A method for state assessment of a concrete-filled steel tube tied-arch bridge

Abstract

The present invention relates to the fields of bridge engineering and structural health monitoring, and particularly relates to a method for evaluating the state of a concrete-filled steel tube tied arch bridge. The content is as follows: Calculate the node deformation based on the vertical displacement of the node, and further calculate the internal force of the bridge component; Introduce a non-linear damage index model, and calculate the damage index of the bridge component by combining the internal force of the bridge component and the node deformation; Based on the damage index of the bridge component, evaluate the damage level of the bridge component; Based on the node deformation, calculate the dynamic response characteristics of the node; Based on the dynamic response characteristics of the node, the node deformation and the internal force of the bridge component, construct a bridge health evaluation model to evaluate the health state of the bridge. It solves the problems that the existing bridge health evaluation methods usually rely on simplified linear models, mostly ignore the spatio-temporal coupling effect between each node of the bridge, and fail to effectively consider the influence of environmental factors, resulting in poor accuracy and reliability of the evaluation results.

Description

Technical Field

[0001] The present invention relates to the fields of bridge engineering and structural health monitoring, and particularly to a method for evaluating the state of a concrete-filled steel tube tied arch bridge. Background Art

[0002] With the improvement of sensor technology and data processing capabilities, more and more bridges have started to adopt real-time monitoring systems to collect multi-dimensional data such as vibration, deformation, temperature, and humidity, and then use data analysis methods to evaluate the health status of the bridges. Especially in dynamic response monitoring, technologies based on accelerometers and displacement sensors have been widely used to capture the vibration characteristics of bridges in real time and infer the health status of bridge structures through vibration response analysis. In addition, the progress of finite element analysis and multi-physics field simulation technologies has made bridge health assessment more accurate, enabling simulation prediction of bridge responses under different working conditions, thereby improving the accuracy and reliability of the assessment.

[0003] However, there are still some key problems to be solved in the existing technology for bridge health assessment. For example, the existing bridge health assessment methods usually rely on simplified linear models, and mostly ignore the spatio-temporal coupling effect between various nodes of the bridge, and the influence of environmental factors is not effectively considered, resulting in poor accuracy and reliability of the assessment results. Therefore, there is an urgent need to provide a method for evaluating the health status of bridges that can solve the above problems. Summary of the Invention

[0004] The present invention provides a method for evaluating the state of a concrete-filled steel tube tied arch bridge to solve the problems that the existing bridge health assessment methods usually rely on simplified linear models and fail to effectively capture the nonlinear relationship between the internal forces of the bridge structure and the node deformations, resulting in the assessment results often being unable to truly reflect the actual damage of the bridge; most of the existing bridge health assessment methods ignore the spatio-temporal coupling effect between various nodes of the bridge, especially the complex interaction between node deformations and vibration responses, resulting in the inability to accurately evaluate the health status of the bridge when facing dynamic loads or environmental changes; and the influence of environmental factors is not effectively considered, resulting in poor accuracy and reliability of the assessment results.

[0005] A method for evaluating the state of a concrete-filled steel tube tied arch bridge includes the following steps:

[0006] S1: Collect the vertical displacements of the nodes, and calculate the node deformation amounts based on the vertical displacements of the nodes; calculate the internal forces of the bridge components based on the node deformation amounts; introduce a nonlinear damage index model, and calculate the damage indices of the bridge components by combining the internal forces of the bridge components and the node deformation amounts; evaluate the damage grades of the bridge components based on the damage indices of the bridge components;

[0007] S2: Calculate the dynamic response characteristics of the nodes using the spatio-temporal coupling dynamic response evaluation method based on the node deformation; construct a bridge health assessment model based on the dynamic response characteristics of the nodes, the node deformation, and the internal forces of the bridge components to evaluate the health status of the bridge.

