JP2008203224A - Diagnostic system and diagnostic technique of concrete structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diagnostic system and diagnostic technique of concrete structure capable of attaching an oscillator easily to diagnose a concrete structure. <P>SOLUTION: The diagnostic system includes a magnetic substance sheet member adhered to a concrete structure, an oscillator fixed adsorptively to magnetic substance sheet member magnetically during the period of operating condition to give local oscillation to the concrete structure to be diagnosed, a driving means for driving the oscillator, a measuring means measuring response to oscillation of the concrete structure to be diagnosed, and an analyzing means for determining soundness of the concrete structure to be diagnosed, based on how the oscillation mode obtained from measurement of a measuring means is varied temporally from oscillation mode at the time of sound condition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a diagnostic system and a diagnostic method for a concrete structure that can detect a minute deformation of the concrete structure and diagnose its soundness.

  Diagnosis of soundness in steel structures such as iron bridges, ships, and railway facilities, and concrete structures such as bridges, tunnels, buildings, and power stations is to visually detect the deformed state and give vibration to the diagnosis object with a hammer. The presence or absence of deformation was judged from the sound at that time.

  However, such a diagnostic method is likely to be overlooked, and has a difference in individual judgment. Therefore, the reliability is low, and it is difficult to make a reproducible diagnosis.

  Therefore, a piezoelectric element is affixed to the structure, and vibrations are applied in a certain frequency range, and changes in the entire structure are detected by observing changes in the vibration mode in the low frequency range. A method for detecting a local defect by detecting a change in electrical impedance at the base has been proposed (Patent Document 1).

  However, originally, in order to identify a deformed part of a structure, a reflected wave caused by the deformation is detected by a piezoelectric element, and the position is determined from the position on the time axis of the point of interest in the detection signal and the propagation speed of the elastic wave. There is a problem that it takes a long time to identify the position.

  In view of such circumstances, the inventors of the present application have proposed a system for diagnosing deformation of a diagnosis object from a change in vibration mode obtained by applying local vibration to a structure and measuring its response (Patent Literature). 2, Patent Document 3, Patent Document 4).

JP 2001-99760 A Japanese Patent No. 3694749 Japanese Patent No. 3705357 JP 2004-301792 A

  The diagnosis system by the present inventors described in Patent Documents 2 to 4 is intended for diagnosis of steel structures such as H-shaped steel, and particularly when a concrete structure is targeted for diagnosis. No consideration was given to how the device was attached to the structure.

  Accordingly, an object of the present invention is to provide a diagnostic system and a diagnostic method for a concrete structure capable of easily attaching a vibration device to the concrete structure and making a diagnosis thereof.

  According to the present invention, a magnetic plate member fixed to a concrete structure, and a vibration device that is magnetically attracted and fixed to the magnetic plate member during operation and applies local vibration to the concrete structure to be diagnosed. , The driving means for driving the vibration exciter, the measuring means for measuring the response to the vibration of the concrete structure to be diagnosed, and how the vibration mode obtained by the measurement means has changed from the vibration mode at the time of sound A diagnostic system for a concrete structure is provided, which includes analysis means for obtaining the soundness of the concrete structure to be diagnosed based on the above.

  The magnetic plate member is fixed to the concrete structure, and the vibration device is fixed to the concrete structure by magnetically adhering to the magnetic plate member, and in this state, the local vibration is applied by the vibration device. The soundness of the concrete structure is obtained by Thus, according to the present invention, since the vibration exciter can be fixed to the concrete structure very easily, the diagnosis becomes very easy. That is, according to the present invention, the diagnosis of a concrete structure can be diagnosed in the same way as a steel structure, so that the peeling and dropping of the concrete structure can be easily predicted. Therefore, the diagnosis of buildings, tunnels, etc. can be performed accurately and easily. The social significance is very large.

  The vibration exciter is mechanically coupled to at least one electromagnet that is energized during operation and is magnetically attracted to the magnetic plate member, and is mechanically coupled to the at least one electromagnet to generate vibration and diagnose the vibration. It is preferable to include a vibration element that is applied to the surface of the power concrete structure.

  More preferably, the vibration element is a piezoelectric vibration element.

  It is also preferable that the magnetic plate member is a steel plate fixed in parallel with the surface of the concrete structure to be diagnosed, and that at least one electromagnet is magnetically attracted to the steel plate during operation. In this case, it is also preferable that the at least one electromagnet is two electromagnets that can be attracted to the steel plate.

  At least one electromagnet is selectively applied to both the steel plate fixed parallel to the surface of the concrete structure to be diagnosed and the steel plate fixed to the concrete structure perpendicular to the surface of the concrete structure to be diagnosed. It is preferable to be configured to be magnetically attractable.

  The magnetic plate member is a steel plate fixed to a concrete structure perpendicular to the surface of the concrete structure to be diagnosed, and is configured such that at least one electromagnet is magnetically attracted to the steel plate during operation. It is also preferable.

  The analysis means analyzes the measurement data from the measurement means to determine the natural frequency of the diagnostic object as the experimental natural frequency, and defines one abnormal state of the diagnostic object. Define a plurality of individuals that use genetic information as information that characterizes deformation such as position, calculate the natural frequency of each individual based on the genetic information, and obtain the theoretical natural frequency. The individual with the theoretical natural frequency that matches with the degree of coincidence is identified, the individual with the highest degree of coincidence is identified, the evaluation unit that estimates the deformed state from the genetic information of this individual, and the individual searched by the evaluation unit It is also preferable to provide an analysis database that stores the theoretical natural frequency using the stored individual in the next diagnosis.

