KR102215035B1 - Crack healing performance monitoring system for self-healing repair mortar based on IoT - Google Patents

Abstract

In the present invention, when a self-healing repair mortar is applied in constructing a repair layer in a concrete structure, the self-healing repair mortar due to cracks as well as cracks in the concrete structure is applied by combining IoT (Internet of Things) IoT technology and wireless communication service technology. It relates to an IoT-based self-healing repair mortar crack healing performance monitoring system that can monitor whether self-healing and repair mortar is installed.In detail, it is mounted on a concrete structure with a self-healing repair mortar layer to measure and measure the temperature and humidity of the concrete structure. One or more sensing units for transmitting one measurement data through a wireless communication network; An analysis server that receives the measurement data transmitted from the sensing unit and compares and analyzes it with a preset reference value to determine whether or not the self-healing repair mortar layer is cured according to cracks and cracks in the concrete structure; And a monitoring unit that receives and monitors the determination result processed by the analysis server.

Description

Crack healing performance monitoring system for self-healing repair mortar based on IoT}

In the present invention, when a self-healing repair mortar is applied in constructing a repair layer in a concrete structure, the self-healing repair mortar due to cracks as well as cracks in the concrete structure is applied by combining IoT (Internet of Things) IoT technology and wireless communication service technology. It relates to an IoT-based self-healing repair mortar crack healing performance monitoring system that can monitor whether or not self-healing.

In general, concrete is the most widely used building material on the planet, and most modern structures from civil engineering and architecture to plants are constructed using concrete.

Concrete deteriorates as its performance gradually decreases after a certain period of time after pouring or molding. In particular, when a crack occurs in concrete, harmful outside air, moisture, and chemical components penetrate into the concrete, which further accelerates the degradation of concrete.

In addition, corrosion may occur in the reinforcing bar inside the concrete structure due to moisture and chloride ions penetrating the inside of the concrete, resulting in additional cracking or falling off of the concrete. As a result, there is a problem that the structure can reach the extent of collapse.

Therefore, regular concrete structures require continuous management and maintenance, and periodic repairs are made to areas where deterioration or cracking occurs or areas where occurrence is predicted, but because they are exposed to the same adverse conditions, not permanent repairs, Due to frequent re-cracking, it is difficult to manage quality due to complicated construction and increased construction cost during renovation.

Therefore, in order to minimize repair defects, there is a need to develop a self-healing repair mortar that has excellent durability of repair mortar and, in particular, has a function to suppress and heal cracks that minimize cracks in repair mortar.

Recently, development and research of self-healing concrete capable of self-healing cracks are being conducted in Korea and abroad. It is expected to have a positive effect.

However, before applying and commercializing repair materials such as self-healing mortar to concrete structures, there are no methods other than regular visual inspections by the manager to determine whether the self-healing mortar is self-healing as well as cracking in the concrete structure. In the case of large structures, a large amount of manpower is required, and time and maintenance costs increase accordingly.

As such, there is currently no way to monitor the degree of self-healing in concrete structures to which self-healing mortar is applied.For effective repair and maintenance of concrete structures, the IoT-based self-healing repair mortar meets the requirements of the 4th Industrial Revolution. It is urgent to introduce a maintenance system for concrete structures that diagnose and monitor the degree and the like.

Korean Patent Registration No. 10-1965886 (2019.04.04)

Therefore, the object of the present invention is to apply self-healing repair mortar in constructing a repair layer in a concrete structure, by combining IoT (Internet of Things) IoT technology and wireless communication service technology, It is to provide an IoT-based self-healing repair mortar crack healing performance monitoring system that can monitor whether the healing repair mortar is self-healing.

As a means for solving the above-described problems, the IoT-based self-healing repair mortar crack healing performance monitoring system (hereinafter referred to as'monitoring system of the present invention') of the present invention is mounted on a concrete structure in which a layer of self-healing repair mortar is formed. One or more sensing units that measure the temperature and humidity of the concrete structure and transmit the measured measurement data through a wireless communication network; An analysis server that receives the measurement data transmitted from the sensing unit and compares and analyzes it with a preset reference value to determine whether or not the self-healing repair mortar layer is cured according to cracks and cracks in the concrete structure; And a monitoring unit that receives and monitors the determination result processed by the analysis server.

As an example, the sensing unit measures the degree of moisture content of the concrete structure and outputs the measured data by measuring a humidity sensor that outputs the measured data and the curing heat generated during the healing process of the self-healing repair mortar. A sensor module including a temperature sensor and a data logger instructing to collect measurement data output from the sensor module and transmit the collected measurement data to the analysis server through a wireless communication network are integrated.