[0008] Preferably, the S1 specifically includes:

[0009] During the process of calculating the node deformation, introduce a weighting factor to evaluate the importance of each node; the formula for calculating the node deformation is as follows:

[0010] ,

[0011] where, represents the node deformation of the th node; is the index variable of the node; is the weighting factor of the th node; is the total number of nodes participating in the calculation; and are the index variables of the nodes; represents the coupling coefficient between node and node ; is the vertical displacement of node collected by the sensor; is the adjustment coefficient; represents the coupling coefficient between node and node ; is the vertical displacement of node collected by the sensor.

[0012] Preferably, the S1 specifically includes:

[0013] Deduce the internal force of the bridge component through the relationship between the node deformation and the mechanical properties of the bridge component. The specific calculation formula is:

[0014] ,

[0015] where, represents the internal force of the th bridge component; is the index variable of the bridge component; is the number of nodes involved in bridge component ; is the external load acting on the th node; is the length of the bridge component related to the th node; is the contribution coefficient of the th node pair to the internal force of the th bridge component, which is calculated based on the geometric and mechanical characteristics of the bridge structure and the coupling relationship between nodes.

[0016] Preferably, the S1 specifically includes:

[0017] The non-linear damage index model evaluates the damage state of bridge components by combining the non-linear relationship between the internal force and the node deformation of bridge components, and controls the influence of node deformation on damage by adjusting the influence coefficient of node deformation on the damage of bridge components.

[0018] Preferably, the S1 specifically includes:

[0019] The damage state refers to the health condition of bridge components under the action of loads, which is quantified by the damage index calculated by the non-linear damage index model; the damage index formula is as follows:

[0020] ,

[0021] where represents the damage index of the th bridge component; is the influence coefficient of the internal force difference of bridge components on damage; represents the initial internal force of the th bridge component; is the influence coefficient of node deformation on the damage of bridge components; is the th node deformation of the th node;

[0022] is the cumulative effect adjustment factor of node deformation on damage.

[0023] Preferably, the S1 specifically includes:

[0024] Preferably, the S2 specifically includes:

[0025] There is a spatio-temporal correlation between the vibration response of the bridge and the node deformation. Based on the spatio-temporal correlation, a spatio-temporal coupling dynamic response evaluation method is proposed, which combines the vibration response of the bridge and the node deformation to calculate the dynamic response characteristics of the nodes; the vibration response of the bridge is the inherent vibration characteristic of the bridge structure.

[0026] Preferably, the S2 specifically includes:

[0027] During the implementation of the bridge health assessment model, an environmental correction factor is introduced to compensate for the impact caused by environmental changes. The formula of the bridge health assessment model is as follows:

[0028] ,

[0029] where, is the bridge health assessment value; is the weighted coefficient of the weighted node deformation of the node for the health status assessment; is the total number of nodes participating in the calculation; is the index variable of the node; is the th weighted factor of the node; represents the th node deformation at the current moment of the node; is the weighted coefficient of the internal force of the bridge component for the bridge health status assessment; is the total number of bridge components; is the index variable of the bridge component; is the th weighted factor of the bridge component; represents the th internal force of the bridge component; is the weighted coefficient of the dynamic response characteristic for the bridge health status assessment; is the th dynamic response characteristic of the node at the current moment; is the environmental correction factor; is the adjustment coefficient of temperature for the environmental correction factor; is the difference between the current environmental temperature and the reference temperature; is the difference between the current environmental humidity and the reference humidity.

[0030] Preferably, the S2 specifically includes:

[0031] Set the bridge health range. When the bridge health assessment value is within the bridge health range, it indicates that the bridge is in good condition, and regular inspections and monitoring are continued; when the bridge health assessment value is not within the bridge health range, the bridge is further inspected to confirm whether there are damages or abnormal conditions, and corresponding countermeasures are taken as appropriate.

[0032] The beneficial effects of the technical solution of the present invention are:

[0033] 1. Based on the node deformation and the internal force of the bridge component, through the non-linear damage index model, the damage state of the bridge component is quantitatively evaluated, effectively improving the accuracy and reliability of the damage assessment.

[0034] 2. By combining the node deformation and the vibration response of the bridge, the dynamic response characteristics are calculated, further enhancing the accuracy of the bridge health state assessment, enabling the assessment results to comprehensively reflect the health state of the bridge.

