JP2003106806A - Inspection method for reinforcing bar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method for reinforcing bars which is capable of estimating rib angle to be a disturbance in inspection of reinforcing bars by electromagnetic induction. SOLUTION: In an inspection of reinforcing bars by electromagnetic induction method, the rib angle of the reinforcing bar is measured with inspection signal (voltage) characteristic for exciting current, and bar diameter and covering are simultaneously measured by referring to the data obtained for every rib angle in advance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing bar inspection method. For example, it relates to a method for inspecting reinforcing bars in reinforced concrete.

[0002]

2. Description of the Related Art The soundness inspection of reinforced concrete includes visual inspection for cracks on the concrete surface, inspection by hammering sound, corrosion inspection of reinforcing steel, measurement of cover thickness of reinforcing steel (distance from concrete surface to reinforcing steel), etc. There is. The radar method, electromagnetic induction method, ultrasonic method, and the like are applicable to the measurement of the cover and the position of the reinforcing bar. However, since the radar method uses the reflection of electromagnetic waves, all objects other than metals such as reinforcing bars that reflect electromagnetic waves are detected, and these become disturbances in the inspection of reinforcing bars.

Further, since the reflection time of the elastic wave is also used in the ultrasonic method, objects other than the reinforcing bar become a disturbance in the reinforcing bar inspection. As described above, the radar method and the ultrasonic method are not necessarily suitable for the cover thickness and the position of the reinforcing bar. On the other hand, since the electromagnetic induction method uses magnetism, it is almost unaffected by objects other than metals (conductors) and is a method suitable for reinforcing bar inspection. In the rebar inspection by electromagnetic induction method,
The position of the reinforcing bar (in the plane parallel to the concrete surface), the distance from the concrete surface to the reinforcing bar (cover or cover thickness) and the diameter of the bar can be measured.

FIG. 7 shows an example of the measurement principle by the electromagnetic induction method. FIG. 7 is an example of a method called a mutual induction type,
The present invention relates to a method of separately providing the exciting coil 20 and the detecting coil 70. That is, an alternating exciting current 30 is passed from the oscillator 10 to the exciting coil 20 to generate a magnetic field (magnetic flux) φ. When there is a reinforcing bar 50 in the concrete 40, this AC magnetic field φ generates an eddy current 60 in the reinforcing bar 50, and the eddy current 6
The action of 0 changes the magnetic field. The change in the magnetic field is detected by the detection coil 70, and amplified by the amplifier 80 if necessary,
Observe as a detection signal. The detection coil 70 is arranged inside the exciting coil 50.

The change in magnetic field is the magnitude (amplitude) of the detection signal.
And the phase difference of the detection signal with respect to the excitation current, and by measuring these, the size of the reinforcing bar and the distance from the coil to the reinforcing bar (fog) are estimated. In addition,
A system that uses both an exciting coil and a detecting coil is called a self-induction type, but it has the same principle in using a change in magnetic field. There is also known a method of using a direct current or a pulse current (Japanese Patent Publication No. 7-11581) instead of an alternating magnetic field, but in this case, the effect of an eddy current is small and a change in magnetic impedance is used. it is conceivable that. FIG. 16 shows a differential coil type device configuration example as a measuring method other than that shown in FIG. FIG. 16 shows an example in the case of the differential coil type and the mutual induction type. In this case, as shown in FIG. 16, there are two sets of exciting coils 20 and 21 and detecting coils 70 and 71, and each detecting coil 70,
The difference between the outputs of 71 is obtained by the differential amplifier 82. In the differential coil type, two sets of coils have different positional relationships with the reinforcing bar 50 to be measured, which causes a magnetic difference. By detecting this difference, the difference between the reinforcing bar diameter and the cover is sensitive. It is possible to detect well.

