JPH1096711A - Nondestructive inspection method for rupture 0f structural member and building equipped with diagnostic function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inspect rupture situation of an electric conductive structural member without removing cladding materials. SOLUTION: Magnetic sensors are arranged at each measuring point of a building (step 200), and an alternating voltage is applied to the building (step 202). Magnetic filed at each measuring point is measured (step 204), a synchronous average of measured values is taken (step 206), a current value of a member at each measuring point is estimated (step 208). Further, resistance of each conductive structural member, which can reproduce the estimated current values, is obtained through simulation (step 210), and rupture situation of each electric conductive structural member is inspected by comparing the resistance value thus obtained with the resistance in the past (step 214). Thereby rupture situation of each electric conductive structural member can be inspected accurately without removing cladding materials.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for nondestructively inspecting structural member breakage and a building with a diagnostic function, and more particularly to an AC voltage applied to a portion of a conductive structural member constituting the building which sandwiches a measured portion. The present invention relates to a nondestructive inspection method for structural member breakage and a building with a diagnostic function capable of accurately detecting a breakage state of a coating material without breaking the coating material by measuring a magnetic field generated by a current applied to and flowing through a portion to be measured.

[0002]

2. Description of the Related Art Generally, in steel-framed buildings, main structural members are often covered with interior and exterior materials. For this reason, conventionally, when encountering deterioration or earthquakes due to aging,
In order to check the state of breakage of the structural member, the coating material is removed by some method and checked visually.

[0003]

However, in the above-mentioned conventional method for checking the state of breakage of a structural member, it takes a lot of time and time to remove the covering material or repair it, etc., in order to check the state of breakage of all members. It is costly and unrealistic.

[0004] In order to solve this problem, it is necessary to reduce the influence of noise or the like when detecting any physical parameter indicating the breakage of the structural member without removing the covering material. Further, it is desired to reduce labor and time for measurement as much as possible.

In view of the above facts, the present invention provides a non-destructive inspection method for a structural member rupture which can accurately detect the rupture state of the structural member based on the electrical characteristics of the structural member without removing the covering material. It is an object of the present invention to provide a building with a diagnostic function that reduces labor and time for measurement as much as possible.

[0006]

To achieve the above object, a first aspect of the present invention is a method of applying an AC voltage to an arbitrary portion of a conductive structural member constituting a building, which sandwiches a portion to be measured. A step of measuring a magnetic field by a magnetic detection unit disposed in the vicinity of the measured part, and an estimation of estimating a current value flowing through the measured part based on a value of the magnetic field measured in the measuring step. Based on the value of the applied AC voltage and the current value estimated at the site to be measured,
A simulation step of determining the resistance value of each conductive structural member in the circuit network equivalent to the building, the resistance value of each conductive structural member determined in the simulation step, and the resistance value of each conductive structural member in a normal state And an inspection step of inspecting the state of breakage of each conductive structural member by comparing

According to a second aspect of the present invention, there is provided a voltage applying step of applying an AC voltage to a portion of a conductive structural member constituting a building, which sandwiches a portion to be measured, and a magnetic detector disposed near the portion to be measured. A measuring step of performing a magnetic field measurement, an estimating step of estimating a current value flowing through the measured site based on the value of the magnetic field measured in the measuring step, and determining whether or not the current value estimated in the estimating step is present Or, based on a comparison between the estimated current value and the current value of the measured part in a normal state,
An inspection step of inspecting the state of breakage of the conductive structural member at the measurement site.

According to a third aspect of the present invention, there is provided a voltage applying step of applying alternating voltages of at least two different frequencies to a portion sandwiching a measured portion of a conductive structural member constituting a building; The arranged magnetic detectors each measure a magnetic field when an alternating voltage of a different frequency is applied, and apply an alternating voltage of a different frequency based on the value of each magnetic field measured in the measuring step. An estimation step of estimating the current value flowing through the measurement site when the measurement is performed, and based on a comparison of the respective current values estimated in the estimation step, a fracture related to a crack on the surface of the conductive structural member of the measurement site is performed. And an inspection step of inspecting the situation.

The invention according to claim 4 is the invention according to claims 1 to 3.
The invention according to any one of the above, further comprising an averaging step of averaging the value of the magnetic field measured in the measurement step, in synchronization with the frequency of the AC voltage applied in the voltage application step, The estimating step estimates a current value flowing through the measurement site based on the value of the magnetic field averaged in the averaging step.

[0010] The invention of claim 5 is the invention of claims 1 to 3.
In the invention according to any one of the above, in the voltage applying step, an AC voltage having an arbitrary waveform is applied, and the value of the magnetic field measured in the measuring step is a coded sequence represented by an M sequence or a chirp signal. And a compression step of performing pulse compression by using the step (a), wherein the estimation step estimates a current value flowing through the measured portion based on a value of the magnetic field pulse-compressed in the compression step. .

The invention of claim 6 is the first to fifth aspects of the present invention.
Wherein the measurement step performs the magnetic field measurement while avoiding a frequency of a commercial power supply used in the building and a frequency that is an integral multiple of the frequency.

According to a seventh aspect of the present invention, there is provided an AC power supply capable of applying an AC voltage of a constant current of an arbitrary frequency and an arbitrary waveform to a predetermined portion of a conductive structural member constituting a building, 7. The non-destructive inspection method for structural member breakage according to any one of claims 1 to 6, using a plurality of magnetic detectors respectively arranged at predetermined locations, and using the AC power supply and the plurality of magnetic detectors. Control means for periodically inspecting the destruction status of the plurality of measurement sites.

(Principle of the Present Invention) FIG. 13 shows a model simply representing a structure (particularly a steel structure) constituted by conductive structural members. Each of the conductive structural members 1 to 6 of the structure shown in FIG. 13 has a unique resistance value determined by its material component, length, cross-sectional area, and the like.

Therefore, when this structure is replaced with an equivalent circuit network as a resistor, an equivalent circuit network as shown in FIG. 14 is obtained. According to FIG. 14, the conductive structural member 1-6 is equivalent respectively resistance r ₁ ~r _6. The total resistance value between points a and b in FIG. 14 is determined as a value unique to the building by the resistance values of these conductive structural members and the coupling method between the members.

When an AC voltage is applied to such a building, an AC current determined by the applied AC voltage value and each resistance value flows through each conductive structural member, and around the conductive structural member, A magnetic field is generated that is determined according to the AC current value and the distance from the current center axis. FIG. 2 shows the distance (X-axis) from the current center and the magnetic flux density at the maximum amplitude (Y-axis) at the distance when an alternating current having a maximum amplitude of 10 A (ampere) is applied to the conductive structural member. In FIG. 2, it is assumed that the conductive structural member is elongated and the magnetic flux density is axially symmetric. According to FIG. 2, when the distance from the current center is 1 m, the magnetic flux density is about 2 μT (tesla; 10 ⁴ gauss).
In the case of m, it decreases to about 1 μT. It can be seen that the magnetic flux density decreases in inverse proportion to the distance from the current center.

