A method for evaluating crack width of a composite bar concrete beam coupled with environment and load

Abstract

This invention relates to the field of bridge engineering structural health monitoring technology, and discloses a method for assessing crack width in composite reinforced concrete beams coupled with environment and load. The method includes: dividing the composite reinforced concrete beam into multiple assessment sections and acquiring its crack appearance characteristics and service background data; comparing the measured crack width with the theoretical crack response under initial interface conditions to determine if there is a deviation, and judging whether the deviation can be explained by an overload event; if not, marking the corresponding section as a suspected interface degradation zone, and using service background data to perform phased corrections to the interface constraint parameters; and outputting the safety assessment results, interface degradation level, and maintenance instructions for the assessment section based on the corrected constraint parameters. This application, by dividing the assessment section and correcting the initial interface constraint parameters, solves the problem in the prior art where the risk of crack propagation is severely underestimated due to neglecting the accumulation of damage within the interface transition zone.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering structural health monitoring technology, and in particular to a method and system for evaluating the crack width of composite reinforced concrete beams coupled with environment and load. Background Technology

[0002] In the maintenance and management of in-service composite reinforced concrete beams of cross-sea highway bridges, assessing crack width based on periodic inspection data is a routine step to ensure structural safety. Typically, inspectors select representative beam segments, measure surface crack widths visually using a combination of visual inspection and reading microscopes, record the maximum values, and then evaluate the beam's crack condition against the specified limits. This assessment usually utilizes the interfacial bond performance parameters and load-crack calculation models from the initial structural design phase, directly providing a conclusion on crack width. However, cross-sea highway bridges are exposed to the chloride environment of the marine atmosphere for extended periods and continuously bear repeated vehicle loads. Under these coupled environmental and load conditions, the implicit aspect of deriving safety assessment from measured crack widths—namely, the input parameter of the bond state in the reinforcement-concrete interface transition zone—often becomes an easily overlooked blind spot. After the beam has undergone sufficiently long environmental exposure and load cycles, the long-term chloride ion penetration and repeated interaction with vehicle loads can cause stress corrosion microcracks and weaken chemical bonding in the interfacial transition zone, leading to a decrease in local interfacial constraint stiffness. At this point, the surface crack width may not yet show obvious abnormalities, and the damage is mainly hidden internally. When processing measured crack data, the evaluation process still assumes the interface is intact and continues to use the initial interface bonding input parameters for back-calculation or comparison, thus ignoring the weakening effect of accumulated damage in the interface transition zone on crack restraint. Because the interface restraint stiffness is overestimated, the evaluation model may consider the load stress level or degree of degradation corresponding to the current crack width to be lower than the actual situation, leading to a severe underestimation of crack propagation risk. If locally wider cracks appear, existing evaluation methods tend to attribute them to accidental load overload rather than interface degradation, resulting in qualitative errors. This approach may mistakenly classify beam segments that have entered the accelerated deterioration stage as safe, delaying maintenance intervention. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this application discloses a method and system for evaluating the crack width of composite reinforced concrete beams that couples environment and load, aiming to solve the technical problem of inaccurate crack propagation risk assessment caused by neglecting the degradation of the reinforcement-concrete interface in existing technologies.

[0004] The technical solution of this application is as follows: In a first aspect, this application discloses a method for evaluating the crack width of composite reinforced concrete beams coupled with environment and load, including: The composite reinforced concrete member is divided into at least one evaluation section, and the crack appearance characteristics information and service background data of each evaluation section within the current inspection cycle are obtained. The crack appearance characteristics information includes at least the measured crack width, and the service background data includes at least environmental erosion data and load data. Based on the initial interface constraint parameters and load data of the interface between the composite reinforcement and concrete in the component, the theoretical benchmark crack width value of each evaluation section is determined. The deviation rate is determined based on the measured crack width and the theoretical benchmark crack width. When the deviation rate is greater than or equal to the preset allowable fluctuation threshold, the load data is used to determine whether the deviation rate can be explained by the overload event in the current detection cycle of the evaluation section. If not, the corresponding evaluation section is marked as a suspected interface degradation area. Based on the environmental erosion and load data of the suspected interface degradation zone, and combined with the preset coupling amplification factor, the interface damage index is calculated. The preset coupling amplification factor is used to characterize the coupling effect of environmental erosion and load on the interface. The interface damage index is used to correct the initial interface constraint parameters to obtain the equivalent interface constraint parameters. Based on the equivalent interface constraint parameters, the corrected theoretical benchmark crack width value of the suspected interface degradation zone is re-determined. Based on the corrected theoretical benchmark crack width value and interface damage index, the structural safety assessment results of the assessment section corresponding to the suspected interface degradation zone are output.

[0005] This technical solution enables dynamic correction of interface constraint parameters by introducing an interface damage index, effectively identifying the crack propagation potential caused by interface degradation and avoiding misjudging interface damage as accidental overload.

[0006] Optionally, the step of determining the theoretical benchmark crack width value for each evaluation section based on the initial interface constraint parameters and load data of the interface between the composite reinforcement and concrete in the member includes: Obtain the initial constitutive parameters of the component, including the initial elastic modulus of the composite reinforcement and the standard value of the tensile strength of the concrete; The comprehensive internal forces of the cross sections under stress state are calculated based on the load data. The comprehensive internal forces of the cross sections include the linear superposition of the extreme value of the live load bending moment and the dead load bending moment. The initial constitutive parameters, initial interface constraint parameters, and comprehensive internal forces of the cross section are input into the crack width analytical model for forward mechanical solution to obtain the theoretical reference crack width value. If the combined internal force of the section is lower than the concrete cracking moment and the measured crack width shows that the evaluation section has cracked, the corresponding evaluation section will be marked as an abnormal cracking state and regarded as a suspected interface degradation zone, directly triggering the calculation of the interface damage index.

[0007] This technical solution enables the rapid identification of abnormal cracked sections by comparing the comprehensive internal forces and cracking status of the cross-section, thereby improving the accuracy of the assessment.

[0008] Optionally, when the deviation rate is less than the preset allowable fluctuation threshold, or when the deviation rate can be explained by the overload event of the evaluation section in the current detection cycle, the corresponding evaluation section is determined as a normal section, and a processing action to maintain normal inspection is output.

[0009] This technical solution enables rapid screening of regular sections, reducing the workload of the assessment.

[0010] Optionally, the step of calculating the interface damage index based on environmental erosion data and load data of the suspected interface degradation zone, combined with a preset coupling amplification factor, includes: A modified chloride ion permeation model based on unsteady diffusion theory is adopted. The actual concentration of chloride ions reaching the surface of the composite reinforcement is calculated based on environmental erosion data. The environmental reduction factor is calculated by calling the preset environmental degradation empirical function. The degree of microcrack accumulation in the interface transition zone is calculated based on the stress amplitude spectrum data in the load data, and the fatigue degradation coefficient is calculated by calling the preset linear fatigue cumulative damage rule. The interface damage index is obtained by multiplying the environmental reduction factor and the fatigue degradation factor, and then multiplying by a preset coupling amplification factor.

[0011] This technical solution enables the quantification of the coupled damage to the interface caused by environmental erosion and fatigue load, and allows for accurate calculation of the degree of interface degradation.

[0012] Optionally, the initial interface constraint parameters include the initial bond stiffness and the ultimate bond strength; Crack appearance characteristics also include the measured thickness of the concrete protective layer; The steps for correcting the initial interface constraint parameters using the interface damage index to obtain the equivalent interface constraint parameters include: Construct stiffness reduction function and strength attenuation function based on interface damage index; Based on the measured concrete cover thickness and service background data, weak sections with measured concrete cover thickness lower than the preset value or with initial construction micro-defects are identified, and the weight of the interface damage index corresponding to the weak sections is increased. By using the weighted interface damage index and applying nonlinear reductions to the initial bond stiffness and ultimate bond strength through stiffness reduction and strength attenuation functions respectively, equivalent interface constraint parameters reflecting the actual bond performance of the suspected interface degradation zone in the current testing cycle are generated.

[0013] This technical solution enables precise correction of interface constraint parameters by combining construction defect information such as the thickness of the protective layer.