[0035] 3. By combining the dynamic response characteristics, node deformation, and internal forces of bridge components, a more comprehensive bridge health assessment model is constructed, and an environmental correction factor is introduced to comprehensively consider the influence of environmental factors such as temperature and humidity on the bridge health state assessment results. The changes in temperature and humidity will affect the stress and deformation of the bridge structure. By adjusting the bridge health assessment model with the environmental correction factor, the error caused by environmental changes can be effectively reduced, and the accuracy of the bridge health state assessment results can be improved. Description of the Drawings

[0036] Figure 1 It is a flowchart of a method for assessing the state of a concrete-filled steel tube tied arch bridge according to the present invention. Detailed Embodiments

[0037] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs.

[0039] The following specifically describes the specific solution of a method for assessing the state of a concrete-filled steel tube tied arch bridge provided by the present invention in conjunction with the drawings.

[0040] Referring to the attached Figure 1 , which shows a flowchart of a method for assessing the state of a concrete-filled steel tube tied arch bridge provided by an embodiment of the present invention. The method includes the following steps:

[0041] S1: Collect the vertical displacement of the node, and calculate the node deformation based on the vertical displacement of the node; calculate the internal force of the bridge component based on the node deformation; introduce a non-linear damage index model, and calculate the damage index of the bridge component by combining the internal force and node deformation of the bridge component; evaluate the damage level of the bridge component based on the damage index of the bridge component.

[0042] First, install sensors at the monitoring points in the bridge structure to collect the deformation data of each monitoring point, that is, the vertical displacement of the nodes. The nodes are the monitoring points in the bridge structure, such as the arch feet, support points, and bridge deck joints, etc., which are the parts bearing large loads. The specific positions are set according to the specific implementation scenarios. The collected vertical displacement of the nodes is used to reflect the deformation of the bridge under the action of the load.

[0043] Furthermore, calculate the node deformation amount using the vertical displacement of the nodes, which is used to evaluate the health status of the nodes. In order to accurately evaluate the relative importance of each node, a weighting factor is used to adjust the node deformation amount. The weighting factor ensures that the influence of the deformation amount of the key parts on the overall evaluation result is more prominent, thereby improving the accuracy of the bridge health status evaluation.

[0044] The node deformation amount is calculated by the following formula:

[0045] ,

[0046] where, represents the node deformation amount of the -th node, which reflects the degree of deformation of the node under the action of the load on the bridge; is the index variable of the node; is the weighting factor of the -th node, indicating the importance of this node to the overall evaluation result in the health status evaluation, and can be set according to factors such as the stress situation of the node, the sensitivity of the deformation to the bridge structure, and the position in the specific implementation scenario; is the total number of nodes participating in the calculation; and are the index variables of the nodes; represents the coupling coefficient between node and node , which is set using the expert experience method, combined with the mechanical characteristics of the bridge structure and the mutual relationship between the nodes, and reflects the mechanical coupling effect between node and node ; is the vertical displacement of node collected by the sensor, indicating the actual deformation situation of each monitoring point; is the adjustment coefficient, which is set according to the specific implementation scenario; represents the coupling coefficient between node and node , which is set using the expert experience method, combined with the mechanical characteristics of the bridge structure and the mutual relationship between the nodes, and reflects the mechanical coupling effect between node and node ; is the vertical displacement of the node collected by the sensor Vertical displacement

[0047] Furthermore, based on the node deformation, the internal forces of bridge components are calculated. Each bridge component is connected to multiple nodes, and the node deformation reflects the stress condition of the corresponding bridge component. The internal forces of the bridge components are deduced through the relationship between the node deformation and the mechanical properties of the bridge components.

