Methods for evaluating structures

Abstract

This method estimates the maximum response displacement that occurs in a structure when subjected to an earthquake. [Solution] The method for evaluating a structure includes: step S10 of obtaining crack information relating to cracks that have occurred in the structure after an earthquake; step S11 of obtaining a plurality of crack occurrence locations indicating the locations where cracks have occurred using the crack information; step S12 of obtaining a plurality of crack widths indicating the widths of the plurality of cracks using the crack information; and step S40 of obtaining the maximum response displacement that occurred at the evaluation position set on the structure when it was subjected to an earthquake, using the plurality of crack occurrence locations and the plurality of crack widths. Step S40 of obtaining the maximum response displacement includes step S41 of obtaining the residual displacement that occurred at the evaluation position when it was subjected to an earthquake, using the plurality of crack occurrence locations and the plurality of crack widths; and step S42 of estimating the maximum response displacement that occurred at the evaluation position using the residual displacement.

Description

[Technical Field]

[0001] The present invention relates to a method for evaluating structures. [Background technology]

[0002] When an earthquake acts on a reinforced concrete structure, it is sometimes necessary to quantitatively evaluate the damage and performance of the structure. Patent documents 1 and 2 disclose methods for evaluating structures that have cracked. Patent document 1 discloses a method for estimating the maximum value of shear crack width using the residual value of shear crack width. Patent document 2 discloses a method for estimating the maximum inter-story deformation using crack width and crack length. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2004-332332 [Patent Document 2] Patent No. 7106472 [Overview of the project] [Problems that the invention aims to solve]

[0004] To quantitatively evaluate the damage and performance of structures, the maximum response displacement generated in a structure by an earthquake (hereinafter referred to as "maximum response displacement") is used. Obtaining the maximum response displacement requires constant dynamic measurements against earthquakes, which can occur at unpredictable times. Such measurements have presented challenges in terms of maintenance and cost of measuring equipment.

[0005] Therefore, the present invention provides a method for evaluating structures that can estimate the maximum response displacement generated in a structure when subjected to an earthquake, based on crack information obtained from measurements and inspections after an earthquake. [Means for solving the problem]

[0006] A method for evaluating a structure according to one embodiment of the present invention includes the steps of: obtaining crack information relating to cracks that have occurred in a structure subjected to an earthquake; obtaining a plurality of crack occurrence locations indicating the locations where cracks have occurred using the crack information; obtaining a plurality of crack widths indicating the widths of the plurality of cracks using the crack information; and obtaining the maximum response displacement that occurred at an evaluation position set on the structure when subjected to an earthquake using the plurality of crack occurrence locations and the plurality of crack widths, wherein the step of obtaining the maximum response displacement includes the steps of obtaining the residual displacement that occurred at the evaluation position when subjected to an earthquake using the plurality of crack occurrence locations and the plurality of crack widths; and estimating the maximum response displacement that occurred at the evaluation position using the residual displacement.

[0007] This evaluation method uses crack information regarding cracks that occurred in a structure subjected to an earthquake to obtain multiple crack locations and multiple crack widths. By using these values, the residual displacement that occurred at the evaluation location when the earthquake occurred can be obtained, and as a result, the maximum response displacement that occurred at the evaluation location can be estimated.

[0008] The above method further includes a step performed before the step of obtaining the maximum response displacement, which involves obtaining a crack occurrence range indicating the range in which cracks exist in the structure using the crack occurrence location, and a step of determining whether the deformation caused to the structure by the earthquake has reached the plastic deformation range, wherein the step of obtaining the maximum response displacement may be performed when it is determined in the determination step that the deformation caused to the structure has reached the plastic deformation range. This step makes it possible to estimate the maximum response displacement that occurred at the evaluation location when the deformation caused to the structure has reached the plastic deformation range.

[0009] In the above method, the step of obtaining the residual displacement may include the steps of obtaining the bending displacement at the evaluation position based on the bending deformation caused in the structure by the earthquake, obtaining the tilt displacement at the evaluation position based on the tilt caused in the structure by the earthquake, and obtaining the residual displacement by adding the bending displacement and the tilt displacement. This step makes it possible to obtain the residual displacement of the structure.

[0010] In the above method, the step of estimating the maximum response displacement may involve preparing a residual displacement ratio, which is defined in advance as the ratio of residual displacement to the maximum response displacement, and estimating the maximum response displacement occurring at the evaluation position using the residual displacement and the residual displacement ratio. According to this step, the maximum response displacement can be obtained from the residual displacement using the residual displacement ratio.

[0011] In the above method, the step of preparing the residual displacement ratio may involve generating an estimation model by machine learning processing with residual displacement, structural specifications of the structure, and seismic characteristics as the first explanatory variables and the residual displacement ratio as the objective function, and then estimating the residual displacement ratio using the estimation model with crack information, structural specifications of the structure, and seismic characteristics as the second explanatory variables. This step allows for obtaining the residual displacement ratio.

[0012] In the method described above, the step of preparing the residual displacement ratio may be performed by obtaining the residual displacement using the simulated maximum response displacement and simulated residual displacement obtained as a result of dynamic analysis using a mechanical model that simulates the structure. The residual displacement ratio can also be obtained by this step.

[0013] In the above method, the step of obtaining the maximum response displacement may involve obtaining the assumed maximum response displacement and assumed residual displacement that occur when an earthquake assumed to be present is applied to a mechanical model simulating the structure, and the step of estimating the maximum response displacement may involve comparing the residual displacement and the assumed residual displacement, and adopting the assumed maximum response displacement as the maximum response displacement when the assumed residual displacement can be evaluated as being the same as the residual displacement. According to this step, the maximum response displacement can be obtained without using the residual displacement ratio.

[0014] Another method for evaluating a structure according to an aspect of the present invention includes steps of obtaining crack information regarding cracks generated in a structure that has experienced an earthquake, obtaining a plurality of crack occurrence positions indicating positions where cracks have occurred using the crack information, obtaining a crack occurrence range indicating a range where a plurality of cracks have occurred using the plurality of crack occurrence positions, and obtaining a maximum response displacement generated at an evaluation position of the structure using the crack occurrence range. The step of obtaining the maximum response displacement includes steps of obtaining the seismic intensity of the earthquake that has acted on the structure using the crack occurrence range, and estimating the maximum response displacement generated at the evaluation position of the structure using the seismic intensity.

[0015] This evaluation method uses the crack information regarding cracks generated in a structure that has experienced an earthquake to obtain a plurality of crack occurrence positions and a crack occurrence range. By using these values, the seismic intensity of the earthquake that has acted on the evaluation position when the structure has experienced an earthquake can be obtained, and as a result, the maximum response displacement generated at the evaluation position can be estimated.

[0016] The above method is implemented before the step of obtaining the maximum response displacement, and further includes a step of determining whether the deformation generated in the structure that has experienced an earthquake has reached the plastic deformation region using the crack occurrence range in the structure. In the determining step, when it is determined that the deformation generated in the structure has reached the plastic deformation region, the step of obtaining the maximum response displacement may be executed. According to this step, the maximum response displacement generated at the evaluation position when the deformation generated in the structure has reached the plastic deformation region can be estimated.

