A method and system for dynamic evaluation of fatigue life of orthotropic steel bridge deck

Abstract

This invention relates to the field of bridge structural health monitoring technology, specifically to a method and system for dynamic assessment of the fatigue life of orthotropic steel bridge decks. The method includes the following steps: obtaining the initial welding residual stress level, structural configuration influence coefficient, and historical traffic load spectrum of the target stud; calculating the residual stress reduction coefficient caused by vibration aging based on the cumulative number of traffic load cycles; quantifying the crack damage index by performing non-destructive testing on the weld between the bridge deck top plate and stiffeners, and determining the stud stress amplification factor caused by damage to the top plate system based on the crack damage index; coupling the initial welding residual stress level, the structural configuration influence coefficient, the residual stress reduction coefficient, the stress amplification factor, and the traffic load spectrum to construct a fatigue damage balance equation, and solving the fatigue damage balance equation to obtain the remaining fatigue life of the stud. This invention effectively improves the reliability and engineering applicability of the assessment results.

Description

Technical Field

[0001] This invention relates to the field of bridge structural health monitoring technology, specifically to a method and system for dynamic evaluation of fatigue life of orthotropic steel bridge decks. Background Technology

[0002] Orthotropic steel bridge decks are widely used in long-span bridges due to their lightweight and high strength. However, their complex welded structure is prone to fatigue cracking under heavy loads and repeated traffic loads. Existing fatigue assessment methods mainly focus on hot spots such as the welds between the top plate and the U-ribs, and do not pay enough attention to the fatigue problems of shear studs that ensure the coordinated work of the bridge deck pavement and steel plates.

[0003] Existing assessment methods typically suffer from the following limitations: 1) Isolated assessment: Treating studs as independent components without considering their interaction with the overall bridge deck structure (such as U-ribs and diaphragms); 2) Static assumptions: Often employing fixed welding residual stress values, neglecting their relaxation (vibration aging) effects under long-term traffic cyclic loads; 3) Lack of feedback: Assessment models are mostly open-loop predictions, unable to utilize easily observable system damage (such as roof cracks) generated during bridge service to invert and correct the hidden damage state of studs. This leads to assessment results that are conservative or risky, failing to achieve accurate life prediction and scientific maintenance decisions based on real-time conditions. Summary of the Invention

[0004] To address the shortcomings of existing methods and the needs of practical applications, and in order to solve the aforementioned problems, this invention provides a dynamic evaluation method for the fatigue life of orthotropic steel bridge decks, comprising the following steps: The initial welding residual stress level, structural configuration influence coefficient, and historical traffic load spectrum of the target stud are obtained. Based on the cumulative number of traffic load cycles, the residual stress reduction coefficient caused by vibration aging is calculated. By performing non-destructive testing on the weld between the bridge deck top plate and the stiffening rib, the crack damage index is quantified, and the stud stress amplification factor caused by damage to the top plate system is determined based on the crack damage index. The initial welding residual stress level, the structural configuration influence coefficient, the residual stress reduction coefficient, the stress amplification factor, and the traffic load spectrum are coupled to construct a fatigue damage balance equation, and the remaining fatigue life of the stud is obtained by solving the fatigue damage balance equation.

[0005] Optionally, the initial welding residual stress level is obtained through thermo-mechanical coupled finite element welding simulation, or by querying a preset residual stress database based on welding process parameters, stud diameter, spacing and ambient temperature.

[0006] Optionally, the structural configuration influence coefficient is obtained through parametric finite element analysis, and the input parameters of the parametric finite element analysis include at least the stiffening rib type, stiffening rib spacing, and top plate thickness.

[0007] Optionally, the residual stress reduction factor caused by vibration aging is calculated based on the cumulative number of traffic load cycles, satisfying the following: in, This represents the residual stress reduction factor. This represents the cumulative equivalent number of reload cycles up to time t. The average load level borne by the stud. For yield load, This represents the relaxation rate coefficient, used to control how quickly the residual stress decreases with the number of cycles. This represents the load sensitivity index, which reflects the degree of nonlinear influence of the average load level on the relaxation rate.

[0008] Optionally, the crack damage index is a scalar value obtained by comprehensively quantifying the crack length, depth, density, and location information obtained from nondestructive testing.

[0009] Optionally, determining the stud stress amplification factor caused by damage to the roof system based on the crack damage index includes the following steps: By establishing a finite element model that includes crack morphology determined based on the crack damage index. By comparing and analyzing the stress response changes at the stud weld toe before and after the crack appeared, the stress amplification factor was obtained.