  According to the present invention, further, the magnetic plate member is fixed to the concrete structure to be diagnosed, the vibration device is magnetically attracted and fixed to the magnetic plate member, and the concrete structure to be diagnosed from the vibration device. Concrete structure to be diagnosed based on how the vibration mode obtained from the measurement is changed from the vibration mode at the time of measurement. A method for diagnosing a concrete structure for determining the soundness of a concrete is provided.

  A magnetic plate member is fixed to a concrete structure, and the vibration device is fixed to the concrete structure by magnetically adsorbing the magnetic plate member, and in this state, vibration is applied from the vibration device. Obtain the soundness of concrete structures. Thus, according to the present invention, since the vibration exciter can be fixed to the concrete structure very easily, the diagnosis becomes very easy. That is, according to the present invention, the diagnosis of a concrete structure can be diagnosed in the same way as a steel structure, so that the peeling and dropping of the concrete structure can be easily predicted. Therefore, the diagnosis of buildings, tunnels, etc. can be performed accurately and easily. The social significance is very large.

  The surface of a concrete structure on which at least one electromagnet of a vibration exciter is magnetically attracted to a magnetic plate member to fix the vibration exciter, and vibration is generated by the vibration element of the vibration exciter and the vibration is diagnosed. It is preferable to apply to. In this case, a piezoelectric vibration element is preferably used as the vibration element.

  It is also preferable that the steel plate is fixed as a magnetic plate member in parallel with the surface of the concrete structure to be diagnosed, and at least one electromagnet is magnetically attracted to the steel plate during operation. In this case, it is preferable to use two electromagnets that can be attracted to the steel plate as at least one electromagnet.

  It is also preferable that the steel plate is fixed to a concrete structure perpendicular to the surface of the concrete structure to be diagnosed as a magnetic plate member, and at least one electromagnet is magnetically attracted to the steel plate during operation.

  Analyzing the measurement data to determine the natural frequency of the diagnosis target as the experimental natural frequency, defining one deformation state of the diagnosis target, and using the genetic information as information that characterizes the deformation such as the position of the deformation point Define multiple individuals, calculate the natural frequency of each individual based on genetic information and make it the theoretical natural frequency, explore individuals with the theoretical natural frequency that matches the experimental natural frequency with a predetermined degree of coincidence, The individual with the highest degree of coincidence is identified, the deformed state is estimated from the genetic information of the individual, the searched individual is stored, and the theoretical natural frequency can be calculated using the stored individual in the next diagnosis It is also preferable to make it.

  According to the present invention, since the vibration exciter can be fixed to the concrete structure very easily, the diagnosis becomes very easy.

  FIG. 1 is a block diagram schematically showing the overall configuration of a concrete structure diagnosis system according to an embodiment of the present invention, and FIG. 2 shows a vibration exciter and its attachment structure to the concrete structure according to this embodiment. FIG. 3 is a partially broken cross-sectional view, and FIG. 3 is a block diagram showing a configuration of a control and diagnostic processing unit in the present embodiment.

  In FIG. 1, 10 is a concrete structure to be diagnosed, 11 is a steel plate as an example of a magnetic plate member fixed to a part of the surface of the concrete structure 10 with, for example, an adhesive, and 12 is a steel plate during operation. 11 is an exciter that is fixed by an electromagnet and applies vibration to the concrete structure 10, 13 is a measuring instrument that measures the response due to the applied vibration, 14 is an overall control unit 140 that controls the overall operation, and a measuring instrument 13 includes an analysis unit 141 that finally obtains the soundness of the concrete structure 10 by obtaining the vibration mode from the response detected by the control unit 13, the drive unit 142 of the vibration exciter 12, and the excitation power source unit 143 of the fixing electromagnet. And a diagnostic processing device, respectively. In the present embodiment, the overall control unit 140 and the analysis unit 141 are configured by a digital computer.

  In this embodiment, the steel plate 11 is directly bonded to the surface thereof so as to be parallel to the surface of the concrete structure 10 to be diagnosed. The thickness of the steel plate 11 is about 2 mm in this embodiment, but is not limited to this. Moreover, the dimension of the steel plate 11 should just be larger than the dimension (for example, rectangle of about 75 mm x 50 mm) of the adsorption | suction surface of the electromagnet for fixation, and the shape may be what kind. The magnetic plate member of the present invention is not limited to a steel plate, and any plate member that can be magnetically attracted can be applied.

  As shown in FIG. 2, the vibration device 12 includes a vibration element 120 that vibrates in a predetermined frequency range, a vibration rod 121 that transmits vibration of the vibration element 120 to a local surface of the concrete structure 10, and a vibration rod 121. A preload spring 122 for applying preload, a spring adjustment knob 123 for adjusting the preload by changing the free length of the preload spring 122, an electromagnet 124 for fixing the entire vibration device 12 to the steel plate 11, and an electromagnet 124 The on / off switch 125 is provided.

  As the vibration element 120, a high-frequency vibration (for example, 500 Hz or more) can be applied to observe local deformation of the concrete structure 10, and the piezoelectric element can be applied with a small and minute force. A laminated piezoelectric element utilizing the piezoelectric effect is used. By applying such high-frequency vibrations, it is possible to observe the deformation of the diagnosis target. This is because when the object of diagnosis is a concrete structure such as a nuclear power plant, chemical plant, ship, etc., its weight is heavy, so these natural frequencies (natural frequencies in the first-order mode) are very low. However, since the natural frequency of the deformation point is high, the change at this frequency can be measured.

