JP2017095980A - Bridge inspection support system, damage determination method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a user with information on a state of a bridge by a method except visual inspection.SOLUTION: A bridge inspection support system includes: a sound acquisition part for acquiring a sound generated from a component of a bridge on which a vehicle travels; a natural frequency detection part for detecting a natural frequency of the component by analyzing the sound acquired by the sound acquisition part; and a determination part for determining an abnormality associated with the component, by comparing the natural frequency, which is detected by the natural frequency detection part, with a criterion frequency.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bridge inspection support system, a damage determination method, and a program.

In order to prevent accidents due to bridge damage, it is important to inspect the bridge and detect damage.
For example, Patent Document 1 describes a technique of using a wireless sensor by grasping the entire natural vibration mode of a bridge. In the technique described in Patent Document 1, specialized knowledge about structural engineering and radio is required for sensor placement and data acquisition. For this reason, what can determine the presence or absence of damage appropriately and easily is required, without requiring the specialized knowledge regarding structural vibration at the time of a measurement operation.

JP 2008-255571 A

  Even if the bridge is damaged, it may be difficult to detect due to adhesion of dirt or the like, or it may be difficult to grasp the degree of damage because the internal state cannot be grasped from the surface state that can be identified by visual inspection. In this case, even if the bridge is photographed with a camera or the like and inspected from the image, the above problem cannot be solved.

  Here, if the inspection worker can obtain information on the state of the bridge by a method other than visual inspection, it becomes possible to diagnose damage more appropriately in the inspection work, and further increase the efficiency of the work. For example, by using both a visual inspection of a bridge and a method other than the visual inspection, if the presence or absence of damage can be detected while reducing the work of removing dirt on the bridge, the burden on the inspection worker can be reduced.

  The present invention provides a bridge inspection support system, a damage determination method, and a program capable of providing a user with information related to a bridge state by a method other than visual inspection.

  According to the first aspect of the present invention, a bridge inspection support system analyzes a sound acquisition unit that acquires sound emitted from a component part of a bridge on which a vehicle travels, and a sound acquired by the sound acquisition unit. A natural frequency detection unit that detects the natural frequency of the component part, and a determination unit that compares the natural frequency detected by the natural frequency detection unit with a determination reference frequency to determine an abnormality related to the component part And comprising.

  The bridge inspection support system may include an imaging unit that images the component, an image captured by the imaging unit, and a display unit that displays the determination result of the determination unit in association with each other.

  The bridge inspection support system may include a determination reference determination unit that determines the determination reference frequency based on a history of sounds emitted from the components.

  The bridge includes a plurality of components having the same material, the same shape, and the same size, and the bridge inspection support system is emitted from each of the components having the same material, the same shape, and the same size. A determination reference determination unit that determines the determination reference frequency based on the sound may be provided.

  The bridge may be a steel girder bridge, and the component may be at least one of a main girder web, a main girder lower flange, a stiffener, and a support of the bridge.

  The sound acquisition unit may acquire a sound emitted from the component when a vehicle travels on the bridge.

  According to the second aspect of the present invention, the damage determination method includes a sound acquisition step of acquiring a sound emitted from a structural part of a bridge on which a vehicle travels, and analyzing the sound acquired in the sound acquisition step, A natural frequency detecting step for detecting the natural frequency of the constituent part; a determination step for comparing the natural frequency detected in the natural frequency detecting step with a determination reference frequency to determine an abnormality related to the constituent part; ,including.

  According to the third aspect of the present invention, the program analyzes, on a computer, a sound acquisition step of acquiring sound emitted from a structural part of a bridge on which the vehicle travels, and the sound acquired in the sound acquisition step. A natural frequency detection step for detecting the natural frequency of the component part, and a determination step for comparing the natural frequency detected in the natural frequency detection step with a determination reference frequency to determine an abnormality related to the component part. And a program for executing.

  ADVANTAGE OF THE INVENTION According to this invention, the information regarding the state of a bridge can be provided to a user by methods other than visual inspection.

It is a schematic block diagram which shows the function structure of the bridge inspection assistance system which concerns on one Embodiment of this invention. It is explanatory drawing which shows the structural example of the steel bridge girder bridge in the same embodiment. It is a flowchart which shows the example of the process sequence in which the processing apparatus in the embodiment determines the abnormality of a bridge. It is explanatory drawing which shows the vibration position in a 1st experiment. It is a graph which shows the frequency spectrum of the vibration detected using the accelerometer in the 1st experiment. It is a graph which shows the frequency spectrum of the vibration obtained by analysis of sound in the 1st experiment. It is explanatory drawing which shows the vibration position in 2nd experiment. It is a graph which shows the frequency spectrum of the vibration obtained when the main girder upper flange was hit in the second experiment. It is a graph which shows the frequency spectrum of the vibration obtained when the joint part was hit in 2nd experiment. It is explanatory drawing which shows the vibration position in the 3rd experiment, and the removed volt | bolt. It is explanatory drawing which shows the example of the natural frequency obtained by the 3rd experiment.

Hereinafter, although embodiment of this invention is described, the following embodiment does not limit the invention concerning a claim. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.
FIG. 1 is a schematic block diagram showing a functional configuration of a bridge inspection support system according to an embodiment of the present invention. As shown in FIG. 1, the bridge inspection system 1 includes a data acquisition device 100 and a processing device 200. The data acquisition device 100 includes an imaging unit 110 and a sound acquisition unit 120. The processing device 200 includes a display unit 210, an operation input unit 220, a storage unit 280, and a control unit 290. The control unit 290 includes a determination criterion determination unit 291, a natural frequency detection unit 292, and a determination unit 293.

