JP4102296B2 - Crack monitoring material and crack monitoring system - Google Patents

Description

  The present invention relates to a crack monitoring material that is formed on the surface of a monitoring object that is predicted to generate cracks, monitors the occurrence of cracks in the monitoring object and the progress of the cracks, and the generation of cracks and the progress of the cracks. The present invention relates to a crack monitoring system to be monitored.

  In steel structures, fatigue cracks occur at sites where tensile loads are applied due to repeated loads, and serious conditions such as loosening or dropping of rivets and bolts at joints occur. If such a serious condition grows to a size that affects the proof stress of the structure, the structure will be destroyed. Construction is being done for. The seriousness of steel structures develops over multiple years under normal conditions, so there is no need to repair or reinforce immediately when deformation occurs. Moreover, since the progress may stop in the middle of the deformation, it is necessary to monitor the progress after the occurrence of the deformation in order to determine the necessity of repair or reinforcement.

  Table 1 is an example in the case where repair or reinforcement is required immediately as a serious problem occurring in a steel structure. For example, as shown in Table 1, when the cracks in the main girder flange, stringer, and cross beam tension side flange reach 20 mm, it is immediately determined that repair or reinforcement is necessary. Here, the group shown in Table 1 means the whole rivet or bolt used for one base material constituting the joint. The serious condition is roughly divided into a decrease in joining force due to loosening and breaking of rivets and bolts, a decrease in breaking strength due to fatigue cracking of members, and a decrease in running stability due to displacement of the entire structure due to ground subsidence. Fatigue cracks occur at sites where a tensile force is applied when a repeated load is applied, so the occurrence location can be assumed to some extent depending on the structure type. In addition, it is known that the influence of the generated crack on the structure differs depending on the part.

  For inspection of steel structures, periodic inspections that are conducted within two years, irregular inspections that are performed when a large load is received during an abnormality such as an earthquake, and abnormalities that are assumed by periodic inspections, etc. There are detailed inspections conducted. The periodic inspection and the irregular inspection mainly consist of visual inspection from the inspection passage by patrol, and in this visual inspection, the breakage portion of the anticorrosion coating film is visually observed in the vicinity of the portion where the occurrence of cracks is assumed. The coating film rupture accompanying the occurrence of cracks in the steel material grows linearly from the portion assumed to be the stress concentration portion, and can be easily distinguished from other coating film rupture causes. Moreover, it is known from past experience that the anticorrosion coating film breaks at the time of fatigue cracking of the steel material. Rupture of rivets and bolts can be easily detected using binoculars if the joint can be observed. Looseness of rivets and bolts can be detected by a hammering test in which the rupture state of the coating film around them is closely observed and a change in the hammering sound is confirmed with a hammer or the like. On the other hand, the detailed inspection may involve the construction of a scaffold for the inspection, although it varies depending on the inspection purpose. Deformation is discovered by visual inspection only at the site close to the inspection passage. In many cases, it is necessary to construct a scaffold and observe it closely, but it requires a lot of cost to construct the scaffold. Become. For this reason, except for highly urgent detailed inspections, inspection is carried out by using the coating scaffolding of the repainting work carried out every 10 to 15 years.

  Conventional crack detection methods include crack detection and length measurement methods using an ultrasonic method and a magnetic particle flaw detection method. Although this method can detect extremely small cracks and evaluate the length with high accuracy, it can measure closely after the cracks are detected by conventional visual inspection. And is not necessary for high-precision measurement beyond visual observation. Further, as a conventional crack detection method, there is a method for predicting a fatigue life by monitoring a cyclic stress applied to a steel structure by an element. In this method, it is possible to monitor a cyclic stress applied to an element installed at an appropriate location of a structure and predict a period using a minor rule based on the number of repetitions until the fracture of the steel material used is empirically known. However, this method does not provide information on the determination of crack initiation time and crack growth, and cannot determine whether the structure needs repair or reinforcement. I can't know. Furthermore, as a conventional crack detection method, there is a method of detecting the occurrence and progress of a crack from a change in characteristics such as electrical resistance of a steel structure. In this method, it is possible to monitor the change in the electrical characteristics of the steel structure itself and determine the occurrence of cracks from the change in the resistance value of the steel material. However, with this method, the resistance of the steel material itself is extremely low, so detection is possible with small test pieces and small structures where the path of the applied current is short, but large structures have large current paths, so cracks The amount of decrease in resistance due to this becomes extremely small, and it becomes difficult to effectively detect a change in resistance.

  In recent years, a method has been proposed in which a conductive thin film is arranged in a structure and the crack is detected by breaking the conductive thin film when a crack occurs in the structure. For example, the conventional crack detection material (Prior Art 1) has a base layer formed by applying a waterproof insulating paint to the wall surface of a tunnel, and a surface of the base layer so as to form a linear pattern electric circuit. And a protective layer formed by applying an insulating paint similar to the base layer to the conductive layer and the base layer to cover them (see Patent Document 1). ). In such a conventional crack detection material, if a crack occurs on the wall surface and an abnormality occurs, the periphery of this abnormal part is peeled off, the conductive layer is disconnected, and the conductive layer is in a non-energized state. An abnormal state of the wall surface can be detected by detecting a non-energized state.

Japanese Unexamined Patent Publication No. 2001-201477 (paragraph numbers 0010 to 0015 and FIG. 2)

  Further, the conventional crack detection material (Prior Art 2) includes a dielectric layer attached to a workpiece or a test piece, a resistance layer that is broken when a crack occurs in the dielectric layer, and the resistance layer. And two curved electrodes that are formed on the surface of the layer and allow current to flow through the resistance layer (see Patent Document 2). In such a conventional crack detection material, the electrode layer is formed in a curved shape so as to have a substantially uniform sensitivity with respect to the crack propagation direction. Therefore, the growth of the crack from the change in the resistance value between the two electrodes. Can be evaluated.

Japanese Patent Laid-Open No. 11-094787 (paragraph numbers 0021 to 0048 and FIG. 1)

  In recent years, two environmental changes have occurred in steel structures: extending the coating cycle (repainting cycle) and the appearance of unpainted structures. Due to the introduction of a highly durable coating system, the repainting cycle has been extended to about 30 years, so the inspection period for proximity inspection using a coating scaffold has become longer. In addition, the use of paint scaffolding can no longer be expected due to the absence of painting due to the use of weather-resistant steel. For this reason, there is a problem that due to such changes in the environment, it will be necessary to construct a scaffold only for inspection in the future, and the inspection cost will increase due to the construction of the scaffold.

  Moreover, in the prior art 1, since it is necessary to paint a base layer, a conductive layer, and a protective layer using a masking tape or the like, the work is difficult and troublesome, and the occurrence of a crack can be detected. There is a problem that the growth of can not be evaluated. Furthermore, in the prior art 2, it is necessary to arrange these electrodes so that a crack is generated at the center of the two curved electrodes, and when the crack occurrence location cannot be accurately predicted, before the crack occurs, There is a problem that electrodes cannot be arranged.

  An object of the present invention is to provide a crack monitoring material and a crack monitoring system capable of reducing inspection costs, improving the reliability of inspection, facilitating on-site construction, and maintaining a detection function for a long time.

