Structure evaluation system, structure evaluation method, and structure evaluation device

Abstract

To provide a structure evaluation system, a structure evaluation method, and a structure evaluation device, which can evaluate the deterioration state of a structure without locating the position of an elastic wave source.SOLUTION: A structure evaluation system includes a plurality of sensors, a vehicle number estimation unit, and an evaluation unit. The plurality of sensors detect elastic waves generated inside a structure. The vehicle number estimation unit estimates the number of vehicles passing through the structure on the basis of a plurality of elastic waves detected by each of the plurality of sensors. The evaluation unit evaluates the deterioration state of the structure using vehicle information relating to the number of vehicles estimated by the vehicle number estimation unit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a structure evaluation system, a structure evaluation method, and a structure evaluation device. [Background technology]

[0002] By installing a sensor on the surface of a structure such as a bridge, it is possible to detect elastic waves generated inside the structure. Furthermore, by installing multiple sensors on the surface of the structure, it is possible to locate the position of the source of the elastic waves (hereinafter referred to as the "elastic wave source") based on the difference in arrival time of the elastic waves detected by each sensor. Elastic waves are also generated inside the structure when an impact is applied to the surface of the structure from the outside. In such cases, the position of the elastic wave source can be located based on the difference in arrival time of the elastic waves detected by each sensor.

[0003] Damage to the propagation path of elastic waves inside a structure will impede the propagation of the elastic waves. When damage inside a structure impedes the propagation of elastic waves, some sensors will be unable to detect them. As a result, the accuracy of the elastic wave source location results will decrease. When a spatially uniform impact, such as raindrops hitting a road surface during rainfall, is applied to the surface of a structure and elastic waves are detected by sensors installed opposite the impact, a decrease in the density of elastic wave sources will be observed in areas with internal damage. This characteristic can be used to evaluate the deterioration state of a structure (whether or not there is internal damage to the structure). In particular, internal damage can be detected using elastic waves generated by vehicles traveling on the road surface.

[0004] However, when performing evaluation using the above method, it is necessary to locate the position of the elastic wave source. The processing load increases as the amount of measurement data increases due to the calculation of position location. Furthermore, since there is no unique calculation method for position location, the results may vary depending on the calculation conditions, etc. Therefore, there is a need for an evaluation method that can evaluate the deterioration state of a structure without locating the position of the elastic wave source. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2017 / 217034 [Patent Document 2] International Publication No. 2020 / 194494 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide a structure evaluation system, a structure evaluation method, and a structure evaluation device that can evaluate the deterioration state of a structure without locating the position of an elastic wave source. [Means for solving the problem]

[0007] The structure evaluation system according to the embodiment includes a plurality of sensors, a vehicle number estimation unit, and an evaluation unit. The plurality of sensors detect elastic waves generated inside the structure. The vehicle number estimation unit calculates, based on the plurality of elastic waves detected by the plurality of sensors, The number of sensors that detected the elastic waves generated by the passage of the same vehicle was counted as the number of simultaneous hit sensors for the evaluation period. The evaluation unit estimates the number of vehicles estimated by the vehicle number estimation unit. for the evaluation period The aforementioned Based on the number of simultaneous hit sensors The deterioration state of the structure is evaluated. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the configuration of a structure evaluation system according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of a signal processing unit according to the first embodiment. [Figure 3] FIG. 2 is a diagram showing an example of the arrangement of a plurality of sensors in the first embodiment. [Figure 4] FIG. 4 is a diagram for explaining the process of estimating the number of passing vehicles in the first embodiment. [Figure 5A] 10A and 10B represent histograms obtained based on healthy structures. [Figure 5B]10 is a diagram showing a histogram obtained based on a structure that has undergone some degree of deterioration. [Figure 5C] 10A and 10B are diagrams showing histograms obtained based on a structure that has undergone some degree of deterioration. [Figure 6] FIG. 3 is a sequence diagram showing the flow of the deterioration state evaluation process performed by the structure evaluation system according to the first embodiment. [Figure 7A] 10 is a diagram showing a histogram of the cumulative number of vehicles obtained based on healthy structures. [Figure 7B] FIG. 10 is a diagram showing a histogram of the cumulative number of vehicles obtained based on structures that have deteriorated to a certain extent. [Figure 7C] FIG. 10 is a diagram showing a histogram of the cumulative number of vehicles obtained based on structures that have deteriorated to a certain extent. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a structure evaluation system, a structure evaluation method, and a structure evaluation device according to embodiments will be described with reference to the drawings. (First embodiment) 1 is a diagram showing the configuration of a structure evaluation system 100 according to the first embodiment. The structure evaluation system 100 is used to evaluate the soundness of a structure 50. In the following description, evaluation means determining the degree of soundness of the structure 50, i.e., the state of deterioration of the structure 50, based on a certain standard.

[0010] In the following description, the structure 50 will be described as a bridge, but the structure 50 does not have to be limited to a bridge. The structure 50 may be any structure in which elastic waves 11 are generated due to the occurrence or growth of cracks or an external impact (for example, rain, artificial rain, etc.). Note that bridges are not limited to structures built over rivers, valleys, etc., but also include various structures built above the ground (for example, highway viaducts).

[0011] Damage that affects the evaluation of the deterioration state of the structure 50 includes damage inside the structure that obstructs the propagation of elastic waves 11, such as cracks, cavities, and sedimentation. Here, cracks include vertical cracks, horizontal cracks, and diagonal cracks. Vertical cracks are cracks that occur in a direction perpendicular to the road surface. Horizontal cracks are cracks that occur horizontally to the road surface. Diagonal cracks are cracks that occur in a direction other than horizontal or vertical to the road surface. Sedimentation is deterioration in which concrete turns into sediment, mainly at the boundary between the asphalt and the concrete deck.

[0012] The structure evaluation system 100 includes a plurality of sensors 20-1 to 20-n (n is an integer of 2 or more), a signal processing unit 30, and a structure evaluation device 40. Each of the plurality of sensors 20-1 to 20-n and the signal processing unit 30 are connected to each other via wires so that they can communicate with each other. The signal processing unit 30 and the structure evaluation device 40 are connected to each other via wires or wirelessly so that they can communicate with each other. In the following description, when there is no need to distinguish between the sensors 20-1 to 20-n, they will be referred to as sensors 20.