  The bridge inspection system 1 is a system that supports inspection of a bridge. Below, although the case where the bridge inspection system 1 is used for the inspection of a steel bridge girder bridge is demonstrated to an example, the object of the inspection performed using the bridge inspection system 1 is not restricted to this. The bridge inspection system 1 can be used for inspection of various bridges that emit sound in response to vibration caused by running of a vehicle or the like.

The data acquisition apparatus 100 is an apparatus that captures an image of a structural part of a bridge and collects sound generated by the structural part of the bridge. The component part of a bridge here is a part which comprises a bridge, and when a component part itself vibrates, it is a part which emits a sound.
The component part of the bridge may be a member of the bridge. For example, when the bridge to be inspected is a steel girder bridge, examples of components include a main girder web (Web Plate), a stiffener, and a support.

Alternatively, the bridge component may be a combination of bridge members. For example, when the bridge to be inspected is a steel girder bridge, an I-shaped steel combining a main girder web, a main girder upper flange, and a main girder lower flange can be given as an example of a component.
Alternatively, the component part of the bridge may be a part of a bridge member or a part of a combination of bridge members. For example, when the bridge to be inspected is a steel girder bridge, examples of the constituent part include a part in which the main girder web is divided by a main girder upper flange, a main girder lower flange, and a stiffener.
Here, with reference to FIG. 2, the example of a structure of the bridge used as the object of inspection using the bridge inspection system 1 is demonstrated.

  FIG. 2 is an explanatory diagram showing a configuration example of a steel bridge girder bridge. A steel girder bridge 910 shown in the figure is composed of a lower pier 911, a support 912, and an upper structure 913, and the pier 911 supports the upper structure 913 via the support 912. The upper structure 913 includes a girder 914 and a floor slab 915, and the girder 914 supports the floor slab 915. A travel route of the vehicle is provided on the floor slab 915.

  The girder 914 includes a main girder web 922, a main girder upper flange 923, a main girder lower flange 924, a stiffener 925, a cross beam 926, a lower horizontal structure 927, and a counter tilt structure 928. , And supported by a pier 911 via a bearing 912.

The combination of the main girder web 922, the main girder upper flange 923, the main girder lower flange 924, and the stiffener 925 constitutes the main girder 921. The main beam 921 supports the floor slab 915.
The main girder web 922 connects the main girder upper flange 923 and the main girder lower flange 924. Main girder web 922 primarily resists shear forces.
The main girder upper flange 923 and the main girder lower flange 924 are provided at the upper and lower portions of the main girder web 922, respectively, and mainly resist bending moment.
The stiffener 925 is provided along the main girder web 922 and connects the main girder web 922, the main girder upper flange 923, and the main girder lower flange 924. The stiffener 925 mainly prevents the main girder 921 from buckling.

The cross beam 926 couples the plurality of main beams 921 and distributes the load of the floor slab 915.
The lower horizontal structure 927 and the counter tilting structure 928 also connect the plurality of main beams 921 together with the horizontal beam 926. The lower horizontal structure 927 mainly resists lateral load. The tilting structure 928 mainly prevents the main girder from being twisted.
The bearing 912 transmits a load from the superstructure 913 to the pier 911.
The bridge pier 911 supports the upper structure 913 through the support 912.
However, the bridge to be inspected by the bridge inspection system 1 is not limited to the bridge having the structure described with reference to FIG. For example, the bridge inspection system 1 may support inspection of a steel bridge girder bridge that does not include any one or both of the lower horizontal structure 927 and the counter tilting structure 928.

The imaging unit 110 is configured to include a camera, and images a part of the bridge. For example, the photographing unit 110 photographs the main girder web 922 from the vicinity of the main girder web 922. The photographing unit 110 may photograph an image showing the entire main digit web 922 or an image showing a part of the main digit web 922. The imaging unit 110 outputs the captured image as image data based on an electrical signal.
A user (hereinafter simply referred to as a user) of the bridge inspection system 1 refers to an image obtained by photographing the main girder web 922 by the photographing unit 110, and whether or not the main girder web 922 is damaged or cracked, and the degree of damage. Can be confirmed.

Here, it may be difficult for the user to visually check the state of the structural parts of the bridge directly. For example, when the user visually confirms the spar 914 at a high position from the ground, since the spar 914 is far from the user, the main girder web 922 and the components of the support 912, the stiffener 925, the main girder web 922, the main girder There is a possibility that the details of the joint with the lower flange 924 cannot be visually confirmed. Furthermore, from the ground, there is a possibility that the joint between the main girder lower flange 924 and the main girder web 922 is hidden by the main girder lower flange 924 and cannot be visually confirmed directly.
Therefore, the imaging unit 110 captures the component part from the vicinity of the component part of the bridge, so that the user refers to the image captured by the imaging unit 110 and confirms the presence / absence and the degree of abnormality of the component part. Can do.

The abnormality relating to the component part here may be damage to the component part or a change in a state in which the component part is fixed. Examples of abnormalities relating to the constituent parts include damage to the constituent parts, damage to the constituent parts due to corrosion, cracks in the constituent parts, and dropping off of the bolts that stop the constituent parts.
In the following, the determination of the presence / absence of an abnormality related to a component and the determination of the degree of abnormality related to the component will be collectively referred to as determination of an abnormality related to the component. The bridge inspection system 1 may perform only one of the determination of the presence / absence of an abnormality regarding the component and the determination of the degree of the abnormality regarding the component, or both.