FIG. 8 shows an example of the measurement result by the mutual induction method (Non-destructive inspection, Vol. 49, No. 12, "Estimation of a reinforcing bar in an electromagnetic induction test by a neural network" p.84.
2). FIG. 8 shows D10 to D25 (nominal 10 mm to 25 m
It is a result of measuring the amplitude and the phase of the reinforcing bar of m) with the diameter and the covering of the reinforcing bar as parameters. As shown in FIG. 8, a calibration curve group (calibration plane) for estimating the reinforcing bar and the covering is created from the amplitude and the phase, and the rib angle θ of the reinforcing bar shown in FIG.
There was a problem that the calibration surface also changed when was changed. That is, it can be seen that if the calibration curve of FIG. 8 is used for estimation without the rib angle θ being unknown, a large error will occur in the estimation of the diameter.

[0007]

SUMMARY OF THE INVENTION The present invention is capable of estimating a rib angle which is a disturbance in an electromagnetic induction type reinforcing bar inspection in view of the above problems in the reinforcing bar inspection by the electromagnetic induction method in the above-mentioned prior art. It is intended to provide a method for inspecting a reinforcing bar.

[0008]

A reinforcing bar inspection method according to claim 1 of the present invention which solves the above-described problems is a rib of a reinforcing bar in the inspection of a reinforcing bar by an electromagnetic induction method from the characteristic of a detection signal (voltage) with respect to an exciting current. Characterized by measuring an angle.

A reinforcing bar inspection method according to a second aspect of the present invention which solves the above-mentioned problems is to measure the rib angle of the reinforcing bar from the characteristic of the detection signal (voltage) with respect to the exciting current in the reinforcing bar inspection by the electromagnetic induction method. The feature is that the diameter of the reinforcing bar and the cover are measured at the same time with reference to the data acquired in advance for each angle.

A reinforcing bar inspection method according to a third aspect of the present invention for solving the above problem is a method for measuring a rib angle of a reinforcing bar from a detection signal (voltage) characteristic with respect to an exciting current in a reinforcing bar inspection by an electromagnetic induction method, It is characterized by using an estimation method such as a neural network or fuzzy theory.

A reinforcing bar inspection method according to a fourth aspect of the present invention for solving the above problems is a method for measuring a rib angle of a reinforcing bar from a detection signal (voltage) characteristic with respect to an exciting current in a reinforcing bar inspection by an electromagnetic induction method, The feature is that the rib angle is estimated by using a neural network, and the diameter of the reinforcing bar and the cover are simultaneously measured with reference to the data acquired in advance.

A method for inspecting a reinforcing bar according to claim 5 of the present invention for solving the above-mentioned problems is characterized in that a corrosion state of the reinforcing bar is measured by using a diameter of the reinforcing bar measured by the method according to claim 2 or 4. To do.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION [Embodiment 1] In this embodiment, in a reinforcing bar inspection by an electromagnetic induction method, a rib angle that causes disturbance is estimated from the characteristics of a detection signal (voltage) with respect to an exciting current. FIG. 1 shows the amplitude characteristic with respect to the reinforcing bar position when the inspection coil by the electromagnetic induction method is scanned on the surface of the reinforced concrete to be inspected, and FIG. 2 shows an example of the measurement result of the phase characteristic.

Scanning of the inspection coil is performed as shown in FIG.
The amplitude characteristics were measured with the horizontal distance to the reinforcing bar taken as the position of the reinforcing bar. An excitation coil and a detection coil are used as the inspection coil in the mutual induction method. In the self-induction method, a coil that doubles as an exciting coil and a detecting coil may be used. In this embodiment, the excitation current waveform is basically S
The IN wave was used. However, the present invention is not limited to this, and a pulse wave (square wave) can also be applied. That is, as the excitation current waveform, a SIN wave or a square wave can be used.

As shown in FIG. 1, the voltage value indicating the amplitude is positive
It is maximized when on = 0 (directly above the reinforcing bar) and is hardly affected by the rib angle. On the other hand, the phase characteristics change differently depending on the rib angle as shown in FIG. For example, when the rib angle is 90 degrees, the position becomes maximum at position = 0, but when the rib angle is 0 degree, the position becomes minimum at position = 0. Further, at a rib angle of 45 degrees, position = -30 mm, and at a rib angle of 135 degrees, a minimum value is obtained at a position of position = + 30 mm, that is, a position displaced from directly above the reinforcing bar.