[0013] As shown in Fig. 1, when a vehicle 10 passes over a structure 50, a load is applied to the road surface due to contact between the running parts (e.g., tires) of the vehicle 10 and the road surface. A large number of elastic waves 11 are generated inside the structure 50 due to deflection and strain caused by the load, and interaction between the running parts and the pavement. Each sensor 20 installed on the underside of the structure 50 can detect the elastic waves 11 generated inside the structure 50.

[0014] The sensor 20 has a piezoelectric element and detects elastic waves 11 generated from inside the structure 50. The sensor 20 is installed at a position where it can detect elastic waves 11 on the surface of the structure 50. For example, the sensors 20-1 to 20-n are installed on any one of the road surface, side surface, and bottom surface, spaced apart at equal or different intervals in the vehicle axis direction and in a direction perpendicular to the vehicle axis direction. The vehicle axis direction refers to the direction in which the vehicle travels on the road surface. The direction perpendicular to the vehicle axis direction refers to a direction perpendicular to the vehicle axis direction. The sensor 20 converts the detected elastic waves 11 into an electrical signal. In the following explanation, a case where the sensor 20 is installed on the bottom surface of the structure 50 will be described as an example.

[0015] A piezoelectric element having sensitivity in the range of, for example, 10 kHz to 1 MHz is used for the sensor 20. There are various types of sensors 20, such as a resonance type that has a resonance peak within a frequency range and a wideband type that suppresses resonance, but any type of sensor 20 may be used. The method by which the sensor 20 detects the elastic wave 11 includes a voltage output type, a resistance change type, and a capacitance type, but any detection method may be used.

[0016] An acceleration sensor may be used instead of the sensor 20. In this case, the acceleration sensor detects the elastic waves 11 generated inside the structure 50. Then, the acceleration sensor converts the detected elastic waves 11 into an electrical signal by performing the same processing as the sensor 20.

[0017] The signal processing unit 30 receives as input the electrical signal output from the sensor 20. The signal processing unit 30 performs signal processing on the input electrical signal. The signal processing performed by the signal processing unit 30 includes, for example, noise removal and extraction of elastic wave feature quantities. The signal processing unit 30 generates transmission data including the processed digital signal. The signal processing unit 30 outputs the generated transmission data to the structure evaluation device 40.

[0018] The signal processing unit 30 is configured using an analog circuit or a digital circuit. When the signal processing unit 30 is configured using an analog circuit, an analog-to-digital converter does not need to be provided between the sensor 20 and the signal processing unit 30. In other words, when the signal processing unit 30 is configured using an analog circuit, an electrical signal from which noise has been removed by a filter is input to the signal processing unit 30. The digital circuit is realized, for example, by an FPGA (Field Programmable Gate Array) or a microcomputer. The digital circuit may also be realized by a dedicated LSI (Large-Scale Integration). The signal processing unit 30 may also be equipped with a non-volatile memory such as a flash memory or a removable memory. The following description will be given of the case where the signal processing unit 30 is configured using a digital circuit.

[0019] 2 is a diagram showing an example of the configuration of the signal processing unit 30 in the first embodiment. The signal processing unit 30 includes an amplifier 301, an A / D converter 302, a waveform shaping filter 303, a gate generation circuit 304, an arrival time determination unit 305, a feature extraction unit 306, a data recording unit 307, a memory 308, and a vehicle number estimation unit 309.

[0020] The amplifier 301 amplifies the electrical signal output from the sensor 20 and outputs the amplified electrical signal to the A / D converter 302. The amplifier 301 amplifies the electrical signal by a predetermined amount (for example, 10 to 100 times).

[0021] The A / D converter 302 quantizes the amplified electrical signal and converts it into a digital signal, which is then output to the waveform shaping filter 303.

[0022] The waveform shaping filter 303 removes noise components outside a predetermined band from the input digital signal. The waveform shaping filter 303 is, for example, a digital band pass filter (BPF). The waveform shaping filter 303 outputs the digital signal after the noise components have been removed (hereinafter referred to as the "noise-removed signal") to the gate generation circuit 304 and the feature extraction unit 306.

[0023] The gate generation circuit 304 receives the noise removal signal output from the waveform shaping filter 303. The gate generation circuit 304 generates a gate signal based on the received noise removal signal. The gate signal indicates whether the waveform of the noise removal signal is sustained.

[0024] The gate generation circuit 304 is realized by, for example, an envelope detector and a comparator. The envelope detector detects the envelope of the noise-removed signal. The envelope is extracted, for example, by squaring the noise-removed signal and performing a predetermined process (e.g., processing using a low-pass filter or a Hilbert transform) on the squared output value. The comparator determines whether the envelope of the noise-removed signal is equal to or greater than a predetermined threshold.

[0025] When the envelope of the noise-removed signal is equal to or greater than a predetermined threshold, the gate generation circuit 304 outputs a first gate signal indicating that the waveform of the noise-removed signal is sustained to the arrival time determination unit 305 and the feature extraction unit 306. On the other hand, when the envelope of the noise-removed signal is less than the predetermined threshold, the gate generation circuit 304 outputs a second gate signal indicating that the waveform of the noise-removed signal is not sustained to the arrival time determination unit 305 and the feature extraction unit 306. Note that while the gate generation circuit 304 is configured to determine whether the waveform of the noise-removed signal is sustained based on the envelope in the above example, the gate generation circuit 304 may also process the noise-removed signal itself or a signal to which an absolute value has been applied. The threshold used for this gate generation is referred to as a measurement threshold.

[0026] The arrival time determination unit 305 receives as input a clock output from a clock source such as a crystal oscillator (not shown) and a gate signal output from the gate generation circuit 304. The arrival time determination unit 305 determines the elastic wave arrival time using the clock input while the first gate signal is being input. The arrival time determination unit 305 outputs the determined elastic wave arrival time to the data recording unit 307 as time information. The arrival time determination unit 305 does not perform any processing while the second gate signal is being input. The arrival time determination unit 305 generates cumulative time information since power-on based on the signal from the clock source. Specifically, the arrival time determination unit 305 may be a counter that counts clock edges, and the value of the counter's register may be used as the time information. The counter's register is determined to have a predetermined bit length.