  The electromagnet 124 is excited when the on / off switch 125 is turned on during the operation of the diagnostic system, and the attracting surface 124 a is magnetically attracted to the steel plate 11. As a result, the vibration device 12 is securely fixed to the concrete structure 10. At that time, the tip of the vibration rod 121 directly contacts the surface of the concrete structure 10. In this embodiment, the electromagnet attracting surface 124a is used, but the electromagnet also has an attracting surface 124b perpendicular to the attracting surface, and the steel plate is oriented in this direction. Can be magnetically attracted using the attracting surface 124b (the embodiment of FIG. 11).

  In this embodiment, the measuring instrument 13 is a small semiconductor accelerometer fixed to the concrete structure 10, and the displacement of the concrete structure 10 is measured in order to measure the response to the vibration given by the vibration device 12. Measure. As the measuring instrument 13, a laser displacement measuring instrument, a piezoelectric element, or the like may be used. When a piezoelectric element is used for the measuring instrument 13, it can be shared with the vibration element 120 in the vibration device 12. The arrangement position of the measuring instrument 13 is appropriately set according to the arrangement position of the vibration device, the expected deformation point position, and the like.

  In the control and diagnosis processing apparatus 14 shown in FIG. 3, the overall control unit 140 indicates an excitation condition for diagnosing the soundness of the concrete structure 10 to be diagnosed most appropriately, and displays a diagnosis result. To oversee the entire diagnostic process. At the start of diagnosis, control data such as a diagnosis start command and an excitation condition is sent to the drive unit 142 via the signal generation unit 144. Further, the measurement data from the measuring instrument 13 is sent to the analysis unit 141, and the diagnosis result is received from the analysis unit 141 and displayed on the screen. Furthermore, supply of the excitation power supply unit 143 can also be controlled.

  The signal generation unit 144 generates a waveform signal of vibration to be applied to the diagnosis target based on the excitation condition from the overall control unit 140. This waveform signal is amplified by the drive unit 142 to become a drive signal, and is applied to the vibration element 120 of the vibration device 12. The signal generation unit 144 includes a function generator, a multi-function synthesizer, and the like, and generates and outputs an analog signal waveform signal corresponding to the excitation condition from the overall control unit 140. In general, multi-function generators and multi-function synthesizers can generate general waveform signals such as sine waves, rectangular waves, and sawtooth waves themselves, but any waveform signal can be created according to the diagnosis target and purpose. It is desirable to have a function. By using the multi-function generator, it is possible to perform multi-channel vibration using a plurality of vibration devices. That is, the timing of vibration is shifted for each vibration device, the phase is changed, the amplitude, the frequency or the vibration time is changed, and further sweep vibration (vibration in which the amplitude or frequency is changed with time) is performed. It is possible to vibrate according to the object of diagnosis and purpose.

  The drive unit 142 amplifies the waveform signal from the signal generation unit 144 with a predetermined gain, and outputs the amplified signal to the vibration element 120 of the vibration device 12 as a drive signal. The gain may be specified from the signal generation unit 144.

  The measuring instrument 13 is connected to an amplifier 145 that amplifies an analog measurement signal that is an output thereof. The amplifier 145 is connected to an A / D converter 146 that digitally converts the output signal. The amplifier 145 includes a signal conditioner provided corresponding to each measuring instrument, and mainly adjusts the signal level input to the A / D converter 146. The gain of each amplifier is set depending on the configuration of the measuring instrument and the configuration of the diagnosis target. That is, it is necessary to set the gain of each amplifier to be constant (at least when the same level signal is input, the same level signal is output), and the signal from the amplifier 145 is a digital signal. Set to prevent overflow when converting to. If you want to adjust the vibration energy to be applied according to the diagnosis target, or if you want to continuously change the vibration energy to be applied, it may cause overflow if it is a fixed gain amplifier, It is desirable that the gain is adjustable. This gain adjustment may be manual adjustment, or gain adjustment from the overall control unit 140.

  The overall control unit 140 is connected to the A / D converter 146, and a digital measurement signal is input to the overall control unit 140.

  The analysis unit 141 includes an experimental mode analysis unit 141a that obtains a natural frequency (hereinafter referred to as an experimental natural frequency) in a primary to nth vibration mode of a diagnosis target from measurement data, and a primary to nth order of a diagnosis target in theory. The theoretical analysis unit 141b for calculating the natural frequency (hereinafter, the theoretical natural frequency) in the vibration mode, and determining whether the theoretical natural frequency matches the experimental natural frequency under a predetermined condition and performing soundness diagnosis An evaluation unit 141c to perform, and an analysis database (analysis DB) unit 141d for storing information such as diagnostic information, theoretical natural frequency, and experimental natural frequency are provided.

  Hereinafter, the analysis unit 141 will be described in more detail.

  When deformation such as damage occurs in the concrete structure 10 to be diagnosed, the response of the applied vibration is measured, and the peak frequency of the power spectrum is displaced. That is, the presence or absence of occurrence of deformation can be known by determining whether or not there is a difference in the power spectrum. Therefore, by comparing how the power spectrum has changed from that at the time of soundness, it is possible to perform soundness diagnosis.

  However, even if the occurrence of the deformation can be determined by this, it is not possible to determine the position of the deformation and whether such a deformation has occurred. Therefore, the evaluation unit 141c uses an analysis algorithm so that the position of the deformation point and the content of the deformation are also diagnosed.

  As such an analysis algorithm, a genetic algorithm (GA), neuronetwork regression analysis, multivariate analysis, pattern recognition analysis, and the like can be applied, but among them, it is very effective for optimization problems. The case where the genetic algorithm currently used is used is demonstrated below.

  First, the outline of GA will be briefly described. GA is a technique originally devised by simulating the laws of heredity in the living world, and is a technique for finding a better solution while genetically changing multiple solutions. This solution is expressed (coded) in the form of a gene.