As described above, the rib angle can be estimated depending on the position where the extreme value of the phase occurs. Also,
The position of the reinforcing bar can be easily estimated as the position where the maximum value of the amplitude occurs as shown in FIG. Therefore, by preparing a calibration surface as shown in FIG. 8 for each rib angle in advance, the reinforcing bar rib angle inside the reinforced concrete to be actually inspected is estimated by the above method, and the calibration surface corresponding to the rib angle is used. It is possible to estimate the rebar diameter and the fogging at the same time.

Here, the JIS standard defines the spacing between circumferential ribs, the angle of axial ribs, and the height of the ribs.
Generally, as shown in FIG. 9, there are two ribs (180 degree pitch) in the axial direction, but even if these ribs become three (120 degree pitch) and four (90 degree pitch), these ribs will be used. It can be estimated by learning the data in the reinforcing bar with a neural network. The rib angle may be based on any
The data may be learned by changing the rib angle from an arbitrary angle as a reference. Since the JIS standard specifies that the angle between the rib and the axis is 45 degrees or more, there is no more than 9 ribs in the axial direction.

In this embodiment, as shown in FIGS. 1 and 2,
When the inspection coil by the electromagnetic induction method is scanned on the surface of the reinforced concrete to be inspected, the rib angle of the reinforcing bar inside the concrete is closely related to the amplitude and phase of the detection signal, and the amplitude of the detection signal is the maximum value. It is possible to estimate the rib angle of the reinforcing bar by measuring the position and the position obtained as the maximum value or the minimum value of the phase change.

In the above-mentioned prior art, Japanese Patent Publication No. 7-1 cited as an example of the inspection (measurement) method by the electromagnetic induction method.
Japanese Patent No. 1581 suggests the relationship between the rib angle of the reinforcing bar and the calibration surface, but there is no clear estimation algorithm as in the present invention, and this point is different from the present invention. still,
In this embodiment, the rib angle can be estimated from the position where the maximum value of the amplitude and the maximum value of the phase occur, but the characteristics slightly change depending on the diameter and the fogging of the reinforcing bar to be measured.

[Embodiment 2] This embodiment relates to a rib angle estimating method by a neural network as shown in FIG. For example, as shown in FIG.
When the inspection coil is scanned every 0 mm, the input is phase 11
The data (11 data / 100 mm) and the maximum amplitude 1 data are 12 data in total, and the output is the rib angle. In the method using the neural network, for example, · Fogging: 10, 11, 12, 13, 14, 15, ...
80, 85, 90, 95, 100 mm (75 data in total)
・ Reinforcing bar diameter: 10, 13, 16, 19, 22, 25 (total 6
As the data), a 75 × 6 = 450 data set is used as the teacher data for learning.

In this case, when the fogging becomes large, the estimation error of the diameter of the reinforcing bar and the fogging becomes large for the reason described later.
Up to 100 mm is an example of measuring every 5 mm. In the actual inspection (measurement), the rib angle of the reinforcing bar is estimated by using the neural network formed as described above, and the calibration surface (approximation function) as shown in FIG. ), It is possible to estimate the rebar diameter and the cover. The details will be described later in "Principle of Method Using Neural Network for Estimating Fogging and Diameter" and "Building Rib Angle Determination Ability of Neural Network by Back Propagation Learning".

As described above, in this embodiment, in addition to the method of using the maximum value of the amplitude and the maximum value or the minimum value of the phase for estimating the rib angle, a neural network using these as input data is created. It is also possible to estimate it by doing so. If the rib angle can be estimated by the above method, the calibration surface shown in FIG. 8 that changes depending on the rib angle is uniquely determined, and the diameter and the fogging of the reinforcing bar can be estimated from the amplitude and phase of the detection signal. As described above, in the method using the neural network, not only the position of the peak but also the phase waveform and the maximum value of the amplitude are consistently used in order to estimate the rib angle regardless of whether the fog is large or small. Therefore, if the fogging becomes large,
Since the SN ratio decreases, the position of the peak of the amplitude becomes difficult to discriminate, and the change in the phase becomes small, the neural network may also cause erroneous estimation.