[0017] Another method for evaluating a structure according to yet another aspect of the present invention includes steps of obtaining crack information regarding cracks generated in a structure that has experienced an earthquake, obtaining a crack occurrence range indicating a range where a plurality of cracks have occurred using the crack information, and determining whether the deformation generated in the structure that has experienced an earthquake has reached the plastic deformation region using the crack occurrence range.

[0018] According to this method, it is possible to determine whether or not the deformation generated in the structure that has experienced an earthquake has reached the plastic deformation range by using the crack generation range.

[0019] In the above method, the step of obtaining crack information may include the step of obtaining crack information by measurement using an optical fiber sensor installed in the structure. According to this step, the strain generated in the structure can be measured spatially and continuously. Furthermore, the measurement using the optical fiber sensor can also measure the crack width and the generation distribution simultaneously.

[0020] In the above method, the step of obtaining the crack generation range may be to obtain a first calculation value indicating the distance from the first crack closest to the reference position to the second crack farthest from the reference position, obtain a second calculation value indicating the crack interval indicating the interval between adjacent cracks, and obtain the value obtained by adding the second calculation value to the first calculation value as the crack generation range. According to this step, the accuracy of the crack generation range can be improved.

[0021] In the above method, the damage degree of the structure may be evaluated using the maximum response displacement and a limit value preset based on the limit state of the structure. According to this step, the damage degree of the structure can be evaluated.

Advantages of the Invention

[0022] According to the present invention, there is provided a method for evaluating a structure capable of estimating the maximum response displacement generated in the structure when it has experienced an earthquake.

Brief Description of the Drawings

[0023] [Figure 1] FIG. 1 is a perspective view showing a pier structure which is an example of an application target of a method for evaluating a structure according to an embodiment. [Figure 2] FIG. 2 is a flowchart showing the main steps of a method for evaluating a structure according to an embodiment. [Figure 3]Figure 3 is a flowchart that shows in detail the steps to obtain the maximum response displacement using the crack initiation range and crack initiation location shown in the flowchart of Figure 1. [Figure 4] Figure 4 is a diagram illustrating some parameters in a method for evaluating a structure, which is an embodiment of the process. [Figure 5] Figure 5 is a diagram illustrating the optical fiber sensor to be installed on the bridge pier shown in Figure 1. [Figure 6] Figure 6(a) is a diagram illustrating the process for calculating residual crack width. Figure 6(b) is a graph showing an example of strain distribution information used in the process for calculating residual crack width. [Figure 7] Figure 7 is a graph illustrating the range of residual cracks after correction. [Figure 8] Figure 8(a) is an analytical model of the bridge pier's framework. Figure 8(b) is a schematic diagram showing the locations where residual cracks occur in the bridge pier shown in Figure 8(a). [Figure 9] Figure 9(a) is a graph showing the curvature that defines the bending that occurs at a given location on the bridge pier. Figure 9(b) is a graph showing the relationship between the horizontal seismic intensity acting on the bridge pier and the maximum response displacement. [Figure 10] Figure 10(a) schematically shows the deformation of a bridge pier defined by bending deformation and rotational deformation. Figure 10(b) schematically shows the deformation of a bridge pier defined by rotational deformation. Figure 10(c) schematically shows the deformation of a bridge pier defined by bending deformation. [Figure 11] Figure 11(a) is a diagram illustrating the calculation process for bending displacement caused by bending deformation. Figure 11(b) is a beam model of a bridge pier illustrating the calculation process for bending displacement caused by bending deformation. [Figure 12] Figure 12 is a diagram illustrating the residual displacement of a bridge pier due to rotational deformation. [Figure 13] Figure 13(a) is a schematic diagram illustrating the process of obtaining the residual displacement of a bridge pier based on rotational deformation. Figure 13(b) is a diagram illustrating the process of calculating the strain occurring in the bridge pier near the footing. [Figure 14] Figures 14(a), 14(b), and 14(c) are diagrams illustrating the process for obtaining the amount of extension of the reinforcing bars. [Figure 15] Figure 15 is a diagram illustrating the process of obtaining the residual displacement ratio using machine learning. [Figure 16] Figure 16 is a graph illustrating the process of obtaining the residual displacement ratio through dynamic analysis. [Figure 17] Figure 17 is a graph illustrating the process of obtaining the maximum response displacement through repeated dynamic analysis. [Modes for carrying out the invention]

[0024] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the attached drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted.

[0025] The method of this embodiment can be used, for example, to evaluate a reinforced concrete (RC) structure. An example of an RC structure is the bridge pier structure 1 shown in Figure 1. The bridge pier structure 1 includes a bridge pier section 2 and a footing 3. The bridge pier section 2 has a structure in which reinforcing bars 22 are embedded in concrete 21. The lower end of the reinforcing bars 22 is embedded in the footing 3.

[0026] For example, seismic motion acting horizontally on the bridge pier 2 can be assumed. The bridge pier 2 subjected to seismic motion undergoes deformation due to bending and rotation. This deformation can also be a factor in causing elongation of the reinforcing bars 22 that make up the bridge pier 2. The deformation of the reinforcing bars 22 is either elastic or plastic, and which type of deformation occurs depends on the relationship between the strain and stress generated in the reinforcing bars 22. If the stress generated in the reinforcing bars 22 does not exceed the so-called yield point, the deformation generated in the reinforcing bars 22 is elastic deformation. If the stress generated in the reinforcing bars 22 exceeds the so-called yield point, the deformation generated in the reinforcing bars 22 is plastic deformation.

[0027] Furthermore, deformation of the pier 2 can cause cracks in the concrete 21 that constitutes the pier 2. Once cracks occur, they do not return to their original state and remain as residual cracks. Depending on the manner of deformation of the reinforcing bars 22, two types of residual cracks can be exemplified. For example, if the deformation of the reinforcing bars 22 is elastic deformation, the width of the residual cracks will be extremely small. On the other hand, if the deformation of the reinforcing bars 22 is plastic deformation, the reinforcing bars 22 do not return to their original length, so the residual cracks will have a predetermined width.

[0028] When these changes occur due to seismic motion, the degree of damage to the pier 2 and the performance of the pier 2 may be evaluated. For such evaluation, it is desirable to obtain the maximum response displacement (hereinafter referred to as "maximum response displacement") that occurs when the pier 2 is subjected to seismic motion at a predetermined location (hereinafter referred to as "evaluation location") of the pier 2.

[0029] The method for evaluating a structure in this embodiment involves estimating the maximum response displacement that occurs at the evaluation location of a reinforced concrete (RC) bridge pier 2, which is an example of a structure. The procedure for estimating the maximum response displacement will be described below.

[0030] The following is an overview of the method for evaluating structures. The evaluation flow shown in Figure 2 evaluates the maximum response displacement that occurred in reinforced concrete members (hereinafter also referred to as "RC members") subjected to an earthquake, based on the residual crack width and the extent of residual crack occurrence.