[0027] The feature extraction unit 306 receives the noise-removed signal output from the waveform shaping filter 303 and the gate signal output from the gate generation circuit 304 as input. The feature extraction unit 306 extracts a feature of the noise-removed signal using the noise-removed signal input while the first gate signal is being input. The feature extraction unit 306 does not perform processing while the second gate signal is being input. The feature is information indicating the feature of the noise-removed signal. In other words, the feature of the noise-removed signal is a feature of the elastic wave detected by the sensor 20.

[0028] The feature quantity may be, for example, the amplitude [mV] of the waveform, the rise time [usec] of the waveform, the duration [usec] of the gate signal, the number of zero crossing counts [times], the energy [arb.] of the waveform, the frequency [Hz], and the root mean square (RMS) value. The feature quantity extraction unit 306 outputs parameters related to the extracted feature quantities to the data recording unit 307. When outputting the parameters related to the feature quantities, the feature quantity extraction unit 306 associates a sensor ID with the parameters related to the feature quantities. The sensor ID represents identification information for identifying the sensor 20 installed in the area (hereinafter referred to as the "evaluation area") to be evaluated for the soundness of the structure 50. This makes it possible to distinguish which sensor 20 detected the parameter related to the feature quantity.

[0029] The waveform amplitude is, for example, the maximum amplitude value of the noise reduction signal. The waveform rise time is, for example, the time T1 from when the gate signal starts rising until the noise reduction signal reaches its maximum value. The gate signal duration is, for example, the time from when the gate signal starts rising until the amplitude becomes smaller than a preset value. The zero cross count is, for example, the number of times the noise reduction signal crosses a reference line that passes through a zero value.

[0030] The waveform energy is, for example, the value obtained by integrating the squared amplitude of the noise-removed signal at each time point over time. Note that the definition of energy is not limited to the above example, and may be approximated using, for example, the envelope of the waveform. The frequency is the frequency of the noise-removed signal. The RMS value is, for example, the value obtained by squaring the amplitude of the noise-removed signal at each time point and taking the square root.

[0031] The data recording unit 307 receives as input a sensor ID, time information, and parameters related to the feature amount. The data recording unit 307 records elastic wave data including the input sensor ID, time information, and parameters related to the feature amount in the memory 308. For example, the data recording unit 307 may record the elastic wave data in the memory 308 in the order in which it was acquired, or may record the elastic wave data in the memory 308 in chronological order based on the time information.

[0032] The memory 308 stores one or more pieces of elastic wave data. The memory 308 is, for example, a dual-port RAM (Random Access Memory). One piece of elastic wave data is data obtained from one elastic wave.

[0033] The vehicle number estimation unit 309 estimates the number of passing vehicles using one or more pieces of elastic wave data stored in the memory 308. More specifically, the vehicle number estimation unit 309 extracts elastic wave features contained in each of the one or more pieces of elastic wave data. The vehicle number estimation unit 309 calculates the time series transition of each extracted elastic wave feature. The time series transition of the feature represents the transition of each elastic wave feature during the period from when the first gate signal is input to when the second gate signal is input. The time series transition of the feature forms a mountain shape, with the feature peaking when the traveling part of the vehicle 10 passes very close to the sensor 20. Depending on conditions such as the type of vehicle 10 and its traveling position, two peaks, one for the front wheels and one for the rear wheels, may be observed. The vehicle number estimation unit 309 estimates the number of passing vehicles based on the time series transition of the calculated feature.

[0034] Furthermore, the vehicle number estimation unit 309 calculates the number of sensors 20 that detected the elastic waves generated by the passage of the same vehicle (hereinafter referred to as "simultaneous Hit Sensor When the structure 50 is in good condition, all the sensors 20 can detect the elastic waves generated by the passing of a vehicle. Hit SensorIt is assumed that the number of sensors 20 installed in the structure 50 is the total number of sensors 20 installed in the structure 50. On the other hand, if there is some damage inside the structure 50, the damage will prevent the propagation of elastic waves. Therefore, the sensors 20 installed near the damaged area may not be able to detect elastic waves. This means that the more severe the damage inside the structure 50, the more sensors 20 that cannot detect elastic waves will increase. In this way, Hit Sensor The number serves as an index for evaluating the deterioration state of the structure 50.

[0035] The vehicle number estimation unit 309 estimates the number of passing vehicles (hereinafter referred to as the "estimated number of vehicles") and the simultaneous Hit Sensor The vehicle number estimation unit 309 transmits the vehicle information for the period to be evaluated (hereinafter referred to as the "evaluation period") together to the structure evaluation device 40 as vehicle information, or may transmit the vehicle information to the structure evaluation device 40 each time vehicle information is obtained, or each time a predetermined number of vehicle information is obtained.

[0036] Continuing the explanation, returning to Fig. 1, the structure evaluation device 40 includes a communication unit 41, a control unit 42, a storage unit 43, and a display unit 44.

[0037] The communication unit 41 receives one or more pieces of vehicle information transmitted from the signal processing unit 30.

[0038] The control unit 42 controls the entire structure evaluation device 40. The control unit 42 is configured using a processor such as a CPU (Central Processing Unit) and a memory. The control unit 42 functions as an acquisition unit 421 and an evaluation unit 422 by executing a program.

[0039] Some or all of the functional units of the acquisition unit 421 and the evaluation unit 422 may be realized by hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA, or may be realized by a combination of software and hardware. The program may be recorded on a computer-readable recording medium. Examples of computer-readable recording media include portable media such as flexible disks, magneto-optical disks, read-only memories (ROMs), and CD-ROMs, and non-transitory storage media such as hard disks built into computer systems. The program may be transmitted via a telecommunications line.

[0040] Some of the functions of the acquisition unit 421 and the evaluation unit 422 do not need to be pre-installed in the structure evaluation device 40, and may be realized by installing an additional application program in the structure evaluation device 40.

[0041] The acquisition unit 421 acquires various types of information. For example, the acquisition unit 421 acquires vehicle information received by the communication unit 41. The acquisition unit 421 acquires vehicle information for the evaluation target period. The acquisition unit 421 stores the acquired vehicle information in the storage unit 43.

[0042] The evaluation unit 422 evaluates the deterioration state of the structure 50 based on the vehicle information acquired by the acquisition unit 421. For example, the evaluation unit 422 evaluates the deterioration state of the structure 50 based on the shape of the distribution obtained based on the vehicle information or the peak position of the distribution. Here, the distribution obtained based on the vehicle information is a histogram with the horizontal axis representing the number of simultaneously hit sensors and the vertical axis representing the estimated number of vehicles. The specific evaluation method performed by the evaluation unit 422 will be described later.