As an example, the sensor module includes a vibration acceleration sensor that has a contact surface that is in close contact with the concrete structure, is attached to the concrete structure, measures vibration at all times, and outputs the measured measurement data, and the vibration acceleration sensor is made of an elastic material. Further comprising an external signal control coating unit applied to the outer surface excluding the contact surface, wherein the external signal control coating unit is applied to the outer periphery excluding the contact surface of the vibration acceleration sensor, the impact resistant coating layer of an elastic material forming a porosity and the impact resistant It is characterized by including a water-repellent coating layer applied to the coating layer.

As an example, the impact resistant coating layer is characterized in that the porous polyurethane resin includes ammonium nitrate and reinforcing fibers.

As an example, the analysis server is characterized in that it receives the measurement data transmitted from the detection unit and analyzes it to further determine the dynamic characteristics and safety of the concrete structure.

As an example, the analysis server may include a signal processing unit for receiving measurement data of a vibration acceleration sensor of the sensor module and processing a signal; A signal analysis unit that analyzes a waveform and a spectrum on the measurement data subjected to signal processing by the signal processing unit, and performs statistical processing on the analyzed waveform and spectrum, and outputs the result; The signal processing unit extracts a mode shape, which is a spatial variable, in the time domain without an FFT operation for measurement data subjected to signal processing by the signal processing unit, and uses the extracted mode shape by the signal processing unit. A time domain decomposition (TDD) unit for extracting a natural frequency and attenuation ratio, which are time variables, by performing a fast Fourier transform (FFT) operation on measurement data on which signal processing has been performed; And a damage determination unit for determining the damage location and degree of damage of the concrete structure using the natural frequency, damping ratio and mode shape extracted by the TDD unit.

As described above, the IoT-based self-healing repair mortar crack healing performance monitoring system of the present invention, when applying the self-healing repair mortar in constructing a repair layer in a concrete structure, combines IoT IoT technology and wireless communication service technology to create a concrete structure. Self-healing repair due to cracks as well as cracks in the mortar can be easily monitored in a remote location rather than on-site, so that more efficient repair and maintenance can be performed.

1 is a diagram schematically showing a monitoring system of the present invention.
2 is a block diagram showing a detailed configuration of a sensing unit, which is one configuration of the present invention.
3 is a block diagram showing a detailed configuration of an analysis server, which is one configuration of the present invention.
4 is a side sectional view showing an example of the sensor module shown in FIG. 2.

Hereinafter, the configuration and operation of the present invention will be described in more detail based on the accompanying drawings. In describing the present invention, terms or words used in the present specification and claims are the present invention based on the principle that the inventor can appropriately define the concept of terms in order to explain his or her invention in the best way. It must be interpreted as a meaning and concept consistent with the technical idea of

1 is a diagram schematically showing a monitoring system of the present invention, and FIG. 2 is a block diagram showing a detailed configuration of a sensing unit, which is a component of the present invention. And FIG. 3 is a block diagram showing a detailed configuration of an analysis server, which is a configuration of the present invention, and FIG. 4 is a side cross-sectional view showing an example of the sensor module shown in FIG. 2.

Referring to FIG. 1, the system of the present invention may include one or more detection units 100, an analysis server 200 and a monitoring unit 300.

The sensing unit 100 is mounted on the concrete structure 10 on which the self-healing repair mortar layer 20 is formed, measures the temperature and humidity of the concrete structure 10, and transmits the measured measurement data through a wireless communication network. have.

The self-healing repair mortar layer 20 may be poured for repair purposes in a region predicting deterioration and cracking of the concrete structure 10.

As an example, the self-healing repair mortar may include a self-healing capsule 21 manufactured in the form of a capsule by using an inorganic material in the form of a powder that reacts with moisture, such as a coagulant. As the inorganic material inside the capsule 21 is discharged and hardened, the self-healing effect on the cracked portion may be expressed.

When the self-healing repair mortar layer 20 is applied as a repair layer, the detection unit 100 measures temperature and humidity, respectively, and provides the measurement data to the analysis server 200 to allow the analysis server 200 to It should be used as basic data to determine whether cracks and self-healing for (10).

At this time, the sensing unit 100 may be installed on a major part of the concrete structure 10 through preliminary irradiation. For example, it is preferable that at least one sensing unit 100 is installed at a location selected as a member to be repaired or a weak member.

Meanwhile, as described above, the sensing unit 100 may measure the temperature and humidity of the concrete structure 10 and transmit the measured measurement data through a wireless communication network.

That is, the sensing unit 100 can implement data transmission using a wireless communication platform to secure mobility and simplify installation while reducing manpower and costs associated with conventional cable installation.

Referring to FIG. 2, the sensing unit 100 may include a sensor module 110 and a data logger 120.

The sensor module 110 measures the degree of moisture content of the concrete structure 10 and measures the curing heat generated during the healing process of the self-healing maintenance mortar and a humidity sensor 111 that outputs the measured data. It may include a temperature sensor 112 for outputting measurement data.

In addition, the data logger 120 may command to collect measurement data output from the sensor module 110 and transmit the collected measurement data to the analysis server 200.

The data logger 120 may be equipped with a communication module supporting wireless communication to transmit measurement data collected through a wireless communication network to the analysis server 200.