The present invention solves the above-mentioned problems by the solving means described below.
In addition, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this embodiment.
According to the first aspect of the present invention, a crack occurrence detecting unit (5) for detecting a crack (C ₁ ) and a crack progress detecting unit (4) for detecting the progress of the crack detected by the crack occurrence detecting unit are provided . A crack monitoring material that is formed on the surface (1b) of a monitoring object (1) that is predicted to be generated, and that monitors the occurrence of cracks in the monitoring object and the progress of the cracks, the crack occurrence detection unit Comprises a crack generation detecting conductive layer (5a) whose electrical resistance changes in accordance with the occurrence of the crack, and a crack generation detecting electrode layer (5b, 5c) for passing a current through the crack generation detecting conductive layer. The crack progress detection unit includes a crack progress detection conductive layer (4a) whose electrical resistance changes in accordance with the progress of the crack, and a crack progress detection electrode layer (4c) for passing a current through the crack progress detection conductive layer. ~ 4f), the crack generation detection conductive layer and the crack The spreading detection conductive layer is formed in a strip shape by applying a conductive paint so that the long side is located on the crack starting point side which is predicted to occur in the monitored object. The layer is a crack monitoring material (3) characterized in that the layer is formed narrower than the crack propagation detection conductive layer .

  According to a second aspect of the present invention, in the crack monitoring material according to the first aspect, the crack progress detection unit detects a position where the crack is generated.

According to a third aspect of the present invention, in the crack monitoring material according to the first or second aspect , the crack propagation detection conductive layer is formed to have a width corresponding to a crack length allowed for the monitored object. It is the crack monitoring material characterized by having.

The invention according to claim 4, in crack monitoring material according to any one of claims 1 to 3, wherein the crack growth detection conductive layer, said plurality by crack propagation detecting electrode layer monitoring region ( A _{1 to} A ₃ ), and one monitoring region is formed by a pair of the crack progress detection electrode layers adjacent to each other in the longitudinal direction of the crack progress detection conductive layer. It is a crack monitoring material.

The invention according to claim 5 is a crack monitoring system for monitoring the generation of cracks (C ₁ ) and the progress of the cracks, and the crack monitoring material according to any one of claims 1 to 4 (3 ) And an energization state measurement unit (S110, S150, S180 to S200, S250, S280 to S300) for measuring energization states of the crack occurrence detection conductive layer (5a) and the crack propagation detection conductive layer (4a) ( 9) and a crack monitoring system comprising an evaluation unit (11) that evaluates cracks occurring in the monitoring object (1) based on the measurement result of the energization state measurement unit (S170, S210, S230, S270). 2).

According to a sixth aspect of the present invention, in the crack monitoring system according to the fifth aspect , the energization state measuring unit includes a plurality of monitoring regions (A _{1 to} A) in which the crack progress detection conductive layer is formed by the crack progress detection electrode layer. ₃ ) When the area is partitioned, the energization state is measured for each monitoring area (S150), and the evaluation unit identifies the monitoring area where the crack has occurred based on the measurement result of the energization state for each monitoring area. (S170) It is a crack monitoring system characterized by carrying out.

A seventh aspect of the present invention is the crack monitoring system according to the fifth or sixth aspect , further comprising a correction unit (12) for correcting (S200, S300) a measurement result of the energization state measurement unit, wherein the evaluation unit includes: The crack monitoring system is characterized in that the crack is evaluated (S210, S230) based on the corrected measurement result.

An eighth aspect of the present invention is the crack monitoring system according to the seventh aspect , wherein in the energization state measuring unit, the crack progress detection conductive layer is partitioned into a plurality of monitoring regions by the crack progress detection electrode layer. In some cases, an energization state is measured for each monitoring region (S150), and the correction unit detects a crack-free monitoring region (A) when a crack occurs in the crack propagation detection conductive layer (4a). based on _2, a ₃ of the energized state) measurements, a crack monitoring system, characterized in that the measurement result of the current state of crack occurrence was monitored area (a ₁₎ is corrected (S200).

According to a ninth aspect of the present invention, in the crack monitoring system according to the seventh or eighth aspect , the energization state measuring unit is configured such that the crack progress detection conductive layer is placed in a plurality of monitoring regions by the crack progress detection electrode layer. When it is partitioned, the energization state is measured for each of the two adjacent monitoring areas (A ₁ , A ₂ ; A ₂ , A ₃ ) (S250), and the correction unit is configured to detect the crack propagation detection electrode layer. When a crack occurs in (4d), based on the measurement result of the energized state of two adjacent monitoring regions (A ₂ , A ₃ ) including the crack growth detection electrode layer (4e) where no crack has occurred. Then, the crack monitoring is characterized in that the measurement result of the energization state of the two adjacent monitoring areas (A ₁ .A ₂ ) including the crack growth detection electrode layer (4d) where the crack has occurred is corrected (S300). System.

  According to the present invention, the inspection cost can be reduced, the reliability of the inspection can be improved, the on-site construction is easy, and the detection function can be maintained for a long time.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view showing a state in which a crack has occurred in a steel structure monitored by a crack monitoring system according to an embodiment of the present invention, and FIG. 1 (A) shows a state in which a crack has occurred in a flange under a main girder. FIG. 1 (B) shows a state where a crack has occurred in the abdomen, and FIG. 1 (C) shows a state where a crack has occurred from the main girder notch.

A steel structure 1 shown in FIG. 1 is a fixed structure made of a steel material. The steel structure 1 is, for example, a bridge that secures a space below a track on which a railway vehicle travels and supports a train load. As shown in FIG. 1, the steel structure 1 is provided with a main girder 1a assembled into an I-shaped girder by joining a steel plate and an angle steel by welding or the like. The main girder 1a is a lower part of the main girder 1a. The lower flange 1b that forms the plate, the upper flange 1c that constitutes the upper plate of the main girder 1a, the belly plate 1d that couples the lower flange 1b and the upper flange 1c, and the buckling due to the shearing force of the main girder 1a are prevented. Intermediate stiffener 1e and a cutout portion 1f formed by cutting out a part of the main beam 1a. For example, in the steel structure 1 shown in FIG. 1 (A), a crack C ₁ is generated from the edge of the lower flange 1b substantially in the middle of the main girder 1a, and the lower flange 1b and the stomach plate 1d Cracks C ₂ and C ₃ are generated from the joint where the joints are joined. In the steel structure 1 shown in FIG. 1 (B), cracks C ₄ and C ₅ are generated in the belly plate 1d from the joint where the belly plate 1d and the intermediate stiffener 1e are joined. In the steel structure 1 shown in FIG. 1 (C), a crack C ₆ is generated from a joint where the lower flange 1b and the belly plate 1d are joined.

FIG. 2 is a configuration diagram of the crack monitoring system according to the embodiment of the present invention.
The crack monitoring system 2 is a system that monitors the occurrence of cracks in the steel structure 1 and the progress of the cracks. As shown in FIG. 2, the crack monitoring system 2 includes a crack monitoring material 3, lead wires 6 and 7, a power supply unit 8, an energization state measurement unit 9, a control unit 10, an evaluation unit 11, and a correction unit. 12, a communication unit 13, and a storage unit 14. The crack monitoring system 2 is installed in each part of the steel structure 1 where the occurrence of cracks C _{1 to} C ₆ shown in FIG. 1 is predicted. Below, as shown to FIG. 1 (A), the case where the crack monitoring material 3 is formed in the edge part (long side part) of the lower flange 1b is mentioned as an example, and is demonstrated.

FIG. 3 is a perspective view showing a part of the crack monitoring material of the crack monitoring system according to the embodiment of the present invention. FIG. 4 is a plan view of a crack monitoring material of the crack monitoring system according to the embodiment of the present invention. FIG. 5 is a cross-sectional view showing a state cut along line VV in FIG.
The crack monitoring material 3 is a member that is formed on the surface of the steel structure 1 where the occurrence of the crack C ₁ is predicted, and monitors the generation of the crack C ₁ of the steel structure 1 and the progress of the crack C ₁ . As shown in FIGS. 3 to 5, the crack monitoring material 3 includes a crack progress detection unit 4 and a crack occurrence detection unit 5. As shown in FIG. 1, the crack monitoring material 3 is formed by applying to the edge of the steel structure 1 where the occurrence of the crack C ₁ is predicted by using a brush, a roller, or a spray.