[0014] Optionally, after the step of redetermining the corrected theoretical benchmark crack width value of the suspected interface degradation zone based on the equivalent interface constraint parameters, the method further includes: Based on the corrected theoretical benchmark crack width value, the rate of change of crack width with load is calculated. The rate of change is used as a crack propagation sensitivity index to characterize the sensitivity of the suspected interface degradation zone to future load fluctuations under the current degradation state. If the crack propagation sensitivity index exceeds the preset sensitivity threshold, the corresponding assessment section will be marked as a high-concealed risk area.

[0015] This technical solution enables the prediction of crack propagation risks under future load fluctuations, achieving a leap from static assessment to dynamic risk warning.

[0016] Optionally, before calculating the rate of change of crack width with load based on the corrected theoretical benchmark crack width value, a residual reverse iterative calibration is performed on the suspected interface degradation zone, including: Obtain the residual value between the measured crack width of the suspected interface degradation zone and the corrected theoretical reference crack width value, and determine the absolute value of the residual value; When the absolute value of the residual is less than the preset allowable residual threshold, the value of the coupling amplification factor remains unchanged, and the crack propagation sensitivity index is determined directly based on the corrected theoretical benchmark crack width value. When the absolute value of the residual is not less than the preset allowable residual threshold, the value of the coupling amplification factor is adjusted according to the positive or negative direction of the residual. Based on the adjusted coupling amplification factor, the interface damage index is recalculated, the corrected theoretical benchmark crack width value is re-determined, and the residual value and the absolute value of the residual are updated until the absolute value of the updated residual is less than the preset allowable residual threshold, or the adjustment range of the coupling amplification factor reaches the preset physical limit boundary. After the residual reverse iterative calibration is completed, the calibrated coupling amplification factor is written into the service background data of the suspected interface degradation area as input for determining the interface damage index in subsequent evaluation cycles.

[0017] This technical solution enables the continuous optimization of the coupling amplification factor value through a reverse iterative calibration mechanism, thereby enhancing the adaptive capability of the evaluation model.

[0018] Optionally, when the adjustment range of the coupling amplification factor reaches the preset physical limit boundary and the absolute value of the updated residual value is still not less than the preset allowable residual threshold, the suspected interface degradation area is marked as a high-risk anomaly area with unknown mechanism, and the determination of the crack propagation sensitivity index is skipped. An abnormal intervention command is output to instruct the local damage exploration of the high-risk anomaly area with unknown mechanism.

[0019] This technical solution can identify anomalies that the model cannot explain and trigger timely human intervention to ensure structural safety.

[0020] Optionally, the steps for outputting the structural safety assessment results of the assessment segment corresponding to the suspected interface degradation zone include: The interface degradation level of the assessment section corresponding to the suspected interface degradation zone is determined by weighted scoring based on the ratio of the modified theoretical benchmark crack width value to the preset limit value, the interface damage index, and the crack propagation sensitivity index. The interface degradation levels include mild, moderate, severe, and critical levels. By combining future traffic flow growth models and environmental erosion data, a nonlinear time-series evolution algorithm is used to predict the crack evolution trajectory of the assessment sections corresponding to each suspected interface degradation zone within a preset future time window. For assessment sections with a severe or critical interface degradation level, the expected time window for the crack width of the assessment section to exceed the safety red line is determined based on the crack evolution trajectory corresponding to the assessment section. Different maintenance instructions are triggered based on the level of interface degradation. These instructions include maintaining routine inspections, increasing the frequency of retesting, introducing non-destructive testing equipment for localized key checks, and implementing early maintenance interventions. The system acquires on-site feedback information after the maintenance command is executed, and then inputs this feedback information back into the service background data of the suspected interface degradation area. This is used to dynamically correct the model parameters in the interface damage index calculation process, forming a closed-loop feedback correction mechanism.

[0021] This technical solution enables closed-loop management from assessment and early warning to maintenance decision-making, thereby improving maintenance efficiency.

[0022] Secondly, this application also discloses a system for evaluating the crack width of composite reinforced concrete beams coupled with environment and load, used to perform the steps in the above method, including: The segment division and data acquisition module is used to divide the composite reinforced concrete member into at least one evaluation segment and acquire the crack appearance characteristics information and service background data of each evaluation segment within the current testing cycle. The crack appearance characteristics information includes at least the measured crack width, and the service background data includes at least environmental erosion data and load data. The benchmark determination module is used to determine the theoretical benchmark crack width value of each evaluation section based on the initial interface constraint parameters and load data of the interface between the composite reinforcement and concrete in the component. The deviation determination module is used to determine the deviation rate based on the measured crack width and the theoretical benchmark crack width. When the deviation rate is greater than or equal to the preset allowable fluctuation threshold, it determines whether the deviation rate can be explained by the overload event in the current detection cycle of the evaluation section based on the load data. If not, the corresponding evaluation section is marked as a suspected interface degradation area. The damage quantification module is used to calculate the interface damage index based on environmental erosion data and load data of suspected interface degradation zones, combined with a preset coupling amplification factor. The preset coupling amplification factor is used to characterize the coupling effect of environmental erosion data and load data on the interface between composite reinforcement and concrete in the component. The interface damage index is used to correct the initial interface constraint parameters to obtain the equivalent interface constraint parameters. The parameter correction module is used to redetermine the corrected theoretical benchmark crack width value of the suspected interface degradation zone based on the equivalent interface constraint parameters. The safety assessment module is used to output the structural safety assessment results of the assessment section corresponding to the suspected interface degradation zone based on the corrected theoretical benchmark crack width value and interface damage index.

[0023] In summary, this application addresses the problem in existing technologies where the risk of crack propagation is severely underestimated due to neglecting the accumulation of damage within the interface transition zone. By dividing the composite reinforced concrete member into evaluation sections and introducing an interface damage index to correct the initial interface constraint parameters, this method solves the problem of severely underestimated crack propagation risk caused by neglecting the accumulation of damage within the interface transition zone. Through coupled calculations using environmental erosion data and load data, this method can accurately quantify the degradation of interfacial bonding performance. Combined with a residual reverse iterative calibration mechanism, it achieves dynamic optimization of the crack width assessment model. Compared to traditional methods, this application can identify hidden risks caused by interface degradation earlier and provide differentiated maintenance decisions, improving the safety and maintenance efficiency of in-service structures such as cross-sea highway bridges. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating a method for evaluating the crack width of a composite reinforced concrete beam coupled with environment and load, as provided in this application.

[0025] Figure 2 This is a structural schematic diagram of a composite reinforced concrete beam crack width assessment system coupled with environment and load, provided in this application.

[0026] Labeling Explanation: 201. Segment Division and Data Acquisition Module; 202. Benchmark Determination Module; 203. Deviation Determination Module; 204. Damage Quantification Module; 205. Parameter Correction Module; 206. Safety Assessment Module. Detailed Implementation

[0027] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0028] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0029] The technical solution of this application will be described in detail below with reference to the accompanying drawings.

[0030] To provide a clearer and more detailed explanation of the technical solutions in this application, the basic concepts involved are explained below.

[0031] Composite reinforced concrete members refer to concrete structural members in which non-metallic composite materials such as fiber-reinforced composites (e.g., FRP bars) replace traditional steel bars as the load-bearing skeleton. The difference between these members and ordinary reinforced concrete members lies not only in the material of the reinforcement, but also in their stress transmission paths, crack propagation mechanisms, and interfacial bond degradation mechanisms. For example, composite reinforcement typically does not experience the electrochemical corrosion expansion seen in steel bars, so surface cracking directly induced by corrosion may not appear. However, this does not mean the internal interface remains stable. Under the combined effects of marine chloride environments and repeated vehicle loads, the interlocking between the ribs, cladding, or sand coating on the composite reinforcement surface and the concrete may gradually weaken, leading to phenomena such as increased crack spacing, abnormal local crack width, and decreased crack recovery capacity under the same load.

[0032] Interface constraint parameters are physical quantities used to characterize the bond-slip properties between the composite reinforcement and the surrounding concrete, primarily reflecting their ability to deform collaboratively under stress. This parameter does not represent a single material strength value, but rather an equivalent representation of interfacial bonding, mechanical interlocking, frictional resistance, and local slip suppression capabilities. In practical applications, interface constraint parameters can be derived from design documents, material test reports, pull-out test results of similar components, or from a pre-established interface performance database. For example, when two beam sections use concrete of the same strength grade but have different surface treatments for the composite reinforcement—one with a plain round surface and the other with a sand-coated or spirally wound reinforced surface—their interface constraint parameters are usually different, with the latter often exhibiting stronger crack propagation suppression capabilities.

