattern from the perspectives of a single day and three consecutive days and plots the short-term time-course variation curve. By comparing the theoretically calculated effect field with actual structural monitoring data, the finite element model can be verified and reasonably corrected. The theoretical effect field is a mathematical model established based on the physical characteristics of the bridge structure and the temperature field variation law, while the measured values ​​are temperature and structural response data collected in real time by on-site monitoring equipment. The comparison between the two helps to reveal the differences between the theoretical model and the actual engineering situation, thereby further correcting the finite element model. Taking the support displacement and mid-span deflection of a long-span railway bridge as an example, we analyze their long-term and short-term time history variation patterns. The support displacement is as follows: Figure 5 and Figure 6 As shown, the mid-span deflection is as follows Figure 9 and Figure 10 As shown.

[0037] Specifically, the multi-indicator long-term and short-term temperature correlation analysis in step F is as follows: Temperature-related indicators were selected from the entire bridge level, including ambient temperature, structural temperature, support displacement, vertical static deflection of the main truss, vertical dynamic deflection of the main truss, lateral deformation of the main truss, modal parameters, and tower top displacement. Temperature correlation analysis is divided into two parts: long-term analysis and short-term analysis. The long-term analysis analyzes the annual correlation at the whole year level and draws a scatter plot, while the short-term analysis analyzes the daily correlation and draws a scatter plot. The correlation variation of various indicators on a single day was studied by nonlinear fitting. The correlation between annual variations was studied by fitting monthly mean values; The summary report on temperature effects includes analysis of the long-term and short-term time history changes of indicators such as ambient temperature, structural temperature, support displacement, vertical static deflection of the main truss, vertical dynamic deflection of the main truss, lateral deformation of the main truss, modal parameters, and tower top displacement, as well as their correlation with temperature.

[0038] Based on the revised and updated finite element model, the analysis of temperature effects is extended from the traditional limited monitoring points to the entire bridge level. The temperature field and temperature effects at different orientations, heights, and locations of the entire bridge are analyzed in detail. The temperature effects require detailed analysis of key indicators of railway bridges, such as bridge alignment and beam end displacement.

[0039] The bridge temperature-induced response assessment report includes the annual extreme values ​​of indicators such as ambient temperature, structural temperature, support displacement, main truss vertical static deflection, main truss vertical dynamic deflection, main truss lateral deformation, modal parameters, and tower top displacement, as well as safety limits considering specifications and design values.

[0040] Taking the bearing displacement and mid-span deflection of a long-span railway bridge as an example, this paper analyzes their long-term and short-term temperature-related variation patterns. The bearing displacement is as follows: Figure 7 and Figure 8 As shown, the mid-span deflection is as follows Figure 11 and Figure 12 As shown.

[0041] The temperature effect analysis method and system of this invention is a key step in ensuring the safe operation of bridges. It can collect bridge temperature and structural response in real time, effectively quantify the degree of influence of temperature on bridge response, analyze the long-term and short-term variation patterns of temperature-induced effects, evaluate the operation of bridges under temperature effects, determine whether there are any over-limit situations, and promptly detect and eliminate potential safety hazards in bridge structures, providing decision-making guidance for bridge maintenance and management.

[0042] This invention enables a comprehensive analysis of temperature fields and temperature effects, providing effective support for improving the analysis of health monitoring data for railway bridges.

Claims

1. A method for analyzing temperature effects of a long-span railway cable-stayed bridge, characterized in that: The method comprises the following steps: A. In the theoretical numerical simulation analysis module, a three-dimensional refined finite element model suitable for temperature field analysis is constructed according to the geometric dimensions and material parameters provided by the design; B. Combined with the geographical location and meteorological data of the bridge, the key parameters, i.e. solar inclination, solar elevation angle and day number, are determined; the solar radiation intensity is calculated, and the corresponding solar radiation absorption coefficient is determined; C. Based on the refined finite element model and the solar radiation amount, heat boundary conditions are applied, appropriate convective heat transfer coefficients are set, the temperature field distribution of the main beam section and the tower is calculated, and then the effect field is calculated based on thermal coupling, the temperature field and effect field cloud map is generated, and the temperature field and temperature effect change rule report is formed; D. In the measured data rule research module, the original data of the bridge health monitoring system is obtained, decoded and classified to form effective data for analysis, and preprocessed; E. Based on multiple indicators in the whole bridge range, the temperature effect is comprehensively analyzed, the long-term and short-term time history change rules are studied, and the measured point temperature effect is compared with the theoretical effect field to verify the effectiveness of the finite element model; F. Combined with the measured temperature and various indicators, the long-term and short-term correlation of temperature is analyzed, the model effectiveness is verified, and the temperature field, temperature effect at different directions, different heights and different positions of the whole bridge are analyzed in detail, and the temperature effect rule summary report and bridge temperature response evaluation report are generated.

2. The method for analyzing temperature effect of long-span railway cable-stayed bridge according to claim 1, characterized in that: Step A: In the theoretical numerical simulation analysis module, a three-dimensional refined finite element model suitable for temperature field analysis is constructed according to the geometric dimensions and material parameters provided by the design, the specific process is as follows: Firstly, the three-dimensional refined finite element model includes the main beam section entity finite element model and the tower entity finite element model; Then, the model construction is operated based on Ansys command stream; Later, the construction process includes size division, material property definition, element type selection, mesh division; Finally, the theoretical numerical analysis subsystem includes the refined finite element model construction module, the solar radiation calculation module, the temperature field calculation and result analysis module.