[0010] Optionally, the fatigue damage balance equation divides the service history into three stages: before the initiation of roof cracks, after the initiation to the present, and the future, satisfying: in, This indicates the accumulated fatigue damage of the studs during the period from the time the bridge was completed and opened to traffic until the first macroscopic fatigue crack appeared in the weld between the top plate and the U-rib. This indicates the accumulated fatigue damage of the studs from the first appearance of a macroscopic crack in the top plate to the current inspection time. This indicates the cumulative fatigue damage that the stud will accumulate from the current detection time until fatigue failure occurs in the future.

[0011] Optionally, the initial welding residual stress level, the structural configuration influence coefficient, the residual stress reduction coefficient, the stress amplification coefficient, and the traffic load spectrum are coupled to construct a fatigue damage equilibrium equation that satisfies: in, The time for crack initiation in the roof slab. Represents the load frequency function. , The SN curve parameters represent the stud welded joint. The SN curve of the stud welded joint is obtained through fatigue testing, and the slope of the straight line obtained after fitting is... And the intercept is , This represents the influence coefficient of structural configuration. The reference stress amplitude function is defined as a function of the nominal stress amplitude at the stud weld toe, obtained from the standard fatigue load model and influence line analysis, under the condition that the orthotropic steel bridge deck structure is intact (i.e., without top plate cracks), and reflects the time-varying characteristics of the traffic load spectrum. This indicates the initial residual stress level at the stud weld toe along the longitudinal direction of the bridge. This represents the residual stress reduction factor. Indicates the tensile strength of the material. Indicates the current service time. Indicates the stress amplification factor. This indicates the remaining fatigue life of the stud.

[0012] Optionally, under the condition that the traffic load spectrum is stable, the damage balance equation can be simplified to an explicit formula solution, satisfying: in, Indicates the average number of equivalent load cycles per year. = Average daily traffic volume × proportion of heavy vehicles × lane distribution coefficient × 365 Take the stable value at the current moment.

[0013] This invention quantitatively couples four dimensions—welding residual stress, traffic load, overall structural configuration, and observable top plate system damage—establishing a link between stud fatigue and the overall mechanical state of the bridge deck. It also considers the relaxation evolution of welding residual stress during service, enabling the assessment model to reflect the time-varying characteristics of the material state. Utilizing easily detectable top plate crack conditions as feedback signals, the assessment model is corrected through a stress amplification factor, placing the assessment of hidden stud damage on visible system damage evidence. This significantly improves the reliability and engineering applicability of the assessment results. Finally, it integrates all key parameters and provides a clear remaining life calculation process, facilitating software development or integration into bridge health monitoring systems for dynamic life prediction and early warning.

[0014] Secondly, to efficiently execute the dynamic fatigue life assessment method for orthotropic steel bridge decks provided by this invention, this invention also provides a dynamic fatigue life assessment system for orthotropic steel bridge decks, comprising: an input device, an output device, a processor, and a memory, wherein the input device, output device, processor, and memory are interconnected, and the memory stores program instructions used for the dynamic fatigue life assessment method for orthotropic steel bridge decks. The dynamic fatigue life assessment system for orthotropic steel bridge decks of this invention has a compact structure and stable performance, and can stably execute the dynamic fatigue life assessment method for orthotropic steel bridge decks provided by this invention, further enhancing the overall applicability and practical application capability of this invention. Attached Figure Description

[0015] Figure 1 A flowchart of a dynamic evaluation method for fatigue life of orthotropic steel bridge decks provided in an embodiment of the present invention; Figure 2 This is a framework diagram of a dynamic fatigue life assessment system for orthotropic steel bridge decks provided in an embodiment of the present invention. Detailed Implementation

[0016] Specific embodiments of the present invention will now be described in detail. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other instances, well-known circuits, software, or methods have not been specifically described to avoid obscuring the invention.

[0017] Throughout this specification, references to "an embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "in an embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale.

[0018] Please see Figure 1 To address the aforementioned problems, this invention provides a method for dynamically evaluating the fatigue life of orthotropic steel bridge decks, such as... Figure 1 As shown, in one embodiment, the method includes the following steps: S1. Obtain the initial welding residual stress level of the target stud, the structural configuration influence coefficient, and the bridge's historical traffic load spectrum.