[0043] The storage unit 43 stores the vehicle information for the evaluation period acquired by the acquisition unit 421 and reference information. The reference information is information that the evaluation unit 422 refers to in order to perform the evaluation. For example, the reference information includes information on the shape of the distribution or the peak position of the distribution for determining whether the vehicle is healthy, and information on the shape of the distribution or the peak position of the distribution for determining whether deterioration has occurred. The storage unit 43 is configured using a storage device such as a magnetic hard disk drive or a semiconductor storage device.

[0044] The display unit 44 displays the evaluation results under the control of the evaluation unit 422. For example, the display unit 44 may display, as the evaluation result, whether or not deterioration has occurred inside the structure 50. The display unit 44 is an image display device such as a liquid crystal display or an organic EL (Electro Luminescence) display. The display unit 44 may also be an interface for connecting an image display device to the structure evaluation device 40. In this case, the display unit 44 generates a video signal for displaying the evaluation results and outputs the video signal to the image display device connected to the display unit 44.

[0045] FIG. 3 is a diagram showing an example of the arrangement of a plurality of sensors 20 in the first embodiment. FIG. 3 shows an example in which 18 sensors 20-1 to 20-18 are arranged in a 3×6 grid. Here, the sensors 20 are numbered 1 to 18ch in order from the right side of FIG. 3. A vehicle 10 enters a structure from the right side of FIG. 3 and exits from the left side. Therefore, an elastic wave generated by the passage of a vehicle 10 is usually first detected by sensors 20-1 to 20-3 arranged at the right end of FIG. 3, then gradually detected by sensors 20 on the left side, and finally detected by sensors 20-16 to 20-18 arranged at the left end.

[0046] Fig. 4 is a diagram for explaining the process of estimating the number of passing vehicles in the first embodiment. The example shown in Fig. 4 shows an excerpt of the time series transition of feature values ​​based on elastic waves detected by the 2-channel sensor 20-2 located at the center of the right edge and the 17-channel sensor 20-17 located at the center of the left edge, among the 18 sensors 20 shown in Fig. 3. In Fig. 4, the horizontal axis represents time t, and the vertical axis represents the integrated value of the duration of elastic waves detected per unit time. Note that the feature value used here does not necessarily have to be the integrated duration, and other feature values ​​such as energy and amplitude can also be used.

[0047] Line segment S1 in FIG. 4 represents the time series transition of the feature value based on the elastic waves detected by sensor 20-2, and line segment S2 represents the time series transition of the feature value based on the elastic waves detected by sensor 20-17. Because vehicles 10 pass over structure 50 at predetermined intervals, time series transitions of multiple feature values ​​appear depending on the number of passing vehicles, as shown in FIG. 4. The mountain-shaped waveform representing the time series transition of the feature value is first observed by sensor 20-2 on the side where vehicle 10 enters, as indicated by circle 55, and is observed a little later by sensor 20-17 on the side where vehicle 10 exits. The time difference when the same vehicle is observed by each sensor 20 can be calculated based on the placement interval of sensors 20, the wheelbase of vehicle 10, and the traveling speed of vehicle 10, and the same vehicle can be identified from the series of detected signals.

[0048] In the example shown in FIG. 4, the vehicle number estimation unit 309 estimates that four vehicles 10 have passed. Two line segments S1 are shown within the circle 55, representing the time series transition of the feature values ​​based on the elastic waves detected by the sensor 20-2. As described above, this is due to the elastic waves generated by the front and rear wheels of the vehicle 10. While only sensors 20-2 and 20-17 are shown in FIG. 4, the time series transition of the feature values ​​would be shown for each sensor 20 that detected the elastic waves. Therefore, the vehicle number estimation unit 309 estimates the number of simultaneously hit sensors based on the time series transition of the feature values. For example, the vehicle number estimation unit 309 counts the number of sensors 20 that detected the vehicle 10 in the time series transition of the feature values ​​within the circle 55. The vehicle number estimation unit 309 estimates the counted number as the number of simultaneously hit sensors. As shown in FIG. 3, if 18 sensors 20 are installed, the maximum number of simultaneously hit sensors is 18.

[0049] Next, a specific evaluation method performed by the evaluation unit 422 will be described with reference to Figures 5A, 5B, and 5C. The evaluation unit 422 generates a histogram (hereinafter referred to as a "simultaneous hit histogram") with the number of simultaneous hit sensors on the horizontal axis and the estimated number of vehicles on the vertical axis based on the vehicle information obtained from the signal processing unit 30. The simultaneous hit histogram is a compilation of the estimated number of vehicles for each number of simultaneous hit sensors. The number of simultaneous hit sensors also varies due to variations in vehicle types and vehicle passing positions, and the simultaneous hit histogram has a characteristic distribution.

[0050] FIG. 5A shows a histogram obtained based on a healthy structure 50, while FIGS. 5B and 5C show histograms obtained based on a structure 50 that has deteriorated to some extent. In the healthy structure 50 shown in FIG. 5A, peaks are observed at positions where the number of simultaneously hit sensors is "1" and "18," forming a bathtub-like shape. In a healthy structure 50, elastic waves propagate easily and reach the sensors 20 easily. Therefore, it is considered that elastic waves from passing vehicles are often detected by almost all sensors 20. The peak at the hit sensor number "1" side is presumed to be due to the detection of elastic waves generated by a vehicle 10 passing through a location far from the measurement target area, or other noise.

[0051] 5B and 5C, the propagation of elastic waves is hindered by damage or other factors in the structure 50, resulting in an increase in the number of sensors 20 that are unable to adequately detect the vehicle 10. As a result, the number of vehicles with a simultaneous hit sensor count of "18" is significantly reduced, and the peak of the histogram shifts toward the side with fewer simultaneous hit sensors. Therefore, the evaluation unit 422 generates a histogram based on the vehicle information obtained from the signal processing unit 30, and can easily evaluate the state of deterioration of the structure 50 based on the shape of the generated histogram or the position of the peak in the histogram.