The crack progress detection unit 4 is a part that detects the progress of the crack C ₁ detected by the crack occurrence detection unit 5, and includes a crack progress detection conductive layer 4a, a rust prevention insulating layer 4b, and a crack progress detection electrode layer 4c. To 4f and an environmental barrier layer 4g. The crack progress detector 4 is formed below the crack occurrence detector 5 so that the progress of the crack C ₁ detected by the crack occurrence detector 5 can be detected. The crack progress detector 4 is made of a coating material that can be expected to have durability over a long period of time, and is formed on the surface of the steel structure 1.

Crack detection conductive layer 4a is a coating film having an electric resistance varying according to the occurrence of the crack C _1. As shown in FIGS. 3 and 4, the crack propagation detection conductive layer 4 a is formed of the rust-proof insulating layer 4 b so that the long side is located on the starting side of the crack C ₁ that is predicted to occur in the steel structure 1. It is formed in a band shape on the surface. The crack propagation detection conductive layer 4a is formed in a width corresponding to the crack length allowed in the steel structure 1, and is formed wider when the crack length allowed in the steel structure 1 is long, When the crack length allowed in the steel structure 1 is short, the width is narrow. Crack detection conductive layer 4a is divided into a plurality of monitoring areas A _1, A _2, A ₃ by crack propagation detecting electrode layer 4C～4f. Crack detection conductive layer 4a, a pair of crack propagation detecting electrode layer 4c adjacent in the length direction of the crack growth detection conductive layer 4a, the monitoring area A ₁ by 4d are formed, a pair of crack growth detection electrodes layer 4d, the monitoring regions a ₂ formed by 4e, a pair of crack propagation detecting electrode layer 4e, the monitoring area a ₃ by the 4f are formed. The crack propagation detection conductive layer 4a is formed, for example, by applying a conductive paint containing a conductive pigment and an organic resin, and the conductive pigment is preferably carbon black, graphite, nickel, copper, silver, or the like. As the resin, epoxy resin, polyurethane resin, acrylic resin, phenol resin, alkyl silicate resin, and the like are preferable.

  If the coating thickness of the conductive layer 4a for crack growth detection is 10 μm or less, there is a possibility that a continuous coating film cannot be obtained by on-site construction, and if it is 100 μm or more, many coating film defects such as dripping occur when applied, If the viscosity is increased to prevent this coating film defect, the workability may be sacrificed. For this reason, the coating thickness of the crack propagation detection conductive layer 4a is preferably 10 to 100 μm, particularly preferably 30 to 60 μm. The physical properties of the coating of the crack propagation detection conductive layer 4a may be broken by other factors such as expansion and contraction due to the temperature difference of the steel structure 1 when the elongation at break by tensile test is 10% or less, and at 30% or more When the crack of the steel structure 1 occurs or when the bolt is loosened, there is a possibility that the crack propagation detection conductive layer 4a is not destroyed at the same time. For this reason, as for the physical property of the coating film of the crack growth detection conductive layer 4a, it is preferable that the elongation at break by a tensile test is 10 to 30%. The conductive layer 4a for detecting crack propagation has a volume resistivity of 1 to 10 Ω · cm, and a combination of a conductive pigment and an organic resin so that the resistance between electrodes after application is 200 to 10,000 Ω, preferably 200 to 2000 Ω. It is formed by adjusting the amount. It is preferable to adjust the paint viscosity of the crack propagation detecting conductive layer 4a to such an extent that it can be applied on site by brush, roller, spray, or the like.

The rust-proof insulating layer 4b is a coating film that electrically insulates the steel structure 1 from the crack propagation detecting conductive layer 4a and prevents corrosion of the steel structure 1. As shown in FIGS. 3 and 5, the rust prevention insulating layer 4 b is widely applied and formed on the surface (steel base) of the steel structure 1 so as to include the detection range of the crack C ₁ . The anticorrosive insulating layer 4b is an undercoat paint applied to an anticorrosion coating system for steel structures such as an epoxy resin containing an antirust pigment or an organic zinc rich paint. The coating thickness of the rust-proof insulating layer 4b is preferably 30 to 100 μm.

The crack growth detection electrode layers 4c to 4f are coating films that allow a current to flow through the crack growth detection conductive layer 4a. As shown in FIGS. 4 and 5, the crack growth detection electrode layers 4 c to 4 f are arranged at four equal intervals on the surface of the crack growth detection conductive layer 4 a in the length direction of the crack growth detection conductive layer 4 a. Has been placed. The crack progress detection electrode layers 4c to 4f are applied in a strip shape with the same length as the width of the crack progress detection conductive layer 4a so as to be parallel to the short side of the crack progress detection conductive layer 4a. As shown in FIGS. 3 and 4, the crack growth detection electrode layers 4 c to 4 f divide the crack growth detection conductive layer 4 a into a plurality of monitoring regions A ₁ to A ₃ . The crack propagation detection electrode layers 4c to 4f are formed by applying the same conductive paint as the crack propagation detection conductive layer 4a, and the coating thickness, the physical properties of the paint, and the paint viscosity are also used for crack propagation detection. It is the same as the conductive layer 4a. The crack propagation detection electrode layers 4c to 4f are preferably formed by adjusting the blending amount of the conductive pigment and the organic resin so that the volume resistivity is 1 to 10 Ω · cm.

  The environmental barrier layer 4g is a coating film that protects the crack propagation detection conductive layer 4a and the crack growth detection electrode layers 4c to 4f and improves the corrosion resistance of the steel structure 1. The environment blocking layer 4g is a coating film that electrically insulates the crack progress detection unit 4 and the crack occurrence detection unit 5 from each other. As shown in FIGS. 3 and 5, the environment blocking layer 4 g is applied and formed on these surfaces so as to cover the crack growth detection conductive layer 4 a and the crack growth detection electrode layers 4 c to 4 f. The environment blocking layer 4g is an intermediate coating applied to an anticorrosion coating system for steel structures such as an epoxy resin coating having excellent environmental blocking properties. The coating thickness of the environmental barrier layer 4g is preferably 60 to 120 μm.

The crack occurrence detection part 5 is a part for detecting a crack C ₁ occurring in the steel structure 1, and as shown in FIGS. 3 to 5, the crack occurrence detection conductive layer 5a, the crack occurrence detection electrode layer 5b, 5c, an environmental barrier layer 5d, and a weather resistant layer 5e. The crack occurrence detection unit 5 is made of the same coating material as that of the crack progress detection unit 4 and is applied to the crack progress detection unit 4 in an overlapping manner.

Crack detection conductive layer 5a is a coating film having an electric resistance varying according to the occurrence of the crack C _1. Crack detection conductive layer 5a, as shown in FIG. 3, so that the long side to the starting point side of the crack C ₁ to occur steel structure 1 is expected to position the strip on the surface of the environmental barrier layer 4g Is formed. The crack generation detecting conductive layer 5a is formed to be narrower than the crack progress detecting conductive layer 4a so as to detect an extremely slight crack length at the time of crack generation. It is applied in a linear shape so as to include the long side. The crack generation detecting conductive layer 5a is formed by applying the same conductive paint as the crack progress detecting conductive layer 4a, and the coating thickness, the physical properties of the paint film, and the paint viscosity are also determined. It is the same as 4a. The coating film width of the crack generation detecting conductive layer 5a is desirably 5 mm or less. The crack generation detecting conductive layer 5a has a volume resistivity lower than that of the crack progress detecting conductive layer 4a of 0.01-1 Ω · cm, and the resistance between the electrodes after coating is 200-10000Ω, preferably 200-2000Ω. Further, it is formed by adjusting the blending amount of the conductive pigment and the organic resin.