[0019] First, determine the initial residual welding stress level at the target stud weld toe along the longitudinal direction of the bridge. The parameters are determined based on welding process parameters, stud diameter and spacing, and ambient temperature through a thermo-mechanical coupled finite element model or empirical database. For example, through finite element thermo-mechanical coupled analysis and experimental data, key welding parameters and the residual stress level at the stud weld toe along the longitudinal direction of the bridge can be established. Quantification relationship: Welding heat input (E): High heat input typically results in higher residual stress; Diameter (d) and spacing (S): The larger the diameter and the smaller the spacing, the stronger the thermal accumulation effect, which may lead to a higher overlap of residual stress zones; Ambient temperature (T): Low-temperature welding may result in a larger thermal gradient.

[0020] Output: A database or empirical formula of initial residual stress field based on design / process parameters.

[0021] Secondly, determine the structural configuration influence coefficient. The stiffening rib type, spacing, and top plate thickness based on orthotropic plates are determined through parametric finite element analysis, reflecting the degree of local stress concentration at the studs under non-destructive conditions, including: Parametric analysis: The stiffening rib type (U-rib, bulb flat steel), spacing, and top plate thickness are used as variables to perform systematic finite element analysis.

[0022] Force distribution: A denser and stiffer U-rib system can transfer more of the bending load of the roof plate directly to the diaphragms, which may reduce the stress at the welds connecting the roof plate and the U-ribs, but may slightly increase the shear force borne by the studs to ensure the coordinated operation of the pavement.

[0023] Local stiffness abrupt change: The stress concentration of the stud weld is located on the upper surface of the top plate and is affected by the position of the U-rib weld below. Staggering the studs and U-rib welds can avoid stress field superposition.

[0024] Output correction factor: Define a configuration influence factor ( ), used to correct stress amplitude. For systems with high stiffness and close ribs, at the studs It may be close to or slightly greater than 1; for systems with weak stiffness, It may be significantly greater than 1.

[0025] Furthermore, based on the bridge's historical traffic flow data, the service time T is determined, and the historical fatigue load cycle spectrum is calculated accordingly.

[0026] Based on historical traffic flow data of the bridge, the following steps are used to determine the historical fatigue load spectrum: (1) Collect historical traffic volume statistics and toll station weighing data for the road section where the bridge is located, and obtain basic information such as vehicle type, total weight, and axle load distribution; (2) Based on the fatigue load model classification standard in the General Specifications for Highway Bridge and Culvert Design (JTG D60-2015), vehicles are classified and statistically analyzed to obtain the annual average daily traffic volume (AADT) of each type of vehicle and its variation over time. (3) Considering the annual growth rate of traffic volume, the service life of the bridge is divided into several characteristic periods, and the cumulative number of times of various types of vehicles pass through each period is counted to form a historical fatigue load frequency spectrum. (4) This load spectrum will be used as input for subsequent influence line analysis to calculate the historical stress history and stress spectrum at the stud weld toe.

[0027] S2. Calculate the residual stress reduction factor caused by vibration aging based on the cumulative number of traffic load cycles.

[0028] In this embodiment, the residual stress reduction factor caused by vibration aging is calculated based on the cumulative number of traffic load cycles, satisfying the following: in, This represents the residual stress reduction factor. This represents the cumulative equivalent number of reload cycles up to time t. The average load level borne by the stud. For yield load, This represents the relaxation rate coefficient, used to control how quickly the residual stress decreases with the number of cycles. This represents the load sensitivity index, which reflects the degree of nonlinear influence of the average load level on the relaxation rate. = Average daily traffic volume × proportion of heavy vehicles × lane distribution coefficient × number of years in service.

[0029] The larger the value, the greater the decrease in residual stress for the same number of cycles. Its physical nature is related to the cyclic softening characteristics of the material, the initial residual stress level, and the microstructure of the weld joint. The larger the load, the more significant the relaxation rate will be, even with a small increase in load. Its physical nature is related to the material's yield ratio and cyclic plastic deformation capacity. These two parameters need to be obtained through laboratory cyclic loading tests, monitoring the decay data of residual stress with the number of cycles, and then fitting the data using nonlinear regression. The calibration process for the β parameter is as follows: Specimen preparation (in accordance with GB / T-3075-2021): Welded test pieces were made using the same materials, welding process, plate thickness, and stud specifications as the actual structure, with a surface roughness Ra≤0.8μm to eliminate the influence of machining.

[0030] Initial residual stress measurement (according to GB / T-7704-2017): The initial residual stress peak at the weld toe was measured using an X-ray diffractometer. According to the specifications, the alignment error measurement accuracy of the calibrated instrument should be controlled within ±10MPa.