Here, when one of the conductive structural members is cut or partially cut due to an earthquake, aging, or the like, the inherent resistance value of the cut conductive structural member changes, and its construction is changed. The resistance value between a and b of the whole object also changes. Therefore, even under the same condition that an alternating voltage of a constant current is applied between a and b, an abnormal case in which at least one of the conductive structural members is broken and a normal case in which at least one of the conductive structural members is not broken at all. The value of the alternating current flowing through the conductive structural member changes. For this reason, the magnetic field around each conductive structural member also changes, and by measuring this magnetic field, the presence or absence of breakage of the conductive structural member can be inspected nondestructively.

As a non-destructive inspection method of the conductive structural members, a method of applying an AC voltage to the entire building and obtaining a resistance value of each conductive structural member by simulation (hereinafter, referred to as a “simulation method”), There is a method of individually measuring the resistance value of each conductive structural member (hereinafter, referred to as an “individual measurement method”).

In the simulation method, an AC voltage is applied between a and b, and a current value flowing through each resistor is estimated from magnetic field data measured in the vicinity of the conductive structural member at the portion to be measured. Then, the value of each resistor in the equivalent circuit network as shown in FIG. 14 is obtained by simulation from the estimated current value, and the state of breakage is inspected from each resistance value. The value of each resistor is obtained, for example, by the following method.

In the equivalent network of FIG. 14, the current flowing through each of the resistors r ₁ , r ₂ , r ₃ , r ₄ , r ₅ , and r ₆ is represented by i
_{1, i 2, i 3,} i 4, i 5, and i _6, when the voltage applied to the resistors _{e 1, e 2, e 3} , e 4, e 5, and _{e 6, i 1 = i 2} + i ₃ , i ₂ = i ₄ = i ₅ , i ₆ = i ₁ (1) e ₁ = r ₁ i ₁ , e ₂ = r ₂ i ₂ , e ₃ = r ₃ i ₃ , e ₄ = r ₄ i ₄ , E ₅ = r ₅ i ₅ , e ₆ = r ₆ i ₆ , (2) E = e ₁ + e ₃ + e ₆ , e ₃ = e ₂ + e ₄ + e ₅ (3) Here, E is the value of the AC voltage applied between a and b. When a power supply having a constant current I is used, the following holds: I = i ₁ = i ₂ + i ₃ = i ₆ (4)

Here, the known value is the estimated current value i.
_{1 to} i ₆ , E and I, and substituting these values into the equations (1) to (3) or (4) determines the resistances r _{1 to} r ₆ .

In this case, (1)
Since the formula holds, measure all conductive structural members
Minimal magnetic field measurement of conductive structural members even if not selected
Thus, the value of the current flowing through each resistor can be predicted. For example,
Anti-r₁And resistance r_FourIs selected as the measurement point and its magnetic field
From the value of i₁And i_FourIs estimated from (1), i_Two,
i _Three, I_Five, I₆Can be automatically obtained. this
In the simulation method, the number of measurement points (
The number of measurement sites) can be reduced to a minimum.

In the individual measuring method, each conductive structural member is sandwiched.
An AC voltage is applied to each of the two points, and the individual conductive structures
Each resistance value is obtained from the magnetic field measurement around the material. Figure
In the example of 14, between ac, between c and e, between cd and ef
AC voltage is applied between f-d and d-b,
From the measurement of the magnetic field caused by the alternating current, the resistance r₁,
r _Two, R_Three, R_Four, R_Five, R₆Respectively.

Further, there are a method 01 and a comparative method as a method for inspecting the breaking condition based on the measured resistance value and the measured value of the magnetic field. According to the method 01, when the measured magnetic field is 0 or less than the noise component, that is, when the resistance value at which no AC current flows is infinite, it is determined that the measurement site is completely broken, and the measured magnetic field is determined. Is larger than 0 or a noise component, it is determined that the measurement site is not completely broken.

In the comparison method, the obtained resistance value is compared with the normal resistance value. The value of the measured magnetic field and the current value obtained from the magnetic field may be compared. The normal resistance values (magnetic field value, current value) to be compared were calculated using the resistance values (magnetic field value, current value) measured in the building at the time of completion, or based on the design drawings etc. A resistance value (magnetic field value, current value) can be used.

By the way, the conductive structural member constituting a building generally has cracks from the surface in many cases, and when there are many cracks near the surface than inside the member, the surface resistance becomes larger than the internal resistance. When an alternating current is passed through the conductive structural member, as the frequency is increased, the current concentrates near the surface due to the so-called skin effect, and therefore, in a member having many cracks near the surface from the inside, The resistance of the high-frequency alternating current is greater than the resistance of the low-frequency alternating current, causing a difference in the current value.

Therefore, in the crack determination method, the presence or absence of a crack on the surface and the approximate location of the crack are determined by comparing the current value between the high frequency and the low frequency.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a block diagram of a measurement system according to a first embodiment.

The measuring system according to the first embodiment is
A building 100 made of a conductive structural member (steel frame) is set as an object to be measured, and a power supply means 97 for applying an AC voltage to the building 100, and a magnetic detection device arranged at a predetermined position near the conductive structural member And a data processing means 99 for processing the measurement data of the magnetic field measured by the magnetic detection unit 98 to inspect the state of destruction of the conductive structural member.

The power supply means 97 includes a function generator 106 for generating an AC voltage signal having an arbitrary frequency and an arbitrary waveform in accordance with the input control signal, and a constant current by amplifying the AC voltage signal generated by the function generator 106. Power amplifier 1 that outputs AC voltage
08.

The power supply ±
The terminals are terminals 1 installed at two predetermined positions of the building 100 via the power cable 102 and the power cable 104.
00A and the terminal 100B. The terminals 100A and 100B correspond to points a and b in the example of the equivalent circuit network of FIG.
When the AC voltage supplied from the power amplifier 108 is applied to A and 100B, an AC current flows through each member of the building 100.

The magnetic detecting section 98 is composed of a coil or a magnetic sensor formed by winding an insulated conductor such as an enameled wire uniformly and closely around a hollow cylinder. The magnetism detection unit 98 is provided at a position near the steel frame at the site to be measured, and is arranged so as to detect a magnetic flux generated around the steel frame by a current flowing through the steel frame.

The data processing means 99 converts the electric signal output from the output terminal of the magnetic detector 98 into a power value, amplifies it, and cuts off noise components.
And an AD converter 113 for converting the analog data of the amplified signal of the amplifier / filter unit 112 into digital data, and a computer 114 for collecting and processing the converted digital data.