At this time, the above-mentioned communication network is an IP network that provides large-capacity data transmission/reception service and data service without interruption through Internet Protocol (IP), which is an IP network structure that integrates different networks based on IP. (All IP) network, mobile communication network (CDMA, 2G, 3G, 4G, LTE), Wibro (Wireless Broadband) network, HSDPA (High Speed Downlink Packet Access) network, satellite communication network and Wi-Fi (Wireless Fidelity) network It may be any one of suitable.

These detection units 100 may be configured in plural and installed at selected major parts of the concrete structure 10, respectively, and identification from the analysis server 200 described below by transmitting unique identification information together with measurement data It can be configured to be possible.

In this case, it is preferable that the sensor module 110 and the data logger 120 are integrated with the sensor module 110 through a single printed circuit board (PCB) design.

The analysis server 200 receives the measurement data transmitted from the detection unit 100 and compares and analyzes it with a preset reference value, and the self-healing repair mortar layer 20 according to the cracks and cracks of the concrete structure 10 Can judge whether or not to heal.

Specifically, the analysis server 200 compares and analyzes the measurement data of the humidity sensor 112 of the sensor module 110 with a preset reference humidity value, and when the measured humidity value exceeds the reference humidity value, the concrete structure ( It can be judged by the crack of 10).

That is, the analysis server 200 may determine the moisture penetration of the concrete structure 10 through the measured humidity, and determine whether the initial humidity is changed after curing of the concrete structure 10 is cracked.

In addition, the analysis server 200 compares and analyzes the measurement data of the temperature sensor 111 of the sensor module 110 with a preset reference humidity value, and when the measured temperature value exceeds the reference temperature value, it is self-healing and maintenance mortar. It can be determined that is in the normal healing process.

That is, the analysis server 200 may determine whether or not the inorganic material of the self-healing repair mortar normally penetrates the crack layer and the temperature value increases due to the curing heat generated during the curing process, and determines whether the temperature value is changed. Through this, the healing performance can be predicted.

As described above, in the system of the present invention, effective repair and maintenance of the concrete structure 10 can be achieved by monitoring the degree of self-healing in the concrete structure 10 to which the self-healing repair mortar is applied. In addition to monitoring the healing performance, a change in the state of the repair section over time can be predicted through the accumulated data of the measurement data of the sensing unit 100, and thus more effective maintenance management can be performed by monitoring this.

The monitoring unit 300 receives the determination result processed by the analysis server 200 and displays it so that the administrator can easily monitor the processing result of the analysis server 200.

The monitoring unit 300 may include a display terminal granted access authority from the analysis server 200, wherein the display terminal is any of a personal computer (PC), a smartphone, a tablet, a cellular phone, a PDA, and a laptop computer. It can be one.

In addition, the display terminal may be loaded with application software and a user interface (UI) capable of displaying data and processing results provided from the analysis server 200 in advance.

Such a monitoring unit 300 may be provided in a remote control center, and receive and store data processed from the analysis server 200 through the analysis server 200 and a wired or wireless communication network, and accumulate the statistics. By providing the system, it is possible for the manager to search the field data from a distance.

Meanwhile, according to the monitoring system of the present invention, the sensor module 110 may further include a vibration acceleration sensor 113 that measures a vibration signal for a selected main part of the concrete structure 10 and outputs the measured measurement data. In addition, the analysis server 200 receives measurement data of the vibration signal of the vibration acceleration sensor 113 transmitted from the detection unit 100 and analyzes the dynamic characteristics and safety of the concrete structure 10 based on this. have.

The analysis server 200 is configured to directly extract a mode shape in a time domain without Fourier transform for a mode shape as a spatial variable. Accordingly, it is possible to quickly extract the mode shape in real time by performing a high-difficulty calculation for the constant vibration signal measured by the detection unit 100 installed in the concrete structure 10 more quickly.

Referring to FIG. 3, the analysis server 200 may include a signal processing unit 210, a signal analysis unit 220, a time domain decomposition (TDD) unit 230, and a damage determination unit 240.

First, the sensing unit 100 may be installed in a plurality of locations of the concrete structure 10 as mentioned above. In this way, when p units of the sensing unit 100 are installed in the structure, it may be configured to output a time history of response acceleration with respect to time t as shown in Equation 1 below.

는 가속도 벡터로서

이고,

는 i번째 모드 형상 벡터로서

이고,

는 i번째 기여도(contribution factor)이고, p는 감지부(100)의 위치를 나타낸다.here,

Is the acceleration vector

ego,

Is the ith mode shape vector

ego,

Is the i-th contribution factor, and p is the location of the sensing unit 100.

The signal processing unit 210 may be configured to receive measurement data for a vibration signal transmitted from the sensing unit 100 and perform signal processing.

For example, the signal processing unit 210 may perform signal processing such as data filtering and noise removal on measurement data.