[0033] Coupling amplification factor: A dimensionless coefficient used to characterize the mutually reinforcing effects of environmental erosion and load fatigue, resulting in interfacial damage exceeding the simple superposition effect of their individual actions. Its initial value is greater than or equal to 1. Environmental erosion weakens the interfacial microstructure, making the interface more susceptible to slippage under cyclic loading. Conversely, cyclic loading promotes the expansion of existing microcracks, providing pathways for chloride and moisture to further penetrate the interface. Therefore, there is a mutually reinforcing relationship between the two. For example, in a chloride-rich environment with low load, interfacial degradation may be slow; however, at the same chloride level, if frequent heavy-load passage occurs simultaneously, the rate of interfacial damage development is usually faster. In this case, the coupling amplification factor is needed to reflect this "mutually reinforcing degradation" effect.

[0034] For this, see Figure 1 The technical solution disclosed in this embodiment is as follows: A method for evaluating the crack width of a composite reinforced concrete beam coupled with environment and load, comprising: S1. Divide the composite reinforced concrete member into at least one evaluation section, and obtain the crack appearance characteristics information and service background data of each evaluation section within the current testing cycle. The crack appearance characteristics information shall include at least the measured crack width, and the service background data shall include at least environmental erosion data and load data. S2. Based on the initial interface constraint parameters and load data of the interface between the composite reinforcement and the concrete in the component, determine the theoretical benchmark crack width value of each evaluation section. S3. Determine the deviation rate based on the measured crack width and the theoretical benchmark crack width. When the deviation rate is greater than or equal to the preset allowable fluctuation threshold, determine whether the deviation rate can be explained by the overload event in the current detection cycle of the evaluation section based on the load data. If not, mark the corresponding evaluation section as a suspected interface degradation area. S4. Based on the environmental erosion data and load data of the suspected interface degradation zone, and combined with the preset coupling amplification factor, calculate the interface damage index. The preset coupling amplification factor is used to characterize the coupling effect of environmental erosion and load on the interface. The interface damage index is used to correct the initial interface constraint parameters to obtain the equivalent interface constraint parameters. S5. Based on the equivalent interface constraint parameters, redetermine the corrected theoretical benchmark crack width value of the suspected interface degradation zone. S6. Based on the corrected theoretical benchmark crack width value and interface damage index, output the structural safety assessment results of the assessment section corresponding to the suspected interface degradation zone.

[0035] The core logic of the above overall technical solution lies in constructing a dynamic crack assessment mechanism capable of identifying hidden damage. First, by comparing on-site measured data with theoretically calculated baseline values, sections with abnormal deviations are preliminarily screened. These theoretically calculated baseline values ​​are not static but correspond to the load state, original material parameters of the component, and initial interface state within the current inspection cycle. Therefore, their function is to provide a comparable starting point for determining whether the current state is abnormal. Subsequently, an overload event investigation mechanism is introduced to eliminate the illusion of crack widening caused by accidental heavy vehicle passage, accurately identifying areas where interface degradation may actually occur. Next, for these suspected areas, the coupling damage between the environment and load is quantified, and the initial interface constraint parameters are reduced and corrected to restore the true internal bonding state of the component. Finally, the theoretical crack width is recalculated based on the corrected true state, and this is used as the basis for the final safety assessment. The key significance of this approach is that the assessment conclusion no longer stops at a single-layer judgment of whether surface cracks exceed limits, but further traces back to why the crack state occurred, thus enabling the assessment results to reflect the more fundamental structural state change of internal interface degradation.

[0036] Regarding the technical approach of "obtaining crack appearance characteristics and service background data for each assessment section within the current testing cycle," one implementation involves dividing the component into continuous assessment sections along its longitudinal axis using a preset grid. The section length is typically 0.5m or 1m. Crack appearance characteristics include at least the measured crack width, i.e., the maximum surface crack width within the section. Another implementation also includes the longitudinal coordinates of the crack, its transverse extension length, crack spacing distribution characteristics, and the measured thickness of the concrete cover. Service background data includes at least environmental erosion data and load data. Environmental erosion data includes, for example, annual average ambient temperature, relative humidity, chloride ion deposition rate, baseline chloride ion concentration on the concrete surface, and cumulative service time. Load data includes, for example, the frequency of heavy-duty vehicle traffic, axle load distribution, stress amplitude spectrum, records of extreme overload events, and the current live load bending moment extreme value. In another implementation, the above data is spatially aligned and temporally synchronized to construct multi-dimensional state-space data for each assessment section, encompassing crack appearance characteristics, environmental erosion background, and load history, serving as the data foundation for subsequent assessments.

[0037] Regarding the technical approach of "determining the theoretical benchmark crack width value for each assessment section," one implementation method involves using initial interface constraint parameters, which are parameters characterizing the relative slip capability of the composite reinforcement and concrete interface transition zone under the initial design or completed construction state. Examples include initial bond stiffness and ultimate bond strength, which can be obtained from the structural design archives. Load data is used to determine the current stress state of the assessment section: the extreme value of the live load bending moment generated by heavy vehicle traffic is linearly superimposed with the beam's self-weight and the dead load bending moment corresponding to the secondary dead load to obtain the comprehensive internal force of the section. The initial interface constraint parameters, initial constitutive parameters, and comprehensive internal force of the section are input into a crack width analytical model based on bond-slip theory for forward mechanical solution, yielding the theoretical benchmark crack width value for each assessment section under the condition that the interface remains initially intact. This theoretical value serves only as a benchmark for subsequent deviation comparison, reflecting the normal mechanical response of the structure to the current load under the assumption of an intact interface, and does not represent the actual crack state of the assessment section.

[0038] Regarding the technical approach of "determining the deviation rate based on the measured crack width and the theoretical benchmark crack width, and judging whether it is explained by an overload event," in one implementation, the deviation rate is calculated using the following formula: the deviation rate equals the absolute difference between the measured crack width and the theoretical benchmark crack width divided by the theoretical benchmark crack width. The allowable fluctuation threshold is a preset dimensionless limit used to filter out minor deviations caused by normal factors such as measurement errors and temperature changes. When the deviation rate is less than the allowable fluctuation threshold, it is determined that the interface constraint capacity of that section has not undergone substantial time-varying attenuation, the current crack width can be reasonably explained by the load level and initial interface parameters, and that section is treated as normal. When the deviation rate is greater than or equal to the allowable fluctuation threshold, high-frequency traffic load monitoring data for that section within the current monitoring cycle is retrieved to investigate whether there are extreme heavy load events. If an overload event exists and its amplitude is sufficient to explain the current deviation after mechanical calculation, the deviation is attributed to overload. If the load data is stable, or the overload amplitude is insufficient to explain the deviation mechanically, the crack width is determined to originate from the internal damage accumulation in the transition zone between the composite reinforcement and concrete interface, and the section is marked as a suspected interface degradation zone. The overload event here is not solely based on the presence of heavy vehicles, but must simultaneously meet two conditions: temporal correlation and stress rationality. On the one hand, the time of the overload event should correspond to the time of abnormal crack observation; on the other hand, the vehicle type, lane, direction of travel, and location of the overload event should be able to exert a stress influence on the section sufficient to cause short-term crack widening. If only an increase in ordinary heavy traffic is detected, but a stress explanation matching the abnormal cracks in the section cannot be formed, it should not be directly considered an overload-explained situation.

[0039] Regarding the technique of "calculating the interface damage index and correcting the initial interface constraint parameters," one implementation involves first calculating the environmental reduction coefficient based on environmental erosion data, and then calculating the fatigue degradation coefficient based on load data. The environmental reduction coefficient characterizes the weakening effect of chloride erosion on interfacial bonding performance. It can be obtained by calculating the concentration of chloride ions reaching the composite reinforcement surface by modifying the chloride ion penetration model, and then converting it using an empirical function for environmental degradation. The fatigue degradation coefficient characterizes the weakening effect of cyclic loading on interfacial slip stiffness, and can be calculated based on stress amplitude spectrum data using the linear fatigue cumulative damage rule. Subsequently, the environmental reduction coefficient and the fatigue degradation coefficient are multiplied by a preset coupling amplification factor to obtain the interface damage index. The interface damage index is dimensionless; a value closer to 0 indicates that the interface is closer to its initial intact state, while a value closer to 1 indicates a greater tendency to lose interfacial constraint capacity. Using the interface damage index, a stiffness reduction function and a strength attenuation function are constructed to nonlinearly reduce the initial bond stiffness and ultimate bond strength, respectively, to obtain equivalent interface constraint parameters reflecting the current actual bonding performance of the evaluation section. This will enable subsequent safety assessments to more accurately reflect the extent to which hidden degradation weakens the ability to control cracks.