[0031] First, if the RC member has not undergone plastic deformation, the sectional forces, such as bending moment, continue to increase in accordance with the magnitude of the external force during an earthquake. As these sectional forces increase, the range over which residual cracks occur (residual crack occurrence range) also expands. On the other hand, when the RC member undergoes plastic deformation, the sectional forces stop increasing. As a result, the residual crack occurrence range remains unchanged. In other words, at the point where the reinforcing bar 22 yields, a certain amount of residual crack width W25 remains. Therefore, using the corrected residual crack occurrence range E25b and residual crack width W25, it is determined whether or not the member under evaluation has undergone plastic deformation (S20).

[0032] In determining whether the member under evaluation has undergone plastic deformation, if the RC member is determined not to have undergone plastic deformation (S20:NO), it is difficult to evaluate the width of the residual cracks because they are minute. On the other hand, at this stage, as mentioned above, the range of crack occurrence changes with the magnitude of the external force during an earthquake. Therefore, the maximum response of the member's displacement is estimated based on the corrected residual crack occurrence range E25b (S30).

[0033] In determining whether the member under evaluation has undergone plastic deformation, if the RC member is determined to have undergone plastic deformation (S20: YES), the sectional force does not increase significantly, and therefore the crack occurrence area does not change significantly. On the other hand, the residual crack width W25 remains to a certain extent after the earthquake. Therefore, the residual displacement D21 is estimated based on the residual crack width W25. Subsequently, the maximum response displacement M21 is estimated from the residual displacement D21, taking into account the dynamic behavior during the earthquake (S40).

[0034] Furthermore, performance evaluation is performed by comparing the maximum response displacement obtained above with the limit value set for the structure (e.g., ultimate displacement).

[0035] The following provides a detailed explanation of each step shown in the flowchart in Figure 2.

[0036] First, information regarding cracks occurring in the bridge pier 2, which is a structural component, is obtained (S10). Here, "information regarding cracks" refers to information that allows us to obtain the location of the cracks, the width of the cracks, and the extent of the cracks, which will be obtained in the later steps S11 to S14.

[0037] Here, we will explain the information regarding the cracks with reference to Figure 4. Figure 4 shows member 100 in which seven residual cracks 25a, 25b, 25c, 25d, 25e, 25f, and 25g (hereinafter referred to as "residual cracks 25a to 25g") have occurred. The information regarding the cracks includes "location of residual crack occurrence," "width of residual crack," "spacing of residual crack," "range of residual crack occurrence before correction," and "range of residual crack occurrence after correction."

[0038] The residual crack occurrence locations L25a, L25b, L25c, L25d, L25e, L25f, and L25g (hereinafter referred to as "residual crack occurrence locations L25a to L25g") are the distances from the evaluation location L20 to each of the residual cracks 25a to 25g. The evaluation location L20 may be set arbitrarily depending on the method of evaluation. The residual crack widths W25a, W25b, W25c, W25d, W25e, W25f, and W25g (hereinafter referred to as "residual crack widths W25a to W25g") are the opening widths of the residual cracks 25a to 25g formed on the surface 100a of the member 100. The residual crack spacings G25a and G25f are the distances from one residual crack 25 to another residual crack 25 adjacent to that residual crack 25. The residual crack occurrence range E25a before correction is the distance from the residual crack 25 closest to the evaluation position L20 to the residual crack 25 furthest from the evaluation position L20. The residual crack occurrence range E25b after correction is the value obtained by adding the residual crack intervals G25a and G25f to the residual crack occurrence range E25a before correction. In general, residual crack intervals are not constant and may vary. Therefore, it is advisable to use the average value of multiple crack intervals when adding the residual crack interval. Alternatively, the residual crack interval to be added may be the value obtained by multiplying the formula described in the concrete standard specifications by (1 / 1.5), as shown in formula (1) below. According to the study by Zhao et al., this value has been shown to correspond to the average crack interval of the member.

number

number

[0039] The first example of information regarding cracks is strain information. The second example of information regarding cracks is image information of the surface of the bridge pier 2. The third example of information regarding cracks is inspection information obtained by visually inspecting the surface of the bridge pier 2. Based on the information exemplified here, the crack location, crack width, and crack range described later can be obtained. Furthermore, the information regarding cracks is not limited to the first to third examples, as long as the crack location, crack width, and crack range can be obtained.

[0040] Therefore, step S10, which involves obtaining information about cracks, is the operation of obtaining strain information using an optical fiber sensor 4 laid on the bridge pier 2, according to the first example of information about cracks. Measurement using an optical fiber sensor allows for spatial and continuous measurement of the strain generated in the bridge pier 2. Furthermore, measurement using an optical fiber sensor can simultaneously measure the crack width and the distribution of occurrence.

[0041] More specifically, as shown in Figure 5, optical fiber sensors 4 are provided on each of the four sides 2a, 2b, 2c, and 2d of the pier section 2. The optical fiber sensors 4 are fixed to the surface of the pier section 2 along the direction in which the pier section 2 extends. In other words, the optical fiber sensors 4 are installed axially on two or four opposing surfaces of the member. When calculating the residual displacement D21, which will be described later, if they are installed on two surfaces, it is possible to calculate the deformation in one direction. If they are installed on four surfaces, it is possible to calculate the displacement in two directions. Since the plastic hinge section of the member accounts for most of the deformation, the optical fiber sensors 4 may be installed only in the plastic hinge section. When strain occurs in the pier section 2, strain also occurs in the optical fiber sensors 4. When measurement light is applied to the optical fiber sensors 4, reflected light such as Rayleigh scattered light and Brillouin scattered light is obtained from the optical fiber sensors 4. The reflected light obtained when strain occurs is different from the reflected light obtained when no strain occurs. By utilizing this reflected light, it is possible to obtain information about the strain occurring in the bridge pier 2.

[0042] Figure 6(b) shows strain distribution information (graph G6), which is an example of information regarding cracks. In Figure 6(b), the horizontal axis indicates the location on the pier 2, and the vertical axis indicates the magnitude of strain at that location. Figure 6(b) illustrates three residual cracks 25a, 25b, and 25c. In the following explanation, when a residual crack is to be identified individually, an alphabet letter is added to the end of the reference number, such as "residual crack 25a". On the other hand, when it is not necessary to identify a residual crack individually and one or more residual cracks are to be identified, the alphabet letter at the end of the reference number is omitted, such as "residual crack 25". The residual crack locations L25a, L25b, and L25c are defined as distances from a predetermined standard (for example, the end of the pier 2 on the footing 3 side).

[0043] Furthermore, referring to graph G6 in Figure 6(b), it can be seen that the strain is greater at the residual crack initiation locations L25a, L25b, and L25c of the residual cracks 25a, 25b, and 25c. Thus, it can be seen that the strain distribution information (graph G6) shows information about the residual cracks 25a, 25b, and 25c. In this embodiment, the information about the cracks is explained as the strain distribution information (graph G6) shown in Figure 6(b). Therefore, a more detailed relationship between the strain distribution information and the residual cracks 25a, 25b, and 25c will be described later.

[0044] Step S10, which involves obtaining information about cracks, is, according to the second example of information about cracks, an operation to acquire image information. This image information can be obtained by various methods. For example, when imaging the high-altitude portion of the bridge pier 2, a drone equipped with a camera may be used to obtain a surface image of the bridge pier 2 including residual cracks.