  The crack occurrence detection electrode layers 5b and 5c are coatings that allow current to flow through the crack occurrence detection conductive layer 5a. As shown in FIGS. 3 to 5, the crack occurrence detection electrode layers 5b and 5c are arranged at both ends in the longitudinal direction of the crack occurrence detection conductive layer 5a, and are short of the crack occurrence detection conductive layer 5a. It is applied in a strip shape with the same width as the width of the crack generation detecting conductive layer 5a so as to be parallel to the side. The crack occurrence detection electrode layers 5b and 5c are formed by applying the same conductive paint as the crack propagation detection conductive layer 4a, and the film thickness, the physical properties of the paint film, and the paint viscosity are also used for crack propagation detection. It is the same as the conductive layer 4a. The crack generation detection electrode layers 5b and 5c are preferably formed by adjusting the blending amount of the conductive pigment and the organic resin so that the volume resistivity of the crack growth detection electrode layers 4c to 4f is the same.

  The environmental barrier layer 5 d is a coating film that protects the crack occurrence detection conductive layer 5 a and the crack occurrence detection electrode layers 5 b and 5 c and improves the corrosion resistance of the steel structure 1. As shown in FIGS. 3 and 5, the environment blocking layer 5 d is applied to these surfaces so as to cover the crack generation detection conductive layer 5 a and the crack generation detection electrode layers 5 b and 5 c. The environmental barrier layer 5d is an intermediate coating similar to the environmental barrier layer 4g, and the coating thickness of the environmental barrier layer 5d is preferably the same as that of the environmental barrier layer 4g.

  The weather resistant layer 5e is a coating film that protects the environmental barrier layer 5d from the action of natural factors. The weather resistant layer 5e is formed by applying a weather resistant paint to the surface so as to cover the environmental barrier layer 5d. The weather resistant layer 5e is a top coating applied to an anticorrosion coating system for a steel structure such as a polyurethane resin or a fluorine resin excellent in ultraviolet resistance and chemical resistance.

  The lead wire 6 is an electric wire that allows current to flow through the conductive layer 4a for detecting crack propagation. As shown in FIG. 2, one end of each lead wire 6 is attached to and connected to the crack growth detection electrode layers 4 c to 4 f, and the other end is connected to the energization state measuring unit 9. . The lead wire 7 is an electric wire that allows a current to flow through the crack occurrence detection conductive layer 5a. One end of the lead wire 7 is attached and connected to the crack generation detecting electrode layers 5 b and 5 c, and the other end is connected to the energization state measuring unit 9.

  The power supply unit 8 shown in FIG. 2 is a DC power supply or an AC power supply that supplies power to the crack growth detection electrode layers 4c to 4 and the crack generation detection electrode layers 5b and 5c. Based on the command from the control unit 10, the power supply unit 8 is connected between the crack propagation detection electrode layers 4c and 4d, between the crack propagation detection electrode layers 4d and 4e, between the crack propagation detection electrode layers 4e and 4f, and cracks. Electric power is supplied between the generation detection electrode layers 5b and 5c.

The energization state measuring unit 9 is a resistance measuring instrument that measures the energization state of the crack propagation detection conductive layer 4a and the crack occurrence detection conductive layer 5a. The energization state measuring unit 9 measures the energization state for each of the monitoring areas A ₁ to A ₃ based on a command from the control unit 10, and two adjacent monitoring areas A ₁ , A ₂ ; A ₂ , A _3. Measure the energization state every time. The energization state measurement unit 9 is connected to the power supply unit 8 and supplies the power from the power supply unit 8 to the crack growth detection electrode layers 4c to 4f and the crack generation detection electrode layers 5b and 5c.

FIG. 6 is a plan view for explaining the measurement operation of the energization state measuring unit of the crack monitoring system according to the embodiment of the present invention, and FIG. 6 (A) is a state in which a crack is generated in the crack propagation detection conductive layer. FIG. 6B shows a state in which a crack has occurred in the crack growth detection electrode layer.
As shown in FIG. 6A, when the crack C ₁ occurs in the monitoring region A ₁ , the energization state measurement unit 9 detects the crack progress between the crack growth detection electrode layers 4c and 4d (monitoring region A ₁ ). with measuring the electrical resistance of the use conductive layer 4a, the electrical crack growth detecting electrode layer 4d, between 4e (monitoring region a ₂₎ of the electrical resistance or crack growth detecting electrode layer 4e, among 4f (surveillance area a ₃₎ Measure resistance. On the other hand, as shown in FIG. 6 (B), when the crack C ₁ is generated in the crack progress detection electrode layer 4d, the energization state measurement unit 9 is connected between the crack progress detection electrode layers 4c and 4e (monitoring region A _1). , A ₂ ), the electrical resistance of the crack growth detection conductive layer 4a and the electrical resistance between the crack growth detection electrode layers 4d, 4f (monitoring areas A ₂ , A ₃ ) are measured.

The control unit 10 shown in FIG. 2 is a central processing unit (CPU) that controls various operations of the crack monitoring system 2. The control unit 10 instructs the power supply unit 8 to supply power, instructs the energization state measurement unit 9 to measure the energization state, or transmits the measurement result of the energization state measurement unit 9 to the correction unit 12 to correct this. the section 12 or to correct the measurement result, transmission by sending a correction result of the correction unit 12 to the evaluation unit 11 to the evaluation unit 11 or to evaluate the crack C _1, the evaluation result of the evaluation unit 11 from the communication unit 13 I will let you. The control unit 10 is connected to a power supply unit 8, an energization state measurement unit 9, an evaluation unit 11, a correction unit 12, and a communication unit 13.

The evaluation unit 11 is a part that evaluates the crack C ₁ generated in the steel structure 1 based on the measurement result of the energization state measurement unit 9. The evaluation unit 11 specifies the monitoring region A ₁ where the crack C ₁ has occurred or evaluates the scale of the crack C ₁ based on the measurement result of the energization state for each of the monitoring regions A _{1 to} A ₃ . When the correction unit 12 corrects the measurement result of the energization state measurement unit 9, the evaluation unit 11 evaluates the crack C ₁ based on the corrected measurement result.

The correction unit 12 is a part that corrects the measurement result of the energization state measurement unit 9. The correction unit 12 compensates the measurement result of the energization state measurement unit 9 when it is affected by a change due to the outside air temperature or a characteristic change due to aging. Correcting unit 12, as shown in FIG. 6 (A), when the cracks C ₁ occurs in crack propagation detection conductive layer 4a, the energization state of the surveillance area A _2, A ₃ which is not cracking C ₁ Based on the measurement result, the measurement result of the energization state of the monitoring area A ₁ where the crack C ₁ has occurred is corrected. Further, as shown in FIG. 6 (B), when the crack C ₁ occurs in the crack growth detection electrode layer 4d, the correction unit 12 applies the crack growth detection electrode layer 4e in which no crack C ₁ is generated. Based on the measurement result of the energization state of the two adjacent monitoring areas A ₂ and A _{3 including} , the energization of the two adjacent monitoring areas A ₁ and A ₂ including the crack growth detection electrode layer 4d in which the crack C ₁ has occurred. Correct the measurement result of the state.

  The communication unit 13 illustrated in FIG. 2 is a part that transmits the evaluation result of the evaluation unit 11. The communication unit 13 transmits the evaluation information output from the control unit 10 to a transceiver in the central monitoring room (not shown) by wire or wirelessly, or receives an evaluation information transmission command from the transceiver in the central monitoring room. Such as a transceiver.

  The accommodating portion 14 is a portion that accommodates the power source portion 8, the energized state measuring portion 9, the control portion 10, the evaluating portion 11, and the correcting portion 12. Lead wires 6 and 7 are drawn into the accommodating portion 14 and are connected to connection terminals (not shown). As shown in FIG. 2, the accommodating part 14 accommodates the power supply part 8 and the energization state measuring part 9 in a united state, and is attached and fixed to the surface of the steel structure 1 as shown in FIG. ing.