The signal analysis unit 220 may analyze a waveform and a spectrum of measurement data subjected to signal processing by the signal processing unit 210, perform statistical processing on the analyzed waveform and spectrum, and output the result.

The signal analysis unit 220 uses the measurement data for the vibration signal to express the calculus of acceleration data, the acceleration vector sum, and the maximum, minimum, average, kurtosis, skewness, root mean square (RMS), and median of the vibration signal. , Can be configured to perform statistical processing such as standard deviation.

In addition, the signal analysis unit 220 expresses PGA (Peak Ground Acceleration) of measurement data for vibration signals, MMA (Min, Max, Avg) data, cumulative absolute speed (CAV) display, time history attenuation, power spectrum, response. It can be configured to perform analysis and statistical functions such as spectrum (acceleration, velocity, displacement response spectrum display), seismic intensity extraction, Arias intensity display, and multiple display of analysis data.

The TDD unit 230 basically calculates and extracts a mode shape in a time domain with respect to measurement data subjected to signal processing by the signal processing unit 210, and calculates a natural frequency and a damping ratio in a spatial domain. It is configured to extract an operation from the phase.

In the past, FFT (Fast Fourier Transform) was performed on the mode shape to increase the amount of computation and the difficulty of computation. Considering that the larger the structure, the greater the number of vibration acceleration sensors 113, the greater the computational amount, and the computational burden was very high. However, in the present invention, it is possible to monitor the mode shape in real time by developing an algorithm capable of directly extracting the mode shape in the time domain without FFT operation. Explain in more detail.

를 심볼

로 표시할 경우 계측 가속도 시간 응답은 하기 수학식 2와 같이 근사화될 수 있다.First, random time in Equation 1

Symbol

When expressed as, the measured acceleration time response can be approximated as in Equation 2 below.

Here, n is the number of modes of the measurement acceleration signal.

를 추출하도록 구성될 수 있다.The TDD unit 230 designs a digital band pass filter to extract the terminal induction signal having only the i-th mode, and the terminal induction signal having the i-th mode by Equation 3 below

Can be configured to extract.

In addition, the TDD unit 230 may be configured to collect N acceleration time samples according to Equation 4 below.

Equation 4 can be simplified as in Equation 5 below.

행렬

i번째 모드만 가지고 있는 단자유도 가속도 신호를 나타낸다. 그리고 벡터

는 i번째 모드의 가속도 신호 이력에 대한 기여도를 나타낸다.here,

procession

It represents a terminal-induced acceleration signal that has only the ith mode. And vector

Denotes the contribution to the history of the acceleration signal in the ith mode.

Meanwhile, the TDD unit 230 may be configured to output an energy correlation of the i-th terminal induced acceleration response signal by an output energy correlation matrix according to Equation 6 below.

는 i번째 단자유도 가속도 신호를 갖는 행렬

를 나타낸다.here,

Is the matrix with the ith terminal-induced acceleration signal

Represents.

The TDD unit 230 may be configured to calculate Equation 7 below by substituting Equation 5 into Equation 6.

는

로서 기여도

의 에너지 강도를 나타낸다. 수학식 7은 i번째 가속도 응답 신호에 잡음이 없는 상태의 이상적인 경우를 나타낸다.here,

Is

Contribution as

Represents the energy intensity of Equation 7 shows an ideal case in which there is no noise in the i-th acceleration response signal.

Meanwhile, noise existing in the energy correlation matrix may be expressed as Equation 8 below as an orthogonal noise space for the i-th mode shape.

는 i번째 잡음 기저를 나타내고,

는 i번째 잡음 모드의 강도를 나타낸다.Where, the px1 vector

Represents the ith noise basis,

Represents the intensity of the ith noise mode.

Equation 8 can be simplified as shown in Equation 9 below.

는

로서 특이 행렬 벡터(singular vector matrix)이고,

는

로서 특이치 행렬을 나타낸다. i번째 단자유도 가속도 응답의 지배적인 에너지는 i번째 모드 형상

이므로, 특이값의 크기 순서는

이 된다.here,

Is

Is a singular vector matrix,

Is

Denotes the singular value matrix. The dominant energy of the ith terminal induced acceleration response is the ith mode shape

So, the order of magnitude of the singular values is

Becomes.

의 특이행렬 벡터 중에서 첫번째 열 벡터(column vector)가 된다. 상기 TDD부(230)에서는 이를 모드 형상으로서 출력하게 된다.Thus, the ith mode shape vector is

It becomes the first column vector among singular matrix vectors of. The TDD unit 230 outputs this as a mode shape.

The TDD unit 230 may be configured to extract a natural frequency and a damping ratio in addition to the mode shape.

The TDD unit 230 performs a fast Fourier transform (FFT) operation on the measurement data for the vibration signal for which the signal processing has been performed by the signal processing unit 210 using the previously extracted mode shape, And a damping ratio.

Hereinafter, the TDD unit 230 will be described in more detail.