  FIG. 4 is a flowchart showing the GA algorithm.

  In GA, first, an initial group (individual group) that is a group of solutions (individuals) is created (step S1). This individual corresponds to one deformed state to be diagnosed, and the position of the deformed point or the like is used as genetic information characterizing this individual.

  Next, evaluation is performed. In the evaluation, the fitness is obtained for all individuals (solutions), and individuals to be left in the next generation are determined based on the fitness (steps S2 and S3). This goodness of fit is like the height of the evaluation of the solution, and the evaluation function is set so that the better the better the solution, the higher the goodness of fit. In the present invention, the theoretical natural frequency of each individual is calculated, and how well this theoretical natural frequency matches (matches) with the experimental natural frequency (is a good solution) by an evaluation function. evaluate. The evaluation function will be described later.

  In the case where the bolt is relaxed in the steel material, the optimal solution can often be found in the assumed individual, but in the case of concrete structure peeling, it is optimal from the assumed individual. Sometimes it is not possible to find a solution. Therefore, in GA, crossover and mutation operations called GA operators are performed (step S4).

  This crossover and mutation operation is based on the laws of heredity. In crossover, new individuals (children) that inherit genes from multiple parents (generally two individuals) are generated with a certain probability, and mutations are made. Then, it sets so that an individual may occur with a lower probability than crossover.

  However, if the deformation is not loosening of the bolt but peeling, the optimum solution cannot be obtained even if the crossover operation is repeated. Will be generated and explored. Such an exploration is considered as one generation, and an optimal solution is obtained by performing a predetermined number of times.

  FIG. 5 is a flowchart showing a procedure when a diagnosis is performed using the GA.

  The diagnostic procedure will be described below with reference to this figure. First, a vibration is applied to the diagnosis target (step S11). Thereby, a response vibration having a vibration mode of the first order to the nth order (n: integer) is measured from the diagnosis target.

  Therefore, the experiment mode analysis unit 141a of the analysis unit 141 analyzes the power spectrum of the measurement data, finds that the outstanding amplitude changes due to the deformation, or a new outstanding amplitude is generated, and searches for this superior point to determine the uniqueness of the experiment. The vibration frequency is set (step S12, step S13).

  For example, when a sweep vibration in which the frequency is continuously changed from the start frequency to the stop frequency as shown in FIG. 6 is applied to the diagnosis target, measurement data as shown in FIG. 7 is observed. Therefore, the experiment mode analysis unit 141a performs a power spectrum analysis on the measurement data to obtain a power spectrum as shown in FIG. 8, and a vertical line in FIG.

  Note that frequency analysis is performed by Fourier transforming the measured data, and the point where the amplitude at each frequency is excellent may be the natural frequency of the experiment. Furthermore, power spectrum analysis is performed on the data obtained by Fourier transform. By doing so, the amplitude change may be clarified, and thereby the experimental natural frequency may be identified with high accuracy.

  The reason for applying the sweep vibration as shown in FIG. 6 is to resonate the deformation point so that information such as the position, size, and type of the deformation point is included in the measurement data.

  That is, since the position of the deformation point is unknown at the time of diagnosis, the deformation point is resonated by vibrating at a wide frequency so that the measurement data includes the information. Of course, when the deformation point can be identified or when the deformation point can be predicted with high accuracy, the vibration may be a constant frequency instead of a sweep vibration, or a vibration whose frequency changes within a narrow range. May be.

  The vibration applied in FIG. 6 is considered to be a surface acoustic wave propagating on or near the surface to be diagnosed, but it is deep like internal defects such as corrosion of reinforcing bars in concrete structures and deformation of concrete due to acid rain. When measuring the deformation at the position, it is natural that energy is required to propagate the vibration to the depth and return the response. For this reason, for example, it is necessary to apply a vibration of energy corresponding to the depth of the detected deformation point, such as applying a sweep vibration whose amplitude increases with time.

  In the case of a diagnosis target as shown in FIG. 6, (1) delamination of concrete, (2) material deterioration, (3) debonding with reinforcing bars, (4) surface cracks, etc. are assumed as deformation modes. be able to.

  The theoretical analysis unit 141b calculates low-order to high-order theoretical natural vibrations to be diagnosed using a finite element method or the like. In the finite element method, a diagnosis target is divided into a plurality of elements, and calculation is performed by changing the boundary conditions of each element.

  For this reason, element division corresponding to the presumed deformation point is important. For example, when peeling is assumed as the deformation, the element is divided so that the peeling position assumed in 1 of the element is included. In addition, when peeling is assumed as the deformation, a boundary condition that there is no continuity with adjacent elements is set in the gene information. Thus, gene information is set according to the assumed property of deformation, and this is used as a calculation parameter.

  At the time of the first diagnosis (K = 1), the theoretical natural frequency is calculated using the constants necessary for calculating the theoretical value of the structure as an operation parameter so that the theoretical natural frequency matches the experimental natural frequency under a predetermined condition. This calculation parameter is changed. Then, the operation parameter when matching is identified as the constant to be diagnosed.

  As a result, a theoretical natural frequency (high accuracy) close to the natural frequency of the actual diagnosis target can be easily obtained, and the time required for calculation can be shortened.

  The first diagnosis (K = 1) means the first diagnosis when the apparatus is installed or when the analysis database data is initialized after installation. Since the change of the diagnosis target is performed by detecting the state change, in the first diagnosis (K = 1), there is no data regarding the original state, so the diagnosis cannot be performed, and no individual group is set in GA. Because it is in a state.

  For this reason, at the time of the first diagnosis, an individual group in GA is set (step S14, step S16), and the genetic information of the individual is coded (step S17).