Next, a method for manufacturing a crack monitoring material in the crack monitoring system according to the embodiment of the present invention will be described.
As shown in FIG. 1, cracks C _{1 to} C ₆ may occur in the steel structure 1 starting from a limited range such as an edge portion of a constituent member. For example, as shown in FIG. 1 (A), when the occurrence of a crack C ₁ is predicted starting from the edge of the lower flange 1b, the steel structure 1 is repainted as shown in FIG. Along with the edge portion, a rust preventive insulating paint is applied to the surface of the steel structure 1 to form a rust preventive insulating layer 4b. Next, a conductive paint is applied in a strip shape on the surface of the anticorrosive insulating layer 4b to form a crack propagation detecting conductive layer 4a. After that, conductive paint is applied to the surface of the crack growth detection conductive layer 4a in four lines at equal intervals to form crack growth detection electrode layers 4c to 4f, and the crack growth detection electrode layers 4c to 4f are formed. Each lead wire 6 is connected. Next, an environmental barrier layer 4g is formed by coating the surface of the crack growth detection conductive layer 4a and the crack growth detection electrode layers 4c to 4f in a strip shape with a coating having an environmental barrier property, on the surface of the steel structure 1. A crack growth detection unit 4 is formed.

  Next, a conductive paint 5a is formed on the surface of the environmental barrier layer 4g along the edge of the lower flange 1b so as to have a width narrower than that of the environmental barrier layer 4g. After that, conductive paint is applied linearly to both ends of the surface of the crack occurrence detection conductive layer 5a to form crack occurrence detection electrode layers 5b and 5c, and the crack occurrence detection electrode layers 5b and 5c are formed. Each lead wire 7 is connected. Next, an environmental barrier layer 5d is formed by coating the surface of the crack generation detecting conductive layer 5a and the crack generation detecting electrode layers 5b and 5c in a strip shape with an environmental barrier coating. After that, a weather-resistant paint is applied in a band shape on the surface of the environmental barrier layer 5d to form the weather-resistant layer 5e, and the crack occurrence detecting part 5 is formed on the surface of the crack progress detecting part 4, and the surface of the steel structure 1 is formed. A crack monitoring material 3 is formed. Finally, the accommodating portion 14 is fixed to the surface of the steel structure 1, and the lead wires 6 and 7 are connected to the connection terminals of the accommodating portion 14.

Next, the operation of the crack monitoring system according to the embodiment of the present invention will be described.
FIG. 7 is a flowchart for explaining the operation of the crack monitoring system according to the embodiment of the present invention.
In step (hereinafter referred to as S) 100, the power is turned on. When the control unit 10 shown in FIG. 2 instructs the power supply unit 8 to supply power, the power supply unit 8 supplies power to the crack growth detection electrode layers 4c to 4f and the crack generation detection electrode layers 5b and 5c shown in FIG. Then, a current flows through the crack propagation detecting conductive layer 4a and the crack occurrence detecting conductive layer 5a.

  In S110, the energization state of the crack occurrence detection conductive layer 5a is measured. When the control unit 10 shown in FIG. 2 instructs the energization state measurement unit 9 to start the measurement of the energization state, the energization state measurement unit 9 measures and measures a change in the energization state of the crack occurrence detection conductive layer 5a shown in FIG. The result is transmitted to the control unit 10.

In S120, it is evaluated whether or not the energization state has changed. When the control unit 10 transmits the measurement result of the energization state measurement unit 9 to the evaluation unit 11, the evaluation unit 11 evaluates the change in the electrical resistance of the crack occurrence detection conductive layer 5a. As shown in FIG. 1A, when a crack C ₁ occurs starting from the edge of the lower flange 1b, the edge of the crack monitoring material 3 on the edge side is partially shown in FIGS. crack C ₁ occurs crack monitoring member 3 to break. When the crack length is very small, the amount of change in the electrical resistance of the crack growth detection conductive layer 4a is small, but the width of the crack generation detection conductive layer 5a is larger than the width of the crack growth detection conductive layer 4a. Is formed narrowly, the amount of change in the electrical resistance of the crack occurrence detecting conductive layer 5a is large. When the energization state changes, the process proceeds to S130, and when the energization state does not change, the determination is repeated until the energization state changes.

In S130, cracking C ₁ is evaluated. When the electrical resistance of crack detection conductive layer 5a has changed, the evaluation unit 11 and the crack C ₁ has occurred is evaluated steel structure 1.

In S140, the evaluation result is transmitted. When the evaluation unit 11 transmits the occurrence of the crack C ₁ as evaluation information to the control unit 10, the control unit 10 transmits this evaluation information to the communication unit 13, and the communication unit 13 transmits this evaluation information to a central monitoring room (not shown). .

In S150, the energized state is measured for each monitoring area A ₁ to A _3. When the control unit 10 instructs the measurement start of the energization state to the energized state measuring unit 9, the change in energization state of crack growth detection conductive layer 4a was measured energized state measurement section 9 for each monitoring area A ₁ to A ₃ The measurement result is transmitted to the control unit 10.

In S160, it is evaluated whether or not the energization state has changed. When the control unit 10 transmits the measurement result of the energization state measurement unit 9 to the evaluation unit 11, the evaluation unit 11 evaluates the change in electrical resistance for each of the monitoring regions A _{1 to} A ₃ . When the energization state has changed, the process proceeds to S170, and when the energization state has not changed, the process proceeds to S250.

In S170, the crack occurrence region is evaluated. As shown in FIG. 6A, when a crack C ₁ is generated in the monitoring region A ₁ of the crack growth detection conductive layer 4a and this crack C ₁ further grows and progresses, the inside of the monitoring regions A ₂ and A ₃ The amount of change in electrical resistance in the monitoring area A ₁ is larger than the amount of change in electrical resistance. Thus, by measuring the electrical resistance conducting state measuring section 9 of the crack growth detection conductive layer 4a in the surveillance area A ₁ to A ₃ are each a change in electrical resistance in each monitoring area A ₁ to A ₃ Evaluation part 11 evaluates. As a result, the evaluation unit 11 evaluates that the crack C ₁ has occurred in the monitoring region A ₁ where the change in electrical resistance is the largest, and specifies the generation position of the crack C ₁ .

In S180, the resistance value of the monitoring area A ₂ or monitoring area A ₃ no cracking C ₁ is measured. When the crack growth detection conductive layer 4a and the crack growth detection electrode layers 4c to 4f are affected by changes in the outside air temperature or changes in characteristics over time, it is necessary to compensate the measurement results of the energization state measurement unit 9. is there. Therefore, as shown in FIG. 6 (A), in the surveillance area A ₁ to the crack growth detection conductive layer 4a when the cracks C ₁ occurs, surveillance area A ₂ or surveillance area A ₃ in the electrical resistance of The energization state measurement unit 9 measures the measurement value and transmits the measurement result to the control unit 10, and the control unit 10 transmits the measurement result to the correction unit 12.

In S190, the resistance value of the monitoring area A ₁ generated cracks C ₁ is measured. The energization state measurement unit 9 measures the resistance value in the monitoring area A ₁ and transmits the measurement result to the control unit 10, and the control unit 10 transmits the measurement result to the correction unit 12.

In S200, the resistance value of the monitoring area A ₁ generated cracks C ₁ is corrected. The correction unit 12 calculates the amount of change from the initial value of the measured value of the electrical resistance in the monitoring area A ₂ or the monitoring area A ₃ (influence value due to changes in outside air temperature or aging). As a result, the correction unit 12 subtracts the amount of change from the measured value of the electrical resistance in the monitoring area A ₁ to compensate for changes in temperature and material. When the correction unit 12 transmits the corrected measurement result to the control unit 10, the control unit 10 transmits the corrected measurement result to the evaluation unit 11.