[0048] The internal force calculation formula for each bridge component is as follows:

[0049] ,

[0050] where represents the internal force of the th bridge component; is the index variable of the bridge component; is the number of nodes involved in the bridge component ; is the index variable of the node; is the external load acting on the th node, which is set using the expert experience method based on factors such as bridge design specifications, traffic flow, and environmental conditions (such as wind, temperature changes, etc.); is the node deformation of the th node; is the length of the bridge component related to the th node, which is obtained from bridge design drawings or structural modeling tools; is the contribution coefficient of the th node to the internal force of the th bridge component, which is calculated based on the geometric and mechanical properties of the bridge structure and the coupling relationship between nodes using existing technologies such as finite element analysis or empirical methods;

[0051] Furthermore, a non - linear damage index model is introduced to evaluate the damage state of bridge components. The non - linear damage index model evaluates the damage state of bridge components by combining the non - linear relationship between the internal forces and node deformations of bridge components, and controls the influence of node deformation on damage by adjusting the influence coefficient of node deformation on the damage of bridge components, thereby improving the accuracy and reliability of damage state evaluation. The damage state refers to the health condition of bridge components under load, which is quantified by the damage index calculated by the non - linear damage index model. The smaller the damage index, the more severe the damage of the bridge component and the worse its load - bearing capacity; while the larger the damage index, the better the health condition of the bridge component.

[0052] The damage index formula is as follows:

[0053] ,

[0054] Among them, represents the damage index of the th bridge component; is the index variable of the bridge component; represents the internal force of the th bridge component; represents the initial internal force of the th bridge component, which is set using the expert experience method during bridge design, representing the normal internal force value of the bridge component in the undamaged state and used to help judge the degree of damage; is the influence coefficient of the internal force difference of the bridge component on damage, used to control the influence degree of the internal force difference of the bridge component on the damage index, and is set according to the specific implementation scenario; is the influence coefficient of the node deformation amount on the damage of the bridge component, used to control the contribution degree of the node deformation amount to the damage index, and is set according to the specific implementation scenario; is the number of nodes involved in the bridge component; is the index variable of the node; is the contribution coefficient of the th node to the internal force of the th bridge component; is the node deformation amount of the th node; is the cumulative effect adjustment factor of the node deformation amount on damage, used to control the influence of the cumulative effect of the node deformation amount on the damage index of the bridge component. A larger value will make the influence of the node deformation amount on damage more significant.

[0055] Divide the damage interval according to the specific implementation scenario, such as the healthy state interval, the slight damage interval, the moderate damage interval, and the severe damage interval. By comparing the damage index of the bridge component with the preset damage interval, evaluate the damage level of the bridge component to help engineers take repair and reinforcement measures in a timely manner to ensure the safe use of the bridge.

[0056] S2: Based on the node deformation amount, use the spatio-temporal coupling dynamic response evaluation method to calculate the dynamic response characteristics of the node; construct a bridge health assessment model based on the dynamic response characteristics of the node, the node deformation amount, and the internal force of the bridge component to evaluate the health state of the bridge.

[0057] There is a certain spatio-temporal correlation between the vibration response of a bridge and the local deformation amount, where the local deformation amount is the node deformation amount. In practical applications, the change in the vibration response of a bridge is closely related to the local deformation amount of the bridge nodes and is affected by both time and space distributions. Based on the spatio-temporal correlation, a spatio-temporal coupled dynamic response evaluation method is proposed, which combines the vibration response of the bridge and the node deformation amount to calculate the dynamic response characteristics of the nodes in order to evaluate the health state of the bridge. The vibration response of a bridge refers to the inherent vibration characteristics of the bridge structure. The dynamic response characteristics of the nodes are jointly determined by the influence of the vibration response of the bridge and the node deformation amount. Specifically, the dynamic response characteristics of the nodes are affected not only by the inherent vibration characteristics of the bridge structure, such as amplitude, attenuation coefficient, and vibration frequency, but also by the node deformation amount.