In order to position the data acquisition device 100 including the imaging unit 110 in the vicinity of the structural part of the bridge, for example, the data acquisition device 100 is installed at the tip of the rod, and the user operates the rod to operate the data acquisition device 100. Move closer to the bridge components. Alternatively, a method other than a method using a rod may be used, such as installing the data acquisition device 100 in a drone (Drone, a radio-controlled small unmanned airplane) and operating the drone closer to a bridge component. It may be.
The photographing unit 110 may photograph a moving image or a still image. When the imaging unit 110 captures a moving image, the user can bring the data acquisition device 100 closer to a component part of the bridge while confirming the image of the imaging unit 110.

The sound acquisition unit 120 is configured to include a microphone having directivity, and acquires sound emitted from a component part of the bridge. The sound acquisition unit 120 is installed so that the direction of directivity matches the direction in which the imaging unit 110 performs imaging. Thereby, the sound acquisition unit 120 acquires the sound emitted by the component imaged by the imaging unit 110.
The sound acquisition unit 120 acquires a sound emitted from a component when the vehicle travels on the bridge. Alternatively, a person (one of the inspection workers) may perform vibration such as hitting a component part of the bridge with a hammer, and the sound acquisition unit 120 may acquire the sound generated by the vibration. The sound acquisition unit 120 outputs the acquired sound as sound data based on an electrical signal.
The sound acquired by the sound acquisition unit 120 is used to determine an abnormality related to the structural part of the bridge. Specifically, the processing device 200 determines the presence and extent of damage in the structural parts of the bridge using the sound acquired by the sound acquisition unit 120.

Here, as described above, the image capturing unit 110 captures an image of a component part of the bridge, thereby assisting the close visual inspection performed by the user.
However, if dirt or the like adheres to the bridge, it may become an obstacle to visual inspection of the bridge. Even when the imaging unit 110 captures a component part of a bridge, there is a possibility that a part to be inspected cannot be photographed if dirt is attached to the component part to be imaged. If the dirt is removed, the bridge can be visually inspected. However, the work for removing the dirt is a burden on the inspection worker, and the work for removing the dirt requires cost and time. Furthermore, when the bridge (particularly the superstructure) is at a high position, it may be difficult to carry out the work for removing the dirt adhering to the bridge. Even if the occurrence of corrosion or the like is recognized, it is difficult to determine the degree of damage because the internal state cannot be grasped visually.

  On the other hand, even when rust or dirt adheres only to the surface of the structural part of the bridge, the natural frequency of the structural part is almost the same as when rust or dirt does not adhere. On the other hand, the natural frequency of a component may change when a large damage occurs, such as when a bolt that stops the component of a bridge falls off, or when a large crack occurs in a component of a bridge. It is done. For this reason, if rust or dirt adheres to the surface of the component part of the bridge and sufficient visual inspection cannot be performed, the component part may be damaged significantly by detecting the natural frequency of the component part. You can get information for judging. That is, the bridge inspection system 1 can provide information for the user to determine whether or not to perform a more detailed inspection.

  The processing device 200 supports the inspection of the bridge based on the data acquired by the data acquisition device 100 (image data indicating an image captured by the imaging unit 110 and sound data indicating a sound acquired by the sound acquisition unit 120). Provide information to do. Specifically, the processing device 200 displays an image captured by the imaging unit 110. Moreover, the processing apparatus 200 determines the abnormality of the structural part of a bridge based on the sound which the sound acquisition part 120 acquired, and displays a determination result.

The processing device 200 includes an information processing device such as a personal computer or a smartphone.
The data acquisition device 100 and the processing device 200 may be configured integrally (that is, as one device) or may be configured as separate devices. For example, when the processing device 200 is configured using a smartphone, the data acquisition device 100 may be configured using a camera and a microphone included in the smartphone.

The display unit 210 has a display screen such as a liquid crystal panel and displays various images. In particular, the display unit 210 displays the image captured by the imaging unit 110 and the determination result of the abnormality of the component part of the bridge in association with each other. However, the display unit 210 is not necessarily configured to display the image captured by the image capturing unit 110 and the determination result of the abnormality of the structural part of the bridge in association with each other. For example, the display unit 210 may switch between display of an image captured by the imaging unit 110 and display of an abnormality determination result of a component part of the bridge in accordance with a user operation.
The display unit 210 may be configured as a part of the processing device 200 or may be configured as a device different from the processing device 200.

The operation input unit 220 includes an input device such as a touch sensor provided on the display screen of the display unit 210 and constituting a touch panel, for example, and receives a user operation. For example, when the imaging unit 110 captures a still image, the operation input unit 220 receives a user operation (shutter operation) indicating the imaging timing.
The storage unit 280 stores various data. The storage unit 280 is configured using a storage device provided in the processing apparatus 200. Alternatively, the storage unit 280 may be configured as a device different from the processing device 200.

The control unit 290 controls each unit of the processing apparatus 200 and executes various functions. The control unit 290 is configured by, for example, a CPU (Central Processing Unit) included in the processing device 200 reading out and executing a program from the storage unit 280.
The determination criterion determination unit 291 determines a determination reference frequency that is used as a determination criterion for an abnormality of a component part of the bridge. Specifically, the determination criterion determination unit 291 obtains a resonance frequency assumed when there is no abnormality in the component (normal time), and sets the obtained resonance frequency as the determination reference frequency.