In S210, the crack length is evaluated. The evaluation unit 11 evaluates the actual length of the crack C ₁ that is not affected by changes in the outside air temperature or aging, based on the amount of change in the resistance value after correction corrected by the correction unit 12.

In S220, the evaluation result is transmitted. When the evaluation unit 11 transmits the occurrence and length of the crack C _{1 to} the control unit 10 as evaluation information, the control unit 10 transmits the evaluation information to the communication unit 13, and this evaluation information is transmitted to the central monitoring room (not shown). Send.

In S230, whether the crack C ₁ has reached evaluates to acceptable crack length. For example, as shown in Table 1, when a crack C ₁ occurs in the lower flange 1b, the steel structure 1 immediately needs to be reinforced when the crack C ₁ reaches an allowable crack length of 20 mm. Become. For this reason, the evaluation unit 11 evaluates whether or not the crack C ₁ has reached the allowable crack length based on the measurement result of the energization state measurement unit 9. Allowable crack proceeds to S240 when the cracks C ₁ reaches the length, repeat the evaluation of crack length returns to S180 when the crack C ₁ to acceptable crack length is not reached.

  In S240, the evaluation result is transmitted. When the evaluation unit 11 transmits the evaluation result that the steel structure 1 needs to be immediately reinforced as the evaluation information to the control unit 10, the control unit 10 transmits the evaluation information to the communication unit 13, and the central monitoring room (not shown). The communication unit 13 transmits this evaluation information.

In S250, the energization state of the crack growth detecting conductive layer 4a is measured for each of the adjacent monitoring areas A ₁ , A ₂ ; A ₂ , A ₃ . As shown in FIG. 6B, when a crack C ₁ occurs in the crack growth detection electrode layer 4d, the conduction state measurement of the crack growth detection conductive layer 4a is performed for each of the monitoring regions A ₁ , A ₂ , A _3. Even if the part 9 measures, there is a possibility that the resistance value does not change. For this reason, when the control unit 10 instructs the energization state measurement unit 9 to start the energization state measurement, the change in the energization state of the adjacent monitoring areas A ₁ and A ₂ and the adjacent monitoring areas A ₂ and A ₃ is measured. The unit 9 measures and transmits the measurement result to the control unit 10.

In S260, it is evaluated whether or not the energization state has changed. When the energized state has not changed, it is considered that the crack C ₁ has not occurred in the steel structure 1, so the process returns to S110 and the energized state of the crack generation detecting conductive layer 5a is repeatedly measured, and the energized state has changed. The process proceeds to S270.

In S270, the crack occurrence region is evaluated. As shown in FIG. 6 (B), when the crack propagation detecting electrode layers 4d and cracks C ₁ occurs the crack C ₁ is further growth progresses, crack growth detecting electrode layer 4d, the electrical resistance between the 4f The amount of decrease in electrical resistance between the crack growth detection electrode layers 4c and 4e is larger than the amount of decrease in. As a result, the evaluation unit 11 evaluates that the crack C ₁ has occurred in the crack growth detection electrode layer 4d in the monitoring regions A ₁ and A ₂ where the change in electrical resistance is the largest, and the occurrence position of the crack C ₁ is specified. Is done.

In S280, the resistance values of the monitoring areas A ₂ and A ₃ including the crack growth detecting conductive layer 4d in which no crack C ₁ is generated are measured. When the crack growth detection conductive layer 4a and the crack growth detection electrode layers 4c to 4f are affected by changes in the outside air temperature or changes in characteristics over time, it is necessary to compensate the measurement results of the energization state measurement unit 9. is there. For this reason, as shown in FIG. 6B, when a crack C ₁ occurs in the crack growth detection electrode layer 4d, between the crack growth detection electrode layers 4d and 4f (in the monitoring regions A ₂ and A ₃ ). Is measured by the energization state measurement unit 9 and the measurement result is transmitted to the control unit 10, and the control unit 10 transmits the measurement result to the correction unit 12.

In S290, the resistance values of the monitoring areas A ₁ and A ₂ including the crack growth detecting conductive layer 4c in which the crack C ₁ has occurred are measured. The resistance state between the crack growth detection electrode layers 4c and 4e (in the monitoring areas A ₁ and A ₂ ) is measured by the energization state measurement unit 9 and the measurement result is transmitted to the control unit 10, and the control unit 10 performs this measurement. The result is transmitted to the correction unit 12.

In S 300 , the resistance values of the monitoring regions A ₁ and A ₂ including the crack growth detection conductive layer 4 c in which the crack C ₁ has occurred are corrected. The correction unit 12 calculates the amount of change from the initial value of the measured value of the electrical resistance between the crack growth detection electrode layers 4d and 4f (within the monitoring areas A ₂ and A ₃ ) To do. As a result, the correction unit 12 subtracts this amount of change from the measured value of the electrical resistance between the crack growth detection electrode layers 4c and 4e (within the monitoring areas A ₁ and A ₂ ) to compensate for changes in temperature and material. The After S300, the process proceeds to S210 and the same processing is performed.

The crack monitoring system and the crack monitoring material according to the embodiment of the present invention have the following effects.
(1) In this embodiment, the crack occurrence detection unit 5 detects the crack C ₁ generated in the steel structure 1, and the crack progress detection unit 4 detects the progress of the crack C ₁ detected by the crack occurrence detection unit 5. To do. As a result, since it is possible to detect the occurrence of a serious deformation that affects the soundness of the steel structure 1 such as a fatigue crack of the steel structure 1, it is also possible to detect the progress of this deformation. Uncertainty due to visual inspection can be eliminated.

(2) In this embodiment, the crack progress detection unit 4 detects the position where the crack C ₁ occurs. Therefore, it is possible to identify the occurrence position of serious Deformation affecting the health of the steel structures 1 can intensively monitor the occurrence position of the crack C _1.

(3) In this embodiment, the crack progress detection unit 4 and the crack occurrence detection unit 5 are formed by applying paint. For this reason, for example, the crack progress detection part 4 and the crack generation | occurrence | production detection part 5 can be formed by apply | coating a coating material according to the repainting construction of the steel structure 1. FIG. As a result, it can be easily constructed outdoors or on site, and it is not necessary to build a scaffold only for inspection, thereby reducing costs.

(4) In this embodiment, the crack propagation detection conductive layer 4a whose electric resistance changes according to the progress of the crack C _1, crack propagation detecting electrode layer current flows in the crack growth detection conductive layer 4a 4C- 4 f is provided in the crack growth detection unit 4. Further, in this embodiment, the cracking detection conductive layer 5a having an electric resistance varying according to the occurrence of the crack C _1, crack detection electrode layer 5b supplying a current to the crack detection conductive layer 5a, 5c Are provided in the crack occurrence detection unit 5. For this reason, the deformation of the steel structure 1 such as the occurrence and development of the crack C ₁ can be confirmed as a change in electrical resistance from a remote place such as an inspection passage.

(5) In this embodiment, as the long side to the origin side of the crack C ₁ to occur steel structure 1 is predicted is positioned, crack detection conductive layer 5a is formed in a strip shape. As a result, even if the crack length is very small at the time of crack occurrence, the change in electrical resistance becomes large, and the occurrence of crack C ₁ can be easily detected.

(6) In this embodiment, the crack occurrence detection conductive layer 5a is formed to be narrower than the crack propagation detection conductive layer 4a. For this reason, the change in electrical resistance when the crack C ₁ occurs is larger in the crack generation detecting conductive layer 5a than in the crack progress detecting conductive layer 4a, and the crack generation detecting conductive layer 5a causes a slight crack. The occurrence of C ₁ can also be detected.