The amplifier / filter unit 112
Is set to a frequency band different from the frequency of the commercial power supply (50 Hz, 60 Hz) and a frequency that is an integral multiple of the frequency. Further, the AC voltage generated by the function generator 106 is set to a frequency different from the commercial frequency and a frequency that is an integral multiple of the commercial frequency. That is, in the measurement system according to the present embodiment, the magnetic field measurement is performed while avoiding the commercial frequency and a frequency that is an integral multiple of the commercial frequency.

The computer 114 is capable of performing arithmetic operations such as averaging and pulse compression of the amplified signal of the amplifier / filter unit 112 as described later.
From this calculated value, the presence or absence of a current flowing through the measured portion or the current value (resistance value) is estimated.

The computer 114 also has a telephone line 11
The function generator 106 is connected to the computer 114 via an interface 8 and sends out a synchronization signal synchronized with the generated electric signal to the computer 114. The computer 114 can add and average the amplified signal from the amplifier / filter unit 112 in synchronization with the synchronization signal sent from the function generator 106. In addition, the telephone line 1 that sends the synchronization signal
The reference numeral 18 is required when the computer 114 is to be externally synchronized, and is unnecessary when the computer 114 is to perform self-synchronization.

When the magnetic detection section 98 is formed of a coil and an AC voltage is applied to a portion to be measured, a magnetic flux which changes with time penetrates the coil, thereby generating an induced voltage. The induced voltage depends on the magnetic flux density in the hollow portion of the coil of the magnetic detection unit 98, its frequency, and the magnetic detection unit 9
8 and the number of turns. Here, a magnetic field having a maximum magnetic flux density of 5 μT is applied at a frequency of 30H in the hollow portion of the coil of the magnetic detection section 98 having a sectional area of 25π × 10 ⁻⁴ m ^2.
FIG. 3 shows the relationship between the induced voltage generated at the coil terminal and the number of turns of the insulated conductor when the sine wave of z changes. According to FIG. 3, when the number of turns is 2000, the induced voltage is about 0.015V,
When the number of turns is 10,000, the induced voltage is about 0.07V,
It can be seen that the induced voltage increases in proportion to the number of turns.

Next, the flow of measurement by the simulation method using the measurement system configured as described above will be described with reference to the flowchart of FIG.

As shown in FIG. 4, first, the magnetic detector 98
Are arranged at each measurement point of the selected plurality of conductive structural members (step 200). In addition, the vicinity of a resistor (conductive structural member) from which a current distribution flowing through each resistor in the equivalent circuit network of the building 100 can be obtained is selected as each measurement point.

Next, the building 1 is powered by the power supply means 97.
An AC voltage having a predetermined current and a constant current is applied between the terminal 100A and the terminal 100B (Step 202).
As a result, an AC voltage is applied to the entire building, and an AC current flows through each member. Note that the waveform of the AC voltage applied here includes, for example, a sine wave, but a waveform other than a sine wave may be used.

Next, a magnetic field is measured at each measurement point (step 204). When the member at each measurement point is not broken, an alternating current flows to generate a magnetic field, and the magnetic detection unit 98 detects the magnetic field and outputs an electric signal. However, when the member at the measurement point is completely broken, no alternating current flows and no magnetic field is generated, and the magnetic detection unit 98 does not detect the magnetic field. At this time, the magnetic detector 98
Is 0.

The electric signal output from the magnetic detector 98 is converted into a power value by the amplifier filter unit 112 and amplified. After the amplified analog data is converted into digital data by the AD converter 113,
Input to the computer 114. In the amplifier filter unit 112, the frequency of the commercial power supply used in the building 100 and a frequency (harmonic) of an integral multiple of the frequency are used.
Is cut by a band-pass filter, and only the component of the magnetic field due to the applied AC voltage is extracted while avoiding this frequency band, so that the influence of the magnetic field from the commercial power supply, which is a main factor of noise, is reduced, and the S / N ratio is reduced. And accurate measurement becomes possible.

Next, the computer 114 calculates an average value obtained by averaging the digital data input from the AD converter 113 in synchronization with the waveform generation timing by the function generator 106 (step 206). ).

By such a synchronous averaging, random noise from the surrounding commercial power supply and various noise sources is smoothed, and the influence of the noise on the measured value can be reduced. Further, a pulse of a synchronization signal is caused to flow through the telephone line 118 to reduce the influence of attenuation due to distance and the influence of noise to ensure thoroughness. However, the computer 11
Telephone line 118 when averaging by self-synchronization of 4
Becomes unnecessary.

Next, the current value of the member at each measurement point is estimated from the average value (step 208). Then, the resistance of each conductive structural member is obtained by simulation from the estimated current value and the value of the applied AC voltage (step 210).

Next, the resistance value of each conductive structural member in the past (when completed) is read (step 212). For example, the average value of the magnetic field measured in the building 100 at a normal time when the steel frame is not affected by aging, such as at the time of completion, is stored in a database in an external storage device in advance, and the computer 114 The resistance value of each conductive structural member when it is not broken is read from an external storage device or the like. Further, a resistance value in the case of no breakage may be obtained by calculation from a design drawing of a building or the like.

Then, the breaking state of each conductive structural member is inspected by comparing the past normal resistance value with the resistance value obtained by simulation (step 214).

Thus, in the first embodiment, the destruction state of the conductive structural member can be inspected nondestructively with the minimum number of measurement points. Step 21
In some cases, the resistance values of all members cannot be obtained only from the estimated current value and the voltage value at 0. In such a case,
In step 202, an AC voltage is applied between the terminals other than the terminals 100A and 100B, and the measurement of FIG. 4 is performed again to obtain the resistance value of each member.

The use of an AC voltage has the following advantages. When an alternating current flows through a steel frame, the current can be distributed around the steel frame due to an eddy current effect (skin depth: 0.65 mm at 100 Hz). In general, when a crack occurs in a steel frame, the steel frame is torn from a peripheral portion. Therefore, by using an alternating current, a difference in resistance value due to the crack can be sensitively reflected.

As a method of installing a power supply when applying an alternating current in step 202 of FIG. 4, for example, there is a method as shown in FIG. According to FIG. 15, one end of the power cable 131 and one end of the power cable 132 which are insulated except for the ends are respectively located at predetermined positions 131A of the steel frame 133 of the steel structure building 130.
And 132A in advance. Further, one end of the power cable 134 and one end of the power cable 136 are connected to different positions 134A and 136A of the steel frame 133 of the steel structure building 130, respectively, and the other power supply ends 134B and 136B.
Exposed outside the ground.

When power is not supplied, nothing is connected to each of the power supply terminals 131B and 134B like the power cable 131 and the power cable 134. When supplying power, for example, the truck 140 on which the power supply 138 is mounted is connected to the power supply terminals (132B, 13B).
6B) and the power supply terminals 132B, 136 of the power cable 132 and the power cable 136, respectively.
The terminals of the power supply 138 are connected to B, respectively. As a result, a voltage is applied between 132A and 136A in the steel structure building 130. Similarly, the power supply end 131B
When the terminals of the power supply 138 are connected to the power supply 138 and the power supply 138B, a voltage can be applied between the power supply 131A and the power supply 134A in the steel structure building 130. Note that the power supply 138 may be provided exclusively for a building.