[0045] Furthermore, step S10, which involves obtaining information about cracks, is performed by a worker visually observing the residual cracks, according to the third example of information about cracks. The worker may also measure the location and width of the residual cracks one by one using a predetermined measuring instrument.

[0046] Next, multiple crack occurrence locations are obtained (S11). As mentioned above, the residual crack occurrence locations L25a, L25b, and L25c included in the strain distribution information (graph G6) correspond to residual crack occurrence locations L25a, L25b, and L25c. Therefore, in this step S11, first, residual crack occurrence locations L25a, L25b, and L25c are extracted from the strain distribution information (graph G6). If multiple residual crack occurrence locations L25a, L25b, and L25c are extracted, it means that multiple residual cracks 25a, 25b, and 25c have occurred.

[0047] Next, multiple crack widths are obtained (S12). In this step S12, the integral value of a predetermined region in the strain distribution information (graph G6) is defined as representing the crack width. Assuming that the deformation of the concrete forming the bridge pier 2 is small, the residual crack width W25 and the elongation of the optical fiber sensor 4 installed around the residual crack 25 coincide. As a result, the residual crack width W25 can be calculated by integrating the strain obtained by the optical fiber sensor 4 around the residual crack 25. The integration interval when calculating the integral value of the strain is, for example, between the midpoints of adjacent cracks.

[0048] More specifically, the first step is to select the peak P25b to be integrated. Next, another peak P25a adjacent to peak P25b is selected. Then, the inter-peak distance (residual crack spacing G25a) from peak P25b to peak P25a is calculated, and a distance that is half of this inter-peak distance is defined as the first integration interval A25a to be integrated. Similarly, a second integration interval A25b is defined using another peak P25c adjacent to the peak P25b by the same process. Then, the strain distribution information (graph G6) is integrated in the defined first integration interval A25a and second integration interval A25b. The result of the integration can be shown as the hatched region Q25b. This integrated result is saved as the residual crack width W25 of the residual crack 25 corresponding to peak P25b. By performing this process for all peaks P25, multiple residual crack widths W25 can be obtained.

[0049] Next, the pre-correction residual crack occurrence range E25A is obtained (S13). As already mentioned, the pre-correction residual crack occurrence range E25A is the distance from the residual crack 25 closest to the evaluation position L20 to the residual crack 25 furthest from the evaluation position L20. Therefore, in this step S13, first, the residual crack 25a closest to the evaluation position L20 is selected, and the residual crack occurrence position L25a representing that residual crack 25a is obtained. Next, the residual crack 25g furthest from the evaluation position L20 is selected, and the residual crack occurrence position L25g representing that residual crack 25g is obtained. Then, the difference between the furthest residual crack occurrence position L25g and the closest residual crack occurrence position L25a is obtained. This difference is saved as the pre-correction residual crack occurrence range E25a.

[0050] Next, the corrected residual crack initiation range is obtained (S14). In the maximum response evaluation based on the corrected residual crack initiation range E25B, the crack initiation range in the analysis is set to the range in which the strain (or curvature) generated in the element exceeds the crack initiation strain (or curvature). However, in actual RC members, the crack initiation range becomes smaller than in the analysis due to the effect of tensile stress being released at the crack surface. This is because, as tensile stress is released at the crack surface, there are sections around the crack where the tensile stress does not reach the crack initiation stress even when the sectional force that causes cracking is acting. Therefore, assuming that the residual crack initiation range corresponds to the crack spacing, the average value of the crack spacing (residual crack spacing G25a, G25f) is added to the measured value of the crack initiation range (pre-corrected residual crack initiation range E25A).

[0051] The value to be added may be the average value of the crack spacing as described above, or a value obtained by other methods may be used. For example, the residual crack spacing to be added may be the value obtained by multiplying the formula described in the Standard Specifications for Concrete, as shown in formula (3) below, by (1 / 1.5).

number

number

[0052] Figure 7 shows the crack initiation range obtained from the analysis and the result of adding the average crack spacing to the crack initiation range obtained from the experiment. Multiple plots D1 represent experimental results based on the first sample, and multiple plots D2 represent experimental results based on the second sample. The closer the graph is to G7, the more the experimental results and analysis results show the same value. As is clear from Figure 7, by adding the average crack spacing to the crack initiation range obtained from the experiment, it can be confirmed that the two show almost the same value.

[0053] As already mentioned, the corrected residual crack occurrence range E25b is the sum of the pre-correction residual crack occurrence range E25a and the residual crack intervals G25a and G25f. Therefore, in this step S14, we first obtain the residual crack intervals G25a and G25f. Specifically, we select the residual crack 25a closest to the evaluation position L20 and another residual crack 25b adjacent to that residual crack 25a. Next, we obtain the difference between the closest residual crack occurrence position L25a and the adjacent residual crack occurrence position L25b. This difference is saved as the first residual crack interval G25a. Next, we select the residual crack 25g furthest from the evaluation position L20 and another residual crack 25f adjacent to that residual crack 25g. Next, we obtain the difference between the furthest residual crack occurrence position L25g and the adjacent residual crack occurrence position L25f. This difference is saved as the second residual crack interval G25f. Then, the first residual crack interval G25a and the second residual crack interval G25f are added to the uncorrected residual crack occurrence range E25A obtained in step S13 (see Figure 4). This value is saved as the corrected residual crack occurrence range E25B.

[0054] Next, it is determined whether the deformation in the reinforcing bars 22 of the bridge pier 2 is elastic or plastic (S20). This step S20 has a first example using the residual crack width W25 and a second example using the corrected residual crack occurrence range E25B. The determination may be made using only the method of the first example, or only the method of the second example. Furthermore, the determination may be made by comprehensively considering the results of both the first and second examples.

[0055] Let's explain the first example in detail. When the pier section 2 undergoes plastic deformation, the residual crack width W25 at the point where the reinforcing bars 22 within the pier section 2 yield increases. When plastic deformation occurs, a predetermined residual crack width W25 remains even after the external load is removed. Therefore, the plastic deformation of the member (pier section 2) is determined based on the residual crack width W25. The threshold value for the residual crack width W25 used to determine the presence or absence of plastic deformation varies depending on the specifications of the member. Accordingly, the threshold value for the residual crack width W25 used to determine the presence or absence of plastic deformation may be set appropriately based on the specifications of the member. For example, the value (0.2 mm) shown as the threshold for plastic deformation of a member in the "Architectural Institute of Japan: Guidelines for Seismic Performance Evaluation of Reinforced Concrete Buildings (Draft)" may be used as the threshold value for the residual crack width W25.

[0056] Specifically, the largest residual crack width W25 among the multiple residual crack widths W25 obtained in step S12 is extracted. Then, the largest residual crack width W25 is compared with a threshold (e.g., 0.2 mm). If the largest residual crack width W25 is greater than the threshold, it may be determined that the deformation of the member is in the plastic region (S20: YES) (R32). If the largest residual crack width W25 is less than the threshold, it may be determined that the deformation of the member is in the elastic region (S20: NO) (R31).