[0031] Multiple sets of cyclic loading tests (according to GB / T-15248-2008): Test grouping: Design 3-5 groups of cyclic loading tests with different load levels. The values ​​can be 0.1, 0.2, 0.3, 0.4, 0.5, etc.

[0032] Loading control: Strain control mode is adopted, following the specifications.

[0033] Waveform settings: Triangle wave or sine wave, frequency 0.1-5Hz (low-cycle fatigue range).

[0034] Number of loops: at least 10 5 ~10 6 The next cycle covers the main phase of residual stress relaxation.

[0035] Periodic residual stress measurement (according to GB / T-7704-2017): During loading, the machine is periodically stopped and unloaded, and residual stress is measured at the same measuring points; the measuring point locations are fixed to ensure data comparability; the number of cycles is recorded. Corresponding measured values ​​of residual stress Calculate the residual stress retention ratio Data fitting and parameter determination: Multiple sets of experimental data points The data is aggregated and fitted to the formula using nonlinear regression (such as least squares): Solve for the optimal solution using mathematical software (MATLAB, etc.) and β value.

[0036] Verification experiment: The accuracy of the prediction formula is verified by validation set experiments independent of the fitted data, ensuring that the model is within the engineering-acceptable error range.

[0037] S3. By performing non-destructive testing on the welds between the top plate of the bridge deck and the stiffening ribs, the crack damage index is quantified, and the stud stress amplification factor caused by the damage to the top plate system is determined based on the crack damage index.

[0038] Determination of Crack Damage Index (CDI) The Crack Damage Index (CDI) is a scalar value obtained by comprehensively quantifying the crack geometric parameters and location information obtained through non-destructive testing. The quantification method is as follows: First, the crack length at the weld between the top plate and the U-rib is obtained through non-destructive testing. ,depth Number of cracks per unit length and the importance coefficient of the location of the crack ; Then, calculate the CDI value using the following formula: in, For reference crack length, For the thickness of the top plate, For reference crack density, The weighting coefficients are satisfied. .

[0039] Stress amplification factor The determination The stress amplification factor Determined through the following steps: (1) Establish a local fine finite element model of the top plate-U rib-stud in good condition, apply representative loads, and extract the stress response at the stud weld toe. ; (2) Based on the crack morphology (crack length, depth, and location) determined by the Crack Damage Index (CDI), cracks are introduced into the intact model using solid modeling to establish a finite element model containing cracks. (3) Apply the same load as in step (1) to the cracked model and extract the stress response at the stud weld toe. ; (4) Calculate the stress amplification factor: The stress concentration effect caused by cracks is known ; (5) Establish through parametric analysis Functional relationship with CDI This is used for subsequent fatigue life assessment. (Take a series of different CDI values ​​(e.g., 0.1, 0.2, 0.3, ..., 1.0), and for each CDI value, calculate its mapping relationship with crack geometry parameters (e.g., ...). Establish the corresponding finite element model containing cracks to calculate the corresponding... Values ​​are fitted to obtain a functional relationship: ) Furthermore, the initiation time of the roof cracks was determined. In this embodiment, if precise records are unavailable, the time point from the last nondestructive testing where no cracks were detected can be conservatively taken.

[0040] S4. Couple the initial welding residual stress level, the structural configuration influence coefficient, the residual stress reduction coefficient, the stress amplification coefficient, and the traffic load spectrum to construct a fatigue damage balance equation, and solve the fatigue damage balance equation to obtain the remaining fatigue life of the stud.

[0041] The fatigue damage balance equation divides the service history into three stages: before the initiation of roof cracks, after the initiation to the present, and the future, satisfying the following: in, This indicates the accumulated fatigue damage of the studs during the period from the time the bridge was completed and opened to traffic until the first macroscopic fatigue crack appeared in the weld between the top plate and the U-rib. This indicates the accumulated fatigue damage of the studs from the first appearance of a macroscopic crack in the top plate to the current inspection time. This indicates the cumulative fatigue damage that the stud will accumulate from the current detection time until fatigue failure occurs in the future.