The determination reference determination unit 291 may determine the determination reference frequency based on the history of sounds emitted from the constituent parts of the bridge.
For example, each time the same bridge is inspected, the storage unit 280 accumulates (stores) the natural frequency obtained by analyzing the sound emitted by the constituent part for each constituent part of the bridge. The natural frequency stored in the storage unit 280 corresponds to an example of a sound history.
Then, the determination criterion determination unit 291 calculates an average value of the natural frequencies stored in the storage unit 280 for each component portion of the bridge, and uses the obtained average value as a determination reference vibration for each component portion of the bridge. Decide on a number.

However, the method by which the determination criterion determination unit 291 obtains the determination reference frequency from the natural frequency is not limited to the method of calculating the average value of the natural frequencies. For example, the determination criterion determination unit 291 may calculate a mode value (Mode) or an intermediate value (Median) instead of the average value of the natural frequencies. Alternatively, the determination criterion determination unit 291 calculates the remaining average of the natural frequencies stored in the storage unit 280 excluding the predetermined number from the maximum and the predetermined number from the minimum. Also good.
The sound history stored in the storage unit 280 is not limited to the accumulation of the natural frequency obtained by the analysis, but may be any accumulation of data from which the natural frequency can be obtained. For example, the storage unit 280 may store sound generated by the component part as sound data for each component part of the bridge.

  Alternatively, when a plurality of constituent parts included in the bridge to be inspected have the same material, the same shape, and the same size, the determination criterion determination unit 291 includes a representative constituent part among these constituent parts. Alternatively, the determination reference frequency may be determined only for the constituent parts. In this case, the storage unit 280 may store the sound history only for the constituent parts that are the representative constituent parts among the constituent parts having the same material, the same shape, and the same size.

Alternatively, the determination reference determination unit 291 may determine the determination reference frequency based on sounds emitted from the same material, the same shape, and the same size.
For example, when the bridge to be inspected is a steel girder bridge, the steel girder bridge usually has a plurality of components in which the main girder web is divided by a main girder upper flange, a main girder lower flange, and a stiffener. The plurality of constituent parts are made of the same material, the same shape and the same size. The sound acquisition unit 120 acquires the sound emitted by the component for each of these components.
Then, the determination criterion determination unit 291 calculates the average value of the natural frequencies obtained by the analysis of the sound acquired by the sound acquisition unit 120 (analysis of the sound emitted by the component), and uses the obtained average value. The determination frequency is determined for each component of the bridge.

  However, the method by which the determination criterion determination unit 291 obtains the determination reference frequency from the natural frequency is not limited to the method of calculating the average value of the natural frequencies. For example, the determination criterion determination unit 291 may calculate a mode value (Mode) or an intermediate value (Median) instead of the average value of the natural frequencies. Alternatively, the determination criterion determination unit 291 includes a remaining number obtained by removing a predetermined number from the maximum and a predetermined number from the minimum among the natural frequencies obtained by analyzing the sound acquired by the sound acquisition unit 120. An average may be calculated.

  The natural frequency detection unit 292 analyzes the sound acquired by the sound acquisition unit 120 and detects the natural frequency of the component. Specifically, the natural frequency detection unit 292 performs spectrum analysis on the sound acquired by the sound acquisition unit 120. A known algorithm such as FFT (Fast Fourier Transform) can be used as an algorithm for the natural frequency detection unit 292 to perform sound spectrum analysis. The natural frequency detection unit 292 detects a frequency component larger than a predetermined condition in the obtained frequency spectrum as the natural frequency.

For example, the natural frequency detection unit 292 detects the frequency having the largest frequency component as the natural frequency from the obtained frequency spectrum.
Alternatively, the natural frequency detection unit 292 may detect the natural frequency for a plurality of vibration modes. For example, the natural frequency detection unit 292 may detect a predetermined number (for example, three) of frequencies as the natural frequency in descending order of frequency components from the obtained frequency spectrum.

  Alternatively, when the approximate value of the natural frequency is known, the natural frequency detection unit 292 may detect the frequency having the largest frequency component in the vicinity of the approximate value of the frequency as the natural frequency. . For example, when the determination criterion determination unit 291 has already determined the determination reference frequency, the natural frequency detection unit 292 has a predetermined frequency width around the determination reference frequency (for example, plus or minus 10 hertz). (Within (Hz)), the frequency having the largest frequency component is detected as the natural frequency. When the determination criterion determination unit 291 determines only one determination reference frequency, the determination criterion determination unit 291 detects one natural frequency based on the determination reference frequency. On the other hand, when the determination criterion determination unit 291 determines the determination reference frequency for each vibration mode, the determination criterion determination unit 291 detects the natural seismic intensity for each vibration mode based on these determination reference frequencies. .

The determination unit 293 compares the natural frequency detected by the natural frequency detection unit 292 with the determination reference frequency determined by the determination reference determination unit 291 to determine an abnormality in the structural part of the bridge.
Specifically, the determination unit 293 subtracts the natural frequency detected by the natural frequency detection unit 292 from the determination reference frequency determined by the determination reference determination unit 291 to obtain a decrease amount from the determination reference frequency. calculate. Then, the determination unit 293 compares the obtained decrease amount with a threshold value, and determines that there is an abnormality (an abnormality is detected) when it is determined that the natural frequency is lower than the threshold value. On the other hand, when it is determined that the natural frequency has not decreased below the threshold (the natural frequency has not decreased, or the amount of decrease in the natural frequency is equal to or less than the threshold), the determination unit 293 has no abnormality. (No abnormality is detected).