[0052] 5A to 5C or information on peak positions in the histograms, and evaluation results (healthy or deteriorated) may be associated with each other by storing reference information in the storage unit 43, and the evaluation unit 422 may compare the generated histogram shape or the peak positions in the histogram with the reference information. In this case, the evaluation unit 422 may determine as the final evaluation result the evaluation result in which the generated histogram shape is associated with the histogram that is closest to the generated histogram shape, or the evaluation result in which the generated histogram is associated with information on the closest peak position.

[0053] 6 is a sequence diagram showing the flow of the deterioration state evaluation process by the structure evaluation system 100 in the first embodiment. The process in FIG. 6 is executed, for example, in response to the vehicle 10 traveling through the structure 50 to be evaluated.

[0054] When a vehicle 10 travels over a structure 50 to be evaluated, the traveling part of the vehicle 10 comes into contact with the road surface. This causes an elastic wave 11 to be generated within the structure 50. Each of the multiple sensors 20 detects the elastic wave 11 generated within the structure 50 (step S101). Each of the multiple sensors 20 converts the detected elastic wave 11 into an electrical signal and outputs it to the signal processing unit 30 (step S102). The signal processing unit 30 receives the electrical signal output from each of the multiple sensors 20. The signal processing unit 30 performs signal processing such as amplification, conversion to a digital signal, and noise removal on each received electrical signal.

[0055] The arrival time determination unit 305 determines the arrival time of each digital signal after signal processing (step S103). Specifically, the arrival time determination unit 305 determines the elastic wave arrival time using the clock input while the first gate signal is being input. The arrival time determination unit 305 outputs the determined elastic wave arrival time as time information to the data recording unit 307. The arrival time determination unit 305 performs this process for all input digital signals.

[0056] The feature extraction unit 306 of the signal processing unit 30 extracts a feature of the denoising signal, which is a digital signal input while the first gate signal is being input (step S104). The feature extraction unit 306 outputs parameters related to the extracted feature to the data recording unit 307. The data recording unit 307 stores elastic wave data including the sensor ID, time information, and the parameters related to the feature in the memory 308 (step S105).

[0057] The vehicle number estimation unit 309 calculates the time series transition of the feature amount using one or more pieces of elastic wave data stored in the memory 308 (step S106). One piece of elastic wave data includes parameters related to the feature amount of the elastic wave 11 detected by one sensor 20 during the period in which one vehicle 10 passed. Therefore, the vehicle number estimation unit 309 calculates the time series transition of the feature amount, such as the line segments S1 and S2 shown in Fig. 4, for each piece of elastic wave data. The vehicle number estimation unit 309 executes the process of step S106 for the evaluation period.

[0058] The vehicle number estimation unit 309 estimates the number of passing vehicles based on the time series transition of the calculated feature amount for the evaluation period (step S107). Furthermore, the vehicle number estimation unit 309 calculates the number of simultaneous hit sensors based on the time series transition of the calculated feature amount for the evaluation period (step S108). The vehicle number estimation unit 309 uses the information on the estimated number of vehicles and the Hit Sensor The information on the number of vehicles is transmitted to the structure evaluation device 40 as vehicle information (step S109).

[0059] The communication unit 41 of the structure evaluation device 40 receives the vehicle information output from the signal processing unit 30. The acquisition unit 421 acquires the vehicle information received by the communication unit 41. The acquisition unit 421 records the acquired vehicle information in the storage unit 43. The evaluation unit 422 generates a simultaneous hit histogram using the vehicle information for the evaluation period stored in the storage unit 43 (step S110). The evaluation unit 422 evaluates the deterioration state of the structure using the generated simultaneous hit histogram (step S111). As a method for the evaluation unit 422 to evaluate the deterioration state of the structure, there are evaluation methods based on either the distribution shape or peak position of the simultaneous hit histogram, as described above. Each evaluation method will be specifically described below using an example.

[0060] (Evaluated based on the distribution shape of the simultaneous hit histogram) For example, if the shape of the generated simultaneous hit histogram indicates soundness (for example, the bathtub shape shown in FIG. 5A ), the evaluation unit 422 evaluates that the structure 50 is sound. Alternatively, the evaluation unit 422 compares the shape of the histogram included in the reference information with the generated simultaneous hit histogram, and if the shape of the generated histogram is closest to the histogram associated with the soundness evaluation result, evaluates that the structure 50 is sound. Here, "the shape of the histogram is closest to the histogram associated with the soundness evaluation result" means that the similarity between the shape of the generated histogram and the histogram associated with the soundness evaluation result is highest or that the similarity is equal to or greater than a threshold.

[0061] On the other hand, for example, if the shape of the generated simultaneous hit histogram indicates deterioration (for example, the shape shown in FIG. 5B or 5C ), the evaluation unit 422 evaluates that the structure 50 is deteriorated. Alternatively, the evaluation unit 422 compares the shape of the histogram included in the reference information with the generated simultaneous hit histogram, and if the shape of the generated histogram is closest to the histogram associated with the deterioration evaluation result, evaluates that the structure 50 is deteriorated. Here, "the shape of the histogram is closest to the histogram associated with the deterioration evaluation result" means that the similarity between the shape of the generated histogram and the histogram associated with the deterioration evaluation result is highest, or that the similarity is equal to or greater than a threshold.

[0062] As described above, the reference information includes multiple histogram shapes associated with evaluation results. For example, the reference information includes multiple histogram shapes associated with evaluation results indicating soundness and multiple histogram shapes associated with evaluation results indicating degradation. Note that the number of histogram shapes associated with evaluation results indicating soundness and evaluation results indicating degradation is not limited to one each, and multiple shapes may be included in the reference information. The evaluation unit 422 calculates the similarity between each histogram shape included in the reference information and the generated simultaneous hit histogram. Next, the evaluation unit 422 selects, from the histogram shapes included in the reference information, the histogram shape with the highest calculated similarity or equal to or greater than a threshold. If the evaluation result associated with the selected histogram shape indicates soundness, the evaluation unit 422 evaluates the structure 50 as sound. If the evaluation result associated with the selected histogram shape indicates degradation, the evaluation unit 422 evaluates the structure 50 as degraded. When there are multiple histogram shapes to select, the evaluation unit 422 may select the one with the most evaluation results as the final evaluation result, or may present the results to the user to select the final result.