을 산출하도록 구성될 수 있다.The TDD unit 230 uses the i-th mode shape vector extracted from the TDD unit 230, as shown in Equation 10 below, as an acceleration cross correlation function representing the i-th mode.

Can be configured to yield.

는 시간 잡음을 포함하고 있기 때문에, TDD부(230)는 q의 시간 샘플에 대하여 하기 수학식 11과 같이 상관 관계 행렬

를 정의한다.Acceleration cross correlation function in Equation 10

Since n contains temporal noise, the TDD unit 230 performs a correlation matrix with respect to the temporal sample of q as shown in Equation 11 below.

Defines

에 대하여 하기 수학식 12에 의해 특이치 분해 과정 SVD(singular value decomposition)을 수행하여 직교 잡음을 제거하도록 구성될 수 있다.And the TDD unit 230 is a correlation matrix

It may be configured to remove orthogonal noise by performing a singular value decomposition (SVD) process according to Equation 12 below.

에서 가장 큰 특이치를 갖는 가속도 상호 상관 함수 벡터

는 특이치 행렬

중에서 가장 큰 특이치에 상응하는 특이치 벡터이며 다음 수학식 13과 같이 산출될 수 있다.Here, a correlation matrix representing the i-th mode from which orthogonal noise is removed

Acceleration cross-correlation function vector with largest singular value in

Is the outlier matrix

Among them, it is a singular value vector corresponding to the largest singular value, and can be calculated as Equation 13 below.

에 대한 고유 진동수와 감쇠비를 추출하도록 구성될 수 있다.Here, the representative single degree of freedom (SDOF) acceleration cross-correlation function for each mode extracted by Equation 13 has the same form as a free vibration function. Accordingly, the acceleration cross-correlation function vector is applied by applying a system identification (SI) technique from the data for each mode extracted using the TDD technique.

It can be configured to extract the natural frequency and damping ratio for.

The SI technique is a kind of inverse analysis and is a technique that optimizes the simulation system variables that make the measured and simulated values the same.

에서 자유진동 함수

를 고려할 수 있다.And the TDD unit 230 is a random time according to Equation 14

Free oscillation function in

Can be considered.

는 진폭,

는 고유 진동수,

는 감쇠비,

는 감쇠 고유 진동수,

는 이동각(translation angle)이며, 이로부터 고유 진동수와 감쇠비를 예측할 수 있다.here,

Is the amplitude,

Is the natural frequency,

Is the damping ratio,

Is the damping natural frequency,

Is the translation angle, from which the natural frequency and the damping ratio can be predicted.

로서 그 크기는 다음 수학식 15와 같이 표현될 수 있다.Variables to be recognized are natural frequency, damping ratio, amplitude, and moving angle, and these are the recognition vectors which are a set of variables.

The size can be expressed as Equation 15 below.

은 인식 변수 벡터의 함수이고 테일러(Taylor) 급수 전개 후 고차항을 무시하면 상호 상관의 변량

는 다음 수학식 16과 같이 정의될 수 있다.Here, the cross-correlation of the ith mode at any time t

Is a function of the vector of recognition variables, and if the higher-order term is ignored after Taylor series expansion,

May be defined as in Equation 16 below.

The cross-correlation variance can be expressed as Equation 17 below.

은 인식 변수 벡터

의 n번째 항이며,

은 i번째 고유 진동수를 나타내고

는 i번째 모드의 감쇠비

를 나타낸다.here,

Is the recognition variable vector

Is the nth term of,

Represents the i-th natural frequency

Is the damping ratio of the ith mode

Represents.

Equation 17 may be standardized as shown in Equation 18 below.

When the number of samples of the cross-correlation function is q, Equation 18 can be described as a simple linear sensitivity equation as shown in Equation 19 below.

는 고유 진동수의 변화율로서 다음 수학식 20과 같이 표현될 수 있다.Where, q X 1 vector

Is a rate of change of the natural frequency and can be expressed as Equation 20 below.

는 인식 변수들의 변화율을 나타내며, 다음 수학식 21과 같이 표현될 수 있다.p X 1 vector

Represents the rate of change of the recognition variables, and can be expressed as Equation 21 below.

는 민감도 행렬(sensitivity matrix)로서 인식 변수들에 대한 고유 진동수의 변화율을 나타낸다.P X q vector in Equation 22

Is a sensitivity matrix and represents the rate of change of natural frequencies for recognition variables.

For example, the TDD unit 230 may obtain a solution to the sensitivity equation of Equation 19 by using an iterative method, and the order is as follows.

1) Assume the recognition variables in the j-th repetition step as shown in Equation 23 below.

Here, the superscript j of the recognition variables means the number of repetition steps.

2) Mutual correlation is obtained by performing the simulation of Equation 14 on the recognition variable vector.