  Here, it is conceivable that when an abnormality relating to the structural part of the bridge occurs, the restraint when the structural part vibrates becomes small, and the natural frequency decreases. For example, if a crack occurs in the vicinity of a welded part where a component currently being inspected (hereinafter referred to as a component to be inspected) and other parts are welded, a node at the time of vibration (fixed portion) It is conceivable that the structural part moves to some extent at the welded part, which causes the natural frequency to decrease. Accordingly, the determination unit 293 can detect a decrease in the natural frequency, thereby detecting an abnormality related to the component. In addition, the natural frequency may increase when the bearing is stuck due to corrosion and the original movable function is lost.

Alternatively, the determination unit 293 may determine the degree of abnormality in addition to or instead of the presence or absence of abnormality. For example, when the determination unit 293 determines that there is an abnormality, the determination unit 293 may display the amount of decrease in the natural frequency on the display unit 210 together with the message that detected the abnormality.
Here, there is a possibility that the amount of decrease in the natural frequency increases as the degree of abnormality related to the constituent parts of the bridge increases. For example, if a crack occurs at a welded part where the component part to be inspected and another part are welded, the larger the crack, the greater the component part moves at the welded part, which increases the natural frequency. It is conceivable that the amount of decrease increases.
Thus, the amount of decrease in the natural frequency can be used as an index value indicating the degree of abnormality. The determination unit 293 causes the display unit 210 to display the decrease amount of the natural frequency, so that the user can estimate the degree of abnormality with reference to the displayed decrease amount.

Next, the operation of the bridge inspection system 1 will be described with reference to FIG.
FIG. 3 is a flowchart illustrating an example of a processing procedure in which the processing device 200 determines a bridge abnormality. The processing apparatus 200 is in a state where the sound acquisition unit 120 is directed to the component to be inspected (the direction of the microphone directivity of the sound acquisition unit 120 is directed to the component to be inspected). Process. In parallel with the processing of FIG. 3, the processing apparatus 200 acquires an image obtained by photographing the component to be inspected by the photographing unit 110 as image data, and causes the display unit 210 to display the obtained image.
In the description of FIG. 3, the component part to be inspected is simply referred to as a component part.

In the process of FIG. 3, the natural frequency detection unit 292 acquires sound data indicating the sound emitted by the component (step S <b> 101). Specifically, when a component emits a sound when the vehicle travels on a bridge or when an inspection worker hits the component, the sound acquisition unit 120 acquires the emitted sound and generates an electrical signal. Convert to sound data. Then, the data acquisition device 100 transmits the obtained sound data to the processing device 200. When the processing device 200 receives the sound data transmitted from the data acquisition device 100, the natural frequency detection unit 292 acquires the sound data.
The process in which the sound acquisition unit 120 acquires sound in step S101 corresponds to an example of the process in the sound acquisition step.

Next, the natural frequency detection unit 292 performs spectrum analysis on the sound obtained in step S101 (step S102). For example, as described above, the natural frequency detection unit 292 performs sound spectrum analysis using a frequency analysis device based on fast Fourier transform (FFT).
Then, the natural frequency detection unit 292 detects the natural frequency of the component from the frequency spectrum obtained in step S102 (step S103). For example, as described above, the natural frequency detection unit 292 detects the frequency having the largest frequency component as the natural frequency from the frequency spectrum in the obtained step S102.
The combination of steps S102 and S103 corresponds to an example of the natural frequency detection step.

Next, the determination unit 293 calculates a reduction amount of the natural frequency detected by the natural frequency detection unit 292 from the determination reference frequency (step S104). Specifically, the determination unit 293 calculates the amount of decrease by subtracting the natural frequency detected by the natural frequency detection unit 292 from the determination reference frequency determined by the determination criterion determination unit 291.
For example, the determination criterion determination unit 291 determines the determination reference frequency as described above and stores it in the storage unit 280. Then, the determination unit 293 reads the determination reference frequency stored in the storage unit 280. When the storage unit 280 stores the determination reference frequency for each component part of the bridge, the determination unit 293 reads the determination reference frequency of the component part to be inspected. Then, the determination criterion determination unit 291 subtracts the natural frequency detected by the natural frequency detection unit 292 from the determination reference frequency read from the storage unit 280.

  Note that the determination unit 293 may calculate the reduction amount of the natural frequency based on the natural frequencies of the plurality of modes. For example, the storage unit 280 stores a determination reference frequency for each of a plurality of vibration modes. In step S103, the natural frequency detection unit 292 detects the natural frequency for each vibration mode in which the storage unit 280 stores the determination reference frequency. Then, the determination unit 293 calculates a reduction amount by subtracting the natural frequency from the determination reference frequency for each vibration mode in which the storage unit 280 stores the determination reference frequency, and obtains a plurality of reductions obtained. You may make it calculate the average of quantity.

Next, the determination criterion determination unit 291 determines whether or not the reduction amount obtained in step S104 is larger than a threshold value (step S105). This threshold value is stored in advance by the storage unit 280 as a positive constant, for example.
The combination of steps S104 and S105 corresponds to an example of a determination step.
When it is determined that the amount of decrease is greater than the threshold (step S105: YES), the display unit 210 displays a message indicating that an abnormality has been detected according to the control of the control unit 290 (step S111).
After step S111, the process of FIG. 3 ends.