[0063] (Evaluated based on peak position of simultaneous hit histogram) The evaluation unit 422 evaluates that the structure 50 is healthy, for example, if the peak position of the number of simultaneous hit sensors in the generated simultaneous hit histogram is close to the total number of the installed multiple sensors 20. Here, a position close to the total number may be a position of the value of the total number, or a position where the difference from the total number is less than a certain value (for example, the difference is "1" or "2"). For example, if the total number of the multiple sensors 20 is "18," the structure 50 is evaluated as healthy if the peak position of the number of simultaneous hit sensors is at "18," or if the peak position of the number of simultaneous hit sensors is at "16" or "17." Note that the value used to determine proximity to the total number is not limited to the above-mentioned value and may be set as appropriate.

[0064] Alternatively, the evaluation unit 422 compares the peak position information contained in the reference information with the peak position of the number of simultaneous hit sensors in the simultaneous hit histogram, and if the peak position of the number of simultaneous hit sensors is included in the value indicated by the peak position information to which the evaluation result of soundness is associated, evaluates that the structure 50 is sound.

[0065] On the other hand, the evaluation unit 422 evaluates that the structure 50 is deteriorated, for example, when the peak position of the number of simultaneous hit sensors in the generated simultaneous hit histogram is not close to the total number of the installed multiple sensors 20 (i.e., when it is a position other than a position close to the total number of the installed multiple sensors 20 described above). Alternatively, the evaluation unit 422 compares the peak position information included in the reference information with the peak position of the number of simultaneous hit sensors in the simultaneous hit histogram, and evaluates that the structure 50 is deteriorated if the peak position of the number of simultaneous hit sensors is included in the value indicated by the peak position information associated with the evaluation result of deterioration.

[0066] The evaluation unit 422 outputs the evaluation result to the display unit 44. The display unit 44 displays the evaluation result output from the evaluation unit 422 (step S112).

[0067] The structure evaluation system 100 configured as described above has multiple sensors 20, a vehicle number estimation unit 309, and an evaluation unit 422. The multiple sensors 20 detect elastic waves generated inside the structure 50. The vehicle number estimation unit 309 estimates the number of vehicles that have passed through the structure 50 based on the multiple elastic waves detected by each of the multiple sensors 20. The evaluation unit 422 evaluates the deterioration state of the structure 50 using vehicle information related to the number of vehicles estimated by the vehicle number estimation unit 309. This makes it possible to evaluate the deterioration state of the structure without locating the position of the elastic wave source.

[0068] (Second embodiment) In the second embodiment, a configuration will be described in which the estimated number of passing vehicles is compared with a reference value and the deterioration state of a structure is evaluated based on the closest threshold value. The system configuration and the configuration of each device in the second embodiment are the same as those in the first embodiment. The following description will focus on the differences from the first embodiment.

[0069] In the simultaneous hit histogram in the first embodiment, when the number of simultaneous hit sensors is small, it is highly likely that the waves are noise rather than elastic waves generated by the passing of the vehicle 10. Therefore, by setting a threshold N for the number of simultaneous hit sensors, and regarding estimated vehicles whose number of simultaneous hit sensors is less than threshold N as noise, and accumulating the number of estimated vehicles whose number of simultaneous hit sensors is equal to or greater than threshold N, the number of passing vehicles can be estimated with higher accuracy.

[0070] 7A to 7C are graphs plotting the estimated number of vehicles against the threshold N for the number of simultaneous hit sensors. FIGS. 7A to 7C are histograms of the number of vehicles obtained by accumulating the number of estimated vehicles for which the number of simultaneous hit sensors is equal to or greater than the threshold N, for example, in FIGS. 5A to 5C, respectively. That is, FIG. 7A shows a histogram of the accumulated number of vehicles obtained based on a healthy structure 50, while FIGS. 7B and 7C show histograms of the accumulated number of vehicles obtained based on a structure 50 that has deteriorated to some extent. In the histogram of the accumulated number of vehicles, the horizontal axis represents the threshold N for the number of simultaneous hit sensors, and the vertical axis represents the estimated number of vehicles (in this embodiment, the number of vehicles obtained by accumulating the estimated number of vehicles). Therefore, when the threshold N=1, the value is a count of all estimated vehicles, including estimated vehicles and estimated noise, while when the threshold N=18, the value is a count of only the estimated vehicles detected by all sensors 20. By appropriately setting the value of the threshold N for the number of simultaneous hit sensors, the number of vehicles passing through the measurement location can be accurately estimated.

[0071] When the structure 50 is healthy, the number of simultaneous hit sensors is large, and therefore, even if the threshold value N is set to a large value, the cumulative number of vehicles will be close to the actual number of passing vehicles (hereinafter referred to as the "measured number of vehicles"). In the example shown in FIG. 7A, the threshold value at which the cumulative number of vehicles (the estimated number of vehicles on the vertical axis in FIG. 7A) and the measured number of vehicles are closest is 15. On the other hand, when the structure 50 is deteriorated, the number of simultaneous hit sensors is small even for vehicles 10 that pass directly above the sensor 20. Therefore, in order to obtain an estimated number of vehicles close to the measured number of vehicles, the threshold value N must be set to a small value. In the example shown in FIG. 7B, the threshold value at which the cumulative number of vehicles (the estimated number of vehicles on the vertical axis in FIG. 7B) and the measured number of vehicles are closest is 11. In the example shown in FIG. 7C, the threshold value at which the cumulative number of vehicles (the estimated number of vehicles on the vertical axis in FIG. 7C) and the measured number of vehicles are closest is 2. If the threshold value N is set to a large value, the estimated number of vehicles will be smaller than the measured number of vehicles. That is, the optimum threshold value N for accurately estimating the number of passing vehicles tends to be larger for a healthier structure 50 and smaller for more deteriorated structures 50. Therefore, by evaluating the optimum threshold value N, the deterioration state of the structure 50 can be easily evaluated.

[0072] Specifically, the evaluation unit 422 first generates a histogram of the cumulative number of vehicles using the generated simultaneous hit histogram as described above. Next, the evaluation unit 422 determines the estimated number of vehicles that has a value closest to the reference value using the generated histogram of the cumulative number of vehicles. The evaluation unit 422 then determines a threshold N at which the determined estimated number of vehicles is obtained. If the determined threshold N is equal to or greater than a predetermined value, the evaluation unit 422 evaluates the structure as being healthy. On the other hand, if the determined threshold N is less than a predetermined value, the evaluation unit 422 evaluates the structure as being deteriorated. Note that in this case, the evaluation unit 422 may evaluate the structure as being more deteriorated as the determined threshold N is lower (as the threshold N decreases from the predetermined value). In other words, the evaluation unit 422 may evaluate the deterioration state in stages according to the value of the determined threshold N.