  Thereafter, the theoretical natural frequency is calculated by the finite element method (step S18). At this time, the deformed point position constituting the gene information is calculated as a calculation parameter, and a curve of amplitude (vertical axis) with respect to the frequency (horizontal axis) as shown in FIG.

  It is assumed that the maximum value of this curve corresponds to the natural frequency in the first to nth vibration modes, and this natural frequency is affected by the occurrence of the deformation and appears as a frequency change or the like.

  The evaluation unit 141c evaluates the fitness by substituting the theoretical natural frequency fa (i) and the experimental natural frequency fe (i) obtained in this way into the preset evaluation function δ (step S19). . Here, i indicates the natural frequency of the i-th vibration mode. As the evaluation function δ, for example, a function that adds the square of the difference between the theoretical natural frequency fa (i) and the experimental natural frequency fe (i) in each vibration mode as shown in the following equation. Of course, various evaluation functions δ can be defined. For example, the absolute value of the difference may be added in each vibration mode.

  On the other hand, if it is determined in step S14 that the diagnosis is not the first diagnosis (K = 1), data D (K-1) which is the previous diagnosis result is read from the analysis DB unit 141d, and this data D (K- The fitness is evaluated using the theoretical natural frequency included in 1) and the experimental natural frequency obtained in step S13 (step S19).

  It is determined whether or not the fitness obtained in this way is smaller than a certain fitness reference value (step S20). If it is larger than the fitness reference value (when the fitness is low), it is set in advance. Genetic manipulation is performed based on the crossover probability Pc and the mutation probability Pm (step S21). Such a process is set as one generation, and an optimum solution is obtained by repeating the process up to a preset number of generations.

  When the optimum solution is obtained, it is determined whether or not the diagnosis is first (K = 1). If K = 1, the individual group including the obtained optimum solution is set as data D (K) in the analysis DB unit 141d. Save (step S25).

  On the other hand, if the diagnosis is not the first (K ≠ 1), the soundness diagnosis is performed by judging the change position and the change contents from the genetic information in the individual with the optimum solution (step S23, step S24), The result is stored (step S25).

  As described above, according to the present embodiment, the steel plate 11 is fixed to the concrete structure 10, and the vibration device 12 is magnetically attracted to the steel plate 11 with an electromagnet to thereby connect the vibration device 12 to the concrete structure 10. Since the soundness of the concrete structure is obtained by applying vibration from the vibration device 12 in this state, the vibration device 12 can be fixed to the concrete structure 10 very easily. It will be easier.

  Of course, by identifying the concrete structure in a healthy state, it is possible to identify a place where a local change caused by some kind of stress such as secular change, strong pressure or impact has occurred. In addition, since it is possible to grasp local changes, it is possible to appropriately deal with the changes, which is very effective from the viewpoint of asset management. In addition, from the viewpoint of structure maintenance management technology, early detection of minute deformations (predictors and signs) and implementation of preventive repair and reinforcement can reduce and maintain the life cycle cost of structures. It can contribute to the effective use of administrative expenses.

  10A is a top view and FIG. 10B is a partially cutaway front view showing a vibration exciter according to another embodiment of the present invention and a structure for attaching it to a concrete structure.

  In this embodiment, the vibration device 102 is provided with two electromagnets, and the steel plate is fixed to the surface of the concrete structure at a position facing each electromagnet, as shown in FIG. The configuration is the same as that of the embodiment.

  That is, as shown in FIG. 10, the two steel plates 101a and 101b are directly bonded to the surface thereof so as to be parallel to the surface of the concrete structure 100 to be diagnosed. The thickness of each of the steel plates 101a and 101b is about 2 mm in this embodiment, but is not limited to this. Moreover, the dimension of each steel plate should just be larger than the dimension (for example, rectangle of about 75 mm x 50 mm) of the attracting surface of the electromagnet for fixation, and the shape may be anything. The magnetic plate member of the present invention is not limited to a steel plate, and any plate member that can be magnetically attracted can be applied.

  As shown in FIG. 10, the vibration device 102 includes a vibration element 1020 that vibrates in a predetermined frequency range, a vibration rod 1021 that transmits the vibration of the vibration element 1020 to a local surface of the concrete structure 100, and a vibration rod 1021. A preload spring 1022 for applying preload, a spring adjusting knob 1023 for adjusting the preload by changing the free length of the preload spring 1022, and 2 for fixing the entire vibration device 102 to the two steel plates 101a and 101b, respectively. Two electromagnets 1024a and 1024b and on / off switches 1025a and 1025b for the electromagnets 1024a and 1024b are provided.

  According to the present embodiment, since the two steel plates are magnetically attracted to the two steel plates, the vibration device can be firmly fixed to the concrete structure. In addition, since magnetic attraction is performed at a symmetric position with respect to the excitation unit, it is stable without being lifted up, and averaged excitation can be performed. Other operations and effects in this embodiment are almost the same as those in the embodiment of FIG.

  FIG. 11 is a partially broken cross-sectional view showing a vibration exciter and its attachment structure to a concrete structure in still another embodiment of the present invention.

  This embodiment has the same configuration as that of the embodiment of FIG. 1 except that different attracting surfaces of the electromagnets of the vibration device 112 are used.

  That is, as shown in FIG. 11, the steel plate 111 is directly bonded to the surface of the concrete structure 110 'perpendicular to the surface of the concrete structure 110 to be diagnosed. Although the thickness of the steel plate 111 is about 2 mm in this embodiment, it is not limited to this. Moreover, the dimension of the steel plate 111 should just be larger than the dimension (for example, rectangle of about 75 mm x 50 mm) of the adsorption surface of the electromagnet for fixation, and the shape may be anything. The magnetic plate member of the present invention is not limited to a steel plate, and any plate member that can be magnetically attracted can be applied.