3. The method for analyzing temperature effect of long-span railway cable-stayed bridge according to claim 1, characterized in that: Step B: Combined with the geographical location and meteorological data of the bridge, the key parameters, i.e. solar inclination, solar elevation angle and day number, are determined; the solar radiation intensity is calculated, and the corresponding solar radiation absorption coefficient is determined, the specific process is as follows: b1. Calculate the direct solar radiation intensity: （1）； wherein is the direct solar radiation value, is the solar constant, is the atmospheric transparency, is the atmospheric optical quality, is the solar incidence angle; b2. Calculate the sky scattering intensity: （2）； wherein is the direct solar radiation value, is the solar constant; b3. Calculate the ground reflection intensity: （3）； wherein is the surface reflectance, is the sky diffuse value on the horizontal plane; b4. Calculate the convective and radiative heat transfer: The total radiation heat transfer of concrete is: （4）； wherein is the radiative heat transfer coefficient; the heat convection transfer is expressed as ; wherein is the heat transfer coefficient, is the structure temperature, is the ambient temperature.

4. The method for analyzing temperature effect of long-span railway cable-stayed bridge according to claim 1, characterized in that: Step C: Based on the refined finite element model and the solar radiation amount, heat boundary conditions are applied, appropriate convective heat transfer coefficients are set, the temperature field distribution of the main beam section and the tower is calculated, and then the effect field is calculated based on thermal coupling, the temperature field and effect field cloud map is generated, and the temperature field and temperature effect change rule report is formed, the specific process is as follows: Firstly, the temperature field calculation includes heat boundary condition application, time step selection, solver setting and calculation; Then, the temperature effect calculation includes constraint boundary condition application, temperature field calculation load application, solver setting and calculation; Then, the thermal coupling calculation includes structural model construction, temperature field calculation result application, boundary constraint application, load application, and solver setting and calculation; Then, the effect field calculation and extraction content should be unified with the health monitoring indicators; Finally, the temperature field change law report includes single-day different time temperature field change law analysis, different direction temperature field change law analysis, and different season temperature field change law analysis.

5. The method for analyzing temperature effect of long-span railway cable-stayed bridge according to claim 1, characterized in that: In the measured data law research module, step D obtains the original data of the bridge health monitoring system, decodes and classifies the data, forms effective data for analysis, and performs preprocessing, the specific process is as follows: First, data decoding includes health monitoring platform entry docking, data packet transmission, timestamp-based data matching, timestamp-based data decoding, and data decoding and arrangement output; Then, data preprocessing includes outlier rejection, sampling frequency conversion, and data separation; Finally, the measured data law research subsystem includes data transmission decoding and preprocessing module, multi-index long-term and short-term time course law analysis module, and multi-index long-term and short-term temperature correlation analysis module.

6. The method for analyzing temperature effect of long-span railway cable-stayed bridge according to claim 1, characterized in that: Step E, based on multiple indicators in the whole bridge range, conducts a comprehensive analysis of temperature effect, focuses on the change law of long-term and short-term time course, and compares the measured point temperature effect with the theoretical effect field to verify the effectiveness of the finite element model, the specific process is as follows: First, the temperature effect analysis indicators are selected from the whole bridge level, including environmental temperature, structural temperature, support displacement, main truss vertical static deflection, main truss vertical dynamic deflection, main truss lateral deformation, modal parameters, and tower top displacement; Then, the temperature effect is divided into long-term analysis and short-term analysis from the time; Then, the temperature effect long-term analysis analyzes the annual change law from the whole year level and draws the long-term time course change curve; Then, the measured point data is compared with the calculated data of the corresponding point of the finite element model to verify the effectiveness of the finite element model and improve the availability of the finite element model calculation results; Finally, the temperature effect short-term analysis analyzes the short-term change law from the single day and three consecutive days and draws the short-term time course change curve.

7. The method for analyzing temperature effect of long-span railway cable-stayed bridge according to claim 1, characterized in that: Step F, combining the measured temperature with various indicators, conducts long-term and short-term correlation analysis of temperature, verifies the effectiveness of the model, and analyzes the temperature field, temperature effect in different directions, different heights, and different positions of the whole bridge in detail, and generates a temperature effect law summary report and a bridge temperature response evaluation report, the specific process is as follows: First, the temperature correlation indicators are selected from the whole bridge level, including environmental temperature, structural temperature, support displacement, main truss vertical static deflection, main truss vertical dynamic deflection, main truss lateral deformation, modal parameters, and tower top displacement; Then, the temperature correlation is divided into long-term analysis and short-term analysis from the time; Then, the long-term analysis analyzes the annual correlation from the whole year level and draws a scatter plot, and the short-term analysis analyzes the daily correlation and draws a scatter plot; Then, the single-day index correlation change law is studied through nonlinear fitting; Then, the annual change correlation is studied through monthly mean fitting; Then, the temperature field of the full bridge in different directions, different heights and different positions is analyzed in detail, and the temperature effect is mainly analyzed in detail on the key indicators such as bridge alignment and beam end displacement; Then, the temperature effect law summary report includes environmental temperature, structure temperature, support displacement, main truss vertical static deflection, main truss vertical dynamic deflection, main truss lateral deformation, modal parameters, tower top displacement and other index long-term and short-term time change law analysis and temperature correlation analysis; Finally, the bridge temperature response evaluation report includes environmental temperature, structure temperature, support displacement, main truss vertical static deflection, main truss vertical dynamic deflection, main truss lateral deformation, modal parameters, tower top displacement and other index annual change extreme value and safety limit considering specification and design value.

8. The system for analyzing temperature effects of long-span railway cable-stayed bridges according to claim 1, wherein: The system of integrated large-span railway cable-stayed bridge temperature effect analysis method includes theoretical numerical simulation analysis module and measured data law research module.

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