[0057] The second example will be explained in detail. In the second example, it is evaluated whether the corrected residual crack occurrence range E25B obtained in step S14 matches one of several judgment values. The judgment values ​​in the second example are obtained by an analysis performed in advance.

[0058] First, a framework analysis model M8 for the entire pier section 2 is defined (see Figures 8(a) and 8(b)). In the framework analysis model M8 in Figure 8(a), the symbols M81, M82, and M83 each represent the pier section 2. The horizontal axis represents the bridge axis position, and the vertical axis represents the height. Furthermore, Figure 8(b) is a schematic diagram showing the pier section 2 indicated by the symbol M83. Next, a horizontal seismic intensity is applied to the framework analysis model M8 to obtain the crack occurrence range in the framework analysis model M8. For example, the crack occurrence range in the framework analysis model M8 is defined as the range where the curvature occurring in the framework analysis model M8 exceeds a predetermined crack occurrence curvature (T9a, T9b or T10a, T10b). Figure 9(a) shows the curvature of the pier section 2 on the horizontal axis, and the position on the pier section 2 on the vertical axis. Cracks are considered to occur in the ranges T9a, T9b, T10a, and T10b where the curvature exceeds the crack-initiating curvature. These ranges T9a, T9b, T10a, and T10b are the judgment values ​​in the second example. Graphs G91, G92, and G93, showing the distribution of curvature occurring at predetermined locations on the bridge pier 2, are obtained for each horizontal seismic intensity. It can be seen that as the horizontal seismic intensity increases, the range with large curvature expands.

[0059] Furthermore, this analysis also provides information for step S40, which will be described later, to obtain the maximum response displacement. Specifically, it obtains the relationship between the response displacement and the horizontal seismic intensity given to the frame analysis model M8 (see Figure 9(b)). Figure 9(b) shows the horizontal displacement (maximum response displacement) of the pier 2 on the horizontal axis and the horizontal seismic intensity on the vertical axis. The process of obtaining the maximum response displacement using Figure 9(b) will be described later.

[0060] Based on the above explanation, the details of step S20 are as follows: First, one judgment value is selected from multiple judgment values ​​set for each graph G91, G92, and G93. Next, it is evaluated whether the corrected residual crack occurrence range E25B can be considered to match the selected judgment value. For example, if the judgment value set for graph G92 can be considered to match the corrected residual crack occurrence range E25B, then it can be seen that the horizontal seismic intensity acting on the corrected residual crack occurrence range E25B is the horizontal seismic intensity corresponding to graph G92.

[0061] When making a determination by comprehensively considering the results of both the first and second examples, for example, if plastic deformation is determined in both the first and second examples, the member may be judged to have undergone plastic deformation.

[0062] <Estimation of maximum displacement response in the case of plastic deformation> The process for estimating the maximum displacement response in the case of plastic deformation follows the flow shown in Figure 3. If the deformation occurring in the reinforcing bar 22 is in the plastic region (S20: YES), the maximum displacement response is estimated using the corrected residual crack occurrence range and crack occurrence location (S40). First, the approximate flow of step S40 is explained. First, the residual displacement D21 is calculated using the residual crack width W25 and the corrected residual crack occurrence range E25b (S41). Then, the maximum response displacement M21 is estimated using the residual displacement D21 (S42).

[0063] Examples of factors contributing to residual displacement D21 in a structure include displacement due to bending deformation of the member (hereinafter referred to as "bending displacement") and displacement due to inclination of the member (hereinafter referred to as "rotational displacement"). For example, in a reinforced concrete member subjected to bending, the effects of bending deformation of the member and rotational deformation due to the extension of the reinforcing bars at the end of the member should be considered. Furthermore, in the case of a member that is not affected by extension at the end, such as the superstructure of pier section 2, the residual displacement D21 may be calculated by considering only bending deformation and applying boundary conditions as necessary. In addition, in the case of a column member, the residual displacement may be calculated by considering both the bending deformation of the member and the rotational deformation due to extension at the end.

[0064] Hereafter, the deformation of pier section 2 (see Figure 10(a)) will be explained as the sum of bending deformation (see Figure 10(b)) and rotational deformation (see Figure 10(c)).

[0065] <Step S411 to obtain bending displacement> Fig. 11(a) is a diagram showing the pier 2 assuming that only bending deformation has occurred. Fig. 11(a) shows a plurality of residual cracks 25a to 25e. Information on the residual crack width W25 and the residual crack generation position L25 is associated with each of these residual cracks 25a to 25e. Fig. 11(b) is the beam model M11 of the pier 2. In the beam model M11, the intermediate point distances x1 to x of the residual cracks 25a to 25e are associated as information. n are associated as information.

[0066] And the bending displacement (δ ls ) at the evaluation position L20 can be obtained by the following formulas (5), (6), and (7). First, the curvature (φ k ) of each element is obtained using formula (5), and a plurality of deflection angles (θ k ) are obtained using formula (6) (S411a). Then, the bending displacement (δ ls ) occurring at the evaluation position L20 is obtained using formula (7) (S411b).

Number

Number

Number

[0067] <Step S412 of obtaining the rotational displacement> As shown in Figure 12, the rotational displacement caused by the rotational deformation of the pier 2 is equal to the rotation angle (θ) of the pier 2. sp All that is needed is to know the rotation angle (θ) of this pier section 2. sp The length of the reinforcing bars 22 extending from the footing 3 (extension amount S1) is obtained based on this length. The length of the reinforcing bars 22 extending from the footing 3 can be obtained based on the strain that occurs at the boundary between the pier 2 and the footing 3. An example of such a method is the method disclosed in the following document. Reference: Kondo, Masuo; Unjo, Shigeki: A study on the amount of axial reinforcement elongation in reinforced concrete bridge piers, Proceedings of the 25th Earthquake Engineering Research Conference, pp. 825-828, 1999.

[0068] Specifically, first, as shown in Figure 13(a), the residual crack 25a closest to the footing 3 is selected from among the multiple residual cracks 25. Then, similar to the method exemplified in step S12, the strain distribution corresponding to the selected residual crack 25a is integrated (see Figure 13(b)). Figure 13(b) is an example of the strain distribution in region K13a of Figure 13(a). The result of the integration is shown as the integral result K13c. The value obtained by this calculation is the reinforcement strain (ε) generated in the reinforcement 22 at the base of the pier 2. k ) is considered to be (S412a). And the rebar strain (ε k The elongation amount S1 of the reinforcing bar 22 is obtained using (S412b). Reinforcing bar strain (ε k The relationship between the reinforcing bar strain and the elongation amount S1 of the reinforcing bar 22 is shown by the following equations (4), (5), and (6). Equations (8), (9), and (10) are selected based on the position where yield strain is reached in the reinforcing bar 22. If the reinforcing bar strain at the base of the pier 2 has not reached yield strain, use equation (8) (see Figure 14(a)). If the reinforcing bar strain at the base of the pier 2 has reached yield strain, and the position of the inflection point P14b is shallower than the top surface reinforcing bar 32 of the footing 3, use equation (9) (see Figure 14(b)). If the reinforcing bar strain at the base of the pier 2 has reached yield strain, and the position of the inflection point P14c is deeper than the top surface reinforcing bar 32 of the footing 3, use equation (10) (see Figure 14(c)).

number

number

number

number

[0069] Since the elongation amounts (S1, S2) of the reinforcing bar 22 were obtained by any of equations (8), (9), or (10), the rotation angle (θ) at the base of the bridge pier 2 was calculated using equation (12). sp ) is obtained (S412c). Then, using equation (13), the rotational displacement (δ) generated at evaluation position L20, where the length from the base of the pier 2 is distance (L) is obtained. sp ) obtain (S412d).

number

number

[0070] And the bending displacement (δ ls ) and rotational displacement (δ sp The residual displacement is obtained by adding up (S413).

