JP2020148679A - Dynamic strain measurement device - Google Patents

Abstract

To provide a measurement device that measures dynamic strain generated on a structure due to an earthquake or the like.SOLUTION: A measurement device 10 of dynamic strain of a structure for measuring dynamic strain acting on a structure 1 based on a light emission state of a stress-induced illuminant 2 applied on a surface of the structure 1 comprises a light-shielding container 11 for shielding a surface of the stress-induced illuminant 2 from external light, photographing means 12 for photographing the light emission state of the stress-induced illuminant 2 continuously, and irradiation means 13 for irradiating the stress-induced illuminant 2 with excitation light at predetermined time intervals. The photographing means 12 and the irradiation means 13 are disposed inside the light-shielding container 11.SELECTED DRAWING: Figure 1

Description

The present invention relates to an apparatus for measuring dynamic strain of structures such as RC columns and beams.

Conventionally, a technique of attaching a stress-stimulated luminescent material to a structure and measuring the amount of longitudinal strain of the structure from the light emitting state thereof has been disclosed (see, for example, Patent Document 1).
A stress luminescent material is excited by light such as ultraviolet rays, electron beams, and X-rays, and emits light when stress is applied. It is known that the larger the amount of change in strain of a structure, the higher the luminescence intensity.

JP-A-2017-44634

However, in addition to the above-mentioned Patent Document 1, the strain measurement of a structure by a conventional stress-stimulated luminescent material generally measures the luminescence intensity under a static load state, and the dynamic deformation of the structure is described. As far as the applicant knows, there was no knowledge.
Therefore, there is a need for the development of a technique for measuring the strain of a structure (hereinafter referred to as dynamic strain) generated when a stress such as an earthquake whose magnitude changes periodically is applied.

The present invention has been made in view of the conventional problems, and an object of the present invention is to provide an apparatus for measuring dynamic strain generated in a structure due to an earthquake or the like.

The present invention is an apparatus for measuring dynamic strain acting on the structure from the light emitting state of the stress-stimulated luminescent material applied to the surface of a structure such as an RC column or a beam, and the light emitting state of the stress-stimulated luminescent material. The imaging means is provided with an imaging means for continuously photographing the stress luminescent material, an irradiation means for irradiating the stress-stimulated luminescent material with excitation light at predetermined time intervals, and a light-shielding container for shielding the surface of the stress-stimulated luminescent material from external light. The means and the irradiation means are arranged inside the light-shielding container.
As a result, it is possible to acquire data on the magnitude of dynamic strain generated in a structure due to an earthquake or the like and the temporal change of its distribution state as a moving image, so that the state of dynamic strain acting on the structure can be accurately grasped. can do.
Further, since the photographing means is arranged inside the light-shielding container to photograph the light emitting state of the stress-stimulated luminescent material, a clear moving image can be obtained. Therefore, the magnitude and distribution of the dynamic strain can be measured accurately.
Further, since the irradiation means for irradiating the stress-stimulated luminescent material with excitation light is arranged inside the light-shielding container at predetermined time intervals, the dynamic strain of the structure can be accurately measured over a long period of time.
Further, since a strain calculation means for calculating the magnitude of the dynamic strain generated in the structure from the photographed image of the stress luminescent material is provided, the calculated dynamic strain magnitude and distribution data can be obtained. By associating with the magnitude and range of damage caused by an earthquake, the location of damage caused by an earthquake can be identified from the magnitude and distribution of dynamic strain.
Further, only when the vibration detecting means attached to the structure and detecting the vibration input to the structure is provided and the magnitude of the vibration input to the vibration detecting means exceeds a preset threshold value. Since the stress luminescent material is photographed, the dynamic strain data of the structure can be efficiently acquired.

It should be noted that the outline of the present invention does not list all the necessary features of the present invention, and subcombinations of these feature groups can also be inventions.

It is a figure which shows the dynamic strain measuring apparatus which concerns on this embodiment. It is a figure which shows the relationship between dynamic strain and light emission of a stress chemoluminescent body.

1 (a) and 1 (b) are diagrams showing the present embodiment, and FIG. 1 (a) is a diagram showing an installed state of a dynamic strain measuring device (hereinafter referred to as a measuring device 10), (b). ) Is a functional block diagram of the measuring device 10.
In this example, when the stress luminescent material 2 is applied to the area where the dynamic strain of the surface of the RC column 1 which is a structure is to be observed, and the stress due to the earthquake acts on the RC column 1 in the measuring device 10. The dynamic strain of the RC column 1 is measured by photographing the light emitting state of the stress mechanoluminescent body 2.
The stress-stimulated luminescent material 2 is a mixture of a stress-stimulated luminescent material and a paint, and the content of the stress-stimulated luminescent material is adjusted according to the amount of strain to be observed.
The measuring device 10 includes a light-shielding container 11, a color CCD camera as an imaging means (hereinafter referred to as a camera 12), an ultraviolet irradiator 13 as an irradiating means, a storage means 14, a strain calculating means 15, and vibration detection. An acceleration sensor 16 and a switch 17 are provided as means. The camera 12 and the ultraviolet irradiator 13 are arranged inside the light-shielding container 11.
In the figure (a), the camera 12, the ultraviolet irradiator 13, the power line of the acceleration sensor 16, and the signal line are omitted.