[0040] The technique of "re-determining the corrected theoretical benchmark crack width value for suspected interface degradation zones based on equivalent interface constraint parameters" involves re-inputting the equivalent interface constraint parameters, along with the initial constitutive parameters and the current comprehensive internal forces of the cross-section, into the crack width analytical model and performing a forward mechanical solution again to obtain the corrected theoretical benchmark crack width value. Because the interface constraint capacity has been weakened, the relative slippage between the composite reinforcement and concrete under the same load increases. Therefore, the corrected theoretical benchmark crack width value is usually larger than the initial theoretical benchmark crack width value, thus more closely approximating the actual stress state corresponding to the measured crack width. The corrected theoretical benchmark crack width value is compared with the measured crack width. If they match, an assessment result including the corrected crack width evaluation conclusion and the interface degradation state is output; if they clearly do not match, a prompt indicating further verification is required is output.

[0041] Through the aforementioned overall technical solution, this application effectively addresses the technical problem of unsafe crack assessment in composite reinforced concrete beams of cross-sea highway bridges under complex service environments. It abandons the static and singular assessment logic of traditional methods, establishing a closed-loop mechanism of "deviation identification - attribution analysis - parameter correction - secondary assessment." By comparing the measured crack width with the theoretical benchmark value and eliminating overload interference, it can accurately identify abnormal crack widening caused by interface degradation, establishing an inversion chain from apparent cracks to the internal interface state. This indirectly identifies interface degradation, originally hidden within the concrete, through crack response, which is the key difference from conventional crack assessment methods. Furthermore, by introducing a coupling amplification factor to quantify the combined destructive effects of environment and load, the previously invisible internal interface damage is transformed into a calculable interface damage index, and the interface constraint parameters are dynamically adjusted accordingly. This derivation logic ensures that the corrected theoretical benchmark crack width value used for safety assessment truly reflects the current deterioration state of the component. The above-mentioned complete set of technical solutions can effectively identify the hidden interface degradation caused by the interaction of long-term chloride salt corrosion and vehicle load, avoid misjudging the crack widening caused by the accelerated deterioration period as accidental overload, thereby improving the accuracy of crack propagation potential prediction and ensuring the scientific determination of the timing of bridge maintenance intervention.

[0042] In some preferred embodiments, the step of determining the theoretical benchmark crack width value for each evaluation section based on the initial interface constraint parameters and load data of the interface between the composite reinforcement and concrete in the member includes: Obtain the initial constitutive parameters of the component, including the initial elastic modulus of the composite reinforcement and the standard value of the tensile strength of the concrete; The comprehensive internal forces of the cross sections under stress state are calculated based on the load data. The comprehensive internal forces of the cross sections include the linear superposition of the extreme value of the live load bending moment and the dead load bending moment. The initial constitutive parameters, initial interface constraint parameters, and comprehensive internal forces of the cross section are input into the crack width analytical model for forward mechanical solution to obtain the theoretical reference crack width value. If the combined internal force of the section is lower than the concrete cracking moment and the measured crack width shows that the evaluation section has cracked, the corresponding evaluation section will be marked as an abnormal cracking state and regarded as a suspected interface degradation zone, directly triggering the calculation of the interface damage index.

[0043] To more clearly and completely describe the implementation process of this step, the analytical model for crack width is based on bond-slip theory. The crack width is calculated by multiplying the average strain difference between the composite reinforcement and the concrete between adjacent cracks by the average crack spacing. The average crack spacing and strain distribution are determined by the elastic modulus of the composite reinforcement, the tensile strength of the concrete, the reinforcement ratio, the thickness of the protective layer, and the interfacial bond stiffness. Substituting the initial constitutive parameters, initial interfacial constraint parameters, and the comprehensive internal forces of the section into the model for forward solving yields the theoretical reference crack width value.

[0044] In this specific implementation plan, the initial elastic modulus of the composite reinforcement and the standard value of the concrete tensile strength are first extracted from design drawings, as-built data, material factory documents, or material test reports as initial constitutive parameters. For initial interface constraint parameters, the interface bond performance parameters explicitly given in the design stage can be used preferentially. Simultaneously, current traffic load level data are obtained from the bridge dynamic weighing system or regional traffic flow statistical model, including the type of heavy-duty vehicles, axle load, wheelbase, lane position, and frequency of traffic passing through the bridge during the current inspection period. The dead load bending moment is calculated based on the beam's self-weight and the secondary dead loads from the bridge deck pavement and ancillary facilities, combined with the span and support conditions of the section, and does not change with time due to vehicle traffic. The extreme value of the live load bending moment is determined based on the frequency of heavy-duty vehicle traffic and axle load distribution in the load data, combined with the bending moment influence line of the section, and the maximum bending moment generated by the vehicle load is determined according to the most unfavorable load arrangement, taking into account the lateral distribution coefficient and dynamic impact coefficient. The extreme value of the live load bending moment is linearly superimposed with the dead load bending moment to obtain the comprehensive internal force of the cross-section of the evaluation section.

[0045] Subsequently, the initial constitutive parameters, initial interface constraint parameters, and comprehensive internal forces of the cross section are input into the pre-constructed analytical model for forward mechanical solution, ultimately yielding the theoretical benchmark crack width value. Further, the system compares the comprehensive internal forces of the cross section with the theoretical concrete cracking moment in real time. The concrete cracking moment can be determined based on the cross section dimensions, the standard value of concrete tensile strength, and the stress state when the tensile edge stress of the cross section reaches the cracking condition. This value provides a mechanical criterion for whether a component should crack under normal interface conditions and material parameters. If the comprehensive internal forces of a certain evaluation section have not yet reached this cracking criterion, but the measured crack width clearly shows the presence of stable cracks in that section, it indicates that the actual crack resistance of that section is lower than the initial design state, suggesting the possibility of internal interface degradation, local material defects, or other abnormal factors. In this case, the system no longer uses the conventional deviation rate screening path but marks the section as an abnormal cracking state and considers it a suspected interface degradation zone, directly forcibly initiating the calculation process of the interface damage index.

[0046] Through the aforementioned specific implementation plan, precise calculation of the comprehensive internal forces of the cross-section and forward mechanical solutions replace the crude empirical estimation, thus providing a rigorous mechanical basis for obtaining the theoretical benchmark crack width value. Simultaneously, by setting an abnormal triggering condition where cracks have already occurred despite internal forces below the cracking moment, the essence lies in using the conflict of mechanical logic to reverse-locate extremely deteriorated areas. This mechanism can keenly detect the premature failure of concrete tensile strength due to the near loss of interfacial bonding. In the early hidden damage investigation of cross-sea bridges, it can serve as a fusing mechanism to prevent severely degraded sections from being smoothed out or concealed in the conventional deviation rate calculation process, improving the sensitivity of identifying extreme deterioration states and reducing the probability of missing high-risk hazards.

[0047] In some possible embodiments, when the deviation rate is less than a preset allowable fluctuation threshold, or when the deviation rate can be explained by the overload event of the evaluation segment in the current detection cycle, the corresponding evaluation segment is determined as a normal segment, and a processing action to maintain normal inspection is output.

[0048] In this specific implementation plan, when the system determines that the deviation rate of a certain assessment section is less than the preset allowable fluctuation threshold, it indicates that the measured crack state of that section is basically consistent with the theoretical baseline state, or although there is a slight deviation, it can still be classified as a normal fluctuation range. In this case, the system directly classifies the section as a regular section. Alternatively, although the deviation rate of a certain section exceeds the preset allowable fluctuation threshold, if the system confirms, through comparison of dynamic weighing records, traffic video records, special transportation approval records, and crack observation time, that the section did indeed experience an overload event that could form a short-term increase in stress during the current inspection cycle, and that this event and crack widening have a reasonable correspondence in terms of time and stress location, then the system also classifies the section as an overload-explainable section among the regular sections. For these two types of sections, the system automatically generates a processing action to maintain regular inspections in the final assessment report. And in the next inspection cycle, crack re-measurement and background data updates will continue according to the established plan.