  As shown in FIG. 11, the vibration device 112 includes a vibration element 1120 that vibrates in a predetermined frequency range, a vibration rod 1121 that transmits vibration of the vibration element 1120 to the local surface of the concrete structure 110, and a vibration rod 1121. A preload spring 1122 for applying preload, a spring adjusting knob 1123 for adjusting the preload by changing the free length of the preload spring 1122, an electromagnet 1124 for fixing the entire vibration device 112 to the steel plate 111, and an electromagnet 1124 on / off switch 1125. The electromagnet 1124 is magnetically attracted to the steel plate 111 using an attracting surface 1124b perpendicular to the surface of the concrete structure 110 to be diagnosed. That is, the vibration device 112 of the present embodiment is a device that is bolted by shifting the position of the electromagnet 124 in the vibration device 12 shown in FIG. 2 of the embodiment of FIG. 1 backward with respect to the concrete structure 110. .

  Other operations and effects in this embodiment are almost the same as those in the embodiment of FIG.

  As still another embodiment of the present invention, the theoretical analysis unit 141b in the analysis unit 141 may be configured to include the vibration mode in the analysis. This is because defect information such as deformation affects not only the frequency peak but also the vibration mode. Therefore, a plurality of measuring instruments 13 are arranged on the concrete structure 10 at equal intervals, and the shape of the vibration mode is obtained by observing the relative change in the response amplitude from these measuring instruments 13 to change from the shape change. The small effect of the shape is detected. A defect can be detected with higher sensitivity when such a change in vibration mode is detected than when a change in frequency is detected.

  Hereinafter, the derivation of the evaluation function used by the theoretical analysis unit 141b of the present embodiment will be specifically described.

この式は複素式でありその大きさは、周波数に対するｍ／ｓ^２又はｇのような工学単位（ＥＵ）でプロットされる。これにより、パワースペクトルは下式のように定義される。ただし、＊は複素共役を示している。

パワースペクトルは、単位（ＥＵ）^２の実数値周波数領域関数である。ＰＳＤであるＧ_ｘ（ｆ）は下式のように定義される。

ここで、Ｅ［ ］はＸ（ｆ）のｎサンプルに渡っての特定の周波数ｆについての集合平均を表している。このＰＳＤの定義より、加振力の測定を行うことなく構造物の計測した応答、例えば加速度応答、からＰＳＤを算出できることが分かる。ただし、加振力は同一振幅及び同一振動波形でなければならない。このように、コンクリート構造物の健全度を診断する場合、加振力は測定する必要がない。 First, the definition of power spectral density (PSD) will be described. Now, assuming that the continuous time series between 0 and T is x (t), the discrete Fourier transform (DFT) X (f) is defined as follows. Here, i = √ (−1) and f = cyclic frequency (Hz).

This equation is a complex equation and its magnitude is plotted in engineering units (EU) such as m / s ² or g versus frequency. Thereby, the power spectrum is defined as follows. Note that * indicates a complex conjugate.

The power spectrum is a real-valued frequency domain function in units (EU) ² . G _x (f), which is a PSD, is defined as:

Here, E [] represents a set average for a specific frequency f over n samples of X (f). From the definition of PSD, it can be seen that the PSD can be calculated from the measured response of the structure, for example, the acceleration response, without measuring the excitation force. However, the excitation force must have the same amplitude and the same vibration waveform. Thus, when diagnosing the soundness of a concrete structure, it is not necessary to measure the excitation force.

ＰＳＤの変化が周波数ｆ_１からｆ_ｍの範囲の異なる周波数で測定された場合、マトリクス［Ｄ］は以下のようになる。ここで、ｎは測定点数である。

このマトリクス［Ｄ］において、各列は同一周波数であるが異なる計測点におけるＰＳＤ変化を表している。異なる周波数におけるＰＳＤ変化の総和が、損傷発生及び損傷増大のインディケータとして使用可能である。換言すれば、損傷インディケータ（Ｔｏｔａｌ Ｃｈａｎｇｅ）が、下式のように、マトリクス［Ｄ］の行の和から算出される。

Next, derivation of the vibration mode will be described. Assuming that D _i (f) is the PSD magnitude at frequency f and channel number i, the absolute value of the difference in PSD magnitude before and after damage is expressed as follows: Here, G _i (f) and G _i ^* (f) represent the size of the PSD when it is not damaged and when it is damaged, respectively.

If a change of the PSD was measured in the range of different frequencies f _m from the frequency f _1, the matrix [D] are as follows. Here, n is the number of measurement points.

In this matrix [D], each column represents the PSD change at the same frequency but at different measurement points. The sum of PSD changes at different frequencies can be used as an indicator of damage occurrence and damage increase. In other words, the damage indicator (Total Change) is calculated from the sum of the rows of the matrix [D] as shown in the following equation.

  However, in this damage indicator (Total Change), since the position of the damage in the concrete structure is unknown, the indicator indicating the damage position was derived as follows.