를 구한다. 이때, 민감도 행렬은 각 인식변수의 단위 변화에 따른 상호상관 변화를 계산하여 근사적으로 산정한다.3) The sensitivity matrix of Equation 22 for the simulation model of 2) above.

Find At this time, the sensitivity matrix is approximated by calculating the cross-correlation change according to the unit change of each recognition variable.

는 다음 수학식 24와 같다.4) Vector of rate of change of cross-correlation

Is represented by Equation 24 below.

는 i번째 모드에 대한

에서 수학식 13으로부터 추출된 계측 상호 상관이고,

는 j번째 반복 단계에서 인식 변수 벡터들을 이용하여 구한

에서 i번째 모드에 대한 수학식 13의 시뮬레이션 값이다.here,

Is for the ith mode

Is the measurement cross-correlation extracted from Equation 13,

Is obtained using the recognition variable vectors in the jth iteration step.

Is the simulation value of Equation 13 for the i-th mode.

는 다음 수학식 25와 같이 표현될 수 있다.5) Rate of change of the recognition variable vectors using Equation 19

Can be expressed as in Equation 25 below.

는

의 의사역행렬(pseudo inverse matrix)이고, 수학식 26에 의해 근사화될 수 있다.here,

Is

Is a pseudo inverse matrix of, and can be approximated by Equation 26.

6) The recognition variable vector may be updated as shown in Equation 27 below in the j+1 th iteration step.

는 j번째 반복 단계에서 인식 변수 벡터

의 n번째 항이며,

은 인식 변수의 변화율 벡터

의 n번째 항이다.here,

Is the vector of the recognized variable in the j iteration step

Is the nth term of,

Is the rate of change vector of the recognition variable

Is the nth term of.

이 0으로 수렴할 때까지 반복한다.7) Change rate of each recognition variable in Equations 23 to 27 for the recognition variable vector updated by Equation 27

Repeat until this converges to zero.

Meanwhile, the damage determination unit 240 may be configured to determine the damage location and degree of damage of the concrete structure 10 using the natural frequency, damping ratio, and mode shape extracted by the TDD unit 230.

Hereinafter, a method of extracting the dynamic characteristics of the concrete structure 10 using the monitoring system of the present invention mentioned above will be described.

First, the sensing unit 100 may measure the real-time vibration of the concrete structure 10 and transmit the measured measurement data through a wireless communication network.

Here, when p units are installed in the structure, the sensing unit 100 may be configured to calculate a time history of the response acceleration with respect to time t as shown in Equation 28 below.

는 가속도 벡터로서

이고,

는 i번째 모드 형상 벡터로서

이고,

는 i번째 기여도(contribution factor)이고, p는 상기 감지부(100)의 위치를 나타낸다.here,

Is the acceleration vector

ego,

Is the ith mode shape vector

ego,

Is the i-th contribution factor, and p is the position of the sensing unit 100.

Next, the signal processing unit 210 receives measurement data for the vibration signal transmitted from the sensing unit 100 through a wireless communication network and processes the signal.

Further, the signal analysis unit 220 analyzes the waveform and spectrum of the measurement data on which the signal processing has been performed by the signal processing unit 210, and performs statistical processing on the analyzed waveform and spectrum, and outputs the result.

Next, the TDD (time domain decomposition) unit 230 is a mode shape that is a spatial variable in the time domain without FFT operation on the measurement data for which signal processing has been performed by the signal processing unit 210 Extract.

를 추출한다.Here, the TDD unit 230 is a terminal induction signal having an i-th mode according to Equation 29 below using a digital band pass filter.

Extract.

Then, N acceleration time samples are collected by Equation 30 below.

Then, the energy correlation of the i-th terminal induced acceleration response signal is output using an output energy correlation matrix according to Equation 31 below.

는 i번째 단자유도 가속도 신호를 갖는 행렬

를 나타내고

로 간략화된다.here,

Is the matrix with the ith terminal-induced acceleration signal

Represents

Is simplified to

를 에너지 상관관계 행렬에 대입하여 하기 수학식 32를 산출한다.And

Substituting in the energy correlation matrix to calculate Equation 32 below.

는

로서 기여도

의 에너지 강도를 나타낸다.here,

Is

Contribution as

Represents the energy intensity of

In addition, the noise existing in the energy correlation matrix is expressed as an orthogonal noise space for the i-th mode shape as shown in Equation 33 below.

는 i번째 잡음 기저를 나타내고,

는 i번째 잡음 모드의 강도를 나타낸다.Where, the px1 vector

Represents the ith noise basis,

Represents the intensity of the ith noise mode.

의 첫번째 열 벡터(column vector)를 i번째 모드 형상 벡터로서 추출한다.And in the following Equation 34 that simplified Equation 33

The first column vector of is extracted as the i-th mode shape vector.

는

로서 특이 행렬 벡터(singular vector matrix)이고,

는

로서 특이치 행렬을 나타낸다.here,

Is

Is a singular vector matrix,

Is

Denotes the singular value matrix.