[0049] By implementing the above-described specific scheme, setting reasonable tolerance boundaries and clear exemption conditions, normal structural responses and short-term responses dominated by a single load are separated from complex coupled degradation analysis. This does not reduce the rigor of the assessment, but rather prioritizes analytical resources on sections that genuinely exhibit anomalies and cannot be explained by external incidental factors. This diversion mechanism allows subsequent damage quantification and parameter correction calculations to focus on suspected interface degradation zones that truly pose potential risks.

[0050] In some preferred embodiments, the step of calculating the interface damage index based on environmental erosion data and load data of the suspected interface degradation zone, combined with a preset coupling amplification factor, includes: A modified chloride ion permeation model based on unsteady diffusion theory is adopted. The actual concentration of chloride ions reaching the surface of the composite reinforcement is calculated based on environmental erosion data. The environmental reduction factor is calculated by calling the preset environmental degradation empirical function. The degree of microcrack accumulation in the interface transition zone is calculated based on the stress amplitude spectrum data in the load data, and the fatigue degradation coefficient is calculated by calling the preset linear fatigue cumulative damage rule. The interface damage index is obtained by multiplying the environmental reduction factor and the fatigue degradation factor, and then multiplying by a preset coupling amplification factor.

[0051] To more clearly and completely describe the implementation process of this step, environmental erosion data is data that characterizes the erosion environment and the intensity of its continuous action in the assessment section. It includes at least the duration of environmental exposure, the concentration of chloride ions on the concrete surface, the ambient temperature and relative humidity, and is used to calculate the amount of chloride ions penetrating into the surface of the composite reinforcement and to assess the degree of interface deterioration. Load data is data that characterizes the vehicle loads on the assessment section. It includes at least the frequency of heavy-duty vehicle traffic, axle load distribution, stress amplitude spectrum and overload event records, and is used to calculate the internal forces of the section, assess the cumulative fatigue damage at the interface and determine the cause of crack deviation.

[0052] In this specific implementation plan, the modified chloride ion permeation model based on the unsteady diffusion theory is typically based on Fick's second law and has undergone multi-parameter corrections to consider factors such as the alternating temperature and humidity of the marine environment where the cross-sea bridge is located, the time-varying porosity of concrete, and the chloride ion binding capacity. By inputting environmental erosion data (such as the initial chloride ion concentration on the component surface, exposure time, and historical environmental temperature and humidity records), the model can accurately calculate the actual chloride ion concentration at a specific protective layer depth (i.e., the surface location of the composite reinforcement) during the current testing period. Subsequently, a preset environmental degradation empirical function is established based on a large amount of long-term accelerated corrosion test data. This function can map the calculated actual concentration to the degradation ratio of interfacial bonding performance, thereby outputting an environmental reduction factor. The so-called "specific protective layer depth" refers to the actual distance from the outer surface of the concrete to the surface of the composite reinforcement. This value can preferentially use the results measured by non-destructive testing equipment. If on-site measurements have not yet been carried out, a combination of the design value from the construction drawings and the sampled values ​​can be used to give a representative value for the section.

[0053] Meanwhile, the stress amplitude spectrum data accurately reflects the fluctuations in vehicle loads experienced by the bridge during its service life. Combined with a pre-defined linear fatigue cumulative damage rule, the initiation and propagation of microcracks in the interface transition zone under different stress levels can be precisely quantified, thus outputting the fatigue degradation coefficient. Finally, the environmental reduction coefficient and the fatigue degradation coefficient are multiplied, and then multiplied by a pre-defined coupling amplification factor to obtain the interface damage index. This interface damage index not only includes information from both environmental and fatigue degradation paths but also incorporates the mutual amplification effect between the two paths, thus serving as a core input for subsequent interface constraint parameter correction. The value of the coupling amplification factor is not static. In subsequent evaluations, the system uses the residual between the measured crack width and the corrected theoretical benchmark crack width to perform reverse iterative calibration of the local coupling amplification factor for the evaluation section, and uses the calibrated value for calculating the interface damage index of that section in subsequent evaluation cycles.

[0054] In the aforementioned technical solution, this application achieves scientific decoupling of complex damage mechanisms by establishing separate physical diffusion paths for environmental erosion and mechanical accumulation paths for load fatigue. Subsequently, the interface damage index is obtained through product operations and coupling amplification factors, realistically reproducing the physical failure process under multi-field coupling. This completely avoids the assessment blind spots and systematic errors caused by a single reduction factor, ensuring that the calculation of the interface damage index has a rigorous physical and mechanical foundation, improving the accuracy and reliability of hidden damage quantification, and better conforming to the actual service mechanism of cross-sea bridges.

[0055] In a preferred embodiment of this application, the initial interface constraint parameters include initial bond stiffness and ultimate bond strength; Crack appearance characteristics information also include the measured thickness of the concrete protective layer; The steps for correcting the initial interface constraint parameters using the interface damage index to obtain the equivalent interface constraint parameters include: Construct stiffness reduction function and strength attenuation function based on interface damage index; Based on the measured concrete cover thickness and service background data, weak sections with measured concrete cover thickness lower than the preset value or with initial construction micro-defects are identified, and the weight of the interface damage index corresponding to the weak sections is increased. By using the weighted interface damage index and applying nonlinear reductions to the initial bond stiffness and ultimate bond strength through stiffness reduction and strength attenuation functions respectively, equivalent interface constraint parameters reflecting the actual bond performance of the suspected interface degradation zone in the current testing cycle are generated.

[0056] To describe this step more clearly and completely, the measured thickness of the concrete protective layer can be obtained through electromagnetic induction non-destructive testing equipment, radar testing equipment, or local drilling verification. The non-destructive testing results can first generate a protective layer thickness distribution map, which is then spatially correlated with crack locations, water seepage marks, and surface deterioration areas to pinpoint locally thinner areas. Service background data, in addition to construction quality inspection records, can also include pouring batches, curing records, formwork removal times, early cracking records, repair and reinforcement history, and information on previously observed defects such as honeycomb, pitting, slag inclusions, and hollow areas.

[0057] In this specific implementation scheme, the stiffness reduction function and strength decay function are nonlinear mathematical models constructed based on the evolution law of interface damage. Typically, the stiffness reduction function shows a rapid decline in the early stages of damage, while the strength decay function only exhibits a sharp drop after the damage has accumulated to a certain extent. The system accurately locates weak sections where the protective layer is too thin or has micro-defects such as honeycomb or pitting by comparing the measured concrete cover thickness with the design preset value, or by combining construction quality inspection records from service background data. For these weak sections, the system increases the weight of their interface damage index by multiplying it by an amplification factor greater than 1, thus characterizing that the area has suffered more severe substantial damage under the same external forces. Subsequently, the weighted interface damage index is substituted into the stiffness reduction function and strength decay function respectively to perform independent, nonlinear reduction calculations on the initial bond stiffness and ultimate bond strength, ultimately outputting equivalent interface constraint parameters. The revised parameter set will directly replace the outdated initial design parameters and serve as the sole basis for the next step of reassessing the true risk of crack width, ensuring that all subsequent mechanical deductions and safety assessments are based on a physical foundation that conforms to the objective deterioration status.

[0058] In the above technical solution, the initial bond stiffness and ultimate bond strength are modified separately by distinguishing different attenuation paths of stiffness and strength, thereby achieving multi-dimensional and refined reconstruction of interface constraint parameters. Simultaneously, the measured protective layer thickness is introduced as a local sensitivity adjustment factor, establishing an adaptive weighting mechanism based on the actual structural state. This enables the system to keenly capture and amplify the accelerated degradation phenomenon in weak sections, especially in applications where construction deviations or local micro-defects are common in cross-sea bridges. It avoids the omission of local high-risk cases caused by "one-size-fits-all" parameter correction, ensuring that the final generated equivalent interface constraint parameters can map the complex non-uniform degradation state within the component.