The light-shielding container 11 is provided with a box body 11a having an opening larger than that of the mechanoluminescent body 2 on the mounting side, and a rubber member 11b as a mounting member mounted on the peripheral edge of the opening of the box body 11a. When the rubber member 11b is attached to the RC pillar 1, the camera 12 and the ultraviolet illuminator 13 form a sealed box so as to be in a dark place. Instead of the rubber member 11b, a mounting member may be provided on the peripheral edge of the opening of the box body 11a, but it is preferable to use the rubber member 11b in order to improve the airtightness.
The camera 12 continuously (every 1/30 second to 1/50 second) captures a color image including the area where the mechanoluminescent body 2 of the RC column 1 is applied, and stores the captured color image data. Send to means 14. As will be described later, the stress-stimulated luminescent material 2 is photographed only when vibration such as an earthquake is input to the RC column 1. As described above, since the camera 12 is arranged inside the light-shielding container 11 so as to prevent outside light from entering, a clear moving image can be obtained when the stress-stimulated luminescent material 2 emits light.
The ultraviolet irradiator 13 irradiates the stress luminescent material 2 with excitation light at predetermined time intervals. Since the stress-stimulated luminescent material 2 after excitation maintains an almost excited state when stress does not act, it is not necessary to irradiate the excitation light every time measurement is performed, but the stress-stimulated luminescent material 2 is surely emitted. For this purpose, irradiation may be performed by a timer (not shown) for about 5 minutes every 24 hours, for example. The irradiation interval and irradiation time may be appropriately determined depending on the composition and content of the stress-stimulated luminescent material.

The storage means 14 includes a moving image storage unit 14a, a strain-luminance table storage unit 14b, and a calculation result storage unit 14c.
The moving image storage unit 14a stores the image data of the captured camera 12 as moving image data, and the strain-luminance table storage unit 14b shows the relationship between the magnitude of the strain obtained in advance and the brightness of the captured image. -Save the brightness table (σ-L table T). Further, the calculation result storage unit 14c stores the calculation result of the strain calculation means 15.
The strain calculation means 15 calculates the dynamic strain generated in the RC column 1 by using the image data stored in the storage means 14. Specifically, after calculating the brightness of each cell of the image data to obtain the brightness distribution of the image, the brightness distribution was converted into a dynamic strain distribution using the σ-L table T, and this conversion was performed. The data of the distribution of the dynamic strain is stored as the calculation result in the calculation result storage unit 14c of the storage means 14.
The storage means 14 and the strain calculation means 15 constitute a storage / arithmetic unit 18. The storage / arithmetic unit 18 is composed of, for example, a memory and software of a microcomputer.
In this example, the storage / arithmetic unit 18 is attached to the outside of the light-shielding container 11 so that the memory can be easily taken out after an earthquake.
After an earthquake, the storage / arithmetic unit 18 may be installed inside the light-shielding container 11 when the entire measuring device 10 is replaced regardless of the magnitude of the earthquake.

The acceleration sensor 16 is attached to the surface of the RC pillar 1 and detects the vibration input to the RC pillar 1. The acceleration sensor 16 is preferably installed near the stress luminescent material 2, and more preferably installed in the area covered by the light-shielding container 11.
The output of the acceleration sensor 16 is sent to the switch 17.
The switch 17 outputs a signal for starting the imaging of the stress-stimulated luminescent material 2 to the camera 12 when the magnitude of the vibration detected by the acceleration sensor 16 exceeds a preset threshold value.
In addition, instead of the information of the acceleration sensor 16, a means for acquiring earthquake information is provided, and when the earthquake information is input, a signal for starting the imaging of the stress luminescent material 2 may be output to the camera 12. Good.
Further, since the emission of the stress-stimulated luminescent material 2 cannot be photographed when the excitation light is irradiated, if the switch 17 is irradiated with the excitation light at the time of the occurrence of an earthquake, an ultraviolet ray is immediately sent to the switch 17 to stop the irradiation of the excitation light. It is preferable to have a function of sending to the irradiator 13.