Next, the TDD unit 230 performs a fast Fourier transform (FFT) operation on the measurement data on which signal processing has been performed by the signal processing unit 210 using the previously extracted mode shape, and the natural frequency and attenuation ratio, which are time variables. Extract.

을 산출한다.Here, an acceleration cross correlation function representing the I-th mode as shown in Equation 35 below using the i-th mode shape vector extracted from the TDD unit 230

Yields

를 정의한다.And the correlation matrix for the time sample of q as shown in Equation 36 below

Defines

에 대하여 수학식 37에 의해 특이치 분해 과정 SVD(singular value decomposition)을 수행하여 직교 잡음을 제거한다.And the correlation matrix

Singular value decomposition (SVD) is performed by Equation 37 to remove orthogonal noise.

에서 가장 큰 특이치를 갖는 가속도 상호 상관 함수 벡터

를 산출한다.And it represents the i-th mode with orthogonal noise removed, and the correlation matrix

Acceleration cross-correlation function vector with largest singular value in

Yields

에 대해 시간

에 대한 자유 진동 함수

를 하기 수학식 39과 같이 산출하고, 산출된

로부터 고유 진동수, 감쇠비를 추출한다.Here, the calculated acceleration cross-correlation function vector

About time

Free vibration function for

Is calculated as in Equation 39 below, and the calculated

The natural frequency and damping ratio are extracted from.

는 진폭,

는 고유 진동수,

는 감쇠비,

는 감쇠 고유 진동수,

는 이동각(translation angle)이다.here,

Is the amplitude,

Is the natural frequency,

Is the damping ratio,

Is the damping natural frequency,

Is the translation angle.

Next, the damage determination unit 240 determines the damage location and degree of damage of the concrete structure 10 using the natural frequency and damping ratio and mode shape extracted by the TDD unit 230.

Meanwhile, the analysis server 200 may further include a display unit 250 for displaying result information processed by itself.

For example, the display unit 250 displays the damage location and degree of damage of the structure derived from the damage determination unit 240 so that the site manager can easily determine the degree of damage.

Meanwhile, in the monitoring system of the present invention, in configuring the sensor module 110 as shown in FIG. 4, a vibration acceleration sensor 113 attached to the structure having a contact surface in close contact with the concrete structure 10, and An example configured to include an external signal control coating unit 130 applied to the outside of the vibration acceleration sensor 113 except for the contact surface of the vibration acceleration sensor 113 made of an elastic material is presented.

That is, in the case of the present embodiment, while protecting the vibration acceleration sensor 113 from the outside, the vibration acceleration sensor 113 blocks the transmission of the shock signal to the vibration acceleration sensor 113 against an external physical shock. This is to accurately sense only the vibration transmitted from the structure 10.

In the case of the external signal control coating unit 130, by mitigating the external shock transmitted to the external signal control coating unit 130, vibration energy caused by the external shock is prevented from being transmitted to the vibration acceleration sensor 113. will be.

The external signal control coating unit 130 should be made of an elastic material so that external shock can be mitigated and absorbed.

However, the external shock mentioned above directly corresponds to a physical shock such as an impact caused by an object, a natural disaster such as rain, wind, etc.In addition to these physical shocks, sound waves such as the sound of wind and bridges Even when the vibration energy caused by is transmitted to the vibration acceleration sensor 113, the sound wave acts as noise when the vibration acceleration sensor 113 senses the vibration of the structure.

In addition, when water droplets due to moisture are formed outside the vibration acceleration sensor 113, these water droplets distort the vibration signal transmitted from the data logger 120 or distort the vibration energy by physical shock and sound waves transmitted from the outside. It acts as a factor deteriorating the accuracy of the vibration signal generated in

Accordingly, in the present invention, in configuring the external signal control coating unit 130 as shown in FIG. 4, the impact resistance of an elastic material that is applied to the outer periphery except for the contact surface of the vibration acceleration sensor 113 and forms a porous An example in which the coating layer 130-2 and the water-repellent coating layer 130-1 applied to the impact-resistant coating layer 130-2 are included is presented.

The above-mentioned physical external shock is alleviated by the impact-resistant coating layer 130-2 of elastic material forming the pores, and the external signal caused by the physical shock and external signal by the sound wave are absorbed by absorbing the vibration energy caused by the sound wave. It is to block the transmission of the signal to the vibration acceleration sensor 111.

The impact resistant coating layer 130-2 is not limited if it is an elastic material forming pores, but when there is a crack in the impact resistant coating layer 130-2, vibration caused by the external factors mentioned above is caused by a vibration acceleration sensor ( 113).

Such cracks may be generated by curing heat during the application process of the impact resistant coating layer 130-2 or by drying shrinkage after curing.

Accordingly, in the present invention, in configuring the impact resistant coating layer 130-2, an example in which ammonium nitrate and reinforcing fibers are included in the porous polyurethane resin is presented.