[0042] Furthermore, based on historical traffic spectra and ,calculate ,include: Reference stress amplitude function Calculation: The Under the condition of structural integrity (no cracks in the roof slab), the time-varying function of the equivalent stress amplitude at the stud weld toe, calculated based on the historical traffic load spectrum, is determined according to the following steps: (1) Establish a local fine finite element model of the location of the target stud, and obtain the longitudinal stress influence line at the weld toe of the stud by moving the unit load. ; (2) Based on the historical traffic flow data of the bridge (including vehicle type, axle load distribution, axle spacing, and number of passes), compile the historical traffic load spectrum; (3) The historical traffic load spectrum is applied to the stress influence line, and the stress time history at the stud weld toe is obtained by convolution calculation. ; (4) The stress time history was statistically processed using the rainflow counting method to obtain the stress amplitude spectrum. ; (5) Based on the Miner linear cumulative damage criterion and the m-th power relationship of the SN curve, calculate the equivalent stress amplitude corresponding to the historical traffic load spectrum: When traffic volume varies over time, the service life needs to be divided into several time periods, and the equivalent stress amplitude for each time period needs to be calculated to form... function.

[0043] Furthermore, by coupling the initial welding residual stress level, the structural configuration influence coefficient, the residual stress reduction coefficient, the stress amplification coefficient, and the traffic load spectrum, a fatigue damage balance equation considering four-dimensional coupling and state feedback is constructed and solved to calculate the remaining life. : in, The time for crack initiation in the roof slab. Represents the load frequency function. , The SN curve parameters represent the stud welded joint. The SN curve of the stud welded joint is obtained through fatigue testing, and the slope of the straight line obtained after fitting is... And the intercept is , This represents the influence coefficient of structural configuration. The reference stress amplitude function is defined as a function of the nominal stress amplitude at the stud weld toe, obtained from the standard fatigue load model and influence line analysis, under the condition that the orthotropic steel bridge deck structure is intact (i.e., without top plate cracks), and reflects the time-varying characteristics of the traffic load spectrum. This indicates the initial residual stress level at the stud weld toe along the longitudinal direction of the bridge. This represents the residual stress reduction factor. Indicates the tensile strength of the material. Indicates the current service time. Indicates the stress amplification factor. This indicates the remaining fatigue life of the stud.

[0044] Based on this, under the condition that the traffic load spectrum is stable, the damage balance equation can be simplified to an explicit formula solution, satisfying: in, Indicates the average number of equivalent load cycles per year. = Average daily traffic volume × proportion of heavy vehicles × lane distribution coefficient × 365 Take the stable value at the current moment. In the original comprehensive integral formula, the stable value used is... The load frequency function, in the simplified formula, assumes that the traffic load is stable. Degenerate into a constant .

[0045] Taking a steel box girder bridge that has been in service for 15 years (T=15 years) as an example, a longitudinal crack was found in the top slab during a recent inspection (initiated when T1=12 years). First, based on the design drawings (U-rib spacing 300mm) and welding records, the following was obtained from the database: , Based on traffic statistics from the past 12 years, the current... The measured crack length ratio was high, with a CDI rating of 0.6, as determined by model analysis. The material parameter is taken as C = 1.2 × 10⁻⁶. 12 m=3. Current equivalent annual stress cycles .

[0046] Substitute the above parameters into the simplified formula to calculate: The assessment results indicate that, under the current damage condition, the remaining fatigue life of the studs in this area is approximately 5 years, requiring close monitoring in subsequent maintenance. A re-inspection or reinforcement measures are recommended within 3 years. Compared to traditional methods that ignore crack feedback, this invention provides an earlier and more targeted early warning.