[0059] Furthermore, after the step of redetermining the corrected theoretical benchmark crack width value of the suspected interface degradation zone based on the equivalent interface constraint parameters, the following steps are also included: Based on the corrected theoretical benchmark crack width value, the rate of change of crack width with load is calculated. The rate of change is used as a crack propagation sensitivity index to characterize the sensitivity of the suspected interface degradation zone to future load fluctuations under the current degradation state. If the crack propagation sensitivity index exceeds the preset sensitivity threshold, the corresponding assessment section will be marked as a high-concealed risk area.

[0060] To more clearly illustrate the implementation of this step, the load change refers to the process of repeated fluctuations in the stress on the beam segment caused by vehicle passage over time. When a heavy-load vehicle passes, the bending moment borne by the evaluation segment is superimposed with a live load pulse on top of the dead load, forming one load cycle. The vehicle load data is converted into the time history of the internal forces in the section of that segment, and then converted into the cyclic shear stress time history of the reinforcement-concrete interface transition zone through cracked section analysis. This is statistically analyzed into stress amplitudes at various levels and their corresponding cycle numbers, i.e., the stress amplitude spectrum. This application uses the stress amplitude spectrum to characterize the load change and to calculate the cumulative fatigue damage of the interface under long-term repeated loading. The preset sensitivity threshold can be determined by calibrating healthy sections of the same bridge, extracting statistical data from similar bridges, or determining the normal elastic stage response range of the test beam.

[0061] In this specific implementation plan, after redetermining the corrected theoretical benchmark crack width value for the suspected interface degradation zone, the structural safety of the component in its current state can be assessed. However, the traffic load on the cross-sea highway bridge is highly dynamic. The rate of change of crack width calculated as a function of load is essentially the slope of the crack width-load response curve under the current stress state, i.e., the partial derivative. In the theoretical calculation model, based on the corrected equivalent interface constraint parameters, the system applies a small virtual load increment (e.g., an increase of 10% standard axle load effect) to the current comprehensive internal forces of the cross section and calculates the resulting crack width increment. Dividing the crack width increment by the load increment yields this rate of change. This rate of change, as a crack propagation sensitivity index, directly reflects the amplification effect of small fluctuations in external forces on the component in its current degradation state. When the index exceeds the preset sensitivity threshold, it means that the section is sensitive to load fluctuations and the interface constraints of the components have been severely degraded. Any slight overload may induce the malignant propagation of cracks. The system then marks the section as a high-hidden-risk area and triggers a high-level warning in the assessment report to remind relevant management and maintenance departments to take action to limit the flow or repair the section in advance.

[0062] In some possible embodiments, before calculating the rate of change of crack width with load based on the corrected theoretical baseline crack width value, a residual reverse iterative calibration is performed on the suspected interface degradation zone, including: Obtain the residual value between the measured crack width of the suspected interface degradation zone and the corrected theoretical reference crack width value, and determine the absolute value of the residual value; When the absolute value of the residual is less than the preset allowable residual threshold, the value of the coupling amplification factor remains unchanged, and the crack propagation sensitivity index is determined directly based on the corrected theoretical benchmark crack width value. When the absolute value of the residual is not less than the preset allowable residual threshold, the value of the coupling amplification factor is adjusted according to the positive or negative direction of the residual. Based on the adjusted coupling amplification factor, the interface damage index is recalculated, the corrected theoretical benchmark crack width value is re-determined, and the residual value and the absolute value of the residual are updated until the absolute value of the updated residual is less than the preset allowable residual threshold, or the adjustment range of the coupling amplification factor reaches the preset physical limit boundary. After the residual reverse iterative calibration is completed, the calibrated coupling amplification factor is written into the service background data of the suspected interface degradation area as input for determining the interface damage index in subsequent evaluation cycles.

[0063] To describe the process more clearly and completely, a preset allowable residual threshold is used to determine whether the measured crack width and the corrected theoretical reference crack width value are sufficiently matched. This threshold is preset based on measurement accuracy and model error. If the residual is less than this threshold, a match is considered; otherwise, a mismatch is considered and calibration is triggered. The preset physical limit boundary should be given based on material mechanism, experimental statistical range, and experience with similar bridges. This is to prevent the coupling amplification factor from being adjusted to a range that does not conform to physical common sense under the influence of extreme noise data. The content written into the service background data preferably includes not only the finally calibrated coupling amplification factor, but also the corresponding inspection date, residual convergence process, the method used to obtain the measured crack width, and the time window of the environmental and load data involved in the calibration, so as to track the historical change trajectory of this parameter in the next inspection cycle.

[0064] In this specific implementation scheme, residual reverse iterative calibration is essentially a parameter optimization and adaptive correction process driven by field measured data. The residual value, calculated as the difference between the measured surface crack width and the corrected theoretical crack width, quantifies the deviation between the theoretical calculation model and the actual physical state. A preset allowable residual threshold represents the lower limit of acceptable computational error in engineering, while a preset physical limit boundary is a protective constraint set to prevent meaningless divergence of parameters under extreme abnormal data interference. When the residual value exceeds the limit, the system intelligently determines the adjustment strategy based on the positive or negative direction of the residual: if the measured crack width is greater than the corrected theoretical value (i.e., the residual value is positive), it indicates that the current coupling amplification factor underestimates the actual degree of coupling damage, and the system will increase the factor positively by a preset step size to quickly approach the target range; if the measured crack width is less than the corrected theoretical value, it indicates that the coupling damage is overestimated, and the factor will decrease negatively by a preset step size. When the residual significantly decreases, the system switches to a smaller step size for refined calibration. Subsequently, the successfully calibrated coupling amplification factor is permanently fixed and written into the service background data of that section, serving as the initial input parameter for the next year or the next testing cycle. This allows subsequent cycles to continue using the calibration results, reducing systematic errors caused by starting from general empirical values ​​each time. Furthermore, it is preferable to keep the environmental erosion data, load data, measured concrete cover thickness, and equivalent interface constraint parameter construction rules unchanged in the system to ensure that residual changes truly originate from the correction of the coupling factor, rather than from the influence of changes in other variables.

[0065] In the above technical solution, by constructing a rigorous closed-loop feedback control system, the measured crack width on site is used as the objective function, and the core model parameters are continuously corrected using a reverse iterative algorithm. This forces the theoretical model output to converge to the real physical state, completely eliminating the systematic static error caused by the initial model parameters, ensuring the reliability of the current detection cycle evaluation results, and realizing the intergenerational inheritance and adaptive evolution of parameters.

[0066] During the aforementioned residual reverse iterative calibration process, extreme non-convergence may occur. Therefore, this application further proposes: When the adjustment range of the coupling amplification factor reaches the preset physical limit boundary and the absolute value of the updated residual value is still not less than the preset allowable residual threshold, the suspected interface degradation area is marked as a high-risk anomaly area with unknown mechanism, and the determination of the crack propagation sensitivity index is skipped. An abnormal intervention command is output to instruct the execution of local damage exploration in the high-risk anomaly area with unknown mechanism.

[0067] In this specific implementation plan, the preset physical limit boundary is a protective constraint set to prevent the parameters from diverging meaninglessly under extreme abnormal data interference. When the adjustment range of the coupling amplification factor has reached this boundary, but the residual value remains high, it indicates that the current theoretical calculation model, based on the assumption of coupled degradation of environmental erosion and load fatigue, can no longer explain the crack widening phenomenon measured in the field. This situation usually means that a sudden or catastrophic failure has occurred inside the component, outside of the model assumptions, such as atypical damage like local fracture of composite reinforcement, severe slippage in the anchorage zone, or serious initial construction quality defects. At this point, if the crack propagation sensitivity index is continued to be calculated, it will not only be physically meaningless, but may even mask the real structural danger by outputting a false index. Therefore, the system sets up a circuit breaker mechanism here, directly skipping the subsequent conventional analysis process and marking this section as a high-risk anomaly zone with an unclear mechanism. At the same time, the system automatically outputs abnormal intervention commands, requiring maintenance personnel to take local damage detection measures, such as partially removing the concrete protective layer to directly observe the condition of the composite reinforcement, or conducting destructive testing such as core drilling, so as to directly find out the truth of the damage from a physical perspective.

[0068] The above-mentioned methods effectively prevented the forced fitting and failure of the evaluation model under extreme and abnormal conditions. By promptly blocking invalid calculations and forcibly introducing manual physical inspections, the safety of the bridge structure was further ensured, and major safety hazards that could not be missed due to model limitations were avoided.