全ての計測点における損傷検出の周波数を監視するため、下記のような新たなマトリクス［Ｃ］が形成される。このマトリクスは、損傷されていない位置である０と、損傷された位置である１とから成っている。例えば、このマトリクス［Ｃ］において、Ｍ_３（ｆ_１）及びＭ_２（ｆ_２）に対応する位置に１が入っている。

ＰＳＤの最大変化の合計ＳＭは、下式のように、マトリクス［Ｍ］の行の和から算出される。

異なる計測点において損傷を検出した回数の合計ＳＣは、下式のように、マトリクス［Ｃ］の行の和から算出される。

ノイズによる影響及び測定エラーを減少するために、ベクトル｛ＳＭ｝からベクトル｛ＳＭ｝における要素の標準偏差σ又はその２倍２σが減算される。負の減算結果は削除される。同様な処理がベクトル｛ＳＣ｝についてもなされ、その結果、下式が得られる。

以上の結果、下式に示すように、損傷インディケータ（Ｄａｍａｇｅ Ｉｎｄｉｃａｔｏｒ １及びＤａｍａｇｅ Ｉｎｄｉｃａｔｏｒ ２）が｛ＳＭＤ｝及び｛ＳＣＤ｝のスカラー積から定義される。

これら損傷インディケータ（Ｄａｍａｇｅ Ｉｎｄｉｃａｔｏｒ １及びＤａｍａｇｅ Ｉｎｄｉｃａｔｏｒ ２）は連続体であるコンクリート構造物の損傷の位置の評価に用いられ、一方、前述した損傷インディケータ（Ｔｏｔａｌ Ｃｈａｎｇｅ）は連続体であるコンクリート構造物の損傷の発生及びその程度の評価に用いられる。 First, a maximum value of PSD change at each frequency (maximum value of each column of matrix [D]) is extracted, and all PSD changes measured at other measurement points are deleted. For example, in the matrix [D], if D ₃ (f ₁ ) is the maximum value in the first column, this value is used as M ₃ (f ₁ ), and all other values in this column are deleted. . By performing the same processing for other columns, a matrix [M] of the maximum change in PSD at different frequencies is obtained as in the following equation.

In order to monitor the frequency of damage detection at all measurement points, the following new matrix [C] is formed. This matrix consists of 0, which is an undamaged position, and 1, which is a damaged position. For example, in this matrix [C], 1 is entered at a position corresponding to M ₃ (f ₁ ) and M ₂ (f ₂ ).

The total maximum change SM of the PSD is calculated from the sum of the rows of the matrix [M] as shown in the following equation.

The total SC of the number of times that damage is detected at different measurement points is calculated from the sum of the rows of the matrix [C] as shown in the following equation.

In order to reduce the influence of noise and measurement error, the standard deviation σ of the element in the vector {SM} or 2 × 2σ is subtracted from the vector {SM}. Negative subtraction results are deleted. Similar processing is performed for the vector {SC}, and as a result, the following equation is obtained.

As a result, as shown in the following formula, the damage indicators (Damage Indicator 1 and Damage Indicator 2) are defined from the scalar product of {SMD} and {SCD}.

These damage indicators (Damage Indicator 1 and Damage Indicator 2) are used for evaluating the position of damage in a continuous concrete structure, while the damage indicator (Total Change) described above is used to evaluate the damage in a continuous concrete structure. Used to evaluate the occurrence and extent of

  As still another embodiment of the present invention, the theoretical analysis unit 141b in the analysis unit 141 may be configured to take into account changes in internal strain energy. This is because if the vibration mode is obtained, a change in internal strain energy during vibration of the entire concrete structure is also obtained, so that defect detection can be performed by comparing energy. Also in this case, a plurality of measuring instruments 13 are arranged on the concrete structure 10 at equal intervals, and a vibration mode is obtained by observing a relative change in response amplitude from these measuring instruments 13 to perform energy comparison. Even when such internal strain energy is compared, a defect can be detected with higher sensitivity than when a frequency change is detected.

  Hereinafter, the derivation of the evaluation function used by the theoretical analysis unit 141b of the present embodiment will be briefly described.

The internal strain energy is calculated from the vibration displacement at the measurement point. The displacement mode shape is determined by complementing the displacement data of limited measurement points. The strain energy of the entire concrete structure is calculated by differentiating the vibration mode function due to the displacement, for example. For example, the strain energy We of the minute element can be obtained from the following equation.
We = (σxεx + σyεy + σzεz + 2τyzγyz + 2τzxγzx + 2τxyγxy) / 2
Since We is a strain energy function of a minute element, this is integrated over the entire volume of the structure portion, and the entire strain energy W as an evaluation function is obtained. That is, by obtaining an evaluation function from W = ∫We · dV, the concrete structure as a continuum is evaluated from the change in the overall strain energy W.

  As still another embodiment of the present invention, the theoretical analysis unit 141b in the analysis unit 141 may be configured to more clearly represent the influence of defects by superimposing vibration mode shape changes due to defects for each frequency. . That is, in the matrix [D] described above, since the row represents the degree of damage D for each frequency f and the column represents the degree of damage D for each measurement point, the influence of the defect is obtained for each frequency. Therefore, by superimposing this matrix [D] at the frequency f, the influence of defects at each measurement point is obtained as the influence of all frequencies, and the damage position becomes very clear.

  All the embodiments described above are illustrative of the present invention and are not intended to be limiting, and the present invention can be implemented in other various modifications and changes. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

1 is a block diagram schematically showing an overall configuration of a concrete structure diagnosis system according to an embodiment of the present invention. It is a partially broken sectional view which shows the vibration exciter in the embodiment of FIG. 1, and its attachment structure to a concrete structure. It is a block diagram which shows the structure of the control and diagnostic processing unit in embodiment of FIG. It is a flowchart which shows the algorithm of GA. It is a flowchart which shows the procedure in the case of making a diagnosis using GA. It is a figure which illustrates a sweep vibration as a vibration waveform provided to a diagnostic object. It is a figure which illustrates measurement data. It is the figure which calculated | required the power spectrum from measurement data. It is the waveform of the vibration mode calculated in the theoretical analysis part. It is the top view and partially broken front view which show the vibration apparatus in other embodiment of this invention, and its attachment structure to a concrete structure. It is a partially broken sectional view which shows the vibration apparatus and the attachment structure to the concrete structure in other embodiment of this invention.