Here, in order not to measure the magnetic field from the power cable itself, it is necessary to pass the cable away from the area to be measured or to change the cable position sequentially and measure the whole. Further, it is necessary to magnetically shield the power cable so as to prevent the magnetic field from the cable from leaking to the outside.

(Second Embodiment) In a second embodiment, an individual measurement method will be described.

FIG. 8 shows an outline of a measuring system according to the second embodiment. This measuring system is similar to the amplifier filter unit 112, A, similar to the first embodiment.
The measurement unit 142 includes a D converter 113 and a computer 114, a power supply 144 including a function generator 116 and a power amplifier 108, and a magnetic sensor 150 for measuring a magnetic field. Further, the terminals 146A and 146B sandwiching the steel frame of the measurement site 148 are connected to the terminals 147A and 147B provided on the surface of the covering material via the cords 149A and 149B, respectively.
Further, an installation place of the magnetic sensor 150 is provided on a wall surface of the covering material surrounding the measurement site 148, and an attachment 141 for fixing the magnetic sensor 150 is provided at the installation place.

At the time of measurement, the measuring unit 142 and the power supply 1
44 is arranged in one room in contact with the measurement site 148 in the building 101, the magnetic sensor 150 is mounted on the attachment 141, and the magnetic sensor 150 and the measurement unit 142 are connected via the data line 143. By the attachment to the attachment 141, the distance between the magnetic sensor 150 and the central axis of the steel frame of the measured portion 148 always keeps a constant value d. Then, the codes 145A, 1
45B are connected to terminals 147A and 147B, respectively. With this connection, the AC voltage supplied from the power supply 144 becomes
The voltage can be applied between the terminals 146A and 146B sandwiching the measured portion 148.

Further, the measuring system according to the second embodiment can be configured as shown in FIG. In the measurement system shown in FIG. 9, the terminal 146A, the terminal 146B, and the cord 149 installed on the steel frame of the measurement site 148 in FIG.
A, terminal 1 installed on the surface of the covering material via 149B
Instead of 47A and 147B, a magnetic flux ring 151 arranged so as to surround the measurement site 148 including the coating material is used. A coil 152 is wound around the magnetic flux ring 151, and two terminals (not shown) of the coil 152 are connected to a power supply 144 via cords 145A and 145B.

As shown in FIG. 20A, the magnetic flux ring 151 can be divided into two parts, ie, divided magnetic flux rings 151A and 151B.
The coils 151A and 151B are wound around 151B, respectively. The coil 151A has terminals 153A, 1
53C, and the coil 151B has terminals 153B and 153.
D is provided.

FIG. 20B shows a state in which the split magnetic flux rings 151A and 151B are joined together around the portion to be measured 148 including the covering material to form one magnetic flux ring 151, and the terminals 153C and 153D are joined together. 1 shows a state in which one coil 152 is formed. FIG.
The terminals 153A and 153B of the coil 152 in (b) are connected to a power supply 144 via cords 145A and 145B, respectively.

In the state of FIG. 20B, the terminals 153A, 153A,
When an AC voltage is applied to 53B, an alternating current is generated in the steel frame of the portion 148 to be measured as shown in the figure, and the magnetic field generated by the AC current is detected by the magnetic sensor 150, so that the fracture of the portion 148 to be measured is performed. The situation can be inspected by destruction. That is, in the measurement system of FIG. 9, the breaking state can be inspected without providing a terminal in advance at a position sandwiching the measured portion 148.

However, in the measurement system of FIG. 9, since the magnetic field from the coil 152 may be directly detected by the magnetic sensor 150, it is necessary to take at least one of the following methods.

The magnetic flux ring 151 is connected to the magnetic sensor 150.
Install away from The coil 152 itself is magnetically shielded.

Since the direction of the magnetic field from the coil 152 can be made orthogonal to the direction of the magnetic field from the steel frame,
The magnetic sensor 150 is made sensitive only to the magnetic field emitted from the steel frame.

Next, the flow in the case of inspecting the breaking condition with the measuring system as shown in FIGS. 8 and 9 will be described with reference to the flowcharts of FIGS.

FIG. 5 is a flow chart showing the flow of the inspection of the breaking state when the method 01 is applied to the individual measurement method. The terminals 146A and 146B are supplied from the power source 14 in the measurement system set as shown in FIG. During this period, an AC voltage is applied (step 220). Alternatively, an AC voltage is applied between the terminals of the coil 152 in the measurement system of FIG.

Next, the magnetic field is measured using the magnetic sensor 150 (step 223), and the measuring unit 142 calculates the synchronous averaging of the measured magnetic field values as in step 206 in FIG. 4 (step 224).

Next, it is determined whether or not the average value obtained in step 224 is equal to or less than a threshold value TH1 (step 225). The threshold value TH1 is obtained from a statistical average value of noise power in the building 101, and is normally set to a positive value near zero. That is, when the averaging value is equal to or less than the threshold value TH1, no current is flowing through the steel frame of the measurement site 148, which indicates that there is a high possibility that no magnetic field is generated. If the value exceeds the threshold value TH1, it indicates that it is highly likely that the magnetic field generated by the current flowing through the steel frame at the measurement site 148 is measured.

If the average value is equal to or smaller than the threshold value TH1 (Yes at step 225), it can be considered that no current has flowed through the steel frame of the measured portion 148 despite the application of the AC voltage. It is determined that the steel frame is completely broken (step 228).

When the averaging value is larger than the threshold value TH1 (No at Step 225), it can be considered that a magnetic field is generated by the current flowing through the measured portion 148, and the steel frame at the measured portion is not completely broken. Is determined (step 226). The determination in steps 226 and 228 may be performed by a computer in the measurement unit 142, and the determination result may be displayed on a display, or a warning may be issued by voice or the like.

As described above, when the presence or absence of breakage is determined, the measurement is completed for this measured portion. Then, the same measurement is performed for the other measurement sites.

In the method 01, since only the measured value at the present time is considered as a problem, it is possible to inspect the breaking condition very easily.

FIG. 6 is a flow chart showing the flow of the inspection of the breaking state when the comparison method is applied in the individual measurement method. In the measurement system set as shown in FIG. 8, the terminals 146A and 146B are operated by the power supply 144. During this period, an AC voltage is applied (step 232). Alternatively, an AC voltage is applied between the terminals of the coil 152 in the measurement system of FIG.