[0073] In this way, the threshold N of the number of simultaneously hit sensors can be used as a simple indicator of the deterioration state of the structure 50. The reference value can be an actual measurement value of passing vehicles measured by other sensing methods that are not affected by the internal damage state of the structure, such as a magnetic sensor or a strain sensor, an actual measurement value of passing vehicles measured based on Weigh-In-Motion (WIM), an average traffic volume under normal circumstances, or an actual measurement value (traffic counter) or statistical value obtained by a road administrator or the like.

[0074] According to the structure evaluation system 100 of the second embodiment configured as described above, the reference value and the estimated number of vehicles are compared to determine the estimated number of vehicles closest to the reference value, and the threshold N for the number of simultaneous hit sensors at which the determined estimated number of vehicles is obtained is determined. The evaluation unit 422 then evaluates the deterioration state of the structure 50 according to the determined threshold N for the number of simultaneous hit sensors. This makes it possible to evaluate the deterioration state of the structure 50 in a simple manner without performing positional determination of the elastic wave source. Furthermore, as described above, it is considered that the lower the threshold N for the number of simultaneous hit sensors, the more advanced the deterioration. Therefore, the evaluation unit 422 can evaluate the degree of deterioration in stages according to the determined threshold N for the number of simultaneous hit sensors.

[0075] (Third embodiment) In the third embodiment, a configuration will be described in which the number of vehicles estimated by a vehicle number estimation unit is compared with a reference value, and the deterioration state of a structure is evaluated according to the degree of deviation. The system configuration and the configuration of each device in the third embodiment are the same as those in the first embodiment. The following description will focus on the differences from the first embodiment.

[0076] As the structure 50 deteriorates, the number of simultaneous hit sensors decreases. Therefore, the number of vehicles simultaneously detected by a large number of sensors 20 decreases as the structure 50 deteriorates. As a result, the more the structure 50 deteriorates, the greater the discrepancy between the measured number of vehicles and the estimated number of vehicles estimated by the vehicle number estimation unit 309 when the value of the threshold N for the number of simultaneous hit sensors is large. Under such assumptions, if the number of vehicles is estimated by fixing the threshold N for the number of simultaneous hit sensors to a large value, such as "15" for a total of "18" sensors 20, the deterioration state of the structure 50 can be easily evaluated by comparing the estimated number of vehicles with the measured number of vehicles. Specifically, the evaluation unit 422 evaluates that the deterioration of the structure 50 is more advanced as the estimated number of vehicles is smaller than the measured number of vehicles. In other words, the evaluation unit 422 evaluates that the greater the discrepancy between the measured number of vehicles and the estimated number of vehicles, the more advanced the deterioration of the structure 50. That is, the evaluation unit 422 may evaluate the state of deterioration in stages according to the degree of discrepancy. Note that, when the difference between the actual number of vehicles and the estimated number of vehicles is smaller than a certain threshold, the evaluation unit 422 may evaluate that the structure 50 is not deteriorated or is healthy.

[0077] Here, the measured number of vehicles is acquired as a reference value by the method described in the second embodiment. The threshold N for the number of simultaneous hit sensors is set appropriately by the user. As described above, it is expected that the larger the value of the threshold N for the number of simultaneous hit sensors, the larger the discrepancy between the measured number of vehicles and the estimated number of vehicles estimated by the vehicle number estimation unit 309. Therefore, it is better to set the threshold N for the number of simultaneous hit sensors to a larger value.

[0078] According to the structure evaluation system 100 of the third embodiment configured as described above, the deterioration state of the structure 50 is evaluated simply according to the degree of discrepancy between the measured number of vehicles and the estimated number of vehicles. This makes it possible to evaluate the deterioration state of the structure 50 in a simple manner without locating the position of the elastic wave source. Furthermore, as described above, it is considered that the greater the degree of discrepancy between the measured number of vehicles and the estimated number of vehicles, the more advanced the deterioration. Therefore, the evaluation unit 422 can evaluate the degree of deterioration in stages according to the degree of discrepancy between the measured number of vehicles and the estimated number of vehicles.

[0079] (Modification 1 common to all embodiments) In each of the above embodiments, a configuration has been shown in which multiple sensors 20-1 to 20-n are connected to one signal processing unit 30. The structure evaluation system 100 may include multiple signal processing units 30, and each sensor 20 may be connected to a different signal processing unit 30.

[0080] (Modification 2 common to all embodiments) Some or all of the functional units included in the structure evaluation device 40 may be included in another device. For example, the display unit 44 included in the structure evaluation device 40 may be included in the other device. When configured in this manner, the structure evaluation device 40 transmits the evaluation results to the other device that is equipped with the display unit 44. The other device that is equipped with the display unit 44 displays the received evaluation results.

[0081] (Modification 3 common to all embodiments) In any of the above methods, the vehicle travel position relative to the sensor position must be taken into consideration to improve evaluation accuracy. For example, if the vehicle traffic position and the measurement range of the sensor 20 are separated by a certain distance or more in the direction perpendicular to the vehicle travel axis, the evaluation unit 422 shifts the histogram of the number of simultaneous hit sensors or the graph of the estimated number of vehicles versus the threshold N of the number of simultaneous hit sensors toward a smaller number of simultaneous hit sensors overall according to the distance. As a result, the evaluation unit 422 changes the evaluation criteria based on the relative positional relationship between the sensor installation position and the vehicle passing position. Therefore, the greater the positional relationship between the vehicle traffic position and the sensor installation position, the more necessary it is to correct the soundness evaluation criteria to shift toward deterioration.