(7) In this embodiment, the crack propagation detection conductive layer 4 a is formed to have a width corresponding to the crack length allowed in the steel structure 1. For this reason, the growth of the crack C ₁ can be monitored and evaluated until the crack length allowed for the steel structure 1 is reached.

(8) In this embodiment, the crack propagation detection conductive layer 4a is the crack propagation detecting electrode layer 4c~4f is divided into a plurality of monitoring areas A ₁ to A _3, the crack growth detection conductive layer 4a one monitoring area a ₁ to a ₃ is formed by the length direction of the adjacent pair of crack growth detecting electrode layer 4C～4f. As a result, it is possible to easily detect in which monitoring area A _{1 to} A ₃ the crack C ₁ has occurred.

(9) In this embodiment, since the evaluation unit 11 evaluates the crack C ₁ generated in the steel structure 1 based on the measurement result of the energization state measurement unit 9, the steel structure 1 is changed based on the change in the energization state. The generated crack C ₁ and the progress of the crack C ₁ can be easily detected.

(10) In this embodiment, since the evaluation unit 11 specifies the monitoring region A ₁ in which the crack C ₁ has occurred based on the measurement result of the energization state measuring unit 9 for each of the monitoring regions A _{1 to} A ₃ , the crack C ₁ Can be detected.

(11) In this embodiment, the measurement result of the energization state measurement unit 9 corrects the correction unit 12, since the evaluation unit 11 crack C ₁ based on the measurement result after the correction are evaluated, the outside air temperature change or aging It is possible to compensate for influences such as a change in characteristics due to.

(12) In this embodiment, when the crack C ₁ is generated in the crack growth detection conductive layer 4a, based on the measurement result of the energization state of the monitoring region A ₂ or the monitoring region A ₃ where the crack C ₁ is not generated. Thus, the correction unit 12 corrects the measurement result of the energization state of the monitoring region A ₁ where the crack C ₁ occurs. As a result, the measurement value in the monitoring area A ₁ can be corrected in consideration of the outside air temperature and the change in material characteristics included in the electrical characteristics in the monitoring area A ₁ where the crack C ₁ occurs.

(13) In this embodiment, when the cracks C ₁ occurs in crack propagation detecting electrode layer 4d, the two adjacent containing no cracking C ₁ Crack detection electrode layer 4e surveillance area A ₂ Based on the measurement result of the energization state of A ₃ , A _3, the correction unit 12 determines the measurement result of the energization state of the two adjacent monitoring regions A ₁ and A ₂ including the crack growth detection electrode layer 4 d where the crack C ₁ has occurred. to correct. As a result, the change in the outside air temperature and the material characteristics included in the electrical characteristics in the adjacent monitoring areas A ₁ and A ₂ including the crack growth detection electrode layer 4d where the crack C ₁ has occurred are evaluated, and the monitoring area A The measured values in ₁ and A ₂ can be corrected.

Next, examples of the present invention will be described.
(Resistance measurement experiment)
FIG. 8 is a configuration diagram of a resistance measurement experiment of a crack detection coating film according to an embodiment of the present invention, FIG. 8 (A) is a plan view, and FIG. 8 (B) is a front view.
The crack detection coating film 15 shown in FIG. 8 is a coating film that is applied to a detection target that is predicted to generate cracks and detects a crack in the detection target. The crack-detecting coating film 15 is formed by applying a crack-detecting coating material in a strip shape, and its electric resistance changes according to the occurrence of a crack. The crack detection coating film 15 is formed by applying a crack detection paint having a resin / pigment ratio of 500% containing carbon black as a conductive pigment and liquid epoxy as an organic material. The electrodes 16a and 16b are portions that allow current to flow through the crack detection coating film 15, and are formed on the surface of the crack detection coating film 15 with a distance L ₁ = 700 mm apart. The crack detection coating film 15 shown in FIG. 8 is formed with a length L = 720 mm and a thickness t = 0.06 mm, and the crack detection coating film 15 is changed to a width W = 1 to 300 mm. A crack C was introduced from one of the long sides, and the electrical resistance between the electrodes 16a and 16b was measured.

FIG. 9 is a graph showing the relationship between the crack length of the crack detection coating film and the amount of increase in the resistance value according to the embodiment of the present invention. FIG. 10 is a graph showing the relationship between the crack length and the increase in resistance value when the crack detection coating film according to the example of the present invention is applied with a width = 50 mm.
The horizontal axis shown in FIGS. 9 and 10 is the length (mm) of the crack C, and the vertical axis is the resistance value increase amount (Ω) between the electrodes. As shown in FIGS. 9 and 10, as the length of the crack C increases, the amount of increase in the resistance value between the electrodes 16a and 16b increases, and as shown in FIG. 9, the width W of the crack detection coating film 15 decreases. It is considered that the crack C having a very small length can be detected. For example, as shown in FIG. 9, when the crack detection coating film 15 is applied with a width W = 5 mm or less, a crack C of 1 mm or less can be detected, and the crack detection coating film 15 has a width W = When applied at about 1 mm, a crack C having a length of about 0.5 mm can be detected. Further, when the crack detection coating film 15 is applied with a width W of about 10 mm, a crack length close to 10 mm can be detected with an accuracy of about 5 mm in length.

Example 1
FIG. 11 is a graph showing the relationship between the resin / pigment ratio and the volume resistivity of the crack detection coating material according to Example 1 of the present invention.
The horizontal axis shown in FIG. 11 is the resin / pigment ratio (wt%), and the vertical axis is the volume resistivity (specific resistivity) (Ω · cm). Here, the resin / pigment ratio indicates the ratio of the mass of the resin to the mass of the pigment, and the smaller the value, the smaller the amount of resin. Example 1 includes carbon black (manufactured by Denki Black Co., Ltd., trade name: Denka Black) as a conductive pigment, and a liquid epoxy resin (trade name: Epicron, produced by Dainippon Ink & Chemicals, Inc.) as an organic material. It is a crack detection coating material containing.

  Table 2 shows the measurement results of the volume resistivity of carbon black / liquid epoxy resin. In Example 1, as shown in FIG. 11 and Table 2, when the resin content decreases, the volume resistivity decreases and the conductivity is improved. When the crack detection coating material of Example 1 is used as the crack propagation detection conductive layer 4a shown in FIGS. 3 to 5, the volume resistivity is about 1 to 10 Ω · cm with respect to the mass of the conductive pigment. It is desirable to adjust the mass of the organic resin to about 300 to 700 wt%.

(Example 2)
FIG. 12 is a graph showing the relationship between the resin / pigment ratio and the volume resistivity of the crack detection coating material according to Example 2 of the present invention.
The horizontal axis shown in FIG. 12 is the resin / pigment ratio (wt%), and the vertical axis is the volume resistivity (mΩ · cm). Example 2 is for crack detection, which contains nickel powder (reagent manufactured by Kanto Chemical Co., Inc.) as a conductive pigment, and liquid epoxy resin (trade name: Epicron, manufactured by Dainippon Ink & Chemicals, Inc.) as an organic material. It is a paint.

  Table 3 shows the measurement results of the volume resistivity of nickel powder / liquid epoxy resin. In Example 2, as shown in FIG. 12 and Table 3, when the resin content decreases, the volume resistivity decreases and the conductivity improves as in Example 1. When the crack detection coating material of Example 2 is used as the crack growth detection electrode layers 4c to 4f, the crack generation detection conductive layer 5a, and the crack generation detection electrode layers 5b and 5c shown in FIGS. It is desirable to adjust the mass of the organic resin to about 20 to 80 wt% with respect to the mass of the conductive pigment so that the volume resistivity is about 0.01 to 0.04 Ω · cm.