On the other hand, when it is determined in step S105 that the amount of decrease is equal to or less than the threshold (step S105: NO), the display unit 210 displays a message indicating that no abnormality is detected according to the control of the control unit 290 (step S105). S121).
After step S121, the process of FIG.

As described above, the determination unit 293 compares the natural frequency detected by the natural frequency detection unit 292 from the sound emitted from the component part of the bridge with the determination reference frequency, and determines an abnormality related to the component part. .
Thus, the determination part 293 determines abnormality regarding a component based on a sound, The bridge inspection system 1 can provide a user with the information regarding the state of a bridge by methods other than visual inspection.
For example, when rust or dirt adheres to the surface of a component part of the bridge and the user (inspection worker) cannot sufficiently perform a visual inspection, the bridge inspection system 1 performs a more detailed inspection on the component part. It is possible to provide information for the user to determine whether or not.

Here, a method of obtaining the natural frequency by installing an acceleration sensor in the structural part of the bridge is also conceivable. However, in this method, it is necessary to install and remove the acceleration sensor for each component. When the number of components is large, it is not realistic to install and remove the acceleration sensor for each component.
On the other hand, in the bridge inspection system 1, since the natural frequency is obtained by sound measurement, it is not necessary to install an acceleration sensor in the component part, and it is not necessary to remove the acceleration sensor. In this respect, according to the bridge inspection system 1, it is possible to reduce the burden of the inspection worker attaching and detaching the acceleration sensor.

  Here, it is conceivable to determine whether or not there is an abnormality based on the natural frequency of the entire bridge instead of the natural frequency of the constituent parts of the bridge. However, in this case, the natural frequency becomes low (for example, about 10 Hz), and it may be difficult to accurately detect the natural frequency. On the other hand, when detecting the natural frequency of the structural part of the bridge, the natural frequency is relatively high, and the natural frequency can be obtained with relatively high accuracy by sound analysis.

Note that the user may inspect all the structural parts of the bridge using the bridge inspection system 1 such as inspecting all the main girders of the bridge.
Or you may make it a user check only the part which is easy to produce damages, such as an edge part of a bridge, using the bridge inspection system 1. FIG.

In addition, the display unit 210 displays an image in which the imaging unit 110 captures the structural part of the bridge and the determination result of the determination unit 293 in association with each other.
Accordingly, the user can easily and accurately associate the situation of the component portion visually with the determination result of the determination unit 293, and which component portion the determination result of the determination unit 293 is the determination result of. Can be grasped. For example, when rust or dirt is attached to the surface of a component part of a bridge, and when determining whether or not to perform further detailed inspection on this component part, the user determines which component part the determination result by the determination unit 293 is The correspondence can be grasped without the need to associate the determination results. In this regard, the user can easily refer to the determination result by the determination unit 293 when determining whether or not to check the component part in more detail.

  In addition, when a visual inspection of the bridge is required, a mechanism for bringing the photographing unit 110 close to the structural part of the bridge and directing the photographing direction toward the structural part is essential. Can be brought close to the component and directivity direction can be directed to the component. In this respect, it is not necessary to provide a separate mechanism for bringing the sound acquisition unit 120 close to the component and directing the direction of directivity toward the component. In this respect, an increase in manufacturing cost of the bridge inspection system 1 can be suppressed. In addition, it is possible to suppress an increase in time and effort of the user because it is not necessary to bring the photographing unit 110 and the sound acquisition unit 120 close to the constituent parts separately.

In addition, the determination criterion determination unit 291 determines a determination criterion frequency based on the history of sounds emitted from the constituent parts of the bridge.
The determination unit 293 can detect a change in the natural frequency by comparing the determination reference frequency with the natural frequency detected by the natural frequency detection unit 292. By detecting a change in the natural frequency, the determination unit 293 can determine an abnormality related to the component.

In addition, the determination criterion determination unit 291 determines a determination criterion frequency based on sounds emitted from the same material, the same shape, and the same size.
The determination unit 293 has the same material, the same shape, and the same size as the other components by comparing the determination reference frequency with the natural frequency detected by the natural frequency detection unit 292. However, it is possible to detect a component having a different natural frequency from other components. This difference in natural frequency is considered to be caused by an abnormality related to the component, for example, a crack has occurred in the vicinity of the welded portion where the component and the other part are welded. Therefore, the determination unit 293 can determine an abnormality related to the component.

  In addition, the bridge inspection system 1 can be used for, for example, inspection of at least one of a main girder web, a main girder lower flange, a stiffener, and a bearing of a steel girder bridge.

  Further, the sound acquisition unit 120 acquires a sound emitted from a component when the vehicle travels on the bridge. Thus, the inspection worker does not need to perform an operation for generating a sound in the component part, for example, by hitting the component part with a hammer. In this respect, the load on the inspection worker can be reduced.