Next, a magnetic field is measured using the magnetic sensor 150 (step 234), and a synchronous addition average of the measured magnetic field values is obtained (step 236). In the case of the comparison method, since the comparison is made with past data, reproducibility of the measurement position is particularly required. In the second embodiment, the magnetic sensor 150 is attached to the attachment 141, and the measurement position is changed to the measurement site 148.
Is fixed at a position at a predetermined distance d from the center of the steel frame, accurate comparison becomes possible. Note that the magnetic sensor 150 may be embedded in a covering material surrounding the measured portion 148 in advance at the time of construction.

Next, the average value of the past magnetic field measured at the measurement site 148 is read (step 23).
8). For example, the average value of the magnetic field measured in the building 101 at a normal time when the steel frame is not affected by the aging such as at the time of completion is stored in a database in advance, and the average value of the measured portion is calculated. The computer in the measurement unit 142 reads the data. Further, an equivalent circuit network of the building may be obtained from a design drawing of the building or the like, and a magnetic field around the measured portion 148 under the same condition may be obtained by simulation.

Next, the difference between the past (normal) average value obtained in step 238 and the average value obtained in step 236 is calculated (step 240), and the difference is used as the threshold value TH2. It is determined whether or not it has exceeded (step 242). Note that this threshold is obtained as a reference value when determining whether the steel frame at the measurement site is normal or abnormal.

The difference between the past and present average value is the threshold T
If it is determined that H2 is exceeded (Yes at Step 242), the degree of breakage of the steel frame at the measurement site 148 is finely determined according to the magnitude of the difference between the past and present average values (Step 246).

The difference between the past and present average value is the threshold T
If it is determined that H2 has not been exceeded (No at Step 242), it is determined that the steel frame of the measurement site 148 has not been broken (Step 232).

As described above, when the breaking condition is inspected,
The measurement is completed for this measured part. The same measurement is performed for the other measurement sites. In the second embodiment, the rupture state is inspected based on the value of the magnetic field averaged and averaged. However, the current value and the resistance value of the measured portion are estimated from the averaged value, and these estimated values are compared with the estimated values. The breaking condition may be inspected by applying a method or a comparison method.

In the second embodiment, the state of breakage of each part to be measured is individually inspected. Therefore, as in the first embodiment, a building is regarded as an equivalent circuit network and a small number of measurement points are used. Compared with the method of estimating the resistance value of the member, the amount of calculation is small. Further, in the first embodiment, the resistance value may not be estimated depending on how to take a measurement point or the breaking state of each resistor. However, in the second embodiment, the resistance value of the measured portion is surely determined. Current value, magnetic field value) can be measured. Therefore, if the inspection method according to the first embodiment is performed first, and the inspection method according to the second embodiment is executed only for the measured part for which resistance could not be estimated, efficient inspection can be performed. It becomes possible.

In the flowchart of FIG. 6, the past (normal) and the present two average values are compared. However, some past data and the present data are compared to determine the secular change. You may.

(Third Embodiment) In a third embodiment, a crack determination method will be described.

FIG. 7 is a flowchart showing the flow of the crack determination method according to the third embodiment. In the following description, the measurement system of FIG. 8 or 9 similar to that of the second embodiment is assumed.

As shown in FIG. 7, first, in the measurement system set as shown in FIG.
A and 146B are applied with two or more different frequencies of a constant current AC voltage, respectively (step 252). Alternatively, in the measurement system of FIG.
The above-described constant current AC voltages having different frequencies are respectively applied. As a frequency of the applied AC voltage, a representative frequency is selected from at least one of a high frequency band and a low frequency band.

Next, a magnetic field measurement in each case where an AC voltage of each frequency is applied is performed using the magnetic sensor 150 (step 254), and a synchronous averaging of each measured value is performed (step 256). An average value corresponding to each frequency is obtained.

Next, it is determined whether or not each of the averaging values obtained in step 256 has abnormal frequency-dependent characteristics different from those in the normal state (step 256). For example, it is determined whether or not the difference between the high frequency averaging value and the low frequency averaging value is greater than or equal to a normal threshold value by a predetermined threshold value.

If each of the average values has a frequency dependence characteristic different from that in the normal state (Yes at step 258), that is, the difference between the average value of the high frequency and the average value of the low frequency is smaller than the value in the normal state. If there is a difference equal to or greater than the predetermined threshold value, it is determined that there is a crack near the surface of the steel frame at the measurement site (step 260). Then, from the comparison of the respective average values, the approximate location of the crack (the exact location within the span is not known) is determined (step 262).

If there is no frequency dependence characteristic different from the normal value in each of the average values (No in step 258), that is, the difference between the high frequency average value and the low frequency average value is smaller than that in the normal case. If there is no difference equal to or greater than the predetermined threshold value, it is determined that there is no crack near the surface of the steel frame at the measurement site (step 264).

As described above, when the presence / absence of a crack and the approximate location of the crack are inspected, the measurement is completed for this measured portion. The same measurement is performed for the other measurement sites. By performing the inspection of the breaking state according to the first to third embodiments described above, the breaking state of the member can be accurately determined without removing the heat insulating material or the decorative board covering the conductive structural member such as the steel frame. And all of labor, time and cost can be reduced.

In this inspection method, since the steel frame itself usually has only an extremely low resistance value, a large voltage is not generated even when a large current is applied, and even if a part is damaged, other peripheral parts are electrically disconnected. If the electronic parts are electrically connected, no damage such as electric shock or damage is caused even if the exposed steel frame is touched or the electronic device is grounded to the steel frame.

Further, in the first to third embodiments, the breaking state is determined using the average value obtained by synchronously averaging the measured magnetic fields, but instead of using the average value, the rupture state is determined. The time-series data of the measured magnetic field may be used to determine the break state using a magnetic field obtained by applying a pulse compression technique using an encoded sequence signal represented by an M sequence or a chirp signal. Also in this case, the magnetic field can be detected by removing the influence of the surrounding magnetic noise.

(Fourth Embodiment) In the fourth embodiment, the structure 100 is provided with a function for checking the state of breakage of the building 100 itself, and the structure thereof will be described with reference to FIGS. 10 and 11. FIG. Note that the same components as those of the first embodiment are denoted by the same reference numerals, and detailed description is omitted.

As shown in FIG. 10, in the fourth embodiment, a magnetic sensor module 170 including a plurality of magnetic detection units respectively disposed at a plurality of measurement sites constituting the building 100, And a terminal for applying an AC voltage, which is embedded in each of the two portions sandwiching the portion. Alternatively, instead of the terminals for applying the AC voltage, magnetic flux rings as shown in FIG. An amplifier filter unit 112 having data lines from a plurality of magnetic detection units of the magnetic sensor module 170 connected to the central control room of the building 100, and A
The D converter 113, the computer 114, the function generator 106, the power amplifier 108, and the terminals embedded in the portions sandwiching each measured portion or the terminals of the coils arranged around each measured portion were connected. And a terminal switching device 168.