Next, the operation of the measuring device 10 will be described.
It is assumed that the light-shielding container 11 is pre-installed on the RC pillar 1 coated with the stress-stimulated luminescent material 2.
When the acceleration sensor 16 detects vibration caused by an earthquake or the like on the RC pillar 1 and the magnitude of the vibration exceeds a preset threshold value (for example, 0.2 G), the switch 17 is activated and the camera 12 is activated. Starts shooting.
As shown in the experimental example below, the stress luminescent material 2 emits light when the magnitude of dynamic strain exceeds a predetermined value.
FIG. 2A is a graph showing the history of dynamic strain when a steel plate is vibrated with a period (about 1 sec.) Close to the period of vibration due to an earthquake with a small vibrating body. Time (sec.) And vertical axis are strain (μ). The solid line in the figure is a graph when a large-amplitude vibration with a strain of ± 1000 μ (± 1 × 10 ^-3 ) is applied to the steel sheet, and the broken line is a medium-amplitude vibration with a strain of ± 500 μ. It is a graph when given to. Further, the circle mark indicates the place where the stress mechanoluminescent body 2 emits light. The strain was measured by attaching a strain gauge to the steel plate.
As shown in the figure, it can be seen that the stress luminescent material 2 does not emit light unless the amount of change in strain is a predetermined magnitude or more.
On the other hand, as shown in FIG. 2B, when the steel sheet is vibrated with a period shorter than the period of vibration due to an earthquake (about 0.2 sec.) In the small vibrating body, the stress luminescent material 2 Did not emit light.
In actual seismic motion, it is difficult for a building to generate large-amplitude strain in a short period of time. Therefore, when a steel sheet is subjected to vibration that causes medium-amplitude strain, and vibration that causes small-amplitude (± 250μ) strain, Experimented with and when given.
Further, the graph of FIG. 2C shows the light emission of the stress mechanoluminescent body 2 by manually bending the steel plate at regular intervals. In the manual experiment, only the negative side of the strain was loaded, but the stress-stimulated luminescent material 2 emitted light because the strain applied when it was assumed to vibrate on the positive side also corresponds to a large amplitude of ± 1000μ. Is.
Further, from these graphs, it can be seen that the stress luminescent material 2 responds not only to static stress but also to vibration having a long period, which is close to the vibration of an earthquake.
The camera 12 photographs the stress-stimulated luminescent material 2 when vibration is input to the RC pillar 1, and sequentially sends the captured image data to the storage means 14. The image data is stored in the moving image storage unit 14a of the storage means 14 as moving image data in time series.
Then, after obtaining the brightness distribution of the image by the strain calculation means 15 for each image data, the brightness distribution is converted into the dynamic strain distribution by using the strain-luminance table T. The distribution of the dynamic strain is stored in the calculation result storage unit 14c of the storage means 14.
In the state where the measuring device 10 is attached to the RC pillar 1, the mechanoluminescent body 2 is blocked from outside light by the light-shielding container 11, so that the mechanoluminescent body 2 is subjected to the ultraviolet irradiator 13 at predetermined time intervals. Needless to say, it is necessary to irradiate the excitation light.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the embodiments. It will be apparent to those skilled in the art that various changes or improvements can be made to the above embodiments. It is clear from the claims that forms with such modifications or improvements may also be included in the technical scope of the invention.

For example, in the above-described embodiment, the structure is the RC column 1, but it may be a steel beam, a steel column, or another structural member such as a steel plate. In short, it may be a structure that generates strain according to the magnitude of the applied stress.
Further, in the above-described embodiment, the brightness of each cell of the image data is calculated, the brightness distribution of the image is obtained, and this is used as the dynamic strain distribution. However, the moving image data itself in which the stress luminescent body 2 repeats light emission is used. , It may be a measurement result of dynamic strain. That is, in the moving image data, the light emitting portion may be a region in which distortion of a predetermined magnitude or more is generated, and the dark portion may be a region in which there is no distortion or there is little distortion.
Further, in the above-described embodiment, the storage / calculation device 18 is attached to the outer wall portion of the light-shielding container 11, but a transmitter is further attached to the dynamic strain stored in the calculation result storage unit 14c of the storage means 14. The data of the distribution of the above may be sent to a building management center or the like (not shown).
Alternatively, the strain measuring means 15 may be provided in the building management center, and the image data of the camera 12 taken may be sent from the transmitter to the building management center.

1 RC column, 2 stress luminescent material,
10 Dynamic strain measuring device, 11 Light-shielding container, 11a box body, 11b rubber member,
12 color CCD camera, 13 UV irradiator, 14 storage means,
14a video storage unit, 14b strain-brightness table storage unit, 14c calculation result storage unit,
15 Strain calculation means, 16 Accelerometer, 17 Switch, 18 Memory / calculator,
T strain-brightness table.

Claims (3)

A device that measures the dynamic strain acting on the structure from the light emitting state of the stress-stimulated luminescent material applied to the surface of the structure.
An imaging means for continuously photographing the light emitting state of the stress-stimulated luminescent material,
An irradiation means for irradiating the stress-stimulated luminescent material with excitation light at predetermined time intervals,
A light-shielding container that shields the surface of the stress-stimulated luminescent material from external light is provided.
A device for measuring dynamic strain of a structure, wherein the photographing means and the irradiation means are arranged inside the light-shielding container. The dynamic strain of the structure according to claim 1, further comprising a strain calculation means for calculating the magnitude of the dynamic strain generated in the structure from the photographed image of the stress luminescent material. Measuring device. The stress is provided only when the vibration detecting means attached to the structure and detecting the vibration input to the structure is provided and the magnitude of the vibration input to the vibration detecting means exceeds a preset threshold value. The device for measuring dynamic strain of a structure according to claim 1 or 2, wherein the luminescent material is photographed.

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