Next, an experiment relating to damage determination based on sound analysis will be described with reference to FIGS.
FIG. 4 is an explanatory diagram showing an excitation position in the first experiment. As shown in the figure, in the first experiment, a main girder constructed by attaching a main girder upper flange 943, a main girder lower flange 944, an intermediate stiffener 945, and an end stiffener 946 to the main girder web 942. A steel model 940 in which 941 and a sole plate 947 were combined was prepared. And the model 940 was vibrated by hitting the position of the point P11 of the main girder upper flange 943 with a mallet, and the vibration of the area A11 of the main girder web 942 was measured. Region A11 is a portion where the main girder web is divided by a main girder upper flange 943, a main girder lower flange 944, an intermediate stiffener 945, and an end stiffener 946. Non-patent literature on the Society of Civil Engineers, Vol. 735 (2003) is that the flat plate primary mode and the secondary mode in the region A11 are structural modes that generate structural sounds when a vehicle passes over a bridge. ), pp 131-144.

The measurement of the vibration in the region A11 was performed by both a method using an accelerometer and a method for analyzing the sound emitted from the region A11 of the main girder web 942.
In the method using an accelerometer, an accelerometer was installed in the area A11 of the main girder web 942, the acceleration was measured, and the frequency spectrum of vibration was obtained by Fourier transforming the amplitude calculated from the measured value of acceleration.
In the method of analyzing sound, a microphone was brought close to the area A11 of the main girder web 942 to acquire sound, and Fourier transform was performed to acquire the frequency spectrum of the sound. The distance between the main girder web 942 and the microphone was about 10 centimeters (cm).

FIG. 5 is a graph showing the frequency spectrum of vibration detected using an accelerometer in the first experiment. The horizontal axis of the graph shown in the figure indicates the frequency, and the vertical axis indicates the intensity of the spectrum at each frequency. In the first experiment, excitation of the model 940 and measurement of acceleration by the acceleration sensor were performed five times, and the frequency spectrum obtained each time is shown in the graph.
As shown in the figure, peaks with particularly strong spectrum appear at 336 hertz and 358 hertz, and at 544 hertz and 578 hertz, 624 hertz, and 663 hertz.
Here, in the natural vibration analysis using the finite element model, two natural frequencies of the mode indicating the primary mode of the flat plate in the region A11 appear around 265 hertz, 311 hertz, and 300 hertz. It was calculated that four frequencies of 433 hertz, 447 hertz, 477 hertz, and 495 hertz appeared, respectively. From this, 336 Hz and 544 Hz with particularly strong spectral intensities are the natural frequencies of the flat plate primary mode and secondary mode of the region A11, respectively.

FIG. 6 is a graph showing a frequency spectrum of vibration obtained by sound analysis in the first experiment. The horizontal axis of the graph shown in the figure indicates the frequency, and the vertical axis indicates the intensity of the spectrum at each frequency. In the experiment, the model 940 was subjected to vibration and sound acquisition five times, and the frequency spectrum obtained each time is shown in the graph.
When the graph of FIG. 5 is compared with the graph of FIG. 6, the spectrum intensity of the graph of FIG. 6 is different, but the spectrum intensity of 336 hertz and 544 hertz is strong as in the case of FIG.

  Thus, in the first experiment, the natural frequency of the model 940 could be detected by Fourier-transforming the sound emitted from the model 940 and detecting the frequency having a strong spectrum intensity. Similarly, it is considered that the natural frequency of the component can be detected by using the bridge inspection system 1 to detect a frequency having a strong spectrum intensity by Fourier transforming sound emitted from the component of the bridge.

  FIG. 7 is an explanatory diagram showing an excitation position in the second experiment. In the second experiment, the same model 940 as in the first experiment was prepared. And the model 940 was vibrated by hitting the joint part shown by the position of the point P21 of the upper girder upper flange 943 and the point P22 with a mallet, and the vibration of the model 940 was measured.

  In the measurement of the vibration of the model 940, the sound was acquired by bringing the microphone close to the area A11 of the main girder web 942, and the frequency spectrum of the sound was acquired by Fourier transform. When the distance between the main girder web 942 and the microphone was about 10 centimeters, when the distance was about 20 centimeters, and when the distance was about 40 centimeters, sounds were obtained with the microphones, and the frequency spectrum of the sound was obtained.

  FIG. 8 is a graph showing a frequency spectrum of vibration obtained when the position of the point P21 of the main girder upper flange 943 is hit in the second experiment. The horizontal axis of the graph shown in the figure indicates the frequency, and the vertical axis indicates the intensity of the spectrum at each frequency. Line L211 shows the frequency spectrum when the distance between the main girder web 942 and the microphone is about 10 centimeters. A line L212 indicates a frequency spectrum when the distance between the main girder web 942 and the microphone is about 20 centimeters. Line L213 shows the frequency spectrum when the distance between the main girder web 942 and the microphone is about 40 centimeters.

  In FIG. 8, even if the distance between the main girder web 942 and the microphone is different, a peak (a portion having a strong spectral intensity) appears at substantially the same frequency. Even when the natural frequency of the structural part of the bridge is obtained using the bridge inspection system 1, it is considered that a substantially constant natural frequency can be obtained even if the distance between the structural part and the microphone is not constant.

  FIG. 9 is a graph showing a frequency spectrum of vibration obtained when the coupling part (position of the point P22) is hit in the second experiment. The horizontal axis of the graph shown in the figure indicates the frequency, and the vertical axis indicates the intensity of the spectrum at each frequency. Line L221 represents the frequency spectrum when the distance between the main girder web 942 and the microphone is about 10 centimeters. A line L222 indicates a frequency spectrum when the distance between the main girder web 942 and the microphone is about 20 centimeters. Line L223 represents the frequency spectrum when the distance between the main girder web 942 and the microphone is about 40 centimeters.