The terminal switching device 168 is connected to the computer 11
4 to select any two terminals specified by the user or the two terminals of the coil of the specified magnetic flux ring.
8 is a switching device for connecting to two output terminals.
By the switching of the terminal switching device, an AC voltage can be applied to any two terminals of the building 100 or the coil of any magnetic flux ring.

Further, the computer 114 has a storage unit 154 for storing the measured magnetic field data of each part to be measured sent from the amplifier filter unit 112, and controls and manages the entire apparatus to periodically check the breaking state of the building 100. Control unit 156, a clock 157 built in the control unit 156, a hard disk 158 storing a database of past measurement data for comparison inspection, and a display for displaying the inspection result of the breaking state and the like. And an input unit 162 as input means for the operator. The control unit 156 is connected to the function generator 106 and the terminal switching device 168.

In the system shown in FIG. 10, the computer 114 in the central control room controls the function generator 106, the power amplifier 108, and the terminal switching device 168 arranged in the central control room to apply an AC voltage to an arbitrary part to be measured. When the magnetic field is applied, the magnetic field is measured by controlling the magnetic detection unit disposed at the measurement site of the magnetic sensor module 171, and the results are sequentially transmitted. Then, it calculates and collects the measurement results, performs tallying processing, simulation, comparison with existing data stored in the database, display, output, and the like.

Further, in the fourth embodiment, a system configuration as shown in FIG. 11 can be adopted.

In the system shown in FIG. 11, a building LAN (Local Area Network) 174 is provided in the building 100, and a magnetic sensor module 171, an amplifier module 172, and a computer 114 connected to the building LAN 174 are provided.

The computer 114 is connected to the in-building LAN 17.
The network interface 175 includes a network interface 175 for performing communication via the communication module 4 and enables data communication between the magnetic sensor module 171 and the amplifier module and command communication for controlling each module. That is, the computer 114 is connected to the in-building LAN.
Via the 174, it performs totalization processing, display, database management, control and management of the entire system, and the like of the received measurement data.

The magnetic sensor module 174 computes a plurality of magnetic detectors disposed at each of the measured parts and measurement data detected by the magnetic detectors (synchronous addition processing,
And a plurality of calculation units for performing pulse compression processing. Each operation unit includes an amplifier filter for removing and amplifying noise components from the measured data, an ADC (analog-to-digital converter), a DSP (digital signal processor) for performing arithmetic processing on digital data, and an L in the building.
Measurement data that has received a command from the computer 114 via the AN 174 or has been processed
And a power supply unit (not shown). These components are integrated on, for example, a small board and operated as a low-cost computer.

The amplifier module 172 is arranged for each part to be measured and generates a plurality of signal generators for generating an arbitrary waveform and an arbitrary frequency signal based on a command from the computer 114. And a plurality of power amplifiers (amplifying units) that amplify each signal and apply an AC voltage to terminals sandwiching each measured part or coil terminals of a magnetic flux ring surrounding each measured part.

Each signal generation unit has a network interface for receiving a command from the computer 114 via the in-building LAN 174, and a D for generating a digital signal of an arbitrary waveform and an arbitrary frequency based on the received command.
An SP (digital signal processor), a DAC (digital-to-analog converter) for converting a generated digital signal into an analog signal, an amplifier filter for removing noise components from the converted analog signal, and a power supply unit (not shown); It is composed of These components are:
For example, it is integrated on a small board and operated as a low-cost computer.

In the system shown in FIG. 11, the computer 114 in the central control room controls an arbitrary signal generating / amplifying unit of the amplifier module 172 arranged in each measured part to apply an AC voltage to any measured part. Then, the magnetic sensor module 171 controls the magnetic detection / arithmetic unit arranged at the measurement site to measure and calculate the magnetic field, and sequentially transmits the results. Then, the measurement results are collected, and a totaling process, simulation, comparison with existing data stored in the database, display, output, and the like are performed.

In other words, the system shown in FIG. 11 is different from the system shown in FIG.
0 and has the following advantages over the system of FIG.

Since an amplifier filter or the like is provided for each magnetic detection unit, the connection becomes easier and the cost can be reduced as compared with the system of FIG. 10 in which many magnetic detection units are connected to one amplifier filter.

In order to convert the measurement data of each magnetic detection unit into digital data and then transfer it to a remote computer via a LAN in the building, the system shown in FIG. In comparison, it is possible to prevent the amount of attenuation of the analog output of the magnetic detection unit from being varied, thereby enabling highly accurate measurement and facilitating the management of the magnetic sensor module.

Next, the building 10 according to the fourth embodiment is described.
The flow of the self-diagnosis function 0 will be described with reference to the flowchart of FIG.

As shown in FIG.
The control unit 156 checks the date and time indicated by the clock 157 to determine whether the current time corresponds to the periodical inspection, or whether the operator instructs the input unit 162 to inspect the breaking state. (Step 270). If not applicable or there is no input during the periodic inspection (step 27
(0 negative judgment), and waits until the periodic inspection or until there is an input.

At the time of the periodic inspection or when there is an input (Yes at Step 270), 1 is substituted for the number k for specifying each part to be measured (Step 272). That is,
This means that the measurement is started from the measurement site 1.

Next, an AC voltage is applied to the portion k to be measured (step 274). In the case of the system shown in FIG. 10, the output terminal of the power amplifier 108 is connected to the two terminals sandwiching the portion to be measured k by the terminal switching device 168, or the two terminals of the coil of the magnetic flux ring disposed around the portion to be measured k. To the output terminal of the power amplifier 108 to apply an AC voltage to the portion k to be measured. In the case of the system shown in FIG. 11, only the signal generation / computation unit corresponding to the measured part k of the amplifier module 172 is controlled to apply an AC voltage to two terminals sandwiching the measured part k connected to the power amplifier. .

Next, the magnetic field is measured by the magnetic detector 98 arranged near the part to be measured k (step 27).
6) Collect measurement data (step 278). Note that the measurement data is stored in the storage unit 154 of the computer 114.

Next, k is incremented by 1 (step 280), and it is determined whether or not k exceeds the number N of the sites to be measured (step 282). If k does not exceed N (No in Step 282), that is, if the measurement has not been completed for all the measured parts, Step 2
Returning to step 74, the same processing is executed with respect to the measured part having the updated number.

When k exceeds N (Yes at step 282), that is, When the measurement has been completed for all the sites to be measured, the state of breakage of each site to be measured is inspected using the collected measurement data (step 284). In addition, the inspection of the breaking state is performed by using 01 shown in the flowchart of FIG.
Inspection methods based on the method, the comparison method shown in the flowchart of FIG. 6, and the crack determination method shown in the flowchart of FIG. 7 are used.

Next, the presence or absence of an abnormality and the breaking state of each measured part inspected in step 284 are displayed on the display unit 160 (step 286). At the time of this display, a warning may be displayed at an abnormal point. Then, the process returns to step 270 to repeat the same processing.