[Embodiment 3] This embodiment relates to a method of estimating the corrosion state of the reinforcing bar by estimating the diameter of the reinforcing bar using the method shown in Example 1 or 2 as shown in FIG. . That is, as a result of the corrosion of the reinforcing bar, the reinforcing bar is thinned and the reinforcing bar diameter becomes smaller, so the reinforcing bar diameter is measured using the method of the present invention, and the reinforcing bar diameter at the time of manufacturing the reinforced concrete (without corrosion) obtained from the drawing Corrosion of the rebar is estimated by comparison with. Specifically, as shown in FIG. 5, an inspection target drawing 1 for reinforcing bar specifications (rebar diameter), bar arrangement (bar arrangement position) and cover, and inspection for reinforcing bar diameter, bar arrangement (bar arrangement position) and cover From the result 2, the reinforcing bar corrosion evaluation 3 is performed, and the corrosion state is displayed in the two-dimensional or three-dimensional display 4.

Since the thickness reduction of the reinforcing bar may not occur uniformly, the expression "reinforcing bar diameter" is not appropriate in some cases, and should be considered as the effective sectional area of the reinforcing bar. Even in the electromagnetic induction method, it is considered that the effective sectional area and the projected area are actually measured due to the measurement principle, but for convenience, the rebar diameter is used as the measurement data. Also in the present invention, the corrosion is not limited to the diameter of the reinforcing bar, but is evaluated by a physical quantity obtained by the electromagnetic induction method such as an effective area, but for convenience, the expression "reinforcing bar diameter" is used. .

Furthermore, if the corrosion status of the reinforcing bar is displayed as a two-dimensional or three-dimensional image using both the reinforcing bar position and the covering data obtained by the method of the present invention, the position, covering and corrosion status of the reinforcing bar can be visually recognized. It is possible to grasp the target. In this case, as shown in FIG. 6, by connecting a display device such as a personal computer 7 to the inspection device body 6 connected to the inspection coil 5,
It can be displayed easily. For bridges, etc. that have passed the time after construction, drawings such as bar arrangement drawings may not remain,
In this case, not only the method of FIG. 5, but also the relative corrosion site in the measurement range may be grasped from the variation (distribution) of the reinforcing bar diameter in the measurement range. That is, of the inspection points, the point where the diameter of the reinforcing bar is relatively small can be evaluated as the point where corrosion has advanced, and it is possible to take measures such as preferentially repairing this point.

In the present embodiment, by estimating the diameter of the reinforcing bar by the above-mentioned method, it is possible to grasp the amount of wall thinning due to corrosion of the reinforcing bar, and regarding the fog which is one of the evaluation indexes of the soundness of the reinforced concrete. It becomes possible to grasp at the same time. As a result, the soundness of a wide range of inspection points can be quickly measured even for large structures such as bridges, and the efficiency of inspection and inspection work of reinforced concrete structures and cost reduction can be achieved. In addition, since it is possible to simultaneously measure the reinforcing bar position (the position where the maximum amplitude of the detection signal is obtained), reinforcing bar diameter, and cover (distance from the concrete surface to the reinforcing bar) in the reinforced concrete to be inspected, these data can be measured. Can be displayed as a two-dimensional or three-dimensional image, and the soundness of reinforced concrete can be visually grasped.