[0069] After completing the above parameter correction and sensitivity analysis, the final safety assessment result needs to be output. In a preferred embodiment of this application, the step of outputting the structural safety assessment result of the assessment segment corresponding to the suspected interface degradation zone includes: The interface degradation level of the assessment section corresponding to the suspected interface degradation zone is determined by weighted scoring based on the ratio of the modified theoretical benchmark crack width value to the preset limit value, the interface damage index, and the crack propagation sensitivity index. The interface degradation levels include mild, moderate, severe, and critical levels. By combining future traffic flow growth models and environmental erosion data, a nonlinear time-series evolution algorithm is used to predict the crack evolution trajectory of the assessment sections corresponding to each suspected interface degradation zone within a preset future time window. For assessment sections with a severe or critical interface degradation level, the expected time window for the crack width of the assessment section to exceed the safety red line is determined based on the crack evolution trajectory corresponding to the assessment section. Different maintenance instructions are triggered based on the level of interface degradation. These instructions include maintaining routine inspections, increasing the frequency of retesting, introducing non-destructive testing equipment for localized key checks, and implementing early maintenance interventions. The system acquires on-site feedback information after the maintenance command is executed, and then inputs this feedback information back into the service background data of the suspected interface degradation area. This is used to dynamically correct the model parameters in the interface damage index calculation process, forming a closed-loop feedback correction mechanism.

[0070] In this specific implementation plan, the weighted scoring mechanism breaks through the limitations of single-indicator evaluation. The ratio of the corrected theoretical benchmark crack width value to the preset limit represents the current static apparent state; the interface damage index reveals the degree of hidden internal degradation; and the crack propagation sensitivity index reflects the structure's dynamic resistance to future load fluctuations. The system assigns reasonable weights to these three dimensions (e.g., 0.3, 0.4, and 0.3 respectively), calculates a comprehensive score, and scientifically classifies the interface degradation state into multiple levels such as mild, moderate, severe, and critical. The level of interface degradation state is divided according to the weighted scoring results within preset scoring intervals. The weighted scoring result corresponds to the mild level when it reaches the first scoring interval, the moderate level when it reaches the second scoring interval, the severe level when it reaches the third scoring interval, and the critical level when it reaches the fourth scoring interval. The boundary values ​​of each scoring interval are preset based on historical detection data, experimental data, or structural safety assessment requirements. Furthermore, the system not only focuses on the current state but also has forward-looking predictive capabilities. The future traffic flow growth model can be generated by fitting local traffic planning and historical traffic flow data. It preferably adopts a nonlinear time-series evolution algorithm to simulate the trajectory curve of the crack width evolution over time in each assessment section. For sections with severe or critical degradation, it can also accurately locate the time point when the curve intersects with the safety red line, i.e. the expected time window.

[0071] Based on the above ratings and predictions, the system automatically triggers differentiated maintenance instructions. For lightly degraded areas, routine inspections are maintained; for moderately degraded areas, the frequency of re-testing is increased; for severely degraded areas, non-destructive testing equipment such as radar or ultrasonic sensors is introduced for focused local inspections; for critical areas or sections with extremely short expected time windows, early maintenance interventions are implemented directly, such as reinforcing with carbon fiber cloth or adding external prestressing. Finally, the system obtains on-site feedback information after the maintenance instructions are executed, including the actual protective layer thickness and actual interface peeling length found during local inspections, and uses this as a true label to input back into the service background data. The system then dynamically corrects the model parameters in the environmental degradation empirical function and the fatigue cumulative damage law once again.

[0072] Through the aforementioned rating and prediction, a full-chain assessment system was constructed, encompassing multi-dimensional condition diagnosis, future trend prediction, and closed-loop feedback optimization. This not only solves the key problem that traditional assessment outputs cannot support tiered management, but also ensures that, under the complex effects of long-term coupled environments and loads, the crack assessment of composite reinforced concrete beams can truly shift from passive superficial observation to proactive, fundamental risk management, thus guaranteeing the structural safety of bridges in service.

[0073] refer to Figure 2 This application also proposes a system for evaluating the crack width of composite reinforced concrete beams coupled with environment and load, used to perform the steps in the above method, including: The segment division and data acquisition module 201 is used to divide the composite reinforced concrete member into at least one evaluation segment and acquire the crack appearance characteristics information and service background data of each evaluation segment in the current testing cycle. The crack appearance characteristics information includes at least the measured crack width, and the service background data includes at least environmental erosion data and load data. The benchmark determination module 202 is used to determine the theoretical benchmark crack width value of each evaluation section based on the initial interface constraint parameters and load data of the interface between the composite reinforcement and concrete in the component. The deviation determination module 203 is used to determine the deviation rate based on the measured crack width and the theoretical benchmark crack width. When the deviation rate is greater than or equal to the preset allowable fluctuation threshold, it determines whether the deviation rate can be explained by the overload event of the evaluation section in the current detection cycle based on the load data. If not, the corresponding evaluation section is marked as a suspected interface degradation area. The damage quantification module 204 is used to calculate the interface damage index based on the environmental erosion data and load data of the suspected interface degradation zone, and in combination with the preset coupling amplification factor. The preset coupling amplification factor is used to characterize the coupling effect of environmental erosion data and load data on the interface between the composite reinforcement and concrete in the component. The interface damage index is used to correct the initial interface constraint parameters to obtain the equivalent interface constraint parameters. The parameter correction module 205 is used to redetermine the corrected theoretical benchmark crack width value of the suspected interface degradation zone based on the equivalent interface constraint parameters. The safety assessment module 206 is used to output the structural safety assessment results of the assessment section corresponding to the suspected interface degradation zone based on the corrected theoretical benchmark crack width value and interface damage index.

[0074] Through the above technical solution, the segment division and data acquisition module 201 is responsible for the collection and preprocessing of basic data; the benchmark determination module 202 provides the initial theoretical reference benchmark; the deviation determination module 203 serves as a preliminary screening mechanism, accurately removing overload interference and locking suspected degradation areas; the damage quantification module 204 is the core computing engine, responsible for decoupling and quantifying multi-field coupled damage; the parameter correction module 205 converts damage into equivalent mechanical parameters; and the safety assessment module 206 outputs the final decision instructions based on the corrected parameters. The collaborative work of these modules automates and systematizes the operation of the aforementioned complex assessment method, improving the efficiency of assessment and maintenance decision support for the maintenance management of large-scale transportation infrastructure.

[0075] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for evaluating the crack width of composite reinforced concrete beams coupled with environment and load, characterized in that, include: The composite reinforced concrete member is divided into at least one evaluation section, and the crack appearance characteristics information and service background data of each evaluation section within the current testing cycle are obtained. The crack appearance characteristics information includes at least the measured crack width, and the service background data includes at least environmental erosion data and load data. Based on the initial interface constraint parameters of the interface between the composite reinforcement and the concrete in the component and the load data, the theoretical benchmark crack width value of each evaluation section is determined. The deviation rate is determined based on the measured crack width and the theoretical benchmark crack width. When the deviation rate reaches a preset allowable fluctuation threshold, it is determined based on the load data whether the deviation rate can be explained by the overload event of the evaluation section in the current detection cycle. If not, the corresponding evaluation section is marked as a suspected interface degradation area. Based on the environmental erosion data of the suspected interface degradation zone and the load data, and combined with the preset coupling amplification factor, the interface damage index is calculated. The preset coupling amplification factor is used to characterize the coupling effect of environmental erosion and load on the interface. The interface damage index is used to correct the initial interface constraint parameters to obtain the equivalent interface constraint parameters. Based on the equivalent interface constraint parameters, the corrected theoretical benchmark crack width value of the suspected interface degradation zone is re-determined. Based on the corrected theoretical benchmark crack width value and the interface damage index, the structural safety assessment result of the assessment section corresponding to the suspected interface degradation zone is output.