[0071] <Step to obtain the maximum response displacement using residual displacement> In step S42, the maximum response displacement M21 is obtained from the residual displacement D21 using the residual displacement ratio. The residual displacement ratio is a parameter defined by the following formula. Residual displacement ratio = Residual displacement / Maximum response displacement ... (14) As can be seen from equation (14), the residual displacement ratio is a value defined by the residual displacement and the maximum response displacement. Therefore, if the residual displacement and the residual displacement ratio are known, the maximum response displacement can be obtained. There are several methods for determining this residual displacement ratio.

[0072] <Obtaining residual displacement ratio using machine learning> The residual displacement ratio may be obtained using machine learning (S421). The residual displacement ratio can vary considerably depending on the characteristics of the seismic motion and the specifications of the structural members. To precisely consider this effect, an estimation model created using machine learning may be used. As a type of machine learning, a supervised learning algorithm can be employed. In supervised learning, as illustrated in Figure 15, an estimation model is constructed by providing explanatory variables and a target variable, which are datasets of the results of dynamic analysis, as training data (N13). Then, the residual displacement ratio is estimated based on the estimation model (N23).

[0073] Figure 15 illustrates a concept for obtaining the residual displacement ratio using machine learning. This method involves a pre-training process N1 and an estimation process N2. As a result of the pre-training process N1, an estimation model is generated (N13). Then, the estimation process N2 is performed using this estimation model and estimation data N21. As a result, the residual displacement D21 can be estimated.

[0074] In the pre-training process N1, explanatory variables N11A and the target variable N11B are defined as training data N11. The explanatory variables N11A as training data N11 include, for example, residual displacement N111, member specifications N112, and seismic motion characteristic values ​​N113. Member specifications N112 include the member's natural period, secondary stiffness ratio, and yield intensity. Seismic motion characteristic values ​​N113 include maximum acceleration and maximum velocity, etc. The target variable N11B as training data N11 is the residual displacement ratio.

[0075] In estimation process N2, explanatory variables N21A are defined as estimation data N21. Explanatory variables N21A as estimation data N21 include measured values ​​N211, member specifications N212, and seismic motion characteristic values ​​N213. Member specifications N212 may be obtained from the analysis model of the bridge pier 2. Member specifications N212 include, for example, natural period, secondary stiffness ratio, and yield intensity. Seismic motion characteristic values ​​N213 may be set based on actual seismic motion. Seismic motion characteristic values ​​N213 include maximum acceleration and maximum velocity.

[0076] In the actual estimation process N2, explanatory variables related to the member specifications N212 may be obtained by an analysis model. If an analysis model has not been constructed, the residual displacement ratio may be estimated by constructing an estimation model excluding the explanatory variables related to the member specifications N212. Similarly, if the characteristic value N213 of the seismic motion cannot be obtained, the residual displacement ratio may be estimated by constructing an estimation model excluding the explanatory variables related to the seismic motion. It has been confirmed that the LightGBM (an estimation method based on gradient boosting decision trees) method of supervised learning can estimate the residual displacement ratio of a member with one degree of freedom with high accuracy.

[0077] <Obtaining the residual displacement ratio using dynamic analysis> The residual displacement ratio may also be obtained using dynamic analysis (S422). First, a mechanical model of the pier 2 is set up. Then, a dynamic analysis is performed assuming that seismic motion defined by a predetermined waveform acts on the mechanical model. As a result, graph G161 shown in Figure 16 is obtained. In Figure 16, time is shown on the horizontal axis and displacement is shown on the vertical axis. Graph G161 shows the residual displacement D161. Furthermore, graph G161 shows the maximum response displacement D162. The residual displacement ratio may then be obtained by substituting these residual displacements D161 and D162 into equation (14) above.

[0078] Furthermore, the residual displacement ratio can be one that is listed in the literature. For example, the residual displacement ratio of "0.291" listed in the literature below may be used. This value is the average value of the dynamic analysis results for one degree of freedom, with member specifications and seismic motion as parameters. Such a value is also called a residual displacement correction coefficient. References: Japan Road Association: Reference materials on the Specifications for Highway Bridges and Commentary V: Seismic Design, Maruzen Publishing, 2015.

[0079] A method different from the one described above can be used to obtain the maximum response displacement using residual displacement. This method involves searching for a method (S423) that uses dynamic analysis parameters so that the residual displacement obtained as a result of the dynamic analysis matches the residual displacement obtained in step S413. For example, Figure 17 shows time on the horizontal axis and displacement on the vertical axis. First, when a first value, the horizontal seismic intensity, is given to the dynamic model of the pier section 2, the time history of the displacement occurring at the evaluation position set on the pier section 2 is obtained (graph G171). This time history (graph G171) shows the residual displacement D171 obtained by the analysis. Next, the residual displacement D171 obtained by the analysis is compared with the residual displacement D175 obtained in step S413. The residual displacement D171 obtained with the first value does not necessarily match the residual displacement D175 obtained in step S413. Therefore, the first value is changed to the second value, and the time history of the displacement occurring at the evaluation position set on the pier section 2 is obtained again (graph G172). Then, comparing the residual displacement D172 obtained in the second step with the residual displacement D175 obtained in step S413, it can be said that the residual displacement D172 obtained in the second step matches the residual displacement D175 obtained in step S413. In this case, the maximum value of the displacement in graph G172 can be obtained as the maximum response displacement D173. In this way, the analysis conditions are changed and repeated until the residual displacements D171 and D172 obtained by the dynamic analysis match the residual displacement D175 obtained in step S413.

[0080] Furthermore, the dynamic analysis conditions that can be changed in each iteration are not limited to the horizontal seismic intensity described above. For example, it is also permissible to change the specifications of the members constituting the bridge pier 2.

[0081] <Estimation of maximum displacement response in the absence of plastic deformation> If the deformation in the reinforcing bar 22 is within the elastic range (S20:NO), the maximum response displacement is estimated using the corrected residual crack occurrence range (S30). First, the corrected residual crack occurrence range of the pier 2 is obtained using the residual crack occurrence location L25. Next, it is identified whether the crack occurrence range corresponds to T9a, T9b or T10a, T10b shown in Figure 9(a). As a result, the horizontal seismic intensity acting on the pier 2 can be estimated (S31). Next, by reading the horizontal displacement (X-axis in Figure 9(b)) corresponding to the estimated horizontal seismic intensity (Y-axis in Figure 9(b)) for graph G94 shown in Figure 9(b), the horizontal displacement corresponding to the horizontal seismic intensity can be estimated (S32). This horizontal displacement is saved as the maximum response displacement.