[0058] The calculation formula for the dynamic response characteristics of the nodes is as follows:

[0059] ,

[0060] where, is the dynamic response characteristic of the th node at the current moment; is the time index variable used to represent the current moment; represents the vibration response of the bridge, is the initial amplitude of the vibration; is the vibration attenuation factor, which reflects the attenuation of the vibration amplitude over time as energy dissipates; is the basic attenuation coefficient of the vibration attenuation factor; is the cosine function; is the angular frequency of the vibration, which reflects the periodicity of the vibration; the initial amplitude of the vibration , the basic attenuation coefficient of the vibration attenuation factor, the angular frequency of the vibration are set according to the specific implementation scenario; represents the influence of the node deformation amount of the th node at the current moment on the dynamic response characteristic; is the vibration sensitivity coefficient, which represents the degree of influence of the node deformation amount on the dynamic response characteristic and is set according to the specific implementation scenario; represents the node deformation amount of the th node at the current moment; is the correction term, which is corrected using the weighted node deformation amount of the node; is the smoothing coefficient, which is used to adjust the correction degree of the weighted node deformation amount on the dynamic response characteristic to avoid affecting the overall evaluation result and is set according to the specific implementation scenario; is the total number of nodes participating in the calculation; is the index variable of the node; is the weighting factor of the

[0061] A bridge health assessment model is constructed by integrating the dynamic response characteristics of nodes, the deformation of nodes, and the internal forces of bridge components to evaluate the overall health status of the bridge. To further improve the accuracy of bridge health status assessment, an environmental correction factor is introduced to adapt to the influence of environmental factors such as temperature and humidity on the health status assessment results and compensate for the influence brought by environmental changes, thereby improving the accuracy of the health status assessment results.

[0062] The formula of the bridge health assessment model is expressed as follows:

[0063] ,

[0064] where, is the health assessment value of the bridge, calculated based on the data of currently sampled sensors, and is used to quantitatively evaluate the health status of the bridge; is the weighting coefficient of the weighted node deformation of the node on the health status assessment, used to control the influence degree of the weighted node deformation of the node on the bridge health status assessment, and is set according to the expert experience method; is the total number of nodes participating in the calculation; is the index variable of the node; is the weighting factor of the is the weighting coefficient of the internal force of the bridge component on the bridge health status assessment, used to control the influence of the internal force of the bridge component on the bridge health status assessment, and is set according to the expert experience method; is the total number of bridge components; is the index variable of the bridge component; is the weighting factor of the th bridge component, used to reflect the importance degree of the th bridge component, and is set according to the specific implementation scenario; represents the internal force of the is the weighting coefficient of the dynamic response characteristics on the bridge health status assessment, used to represent the contribution degree of the dynamic response characteristics to the bridge health status assessment; is the dynamic response characteristic of the is the environmental correction factor, used to adjust the influence of environmental changes on the bridge health assessment model; is the adjustment coefficient of temperature on the environmental correction factor, and is set by the expert experience method; is the difference between the current environmental temperature and the reference temperature; is the difference between the current environmental humidity and the reference humidity; the reference temperature and reference humidity are set according to specific implementation scenarios.

[0065] Finally, the bridge health range is set according to specific implementation scenarios. When the bridge health assessment value is within the bridge health range, it indicates that the bridge is in good condition. At this time, regular inspections and monitoring can continue to ensure the stability of the bridge structure. If the bridge health assessment value is not within the bridge health range, further inspections of the bridge are required to confirm whether there are damages or abnormal conditions. At the same time, appropriate maintenance, strengthening or other countermeasures are taken according to the specific situation to ensure the safety of the bridge.

[0066] In summary, a method for evaluating the state of a concrete-filled steel tube tied arch bridge is completed.