[0047] Please see Figure 2 In an embodiment, to efficiently execute the dynamic fatigue life assessment method for orthotropic steel bridge decks provided by this invention, this invention also provides a dynamic fatigue life assessment system for orthotropic steel bridge decks, comprising: an input device 1, an output device 2, a processor 3, and a memory 4. The input device 1, output device 2, processor 3, and memory 4 are interconnected. The memory 4 stores program instructions used to execute the steps of the dynamic fatigue life assessment method for orthotropic steel bridge decks. The dynamic fatigue life assessment system for orthotropic steel bridge decks of this invention has a compact structure and stable performance, and can stably execute the dynamic fatigue life assessment method for orthotropic steel bridge decks of this invention, further improving the overall applicability and practical application capability of this invention.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A method for dynamic evaluation of fatigue life of orthotropic steel bridge decks, characterized in that, Includes the following steps: Obtain the initial welding residual stress level, structural configuration influence coefficient, and historical traffic load spectrum of the target stud; The residual stress reduction factor caused by vibration aging is calculated based on the cumulative number of traffic load cycles. By performing non-destructive testing on the welds between the top plate of the bridge deck and the stiffening ribs, the crack damage index is quantified, and the stud stress amplification factor caused by the damage to the top plate system is determined based on the crack damage index. By coupling the initial welding residual stress level, the structural configuration influence coefficient, the residual stress reduction coefficient, the stress amplification coefficient, and the traffic load spectrum, a fatigue damage balance equation is constructed, and the remaining fatigue life of the stud is obtained by solving the fatigue damage balance equation. The structural configuration influence coefficient is used to correct the stress amplitude; The residual stress reduction factor caused by vibration aging is calculated based on the cumulative number of traffic load cycles, satisfying the following: in, This represents the residual stress reduction factor. This represents the cumulative equivalent number of reload cycles up to time t. The average load level borne by the stud. For yield load, This represents the relaxation rate coefficient, used to control how quickly the residual stress decreases with the number of cycles. This represents the load sensitivity index, used to reflect the degree of nonlinear influence of the average load level on the relaxation rate; The fatigue damage equilibrium equation is constructed by coupling the initial welding residual stress level, the structural configuration influence coefficient, the residual stress reduction coefficient, the stress amplification coefficient, and the traffic load spectrum, satisfying: in, The time for crack initiation in the roof slab. Represents the load frequency function. , The SN curve parameters represent the stud welded joint. The SN curve of the stud welded joint is obtained through fatigue testing, and the slope of the straight line obtained after fitting is... And the intercept is , Indicates the influence coefficient of structural configuration. The reference stress amplitude function is defined as a function of the nominal stress amplitude at the stud weld toe, obtained from the standard fatigue load model and influence line analysis, under the condition that the orthotropic steel bridge deck structure is intact (i.e., without top plate cracks), and reflects the time-varying characteristics of the traffic load spectrum. This indicates the initial residual stress level at the stud weld toe along the longitudinal direction of the bridge. This represents the residual stress reduction factor. Indicates the tensile strength of the material. Indicates the current service time. Indicates the stress amplification factor. This indicates the remaining fatigue life of the stud.

2. The method for dynamic evaluation of fatigue life of orthotropic steel bridge decks according to claim 1, characterized in that, The initial residual stress level is obtained through thermo-mechanical coupled finite element welding simulation, or by querying a preset residual stress database based on welding process parameters, stud diameter, spacing and ambient temperature.

3. The method for dynamic evaluation of fatigue life of orthotropic steel bridge decks according to claim 1, characterized in that, The structural configuration influence coefficient is obtained through parametric finite element analysis. The input parameters of the parametric finite element analysis include at least the stiffening rib type, stiffening rib spacing, and top plate thickness.

4. The method for dynamic evaluation of fatigue life of orthotropic steel bridge decks according to claim 1, characterized in that, The crack damage index is a scalar value obtained by comprehensively quantifying the crack length, depth, density, and location information obtained from nondestructive testing.

5. The method for dynamic evaluation of fatigue life of orthotropic steel bridge decks according to claim 1, characterized in that, The determination of the stud stress amplification factor caused by damage to the roof system based on the crack damage index includes the following steps: By establishing a finite element model that includes crack morphology determined based on the crack damage index. By comparing and analyzing the stress response changes at the stud weld toe before and after the crack appeared, the stress amplification factor was obtained.

6. The method for dynamic evaluation of fatigue life of orthotropic steel bridge decks according to claim 1, characterized in that, The fatigue damage balance equation divides the service history into three stages: before the initiation of roof cracks, after the initiation to the present, and the future, satisfying the following: in, This indicates the accumulated fatigue damage of the studs during the period from the time the bridge was completed and opened to traffic until the first macroscopic fatigue crack appeared in the weld between the top plate and the U-rib. This indicates the accumulated fatigue damage of the studs from the first appearance of a macroscopic crack in the top plate to the current inspection time. This indicates the cumulative fatigue damage that the stud will accumulate from the current detection time until fatigue failure occurs in the future.

7. The method for dynamic evaluation of fatigue life of orthotropic steel bridge decks according to claim 1, characterized in that, Under stable traffic load spectrum conditions, the damage balance equation can be simplified to an explicit formula solution, satisfying: in, Indicates the average number of equivalent load cycles per year. Take the stable value at the current moment.

8. A dynamic evaluation system for the fatigue life of orthotropic steel bridge decks, characterized in that, The orthotropic steel bridge deck fatigue life dynamic evaluation system includes: an input device, an output device, a processor, and a memory. The input device, output device, processor, and memory are interconnected. The memory stores program instructions, which are used to execute the orthotropic steel bridge deck fatigue life dynamic evaluation method according to any one of claims 1-7.

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