[Principle of Method Using Neural Network for Estimating Fogging and Diameter] 1) In the conventional electromagnetic induction type reinforcing bar exploration method, from a single set of amplitude and phase values obtained right above the reinforcing bar, ,
Both the fogging and the diameter are estimated from two sets of calibration curves of diameter vs. phase. 2) However, if the rib angle of the deformed bar changes, this calibration curve group changes. However, the rib angle of rebar in concrete cannot be obtained from the single set of amplitude and phase values obtained just above the rebar. (It is impossible to estimate if there are only three sets of amplitude and phase as the information sources, but there are three factors that you want to know: diameter, rib angle, and information: insufficient information)

3) Then, in order to increase the information, it was devised to scan the coil directly above the reinforcing bar. It was found that the waveform of the signal phase obtained by this has a good correlation with the rib angle (the deviation of the peak position and the difference in absolute value). 4) This signal phase waveform having a good correlation with the rib angle and the maximum value of the amplitude waveform (the amplitude waveform is not necessary: the number of data increases and the number of learning increases, and the convergence of learning deteriorates, which is not good. ), The rib angle can be discriminated, so that the fogging and the diameter can be estimated without the influence of the rib angle. However, since this refers to a large amount of waveform data, we decided to use a neural network.

5) It is also a characteristic of this method that the neural network is divided into two stages. That is, although it is possible to use a single neural network to simultaneously estimate the fogging and the diameter, the structure of the neural network becomes complicated, so that the learning progresses slowly and the convergence is poor. Therefore, first, a neural network for estimating the diameter is constructed while eliminating the influence of the rib angle by using the phase waveform and the maximum value of the amplitude. Then, in the latter-stage neural network, the fog is estimated using the diameter estimation value and the maximum amplitude value of the preceding-stage neural network. 6) The conventional neural network assigns one output cell to one cover or diameter, so-called,
It is a digital form. Therefore, in this neural network, the nominal diameters of deformed reinforcing bars manufactured every 3 mm are estimated. In order to estimate the minute change in the diameter, it must be a method that enables analog estimation.

7) Therefore, a method using an approximate function was devised as a precise estimation method of the diameter and the fog. The feature of this method is that, unlike the method using the conventional calibration curve, not only the relationship of fog vs. amplitude, diameter vs. phase, but also fog vs. phase,
The point is that the relationship between the amplitude and the phase with respect to the fogging and the diameter is used by using the relationship between the diameter and the amplitude. This method uses only one set of signal and phase directly above the rebar, rather than the signal waveform. 8) FIG. 8 shows all the relationships between the amplitude and the phase of the signal immediately above the reinforcing bar with respect to the cover and the diameter. The amplitude and phase obtained for the reinforcing bars of unknown cover and diameter are shown in Fig. 8, and the diameter can be estimated by extending it along the grid (not in the vertical direction in the figure), and the diameter can be estimated in the horizontal direction. Fogging can be estimated by extending along the scale. This is done automatically by creating an approximate function.

9) There are as many fog vs. amplitude curves as there are diameters. Therefore, if this curve is created as an approximate function, as shown in FIG. 10A, the number of calibration curves (that is, the database is created) is the combination of possible diameter and fogging for any amplitude. Sometimes only the number of diameters prepared) is obtained. If this is taken on the cover vs. diameter plane and they are connected, as shown in FIG. 12 (a), one curve (fp)
A curve) is drawn. If this curve is also constructed as an approximate function, possible combinations of fog and amplitude for a given amplitude can be continuously obtained from this approximate function. 10) On the other hand, also from the diameter-phase curve group, from the given phase, as shown in FIG. 10B, as many possible combinations of the fogging and the diameter as the prepared curves can be obtained. When this is connected, as shown in FIG. 12 (b), one curve (f
q curve) is drawn. If this curve is also constructed as an approximate function, combinations of possible fog and amplitude for a given amplitude are continuously given from this approximate function.

11) Then, as shown in FIG. 13, fp
And the fq curve intersect, the coordinates give unknown fog and diameter. 12) The characteristic of this method is that, as shown in FIG. 11, by using all the relationships between the factors of fogging and diameter and the amplitude and phase of the signal, fogging can be performed analogically, that is, with high precision. It is possible to estimate the diameter. 13) In order to perform accurate estimation of the fogging and the diameter, the continuous function is possible as a method, and the approximation function method with high estimation accuracy is preferable. However, this method cannot reduce the influence of the rib angle, and therefore a countermeasure is required for this.