In FIG. 9, even if the distance between the main girder web 942 and the microphone is different, a peak (a portion having a strong spectral intensity) appears at substantially the same frequency. Even when the natural frequency of the structural part of the bridge is obtained using the bridge inspection system 1, it is considered that a substantially constant natural frequency can be obtained even if the distance between the structural part and the microphone is not constant.
Further, when the graph of FIG. 8 is compared with the graph of FIG. 9, although the peak frequency is different, in the graph of FIG. 9, the natural frequency of the intermediate stiffener 945 and the end stiffener 946 is the peak frequency. It is thought that has appeared in.

  Thus, in the second experiment, the natural frequencies of the different portions were obtained. Even when the bridge inspection system 1 is used to detect the natural frequency of the component part of the bridge, it is considered that the natural frequency of each component part can be detected. At that time, it is considered that the sound emitted from the component part to be inspected can be selectively acquired and the natural frequency can be detected by using the microphone for the component part to be inspected using a microphone having strong directivity.

FIG. 10 is an explanatory diagram of a state where the vibration position and the bolt are removed in the third experiment. In the third experiment, the same model 940 as in the first experiment was prepared. In the third experiment, the model 940 is vibrated by hitting the position of the point P31 of the main girder upper flange 943 with a mallet with some or all of the bolts 951, 952, 953, and 954 removed. The vibration in the area A11 of the main girder web 942 was measured.
The vibration of the area A11 was measured by a method of analyzing the sound emitted from the area A11 of the main girder web 942. Specifically, a microphone was brought close to the area A11 of the main girder web 942 to obtain a sound, and Fourier transform was performed to obtain a frequency spectrum of the sound.

  FIG. 11 is an explanatory diagram showing an example of the natural frequency obtained in the third experiment. In the same figure, the obtained natural frequency is shown for each of the case where the number of removed bolts is 0 to 4. Specifically, when the bolt is not removed, when the bolt 951 is removed, when the bolts 951 and 952 are removed, when the bolts 951, 952 and 953 are removed, when the bolts 951, 952, 953 and 954 are removed The natural frequencies obtained for each of the above are shown. Each of the models 940 is subjected to vibration and sound acquisition five times to obtain the natural frequency five times, and the average value of the five natural frequencies obtained is shown.

As shown in FIG. 11, in the third experiment, the natural frequency is lower when the bolt is removed than when the bolt is not removed. Even when the abnormality relating to the structural part of the bridge is determined using the bridge inspection system 1, the bridge inspection system 1 can detect the abnormality if the natural frequency decreases when there is an abnormality related to the structural part.
In FIG. 11, when the bolts 951 and 952 are removed, the natural frequency decreases as the number of bolts removed increases, except that the natural frequency is higher than when only the bolt 951 is removed. ing. Even when the abnormality relating to the structural components of the bridge is determined using the bridge inspection system 1, the bridge inspection system 1 can determine the degree of abnormality based on the magnitude of the decrease in the natural frequency.

Note that a program for realizing all or part of the functions of the control unit 290 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed. You may perform the process of. Here, the “computer system” includes an OS and hardware such as peripheral devices.
Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the gist of the present invention. .

DESCRIPTION OF SYMBOLS 1 Bridge inspection system 100 Data acquisition apparatus 110 Image pick-up part 120 Sound acquisition part 200 Processing apparatus 210 Display part 220 Operation input part 280 Memory | storage part 290 Control part 291 Determination reference | standard determination part 292 Natural frequency detection part 293 Determination part

Claims (8)

A sound acquisition unit for acquiring sounds emitted from the components of the bridge on which the vehicle travels;
A natural frequency detector that detects the natural frequency of the component by analyzing the sound acquired by the sound acquisition unit;
A determination unit for comparing the natural frequency detected by the natural frequency detection unit with a determination reference frequency to determine an abnormality related to the component;
Bridge inspection support system with An imaging unit for imaging the component;
A display unit that displays the image captured by the imaging unit in association with the determination result of the determination unit;
The bridge inspection support system according to claim 1, comprising:   The bridge inspection support system according to claim 1 or 2, further comprising a determination reference determination unit that determines the determination reference frequency based on a history of sounds emitted from the component. The bridge comprises a plurality of components of the same material, the same shape and the same size,
The bridge inspection support system includes a determination criterion determination unit that determines the determination reference frequency based on sound emitted from each of the same material, the same shape, and the same size component. Or the bridge inspection support system of Claim 2. The bridge is a steel girder bridge,
The bridge inspection support system according to any one of claims 1 to 4, wherein the component is at least one of a main girder web, a main girder flange, a stiffener, and a support of the bridge.   The bridge inspection support system according to any one of claims 1 to 5, wherein the sound acquisition unit acquires a sound emitted from the component when a vehicle travels on the bridge. A sound acquisition step of acquiring sound emitted from a component part of the bridge on which the vehicle travels;
A natural frequency detection step of analyzing the sound acquired in the sound acquisition step and detecting the natural frequency of the component;
A determination step of comparing the natural frequency detected in the natural frequency detection step with a determination reference frequency to determine an abnormality related to the component;
Damage determination method including On the computer,
A sound acquisition step of acquiring sound emitted from a component part of the bridge on which the vehicle travels;
A natural frequency detection step of analyzing the sound acquired in the sound acquisition step and detecting the natural frequency of the component;
A determination step of comparing the natural frequency detected in the natural frequency detection step with a determination reference frequency to determine an abnormality related to the component;
A program for running

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