[0082] (Modification 4 common to all embodiments) If the structure 50 being evaluated is deteriorating and the number of simultaneous hit sensors tends to be low, it is possible that vehicle non-detections are concentrated among sensors 20 installed at specific locations. In this case, there is a high possibility that localized damage exists between the vehicle passing position and the installation location of the sensor 20 where the non-detections are concentrated. Therefore, if the sensors 20 that are non-detecting vehicles are concentrated at specific sensors 20, the evaluation unit 422 can estimate the location of damage within the structure 50. For example, if a group of sensors is one-dimensionally arranged along an average vehicle passing position at a certain distance from the passing position, the evaluation unit 422 can identify the location of damage along the passing position based on changes or differences in the vehicle detection status of each sensor. In this way, if there is a sensor 20 among the multiple installed sensors 20 that detects a relatively small number of passing vehicles, the evaluation unit 422 may determine that the area around the installation location of the sensor with the relatively small number of passing vehicles is a region where deterioration is occurring. Here, a sensor 20 with a relatively small number of passing vehicles is a sensor with a number of vehicles detected that is less than a threshold value or more compared to the number of vehicles detected by other sensors 20.

[0083] According to at least one embodiment described above, the structure evaluation system 100 of the embodiment has a plurality of sensors 20, a vehicle number estimation unit 309, and an evaluation unit 422. The plurality of sensors 20 detect elastic waves generated inside the structure 50. The vehicle number estimation unit 309 estimates the number of vehicles that have passed through the structure 50 based on the plurality of elastic waves detected by each of the plurality of sensors 20. The evaluation unit 422 evaluates the deterioration state of the structure 50 using vehicle information related to the number of vehicles estimated by the vehicle number estimation unit 309, thereby making it possible to evaluate the deterioration state of the structure without locating the position of the elastic wave source.

[0084] Some of the processing performed by the signal processing unit 30 in the above-described embodiment (e.g., the processing performed by the vehicle count estimation unit 309) may be implemented by a computer. In this case, a program for implementing this function may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed. Note that the term "computer system" herein includes hardware such as an OS and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into a computer system. Furthermore, the term "computer-readable recording medium" may also include devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or telephone lines, or devices that store programs for a fixed period of time, such as volatile memory within a computer system that serves as a server or client. The program may be for implementing some of the above-described functions, or may be capable of implementing the above-described functions in combination with a program already stored in the computer system, or may be implemented using a programmable logic device such as an FPGA.

[0085] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents. [Explanation of symbols]

[0086] 20-1 to 20-n... sensors, 30... signal processing unit, 40... structure evaluation device, 41... communication unit, 42... control unit, 43... memory unit, 44... display unit, 301... amplifier, 302... A / D converter, 303... waveform shaping filter, 304... gate generation circuit, 305... arrival time determination unit, 306... feature extraction unit, 307... data recording unit, 308... memory, 309... vehicle number estimation unit, 421... acquisition unit, 422... evaluation unit

Claims

1. a plurality of sensors for detecting elastic waves generated inside the structure; a vehicle number estimation unit that estimates the number of sensors that detected elastic waves generated by the passage of the same vehicle as the number of simultaneous hit sensors for an evaluation period based on the plurality of elastic waves detected by each of the plurality of sensors; an evaluation unit that evaluates a deterioration state of the structure based on the number of simultaneous hit sensors for the evaluation period estimated by the vehicle number estimation unit; A structure evaluation system comprising:

2. The evaluation unit uses the number of simultaneously hit sensors for the evaluation period to count the number of times that N sensors detect elastic waves generated by the passage of the same vehicle, for each integer N (N is an integer of 1 or more) up to the total number of the multiple sensors, and evaluates the deterioration state of the structure based on the distribution shape or peak position of a histogram in which the measured number of times is used as a frequency. The structure evaluation system according to claim 1 .

3. The evaluation unit evaluates the structure to be healthy when the distribution shape of the histogram is such that the number of simultaneous hit sensors is greatest at a position close to the total number of the plurality of sensors, or when the peak position of the histogram is such that the number of simultaneous hit sensors is close to the total number of the plurality of sensors, and evaluates the structure to be deteriorated in other cases. The structure evaluation system according to claim 2 .

4. The evaluation unit uses the number of simultaneously hit sensors for the evaluation period to count the number of times that N sensors detected elastic waves generated by the passage of the same vehicle for each integer N (N is an integer of 1 or more) up to the total number of the plurality of sensors, generates a histogram in which the cumulative value of the number of times measured for each integer greater than or equal to N is used as a frequency for each integer N, and compares the multiple cumulative values ​​in the generated histogram with a reference value to evaluate the deterioration state of the structure based on the value of the integer N that is closest to the reference value. The structure evaluation system according to claim 1 .

5. The evaluation unit uses the number of simultaneously hit sensors for the evaluation period to count the number of times that N sensors detected elastic waves generated by the passage of the same vehicle, for each integer N (N is an integer of 1 or more) up to the total number of the plurality of sensors, calculates an integrated value of the number of times measured at each integer equal to or greater than N, and compares a predetermined integrated value among the calculated plurality of integrated values ​​with a reference value to evaluate the deterioration state of the structure according to the degree of deviation. The structure evaluation system according to claim 1 .

6. The reference value is any one of an estimated number of vehicles measured using a magnetic sensor, a statistical average traffic volume under normal circumstances, a value obtained by a traffic counter, or an actual measurement value of the number of passing vehicles. The structure evaluation system according to claim 4 or 5.

7. the evaluation unit changes the evaluation criteria by shifting the histogram to a smaller number of simultaneously hit sensors depending on the distance between the sensor installation position and the vehicle passing position. The structure evaluation system according to claim 2 or 4.

8. When there is a sensor among the plurality of installed sensors that has detected elastic waves generated by the passage of vehicles relatively few times, the evaluation unit determines that an area around the installation location of the sensor with a relatively small number of passing vehicles is an area where deterioration has occurred. The structure evaluation system according to any one of claims 1 to 5.

9. Based on the multiple elastic waves detected by each of the multiple sensors that detect elastic waves generated inside the structure, the number of sensors that detected elastic waves generated by the same vehicle passing through is estimated as the number of simultaneous hit sensors for the evaluation period; evaluating the deterioration state of the structure based on the estimated number of simultaneous hit sensors for the evaluation period; Structural evaluation methods.

10. a vehicle number estimation unit that estimates the number of sensors that detected elastic waves generated by the same vehicle passing as the number of simultaneous hit sensors for the evaluation period based on multiple elastic waves detected by each of multiple sensors that detect elastic waves generated inside the structure; an evaluation unit that evaluates a deterioration state of the structure based on the estimated number of simultaneous hit sensors for the evaluation period; A structure evaluation device comprising:

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