14) Then, as shown in FIG. 14, the rib angle is estimated using a neural network. Then, the approximate function method is constructed for some rib angles. Then, using the rib angle estimated value by the neural network, the corresponding approximation function is selected and analog estimation is performed. This is expected to enable highly accurate estimation of the diameter and cover of the reinforcing bar.

"Building Rib Angle Judging Ability of Neural Network by Back Propagation Learning" As shown in FIG. 4, when the test coil is scanned directly above the reinforcing bar, the amplitude shows the maximum value directly above the reinforcing bar. The maximum value of this amplitude and the scanning waveform are hardly affected by the rib angle. On the other hand, the scanning waveform of the signal phase is
As shown in FIG. 4, the waveform clearly changes depending on the rib angle. On the other hand, neural networks can develop their own ability to extract features of input data. The back propagation learning rule is used for the learning algorithm.

As shown in FIG. 15, the maximum value of the amplitude and the sampled phase waveform are given as data to the input cell of the neural network. In response to this input, the neural network propagates a signal from the input layer to the intermediate layer and the output layer and outputs some output data to the output cell. On the other hand, when the correct rib angle data corresponding to the given data is compared with the value output by the neural network for the time being, there is an error between the two. Therefore, by changing the weighting coefficient and the threshold value of each cell in the direction of reducing this error, the estimated output approaches the correct answer.

Although this operation is called learning, the estimation ability of the neural network is improved by repeating this learning until the error becomes smaller than an arbitrary judgment value. This is called the back propagation learning rule. Therefore, a reinforcing bar having a diameter within the range of estimation is prepared and installed at an arbitrary rib angle.
Then, by changing the fog in an arbitrary range,
Each time, the test coil is scanned to acquire amplitude and phase data. By setting this and a database that gives the correct answer of the rib angle to the neural network, and performing learning repeatedly by the back propagation learning rule, the rib angle determination capability is constructed.

[0037]

As described above in detail, in the reinforcing bar inspection method according to claim 1 of the present invention, in the reinforcing bar inspection by the electromagnetic induction method, the rib of the reinforcing bar is detected from the characteristic of the detection signal (voltage) with respect to the exciting current. Since the angle is measured, it is possible to reliably estimate the reinforcing bar and the cover.

Further, in the reinforcing bar inspection method according to claim 2 of the present invention, in the reinforcing bar inspection by the electromagnetic induction method, the rib angle of the reinforcing bar is measured from the detection signal (voltage) characteristic with respect to the exciting current, and the rib angle is measured for each rib angle. Since the diameter and the cover of the rebar are measured at the same time with reference to the data acquired in advance, the corrosion state of the rebar can be estimated.

The reinforcing bar inspection method according to claim 3 of the present invention is a method for measuring a rib angle of a reinforcing bar from a detection signal (voltage) characteristic with respect to an exciting current in a reinforcing bar inspection by an electromagnetic induction method. Since the estimation method such as the fuzzy theory is used, the rib angle of the reinforcing bar can be reliably measured based on the result learned in advance.

Further, a reinforcing bar inspection method according to a fourth aspect of the present invention uses a neural network in a method of measuring a rib angle of a reinforcing bar from a detection signal (voltage) characteristic with respect to an exciting current in a reinforcing bar inspection by an electromagnetic induction method. Estimate the rib angle using, and measure the reinforcing bar diameter and cover at the same time with reference to the data acquired in advance, so it is possible to reliably measure the rib angle of the reinforcing bar based on the results learned in advance. , It is possible to estimate the corrosion status of rebar.

Further, in the reinforcing bar inspection method according to the fifth aspect of the present invention, the corrosion state of the reinforcing bar can be measured by using the diameter of the reinforcing bar measured by the method according to the second or fourth aspect. If the corrosion state is displayed as a two-dimensional or three-dimensional image, it becomes possible to visually grasp the position of the reinforcing bar, the fogging, and the corrosion state.