The present invention is not limited to the embodiment described above, and various modifications or changes can be made as described below, and these are also within the scope of the present invention.
(1) In this embodiment, the steel structure 1 has been described as an example of the monitoring object, but the present invention can also be applied to other structures such as a concrete structure. Further, in this embodiment, the case where the crack C ₁ occurs in the steel structure 1 due to fatigue cracks has been described as an example. However, this case also occurs when cracks occur in the coating film due to loosening of rivets, bolts, and the like. The invention can be applied. Furthermore, in this embodiment, the case where the crack occurrence detection unit 5 is formed on the crack progress detection unit 4 has been described as an example, but the crack progress detection unit 4 can also be formed on the crack occurrence detection unit 5. .

(2) In this embodiment, a case defining the crack growth detection conductive layer 4a into three monitoring regions A ₁ to A ₃ by four crack propagation detecting electrode layer 4c~4f been described as an example However, the present invention is not limited to this, and can be divided into four or more monitoring areas. Also, in this embodiment, the case where the crack detection coating material is manufactured using a liquid epoxy resin whose resin itself is liquid has been described as an example. However, the solid epoxy which has a higher molecular weight than that of the liquid epoxy resin and is solid at room temperature. It is also possible to produce a crack detection coating material with a resin. Furthermore, in this embodiment, the case where the crack detection coating material is manufactured using nickel powder has been described as an example, but the present invention is not limited to this. For example, even if other metal pigments other than nickel powder whose surface is covered with an oxide can be formed into a conductive coating film by being pulverized in a resin, cracks are caused by such other metal pigments. A detection paint can also be produced.

It is a perspective view which shows the state which the crack generate | occur | produced in the steel structure monitored by the crack monitoring system which concerns on embodiment of this invention, (A) shows the state which the crack generate | occur | produced in the main girder lower flange, (B) Shows a state where a crack is generated in the abdominal plate, and (C) shows a state where a crack is generated from the main girder notch. It is a block diagram of the crack monitoring system which concerns on embodiment of this invention. It is a perspective view which fractures | ruptures and shows a part of crack monitoring material of the crack monitoring system which concerns on embodiment of this invention. It is a top view of the crack monitoring material of the crack monitoring system concerning an embodiment of this invention. It is sectional drawing which shows the state cut | disconnected by the VV line | wire of FIG. It is a top view for demonstrating the measurement operation | movement of the electricity supply state measuring part of the crack monitoring system which concerns on embodiment of this invention, (A) shows the state which the crack generate | occur | produced in the conductive layer for crack progress detection, (B) Indicates a state in which cracks are generated in the electrode layer for detecting crack propagation. It is a flowchart for demonstrating operation | movement of the crack monitoring system which concerns on embodiment of this invention. It is a block diagram of the resistance measurement experiment of the coating film for a crack detection which concerns on the Example of this invention, (A) is a top view, (B) is a front view. It is a graph which shows the relationship between the crack length of the coating film for a crack detection which concerns on the Example of this invention, and the increase amount of resistance value. It is a graph which shows the relationship between the crack length when the coating film for a crack detection based on the Example of this invention is apply | coated by width = 50mm, and the increase amount of resistance value. It is a graph which shows the relationship between the resin / pigment ratio and volume resistivity of the crack detection coating material which concerns on Example 1 of this invention. It is a graph which shows the relationship between resin / pigment ratio of the coating material for crack detections based on Example 2 of this invention, and volume resistivity.

Explanation of symbols

1 Steel structure (monitoring object)
DESCRIPTION OF SYMBOLS 2 Crack monitoring system 3 Crack monitoring material 4 Crack progress detection part 4a Conductive layer for crack progress detection 4b Rust prevention insulating layer 4c-4f Electrode layer for crack progress detection 4g Environmental barrier layer 5 Crack occurrence detection part 5a Conductive layer for crack occurrence detection 5b, 5c Crack generation detection electrode layer 5d Environmental barrier layer 5e Weatherproof layer 6, 7 Lead wire 8 Power supply unit 9 Current state measurement unit 10 Control unit 11 Evaluation unit 12 Correction unit 13 Communication unit 14 Housing unit 15 Crack detection coating film 16a, 16b electrodes A ₁ to A ₃ monitoring area C ₁ -C ₆ crack

Claims (9)

A crack propagation detecting unit for detecting the development of a crack that the crack detector and the crack detection unit has detected that detects cracks, is formed to overlap the surface of the object to be monitored by this cracking is expected, this A crack monitoring material for monitoring the occurrence of cracks in the monitored object and the progress of the cracks,
The crack occurrence detection unit,
A conductive layer for detecting the occurrence of cracks, the electrical resistance of which changes according to the occurrence of cracks;
A crack occurrence detection electrode layer for passing an electric current to the crack occurrence detection conductive layer,
The crack progress detector is
A conductive layer for detecting crack progress in which electrical resistance changes in accordance with the progress of the crack;
A crack progress detection electrode layer for passing an electric current to the crack progress detection conductive layer;
The crack generation detection conductive layer and the crack progress detection conductive layer are formed in a strip shape by applying a conductive paint so that the long side is located on the start side of the crack that is predicted to occur in the monitored object. Has been
The crack occurrence detection conductive layer is formed narrower than the crack propagation detection conductive layer,
Crack monitoring material characterized by In the crack monitoring material according to claim 1,
The crack progress detector detects a position where the crack has occurred;
Crack monitoring material characterized by In the crack monitoring material according to claim 1 or claim 2 ,
The crack propagation detection conductive layer is formed to have a width corresponding to the crack length allowed for the monitoring object;
Crack monitoring material characterized by In the crack monitoring material according to any one of claims 1 to 3 ,
The crack progress detection conductive layer is partitioned into a plurality of monitoring regions by the crack progress detection electrode layer, and a pair of adjacent crack progress detection electrode layers in the length direction of the crack progress detection conductive layer. That one monitoring area is formed by
Crack monitoring material characterized by A crack monitoring system for monitoring the occurrence of cracks and the progress of the cracks,
The crack monitoring material according to any one of claims 1 to 4 ,
An energization state measuring unit for measuring an energization state of the crack occurrence detection conductive layer and the crack propagation detection conductive layer;
An evaluation unit for evaluating a crack generated in the monitoring object based on a measurement result of the energization state measurement unit;
Crack monitoring system with. The crack monitoring system according to claim 5 , wherein
The energization state measurement unit measures the energization state for each monitoring region when the crack propagation detection conductive layer is partitioned into a plurality of monitoring regions by the crack propagation detection electrode layer,
The evaluation unit specifies a monitoring region where a crack has occurred based on a measurement result of an energization state for each monitoring region;
A crack monitoring system characterized by. In the crack monitoring system according to claim 5 or 6 ,
A correction unit for correcting the measurement result of the energization state measurement unit;
The evaluation unit evaluates the crack based on a corrected measurement result;
A crack monitoring system characterized by. The crack monitoring system according to claim 7 , wherein
The energization state measurement unit measures the energization state for each monitoring region when the crack propagation detection conductive layer is partitioned into a plurality of monitoring regions by the crack propagation detection electrode layer,
When the crack is generated in the crack propagation detection conductive layer, the correction unit is based on the measurement result of the energization state of the monitoring region where no crack is generated, and the measurement result of the energization state of the monitoring region where the crack is generated Correcting
A crack monitoring system characterized by. In the crack monitoring system according to claim 7 or claim 8 ,
The energization state measurement unit measures the energization state for each of the two adjacent monitoring regions when the crack propagation detection conductive layer is partitioned into a plurality of monitoring regions by the crack propagation detection electrode layer,
When the crack is generated in the crack progress detection electrode layer, the correction unit is based on the measurement result of the energization state of two adjacent monitoring regions including the crack progress detection electrode layer in which no crack is generated. Correcting the measurement result of the energization state of two adjacent monitoring regions including the crack growth detection electrode layer where the crack has occurred,
A crack monitoring system characterized by.

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