Explanation of symbols

10, 100, 110, 110 ′ Concrete structure 11, 101a, 101b, 111 Steel plate 12, 102, 112 Exciting device 13 Measuring instrument 14 Control and diagnostic processing device 120, 1020, 1120 Vibration element 121, 1021, 1121 Vibration Rod 122, 1022, 1122 Preload spring 123, 1023, 1123 Spring adjustment knob 124, 1024a, 1024b, 1124 Electromagnet 124a, 124b, 1124b Adsorption surface 125, 1025a, 1025b, 1125 On-off switch 140 Overall control unit 141 Analysis unit 141a Experiment Mode analysis unit 141b Theoretical analysis unit 141c Evaluation unit 141d Analysis DB unit 142 Drive unit 143 Excitation power supply unit 144 Signal generation unit 145 Amplifier 146 A / D converter

Claims (15)

  A magnetic plate member fixed to a concrete structure, a vibration device that is magnetically attracted and fixed to the magnetic plate member during operation, and applies local vibration to the concrete structure to be diagnosed, and the vibration device Based on how the vibration mode obtained by the measurement by the measurement means changes from the vibration mode in the healthy state, the drive means for driving the measurement, the measurement means for measuring the response to the vibration of the concrete structure to be diagnosed And a means for analyzing the soundness of the concrete structure to be diagnosed.   The vibration generator is mechanically connected to at least one electromagnet that is energized during operation and is magnetically attracted to the magnetic plate member, and generates vibration and generates vibration. The diagnostic system according to claim 1, further comprising: a vibration element that applies a vibration to a surface of the concrete structure to be diagnosed.   The diagnostic system according to claim 2, wherein the vibration element is a piezoelectric vibration element.   The magnetic plate member is a steel plate fixed parallel to the surface of the concrete structure to be diagnosed, and the at least one electromagnet is configured to be magnetically attracted to the steel plate during operation. The diagnostic system according to claim 2 or 3, characterized in that.   The diagnostic system according to claim 4, wherein the at least one electromagnet is two electromagnets that can be attracted to the steel plate.   The magnetic plate member is a steel plate fixed to a concrete structure perpendicular to the surface of the concrete structure to be diagnosed, and the at least one electromagnet is magnetically attracted to the steel plate during operation. The diagnostic system according to claim 2, wherein the diagnostic system is configured.   The at least one electromagnet is attached to both a steel plate fixed parallel to the surface of the concrete structure to be diagnosed and a steel plate fixed to a concrete structure perpendicular to the surface of the concrete structure to be diagnosed. The diagnostic system according to claim 4 or 6, wherein the diagnostic system is configured to be selectively magnetically attractable.   The analysis means analyzes the measurement data from the measurement means to determine the natural frequency of the diagnostic object as the experimental natural frequency, and defines one abnormal state of the diagnostic object. Define a plurality of individuals as genetic information that characterize the deformation such as the position of the point, and calculate the natural frequency of each individual based on the genetic information to obtain the theoretical natural frequency, and the experiment specific Exploring the individual having the theoretical natural frequency that coincides with the frequency with a predetermined degree of coincidence, identifying the individual with the highest degree of coincidence, and estimating the deformed state from the genetic information of the individual, An analysis database for storing an individual searched by the evaluation unit and enabling the theoretical analysis unit to calculate a theoretical natural frequency using the stored individual in a next diagnosis, Request Diagnostic system according to any one of 1 to 7.   A magnetic plate member is fixed to a concrete structure to be diagnosed, and a vibration device is magnetically adsorbed and fixed to the magnetic plate member, and local vibration is applied from the vibration device to the concrete structure to be diagnosed. And measuring the response to the vibration of the concrete structure to be diagnosed, and the soundness of the concrete structure to be diagnosed based on how the vibration mode obtained by the measurement has changed from the vibration mode at the time of soundness. A method for diagnosing a concrete structure characterized by obtaining a degree.   At least one electromagnet of the vibration device should be magnetically attracted to the magnetic plate member to fix the vibration device, and vibration should be generated by the vibration element of the vibration device to diagnose the vibration. The diagnostic method according to claim 9, wherein the diagnostic method is applied to a surface of a concrete structure.   The diagnostic method according to claim 10, wherein a piezoelectric vibration element is used as the vibration element.   The steel plate as the magnetic plate member is fixed in parallel with the surface of the concrete structure to be diagnosed, and the at least one electromagnet is magnetically attracted to the steel plate during operation. The diagnostic method according to 11.   The diagnostic method according to claim 12, wherein two electromagnets that can be attracted to the steel plate are used as the at least one electromagnet.   A steel plate is fixed to a concrete structure perpendicular to the surface of the concrete structure to be diagnosed as the magnetic plate member, and the at least one electromagnet is magnetically attracted to the steel plate during operation. The diagnostic method according to 10 or 11.   Analyzing the measurement data to determine the natural frequency of the diagnostic object as the experimental natural frequency, defining one abnormal state of the diagnostic object, and information characterizing the abnormality such as the position of the abnormality point as genetic information A plurality of individuals, and calculating the natural frequency of each individual based on the genetic information to obtain a theoretical natural frequency, and the individual having the theoretical natural frequency that matches the experimental natural frequency with a predetermined degree of coincidence To identify the individual with the highest degree of coincidence, estimate the deformed state from the genetic information of the individual, store the searched individual, and use the stored individual in the next diagnosis The diagnostic method according to any one of claims 9 to 14, wherein the natural frequency can be calculated.

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