[Brief description of drawings]

FIG. 1 is a graph showing an example of amplitude characteristics of a detection signal used for estimating a reinforcing bar rib angle according to a first embodiment of the present invention.

FIG. 2 is a graph showing an example of phase characteristics of a detection signal used for estimating the reinforcing bar rib angle according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a reinforcing bar rib angle estimating method using a neural network according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of an input data measuring method in FIG.

FIG. 5 is an explanatory diagram of a reinforcing bar corrosion evaluation method according to Example 3 of the present invention.

FIG. 6 is an explanatory diagram showing a configuration example of an inspection device to which the reinforcing bar inspection method of the present invention is applied.

FIG. 7 is an explanatory diagram of a measurement principle by an electromagnetic induction method.

FIG. 8 is a graph showing an example of measurement results by a mutual induction method.

FIG. 9 is an explanatory diagram showing rib angles.

FIG. 10 is a graph schematically showing a fog vs. amplitude curve and a diameter vs. phase curve.

FIG. 11 is a graph showing a relationship between a signal and a parameter of a reinforcing bar.

FIG. 12 is a graph schematically showing approximate functions of possible combinations of fogging and diameter.

FIG. 13 is a graph showing the determination of fogging and diameter by two fogging-diameter curves.

FIG. 14 is a conceptual diagram of a precision estimation system.

FIG. 15 is an explanatory diagram showing the construction of rib angle determination capability based on the back propagation learning rule.

FIG. 16 is an explanatory diagram showing a configuration example of a differential coil type device.

[Explanation of symbols]

1 Inspection target drawing 2 inspection results 3 Reinforcing bar corrosion evaluation 4 Two-dimensional (three-dimensional) display of corrosion status 5 inspection coil 6 Inspection device body 7 PC

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hirabayashi             1-8 Koura, Kanazawa-ku, Yokohama-shi, Kanagawa               Mitsubishi Heavy Industries Yokohama Research Center (72) Inventor Seiji Okubo             1-8 Koura, Kanazawa-ku, Yokohama-shi, Kanagawa               Mitsubishi Heavy Industries Yokohama Research Center (72) Inventor Toshio Mizunoue             1-8 Koura, Kanazawa-ku, Yokohama-shi, Kanagawa               Mitsubishi Heavy Industries Yokohama Research Center F-term (reference) 2E176 AA01 BB38                 2F063 AA19 AA22 AA30 AA31 BA30                       BB02 BB03 BB05 BC04 BD05                       BD20 CA08 DA01 DA05 DB05                       GA29 KA01 LA01 LA11 LA17                       LA30                 2G053 AA12 BA02 BA15 BB11 BC02                       BC05 CA18 CB25 DA01 DA08                       DA09

Claims (5)

[Claims] 1. A method for inspecting a reinforcing bar, which comprises measuring a rib angle of the reinforcing bar from a characteristic of a detection signal (voltage) with respect to an exciting current in a reinforcing bar inspection by an electromagnetic induction method. 2. In the rebar inspection by the electromagnetic induction method, the rib angle of the rebar is measured from the detection signal (voltage) characteristic with respect to the exciting current, and the rebar diameter and the rebar diameter are measured with reference to the data acquired in advance for each rib angle. A method for inspecting reinforcing bars, which is characterized by simultaneously measuring fogging. 3. In a reinforcing bar inspection by an electromagnetic induction method, a method of measuring a rib angle of a reinforcing bar from a detection signal (voltage) characteristic with respect to an exciting current uses an estimation method such as a neural network or fuzzy theory. Inspection method. 4. In a reinforcing bar inspection by an electromagnetic induction method, in a method of measuring a rib angle of a reinforcing bar from a detection signal (voltage) characteristic with respect to an exciting current, the rib angle is estimated by using a neural network and acquired in advance. A method for inspecting a reinforcing bar, which comprises simultaneously measuring the diameter and the cover of the reinforcing bar with reference to the data. 5. A method for inspecting a reinforcing bar, which comprises measuring a corrosion state of the reinforcing bar by using the diameter of the reinforcing bar measured by the method according to claim 2.