As described above, in the present embodiment, the self-diagnosis function of the conductive structural member is provided to the building itself, and the state of breakage is periodically diagnosed. The breaking condition can be checked accurately without omission. Also, after an earthquake occurs, the input unit 16
2 can be used to instruct the diagnosis of the rupture situation, so that the damage caused by a sudden earthquake can be immediately diagnosed and dealt with.

In the fourth embodiment, all the sites to be measured are diagnosed in order. However, it is also possible to diagnose only a specific site to be input and specified.
Further, in the case of the system shown in FIG. 11, it is also possible to inspect the breaking state of a plurality of measured parts at once. Further, the inspection method (simulation method) of FIG. 4 according to the first embodiment can be periodically performed, or can be used in combination with the inspection methods of FIGS. 4 and 12.

[0115]

EXAMPLE In this example, a building model as shown in FIG. 16 was prepared, and calculations were performed under each of three conditions (1. no break, 2. partial break of member, 3. break). The difference between the current value and the voltage value in the case is specifically shown. This building model is a 3 × 2 × 2 two-story rectangular structure having a conductive unit having a length of 4 m and a resistivity of 9.71 × 10 ⁻⁶ Ω · cm as one unit. , C and d (ground connection).

First, FIG. 17 shows an equivalent circuit network in the case where there is no break in the conductive structural member in the building model of FIG.

As shown in FIG. 17, each unit span (corresponding to one conductive structure) of the building model of FIG.
The resistors are replaced by resistors R1 to R81 of 0.2 mΩ.
Since FIG. 17 deals with the case where there is no breakage, the resistance R
Each of 1 to R81 has the same resistance value. A constant-current power supply VC76 that generates an AC voltage having a maximum amplitude of 0.1 V is connected between cd. Note that the AC frequency of the power supply VC76 can be changed within a predetermined range.

The alternating current applied between the cd by the power supply VC76 causes an alternating current to flow through the resistors R1 to R81. To measure the value of the alternating current, the resistors R1 and R1 are used.
AC current meter (AMMTR) 80, 7 for R4 and R9 respectively
8, 77 are connected in series. Further, an AC voltmeter (VMTR) 7 is used to measure the voltage applied to the resistor R23.
9 is connected in parallel with the resistor R23.

In the example of the equivalent network shown in FIG. 17, the effective values of the currents measured by the respective AC ammeters 77, 78 and 80 are 50.419 A (ampere), 19.690 A and 1
59.900 A, and the effective value of the voltage measured by the AC voltmeter 79 is 3.269 mV.

Next, FIG. 18 shows an equivalent circuit network when a part of the conductive structural member is broken. In FIG. 14, the resistor R8
It is assumed that a part of the member corresponding to 1 is broken. By the way, when a part of the member breaks, its cross-sectional area decreases, and the resistance value increases. Therefore, in FIG. 18, the resistance value R82 (2 MΩ) increased by the fracture is represented by R
By connecting in series with 81, a partially broken state is equivalently represented.

In the example of the equivalent network shown in FIG. 18, the effective values of the currents measured by the respective AC ammeters 77, 78 and 80 are 17.874A, 24.476A and 188.951, respectively.
A, and the effective value of the voltage measured by the AC voltmeter 79 is 1.693 mV. Thus, it can be seen that even if a part of one conductive structural member is broken, a large change appears in the electrical characteristics measured at a location different from this member.

Next, FIG. 19 shows an equivalent circuit network when the conductive structural member is completely broken. In FIG. 19, the resistor R8
It is assumed that the member corresponding to No. 1 is completely broken. By the way, when the member is completely broken, a capacitor having an electric capacity is generated by one cut surface and the other cut surface. In the equivalent circuit of FIG. 19, a capacitor C16 is connected in series with the resistor R81. This situation is represented.
The capacitance of the capacitor C16 is proportional to the cross-sectional area of the member, and is inversely proportional to the gap at the break. Cross section is 30c
In the case of a conductive member having a gap of 10 μm and a break portion of m ² , when the dielectric constant of air is used, the capacitance C is 266.
0 pF (10 ⁻¹² F) is obtained.

In the example of the equivalent circuit network shown in FIG. 19, the effective values of the currents measured by the respective AC ammeters 77, 78 and 80 are 12.078 A, 25.329 A and 194.125, respectively.
A, and the effective value of the voltage measured by the AC voltmeter 79 is 1.412 mV. As in the case of FIG. 18, it can be seen that the current value or the like measured at another location changes due to the breakage of the conductive structural member.

As described above, due to partial or complete breakage of some conductive structural members, the value of the current flowing through each conductive structural member changes as compared with the normal state. Since the magnetic field around each resistor also changes, it can be seen that the state of breakage of the conductive structural member can be inspected by detecting a change in the magnetic field as compared to a normal state.

[0125]

As described above, according to the first aspect of the present invention, a magnetic field generated by applying an AC voltage to a portion to be measured is measured, and each of the conductive magnetic fields determined from the value of the measured magnetic field is measured. By comparing the resistance value of the conductive structural member with the resistance value of each conductive structural member at normal time, the state of breakage of each conductive structural member was inspected, so each conductive structure member was removed without removing the covering material. The effect is obtained that the breaking condition of the structural member can be accurately inspected.

According to the second aspect of the present invention, the magnetic field generated by applying an AC voltage to the measured portion is measured, and the measured magnetic field is determined based on the current value of the measured portion obtained from the measured value of the magnetic field. Since the breaking condition of the measurement site is inspected, an effect is obtained that the breaking condition of the measurement site can be accurately inspected without removing the covering material.

According to the third aspect of the invention, the magnetic fields generated when at least two different frequencies of the AC voltage are applied to the measurement site are measured, and the respective currents obtained from the measured values of the magnetic fields are measured. Since the breaking condition of the measured portion is inspected based on the comparison of the values, an effect is obtained that the breaking condition of the crack on the surface of the measured portion can be accurately inspected without removing the covering material.

According to the fourth aspect of the invention, the measured magnetic field is added and averaged in synchronization with the frequency of the applied AC voltage, and the value of the current flowing through the portion to be measured is estimated based on the value of the added and averaged magnetic field. As a result, the effect of noise can be reduced, and a more accurate inspection of the breaking state can be performed.

According to the fifth aspect of the present invention, the measured magnetic field value is pulse-compressed using a coded sequence represented by an M-sequence or a chirp signal, and based on the pulse-compressed magnetic field value. Since the current value flowing through the measured part is estimated, the influence of noise can be reduced.
A further effect is obtained that a more accurate inspection of the breaking state can be performed.

According to the invention of claim 6, since the magnetic field measurement is performed while avoiding the frequency of the commercial power supply used in the building and an integer multiple of the frequency, the influence of noise due to the commercial power supply is reduced. And a more accurate inspection of the breaking state can be obtained.