2. The method for evaluating the crack width of a composite reinforced concrete beam coupled with environment and load as described in claim 1, characterized in that, The step of determining the theoretical reference crack width value of each evaluation section based on the initial interface constraint parameters of the interface between the composite reinforcement and concrete in the component and the load data includes: Obtain the initial constitutive parameters of the component, including the initial elastic modulus of the composite reinforcement and the standard value of the tensile strength of the concrete; The comprehensive internal forces of the cross sections under stress in each evaluation section are calculated based on the load data. The comprehensive internal forces of the cross sections include the linear superposition of the extreme value of the live load bending moment and the dead load bending moment. The initial constitutive parameters, the initial interface constraint parameters, and the comprehensive internal forces of the cross section are input into the analytical model for crack width and a forward mechanical solution is performed to obtain the theoretical reference crack width value. If the combined internal force of the cross section is lower than the concrete cracking moment and the measured crack width shows that the evaluation section has cracked, then the corresponding evaluation section is marked as an abnormal cracking state and regarded as a suspected interface degradation zone, directly triggering the calculation of the interface damage index.

3. The method for evaluating the crack width of a composite reinforced concrete beam coupled with environment and load as described in claim 1, characterized in that, When the deviation rate is less than the preset allowable fluctuation threshold, or when the deviation rate can be explained by the overload event in the current detection cycle by the evaluation segment, the corresponding evaluation segment is determined as a normal segment, and a processing action to maintain normal inspection is output.

4. The method for evaluating the crack width of a composite reinforced concrete beam coupled with environment and load as described in claim 1, characterized in that, The step of calculating the interface damage index based on the environmental erosion data of the suspected interface degradation zone and the load data, combined with a preset coupling amplification factor, includes: A modified chloride ion permeation model based on unsteady diffusion theory is used to calculate the actual concentration of chloride ions reaching the surface of the composite reinforcement based on the environmental erosion data, and the environmental reduction coefficient is calculated by calling a preset environmental degradation empirical function. The degree of microcrack accumulation in the interface transition zone is calculated based on the stress amplitude spectrum data in the load data, and the fatigue degradation coefficient is calculated by calling the preset linear fatigue cumulative damage rule. The interface damage index is obtained by multiplying the environmental reduction factor and the fatigue degradation factor, and then multiplying by the preset coupling amplification factor.

5. The method for evaluating the crack width of a composite reinforced concrete beam coupled with environment and load according to claim 1, characterized in that, The initial interface constraint parameters include initial bond stiffness and ultimate bond strength; The crack appearance feature information also includes the measured thickness of the concrete protective layer; The step of correcting the initial interface constraint parameters using the interface damage index to obtain equivalent interface constraint parameters includes: Based on the interface damage index, construct the stiffness reduction function and the strength attenuation function; Based on the measured concrete protective layer thickness and the service background data, weak sections with measured concrete protective layer thickness lower than the preset value or with initial construction micro-defects are identified, and the weight of the interface damage index corresponding to the weak sections is increased. By using the weighted interface damage index, and by applying the stiffness reduction function and the strength attenuation function to nonlinearly reduce the initial bond stiffness and the ultimate bond strength, equivalent interface constraint parameters reflecting the actual bond performance of the suspected interface degradation zone in the current detection cycle are generated.

6. The method for evaluating the crack width of a composite reinforced concrete beam coupled with environment and load as described in claim 1, characterized in that, The step of re-determining the corrected theoretical benchmark crack width value of the suspected interface degradation zone based on the equivalent interface constraint parameters further includes: Based on the corrected theoretical benchmark crack width value, the rate of change of crack width with load is calculated, and the rate of change is used as a crack propagation sensitivity index to characterize the sensitivity of the suspected interface degradation zone to future load fluctuations in the current degradation state. If the crack propagation sensitivity index exceeds the preset sensitivity threshold, the corresponding evaluation section will be marked as a high-concealment risk area.

7. The method for evaluating the crack width of a composite reinforced concrete beam coupled with environment and load as described in claim 6, characterized in that, Before calculating the rate of change of crack width with load based on the corrected theoretical benchmark crack width value, residual reverse iterative calibration is performed on the suspected interface degradation zone, including: Obtain the residual value between the measured crack width of the suspected interface degradation zone and the corrected theoretical reference crack width value, and determine the absolute value of the residual value; When the absolute value of the residual value is less than the preset allowable residual threshold, the value of the coupling amplification factor is kept unchanged, and the crack propagation sensitivity index is determined directly based on the corrected theoretical benchmark crack width value. When the absolute value of the residual value is not less than the preset allowable residual threshold, the value of the coupling amplification factor is adjusted according to the positive or negative direction of the residual value. Based on the adjusted coupling amplification factor, the interface damage index is recalculated, the corrected theoretical benchmark crack width value is re-determined, and the residual value and the absolute value of the residual value are updated until the absolute value of the updated residual value is less than the preset allowable residual threshold, or the adjustment range of the coupling amplification factor reaches the preset physical limit boundary. After the residual reverse iterative calibration is completed, the calibrated coupling amplification factor is written into the service background data of the suspected interface degradation zone as input for determining the interface damage index in subsequent evaluation cycles.

8. The method for evaluating the crack width of a composite reinforced concrete beam coupled with environment and load according to claim 7, characterized in that, When the adjustment range of the coupling amplification factor reaches the preset physical limit boundary and the absolute value of the updated residual value is still not less than the preset allowable residual threshold, the suspected interface degradation area is marked as a high-risk anomaly area with unknown mechanism, and the determination of the crack propagation sensitivity index is skipped. An abnormal intervention command is output to instruct the local damage exploration to be performed on the high-risk anomaly area with unknown mechanism.

9. The method for evaluating the crack width of a composite reinforced concrete beam coupled with environment and load as described in claim 6, characterized in that, The step of outputting the structural safety assessment result of the assessment segment corresponding to the suspected interface degradation zone includes: The interface degradation level of the assessment section corresponding to the suspected interface degradation zone is determined by weighted scoring based on the ratio of the corrected theoretical benchmark crack width value to the preset limit value, the interface damage index, and the crack propagation sensitivity index. The interface degradation level includes mild, moderate, severe, and critical levels. Combining future traffic flow growth models and environmental erosion data, a nonlinear temporal evolution algorithm is used to predict the crack evolution trajectory of the assessment sections corresponding to each suspected interface degradation zone within a preset future time window. For the assessment section with an interface degradation level of severe or critical, the expected time window for the crack width of the assessment section to exceed the safety red line is determined based on the crack evolution trajectory corresponding to the assessment section. Different maintenance instructions are triggered based on the interface degradation level. These maintenance instructions include maintaining routine inspections, increasing the frequency of retesting, introducing non-destructive testing equipment for localized key checks, and implementing early maintenance interventions. The field feedback information after the maintenance command is executed is obtained, and the field feedback information is input in reverse into the service background data of the suspected interface degradation area to dynamically correct the model parameters in the interface damage index calculation process, forming a closed-loop feedback correction mechanism.

10. A system for evaluating the crack width of a composite reinforced concrete beam coupled with environment and load, used to perform the steps of the method according to any one of claims 1 to 9, characterized in that, include: The segment division and data acquisition module is used to divide the composite reinforced concrete member into at least one evaluation segment and acquire the crack appearance characteristics information and service background data of each evaluation segment in the current testing cycle. The crack appearance characteristics information includes at least the measured crack width, and the service background data includes at least environmental erosion data and load data. The benchmark determination module is used to determine the theoretical benchmark crack width value of each evaluation section based on the initial interface constraint parameters of the interface between the composite reinforcement and concrete in the component and the load data. The deviation determination module is used to determine the deviation rate based on the measured crack width and the theoretical benchmark crack width. When the deviation rate reaches a preset allowable fluctuation threshold, it determines whether the deviation rate can be explained by the overload event of the evaluation section in the current detection cycle based on the load data. If not, the corresponding evaluation section is marked as a suspected interface degradation area. The damage quantification module is used to calculate the interface damage index based on the environmental erosion data of the suspected interface degradation zone and the load data, combined with a preset coupling amplification factor. The preset coupling amplification factor is used to characterize the coupling effect of the environmental erosion data and the load data on the interface between the composite reinforcement and concrete in the component. The interface damage index is used to correct the initial interface constraint parameters to obtain the equivalent interface constraint parameters. The parameter correction module is used to redetermine the corrected theoretical benchmark crack width value of the suspected interface degradation zone based on the equivalent interface constraint parameters. The safety assessment module is used to output the structural safety assessment result of the assessment section corresponding to the suspected interface degradation zone based on the corrected theoretical benchmark crack width value and the interface damage index.

Images