[0067] The order of the invention embodiments is only for description and does not represent the superiority or inferiority of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0068] Each embodiment in this specification is described in a progressive manner. For the same or similar parts between each embodiment, reference can be made to each other. Each embodiment focuses on the differences from other embodiments.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A method for evaluating the state of a steel tube concrete tied arch bridge, characterized in that: The following steps are involved: S1: Collect the vertical displacement of the node and calculate the node deformation based on the vertical displacement of the node; calculate the internal force of the bridge component based on the node deformation; introduce a nonlinear damage index model to calculate the damage index of the bridge component by combining the internal force and node deformation of the bridge component; evaluate the damage level of the bridge component based on the damage index of the bridge component; S2: There is a spatiotemporal correlation between the vibration response of the bridge and the node deformation. Based on the spatiotemporal correlation, a spatiotemporal coupling dynamic response evaluation method is proposed to combine the vibration response of the bridge and the node deformation to calculate the dynamic response characteristics of the node; A bridge health assessment model is constructed based on the dynamic response characteristics of nodes, node deformation and internal forces of bridge components to evaluate the health status of the bridge. In the process of implementing the bridge health assessment model, an environmental correction factor is introduced to compensate for the impact caused by environmental changes. The formula of the bridge health assessment model is as follows: ， in, is the health assessment value of the bridge; is the weighting coefficient of the node's weighted node deformation for health status assessment; is the total number of nodes participating in the calculation; is the index variable of the node; It is The weighting factor of each node; Indicates The node deformation of each node at the current moment; is the weighting coefficient of the internal forces of bridge components for the assessment of bridge health status; is the total number of bridge components; is the index variable of the bridge component; It is Weighting factors for each bridge component; Indicates Internal forces of bridge components; is the weighting coefficient of the dynamic response characteristics for the assessment of bridge health status; It is The dynamic response characteristics of each node at the current moment; is the environmental correction factor; is the adjustment coefficient of temperature to the environmental correction factor; is the difference between the current ambient temperature and the reference temperature; It is the difference between the current ambient humidity and the reference humidity.

2. The method for evaluating the state of a steel tube concrete tied arch bridge according to claim 1, characterized in that: The S1 specifically includes: In the process of calculating the node deformation, a weighting factor is introduced to evaluate the importance of each node; the node deformation calculation formula is as follows: ， in, Indicates The node deformation of each node; is the index variable of the node; It is The weighting factor of each node; is the total number of nodes participating in the calculation; and is the index variable of the node; It represents a node and nodes The coupling coefficient between It is a node collected by sensors The vertical displacement of is the adjustment coefficient; It represents a node and nodes The coupling coefficient between It is a node collected by sensors vertical displacement.

3. The method for evaluating the state of a steel tube concrete tied arch bridge according to claim 2, characterized in that: The S1 specifically includes: The internal force of the bridge component is calculated through the relationship between the node deformation and the mechanical properties of the bridge component. The specific calculation formula is: ， in, Indicates Internal forces of bridge components; is the index variable of the bridge component; It is a bridge component The number of nodes involved; It acts on External loads on nodes; It is with The length of the bridge component associated with each node; It is Node pair The contribution coefficient of the internal force of each bridge component is calculated based on the geometry and mechanical properties of the bridge structure and the coupling relationship between the nodes.

4. The method for evaluating the state of a steel tube concrete tied arch bridge according to claim 3 is characterized in that: The S1 specifically includes: The nonlinear damage index model evaluates the damage state of bridge components by combining the nonlinear relationship between the internal force and node deformation of bridge components, and controls the influence of node deformation on damage by adjusting the influence coefficient of node deformation on the damage of bridge components.

5. The method for evaluating the state of a steel tube concrete tied arch bridge according to claim 4, characterized in that: The S1 specifically includes: The damage state refers to the health of bridge components under load, which is quantified by the damage index calculated by the nonlinear damage index model; the damage index formula is as follows: ， in, Indicates Damage index of each bridge component; is the influence coefficient of the internal force difference of bridge components on damage; Indicates Initial internal forces of each bridge component; is the influence coefficient of node deformation on the damage of bridge components; It is The node deformation of each node; It is the adjustment factor of the cumulative effect of node deformation on damage.

6. The method for evaluating the state of a steel tube concrete tied arch bridge according to claim 5, characterized in that: The S1 specifically includes: The damage intervals are divided into healthy state interval, slight damage interval, moderate damage interval and severe damage interval. The damage level of the bridge components is evaluated by comparing the damage index and damage interval of the bridge components.

7. The method for evaluating the state of a steel tube concrete tied arch bridge according to claim 1, characterized in that: The S2 specifically includes: Set a bridge health range. When the bridge health assessment value is within the bridge health range, it means that the bridge is in good condition and regular inspections and monitoring should continue. When the bridge health assessment value is not within the bridge health range, further inspection of the bridge should be carried out to confirm whether there is any damage or abnormality, and appropriate response measures should be taken as appropriate.

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