According to the seventh aspect of the present invention, the destruction state of a plurality of measurement sites is periodically inspected by the nondestructive inspection method for structural member breakage according to any one of the first to sixth aspects. Therefore, it is possible to greatly reduce the labor and time required for the measurement, and it is possible to accurately and promptly inspect the breaking state without omission.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a measurement system according to a first embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a distance from a current center and a magnetic flux density when a current of 10 A flows through a steel frame.

FIG. 3 is a graph showing a relationship between an induced voltage generated at a coil terminal having a sectional area of 25π × 10 ⁻⁴ mm ² and a number of turns when a magnetic field having a magnetic flux density of 5 μT changes at 30 Hz.

FIG. 4 is a flowchart showing a flow of measurement by a simulation method according to the first embodiment.

FIG. 5 is a flowchart showing a measurement flow when the 01 method is applied to the individual measurement method according to the second embodiment.

FIG. 6 is a flowchart illustrating a measurement flow when a comparison method is applied to the individual measurement method according to the second embodiment.

FIG. 7 is a flowchart illustrating a flow of measurement by a crack determination method according to a third embodiment.

FIG. 8 is a configuration block diagram of a measurement system (first example) according to a second embodiment of the present invention.

FIG. 9 is a configuration block diagram of a measurement system (second example) according to a second embodiment of the present invention.

FIG. 10 is a configuration block diagram of a measurement system (first example) according to a fourth embodiment of the present invention.

FIG. 11 is a configuration block diagram of a measurement system (second example) according to a fourth embodiment of the present invention.

FIG. 12 is a flowchart illustrating a flow of measurement by a self-diagnosis function according to a fourth embodiment.

FIG. 13 is a diagram showing a simple building model for explaining the principle of the present invention.

14 is a diagram showing an equivalent circuit network of the building model of FIG.

FIG. 15 shows one of the power supply methods according to the first embodiment.
It is a figure showing an example.

FIG. 16 is a diagram showing a model of a specific building according to an example of the present invention.

FIG. 17 is an equivalent circuit network in the case where there is no breakage of the electric structural member in the building model of FIG. 16;

FIG. 18 is an equivalent circuit network in a case where a part of one electric structural member is broken in the building model of FIG.

FIG. 19 is an equivalent circuit network when one electric structural member is completely broken in the building model of FIG. 16;

FIGS. 20A and 20B are diagrams showing a magnetic flux ring for generating an induced current in a measurement site and a coil wound around the magnetic flux ring, where FIG. 20A shows a state where the magnetic flux ring and the coil are divided, and FIG. It is a figure which shows the state which combined the ring and the coil into one, and attached around the to-be-measured part.

[Explanation of symbols]

 97 power supply means 98 magnetism detection unit 99 data processing means 106 function generator 108 power amplifier 114 computer 118 telephone line

 ──────────────────────────────────────────────────の Continuation of the front page (72) Inventor Sadatoshi Ohno 1-5-1, Otsuka, Inzai City, Chiba Prefecture Inside the Technical Research Institute, Takenaka Corporation (72) Inventor Toshio Saito 1-5-1, Otsuka 1, Inzai City, Chiba Prefecture Inside the Takenaka Corporation Technical Research Institute (72) Keita Yamazaki 1-5-1, Otsuka, Inzai City, Chiba Prefecture Inside the Technical Research Center Takenaka Corporation (72) Inventor Tadahiro Kakizawa 1-5, Otsuka, Inzai City, Chiba Prefecture Address 1 Takenaka Corporation Technical Research Institute (72) Inventor Tadao Mikami 1-5-1, Otsuka, Inzai City, Chiba Prefecture Inside Takenaka Corporation Technical Research Center

Claims (7)

[Claims] 1. A voltage application step of applying an AC voltage to an arbitrary portion of a conductive structural member constituting a building sandwiching a measured portion, and a magnetic field measurement by a magnetic detector arranged near the measured portion. A measuring step of performing, and an estimating step of estimating a current value flowing through the measured part based on a value of the magnetic field measured in the measuring step; a value of an applied AC voltage and a current estimated at the measured part A simulation step for determining the resistance value of each conductive structural member in a circuit network equivalent to the building based on the value, and the resistance value of each conductive structural member obtained in the simulation step and each normal conductivity An inspection step of inspecting the breaking state of each conductive structural member by comparing the resistance value of the structural member with a resistance value of the structural member. 2. A voltage application step of applying an AC voltage to a portion of a conductive structural member constituting a building that sandwiches a measurement site, and a magnetic field measurement is performed by a magnetic detection unit disposed near the measurement site. A measuring step, an estimating step of estimating a current value flowing through the measured site based on the value of the magnetic field measured in the measuring step, and a determination of the presence or absence of the current value estimated in the estimating step or the estimated current. An inspection step of inspecting the state of breakage of the conductive structural member of the measured part based on a comparison between the measured value and the current value of the measured part in a normal state. Destructive inspection method. 3. A voltage applying step of applying alternating voltages of at least two different frequencies to a portion of the conductive structural member constituting the building that sandwiches the measured portion, and a magnetic detection disposed near the measured portion. By department
A measurement step of performing a magnetic field measurement when an AC voltage having a different frequency is applied, and the measurement site when an AC voltage having a different frequency is applied based on the value of each magnetic field measured in the measurement step. An estimation step of estimating a flowing current value, and an inspection step of inspecting a rupture situation related to a crack on a surface of the conductive structural member of the measurement site based on a comparison of the respective current values estimated in the estimation step, A nondestructive inspection method for structural member breakage, comprising: 4. The value of the magnetic field measured in the measuring step is:
An averaging step of performing averaging in synchronization with the frequency of the AC voltage applied in the voltage applying step, wherein the estimating step is performed based on the value of the magnetic field averaged in the averaging step. 4. The non-destructive inspection method for structural member breakage according to claim 1, wherein a current value flowing through the measurement site is estimated. 5. The voltage applying step applies an AC voltage having an arbitrary waveform, and compresses a value of the magnetic field measured in the measuring step using a coded sequence represented by an M sequence or a chirp signal. And a compression step of: estimating a current value flowing through the measured portion based on a value of the magnetic field pulse-compressed in the compression step. Any one of item 3
Non-destructive inspection method for structural member breakage described in the paragraph. 6. The magnetic field measurement according to claim 1, wherein the measurement step performs the magnetic field measurement while avoiding a frequency of a commercial power supply used in the building and a frequency that is an integral multiple of the frequency. 2. The nondestructive inspection method for structural member breakage according to claim 1. 7. An AC power supply capable of applying an AC voltage of a constant current having an arbitrary frequency and an arbitrary waveform to a predetermined location of a conductive structural member constituting a building; 7. The non-destructive inspection method for structural member breakage according to any one of claims 1 to 6, wherein the plurality of magnetic detection units are arranged, and the AC power supply and the plurality of magnetic detection units are used. And a control means for inspecting the destruction state of the measured part of (1), and a building with a diagnostic function.