[0082] <Effects and Effects> The method for evaluating a structure includes: step S10 of obtaining crack information regarding cracks that have occurred in the structure after an earthquake; step S11 of obtaining a plurality of crack occurrence locations indicating the locations where cracks have occurred using the crack information; step S12 of obtaining a plurality of crack widths indicating the widths of the plurality of cracks using the crack information; and step S40 of obtaining the maximum response displacement that occurred at the evaluation position set on the structure when it was subjected to an earthquake, using the plurality of crack occurrence locations and the plurality of crack widths. Step S40 of obtaining the maximum response displacement includes step S41 of obtaining the residual displacement that occurred at the evaluation position when it was subjected to an earthquake, using the plurality of crack occurrence locations and the plurality of crack widths; and step S42 of estimating the maximum response displacement that occurred at the evaluation position using the residual displacement.

[0083] This evaluation method uses crack information regarding cracks that occurred in a structure subjected to an earthquake to obtain multiple crack locations and multiple crack widths. By using these values, the residual displacement that occurred at the evaluation location when the earthquake occurred can be obtained, and as a result, the maximum response displacement that occurred at the evaluation location can be estimated.

[0084] The above method further includes steps S13 and S14, which are performed before step S40 to obtain the maximum response displacement, and which use the crack occurrence location to obtain a crack occurrence range indicating the range in which cracks exist in the structure, and step S20, which uses the crack occurrence range to determine whether or not the deformation caused by the earthquake in the structure has reached the plastic deformation range. Step S40 to obtain the maximum response displacement may be performed when it is determined in the determination step S20 that the deformation caused in the structure has reached the plastic deformation range. According to step S20, it is possible to estimate the maximum response displacement that occurred at the evaluation location when the deformation caused in the structure has reached the plastic deformation range.

[0085] In the above method, step S41 for obtaining residual displacement may include step S411 for obtaining bending displacement at the evaluation position based on the bending deformation caused in the structure by the earthquake, step S412 for obtaining tilt displacement at the evaluation position based on the tilt caused in the structure by the earthquake, and step S413 for obtaining residual displacement by adding the bending displacement and the tilt displacement. By this step S41, the residual displacement of the structure can be obtained.

[0086] In the above method, step S40, which estimates the maximum response displacement, prepares a residual displacement ratio, which is defined in advance as the ratio of the residual displacement to the maximum response displacement, and estimates the maximum response displacement that occurred at the evaluation position using the residual displacement and the residual displacement ratio. According to this step S40, the maximum response displacement can be obtained from the residual displacement using the residual displacement ratio.

[0087] In the method described above, the step of preparing the residual displacement ratio involves generating an estimation model using machine learning processing with the residual displacement, structural specifications of the structure, and seismic characteristics as the first explanatory variables, and the residual displacement ratio as the objective function. The residual displacement ratio is then estimated using the estimation model and the second explanatory variables, which are crack information, structural specifications of the structure, and seismic characteristics. This step allows the residual displacement ratio to be obtained.

[0088] In the method described above, the step of preparing the residual displacement ratio may be performed by obtaining the residual displacement using the simulated maximum response displacement and simulated residual displacement obtained as a result of dynamic analysis using a mechanical model that simulates the structure. The residual displacement ratio can also be obtained by this step.

[0089] In the above method, step S40, which obtains the maximum response displacement, obtains the assumed maximum response displacement and assumed residual displacement that occur when an earthquake assumed to be present is applied to a mechanical model simulating the structure. In the step of estimating the maximum response displacement, the residual displacement and the assumed residual displacement are compared, and the assumed maximum response displacement when the assumed residual displacement can be evaluated as being the same as the residual displacement is adopted as the maximum response displacement. According to this step, the maximum response displacement can be obtained without using the residual displacement ratio.

[0090] The method for evaluating a structure includes: step S10 obtaining crack information regarding cracks that have occurred in the structure after an earthquake; step S11 obtaining a plurality of crack occurrence locations indicating the locations where cracks have occurred using the crack information; step S13 obtaining a crack occurrence range indicating the range where multiple cracks have occurred using the plurality of crack occurrence locations; and step S30 obtaining the maximum response displacement that occurred at the evaluation location of the structure using the crack occurrence range. Step S30 for obtaining the maximum response displacement includes step S31 obtaining the seismic intensity of the earthquake that acted on the structure using the crack occurrence range, and step S32 estimating the maximum response displacement that occurred at the evaluation location of the structure using the seismic intensity.

[0091] This evaluation method uses crack information regarding cracks that occurred in a structure subjected to an earthquake to obtain multiple crack locations and crack locations. By using these values, the seismic intensity of the earthquake that acted on the evaluation location when the earthquake occurred can be obtained, and as a result, the maximum response displacement that occurred at the evaluation location can be estimated.

[0092] The above method is performed before step S30, which is used to obtain the maximum response displacement. It further includes step S20, which uses the crack occurrence range in the structure to determine whether the deformation in the structure subjected to the earthquake has reached the plastic deformation range. If, in step S20, it is determined that the deformation in the structure has not reached the plastic deformation range, then step S30, which is used to obtain the maximum response displacement, may be performed. This step S30 allows for the estimation of the maximum response displacement at the evaluation position when the deformation in the structure has reached the plastic deformation range.

[0093] The method for evaluating a structure includes steps S10 of obtaining crack information regarding cracks that have occurred in the structure subjected to an earthquake, step S11 of obtaining a plurality of crack occurrence locations indicating the locations where cracks have occurred using the crack information, and step S11 of determining whether or not the deformation that has occurred in the structure subjected to the earthquake has reached the plastic deformation range using the crack occurrence range.

[0094] This method allows for the determination of whether or not the deformation in a structure subjected to an earthquake has reached the plastic deformation zone, using the extent of crack occurrence.

[0095] In the method described above, step S10, which involves obtaining crack information, includes obtaining crack information by measurement using an optical fiber sensor installed on the structure. This step S10 allows for spatial and continuous measurement of the strain generated in the structure. Furthermore, measurement using an optical fiber sensor can simultaneously measure crack width and occurrence distribution.

[0096] In the above method, steps S13 and S14 for obtaining the crack occurrence range obtain a first calculated value indicating the distance from the first crack closest to the reference position to the second crack furthest from the reference position, and obtain a second calculated value indicating the crack interval indicating the interval between adjacent cracks, and obtain the value obtained by adding the second calculated value to the first calculated value as the crack occurrence range. By following these steps S13 and S14, the accuracy of the crack occurrence range can be improved.

[0097] <Variation> The method for evaluating structures according to the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the present invention.

[0098] A method for evaluating a structure yields the maximum response displacement as a result. This maximum response displacement may be used to perform further evaluations of the structure. For example, the method may evaluate the degree of damage to the structure using the maximum response displacement and a predetermined limit value based on the structure's limit state. This modification allows for the rapid and accurate estimation of the maximum response of reinforcement strain or displacement in RC members based on cracks remaining after an earthquake, thereby providing an effective post-earthquake damage assessment.

[0099] <Additional Note> The methods for evaluating structures in this disclosure also include the following:

[0100] This disclosure [1] is "an estimation method for estimating whether or not a member has undergone plastic deformation and the maximum amount of deformation that occurred when an external force was applied, based on the width and distribution of cracks remaining on the surface of the RC member after an external force has been applied." This disclosure [2] is "the estimation method described in [1] above, which estimates whether or not a reinforced concrete member has undergone plastic deformation and the maximum amount of deformation if the member had not undergone plastic deformation, based on the range of residual cracks observed after an external force is applied and the relationship between the range of cracks and the amount of deformation." This disclosure [3] is “the estimation method described in [2] above, characterized by identifying the crack occurrence area by adding the crack interval to the observed crack occurrence area.” This disclosure [4] is “the estimation method described in [1] above, characterized by estimating the residual deformation of a concrete member based on the residual crack width and its distribution.” This disclosure [5] is "the estimation method described in [1] above, which estimates the maximum deformation amount from the residual deformation amount based on a predetermined ratio of maximum deformation to residual displacement or an analysis result that evaluates the behavior when an external force is applied." This disclosure [6] is “the estimation method described in [1] above, characterized by evaluating the width and distribution of residual cracks from measurement results obtained by an optical fiber sensor installed on a concrete member.” This disclosure [7] is "a method for evaluating the degree of damage to a structure by comparing the maximum deformation estimated by the method described in [1] above with a limit value set according to the limit state of the structure." [Explanation of symbols]

[0101] 1...Bridge pier structure, 2...Bridge pier section, 21...Concrete, 22...Reinforcement, 3...Footing, S10...Step to obtain crack information, S11...Step to obtain multiple crack occurrence locations, S12...Step to obtain multiple crack widths, S13, S14...Step to obtain crack occurrence range, S20...Step to determine whether or not the plastic deformation region has been reached, S30, S40...Step to obtain maximum response displacement.

Claims

1. Steps to obtain information on cracks that occurred in structures affected by earthquakes, Using the aforementioned crack information, a step of obtaining a plurality of crack occurrence locations indicating the locations where the cracks have occurred, Using the aforementioned crack information, a step of obtaining a plurality of crack widths, each representing the width of a plurality of the aforementioned cracks, The method includes the step of obtaining the maximum response displacement that occurred at an evaluation position set on the structure when subjected to the earthquake, using a plurality of the crack occurrence locations and a plurality of the crack widths. The step of obtaining the maximum response displacement is: Using the plurality of crack occurrence locations and the plurality of crack widths, the step of obtaining the residual displacement that occurred at the evaluation location when subjected to the earthquake, A method for evaluating a structure, comprising the step of estimating the maximum response displacement occurring at the evaluation position using the residual displacement.

2. A step performed before the step of obtaining the maximum response displacement, which uses the crack initiation location to obtain a crack initiation range indicating the range in which the crack exists in the structure, The method further includes the step of determining whether the deformation caused to the structure by the earthquake has reached the plastic deformation region, using the crack occurrence range. The method for evaluating a structure according to claim 1, wherein the step of obtaining the maximum response displacement is performed when it is determined in the determination step that the deformation occurring in the structure has reached the plastic deformation region.

3. The step of obtaining the residual displacement is: The steps include obtaining the bending displacement at the evaluation position based on the bending deformation that occurred in the structure due to the earthquake, The steps include obtaining the tilt displacement at the evaluation position based on the tilt caused to the structure by the earthquake, A method for evaluating a structure according to any one of claims 1 to 2, comprising the step of obtaining the residual displacement by adding the bending displacement and the tilting displacement.

4. The step of estimating the maximum response displacement is: A residual displacement ratio, defined in advance as the ratio of the residual displacement to the maximum response displacement, is prepared. A method for evaluating a structure according to claim 2, comprising estimating the maximum response displacement occurring at the evaluation position using the residual displacement and the residual displacement ratio.

5. The step of preparing the residual displacement ratio is: An estimation model is generated by machine learning processing using the residual displacement, the structural specifications of the structure, and the characteristic values ​​of the earthquake as the first explanatory variables, and the residual displacement ratio as the objective function. A method for evaluating a structure according to claim 4, comprising estimating the residual displacement ratio by estimation processing using the estimation model, with the crack information, structural specifications of the structure, and characteristic values ​​of the earthquake being second explanatory variables.

6. The step of preparing the residual displacement ratio is: A method for evaluating a structure according to claim 4, wherein the residual displacement ratio is obtained using the simulated maximum response displacement and the simulated residual displacement obtained as a result of dynamic analysis using a mechanical model that simulates the structure.

7. The step of obtaining the maximum response displacement is: When an earthquake is applied to a mechanical model simulating the aforementioned structure, the assumed maximum response displacement and assumed residual displacement are obtained. The method for evaluating a structure according to claim 4, wherein the step of estimating the maximum response displacement involves comparing the residual displacement with the assumed residual displacement, and adopting the assumed maximum response displacement as the maximum response displacement when the assumed residual displacement can be evaluated as being the same as the residual displacement.

8. Steps to obtain information on cracks that occurred in structures affected by earthquakes, Using the aforementioned crack information, a step of obtaining a plurality of crack occurrence locations indicating the locations where the cracks have occurred, A step of obtaining a crack occurrence range indicating the range in which multiple cracks occur, using multiple crack occurrence locations, The step of obtaining the maximum response displacement occurring at the evaluation position of the structure using the crack occurrence range, The step of obtaining the maximum response displacement is: Using the crack occurrence range, the steps include obtaining the seismic intensity of the earthquake that acted on the structure, A method for evaluating a structure, comprising the step of estimating the maximum response displacement occurring at the evaluation location of the structure using the seismic intensity.

9. The process is performed prior to the step of obtaining the maximum response displacement, and further includes a step of determining whether the deformation in the structure subjected to the earthquake has reached the plastic deformation region, using the crack occurrence range in the structure. A method for evaluating a structure according to claim 8, wherein, in the determination step, if it is determined that the deformation occurring in the structure has not reached the plastic deformation range, the step of obtaining the maximum response displacement is performed.

10. Steps to obtain information on cracks that occurred in structures affected by earthquakes, Using the aforementioned crack information, a step is to obtain a crack occurrence range indicating the area where multiple such cracks have occurred, A method for evaluating a structure, comprising the step of determining whether the deformation that occurred in the structure subjected to the earthquake has reached the plastic deformation region using the crack occurrence range.

11. The method for evaluating a structure according to any one of claims 1, 8, and 10, wherein the step of obtaining the crack information is to obtain the crack information by measurement using an optical fiber sensor installed on the structure.

12. The step of obtaining the crack occurrence area is: A first calculated value is obtained that indicates the distance from the first crack closest to the reference position to the second crack furthest from the reference position. A second calculated value is obtained that represents the crack interval, which indicates the distance between adjacent cracks. A method for evaluating a structure according to claim 2 or 8, wherein the value obtained by adding the second calculated value to the first calculated value is obtained as the crack occurrence range.

13. A method for evaluating a structure according to claim 1 or 8, comprising evaluating the degree of damage to the structure using the maximum response displacement and a limit value predetermined based on the limit state of the structure.

Images