Ammonium nitrate absorbs heat generated during the curing process of the porous polyurethane resin and at the same time absorbs organic substances contained in the paste. As described above, by absorbing heat from the paste during the curing process, the ammonium nitrate controls cracking due to the curing heat, that is, the shrinkage of the impact resistant coating layer 130-2.

That is, ammonium nitrate absorbs the heat of hardening to control cracking. In addition, when organic substances are present in the pores of the impact-resistant coating layer 130-2 formed of porous polyurethane resin, there may be a problem that the sound absorbing function is deteriorated due to the function expressed by the pores by the organic substances. It is to solve this problem by adsorption.

In addition, the reinforcing fiber is not limited to its type, such as polyvinyl chloride and polypropylene, but the reinforcing fiber is included in the impact resistant coating layer 130-2 to control cracking due to drying shrinkage after curing by the expression of physical crosslinking action. Is to do. In other words, it is to physically control the crack.

Preferably, in constructing the impact resistant coating layer 130-2, it is reasonable to include 1 to 10 parts by weight of ammonium nitrate and 1 to 3 parts by weight of reinforcing fibers per 100 parts by weight of the porous polyurethane resin.

In addition, the water-repellent coating layer 130-1 applied to the impact-resistant coating layer 130-2 distorts the vibration signal from the outside or inside, as mentioned above, when water droplets form on the impact-resistant coating layer 130-2 due to moisture, etc. This is to prevent water droplets from forming on the impact resistant coating layer 130-2. Since the water-repellent coating layer 130-1 includes various known materials, detailed descriptions thereof will be omitted.

It will be appreciated by those skilled in the art through the above description that various changes and modifications can be made without departing from the technical idea of the present invention. Therefore, the technical scope of the present invention is not limited to the contents described in the detailed description of the specification, but should be determined by the claims.

100: sensing unit 110: sensor module
111: temperature sensor 112: humidity sensor
113: vibration acceleration sensor 120: data logger
130: external signal control coating unit 200: analysis module
210: signal processing unit 220: signal analysis unit
230: TDD unit 240: damage judgment unit
250: display unit 300: monitoring unit

Claims (6)

At least one sensing unit mounted on a concrete structure on which a self-healing repair mortar layer is formed to measure the temperature and humidity of the concrete structure and transmit the measured measurement data through a wireless communication network;
An analysis server that receives the measurement data transmitted from the sensing unit and compares and analyzes it with a preset reference value to determine whether or not the self-healing repair mortar layer is cured according to cracks and cracks in the concrete structure; And
Including; a monitoring unit for receiving and monitoring the determination result processed by the analysis server,
The sensing unit,
A sensor module including a humidity sensor that measures the degree of moisture content of the concrete structure and outputs the measured data, and a temperature sensor that measures the curing heat generated during the healing process of the self-healing mortar and outputs the measured data, An IoT-based self-healing maintenance mortar crack healing performance monitoring system, characterized in that a data logger commanding to collect measurement data output from the sensor module and transmit the collected measurement data to the analysis server is integrated. .
delete The method of claim 1,
The sensor module,
A vibration acceleration sensor that has a contact surface that is in close contact with the concrete structure and is attached to the concrete structure to measure vibration at all times and outputs the measured measurement data, and an external signal applied to the outside except the contact surface of the vibration acceleration sensor made of an elastic material. Further comprising a control coating unit,
The external signal control coating unit,
It is applied to the outer periphery of the vibration acceleration sensor, excluding the contact surface, and includes an impact-resistant coating layer of elastic material that forms a pore and a water-repellent coating layer applied to the impact-resistant coating layer. system.
The method of claim 3,
An IoT-based self-healing repair mortar crack healing performance monitoring system, characterized in that the impact resistant coating layer contains ammonium nitrate and reinforcing fibers in a porous polyurethane resin.
The method of claim 3,
The analysis server,
A crack healing performance monitoring system for IoT-based self-healing repair mortar, characterized in that it further determines the dynamic characteristics and safety of the concrete structure by receiving the measurement data transmitted from the sensing unit and analyzing it.
The method of claim 5,
The analysis server,
A signal processing unit that receives measurement data of the vibration acceleration sensor of the sensor module and performs signal processing;
A signal analysis unit that analyzes a waveform and a spectrum on the measurement data subjected to signal processing by the signal processing unit, and performs statistical processing on the analyzed waveform and spectrum, and outputs the result;
The signal processing unit extracts a mode shape, which is a spatial variable, in the time domain without an FFT operation for measurement data subjected to signal processing by the signal processing unit, and uses the extracted mode shape by the signal processing unit. A time domain decomposition (TDD) unit for extracting a natural frequency and attenuation ratio, which are time variables, by performing a fast Fourier transform (FFT) operation on measurement data on which signal processing has been performed; And
The crack healing performance of the IoT-based self-healing repair mortar, comprising: a damage determination unit that determines the damage location and degree of damage of the concrete structure using the natural frequency, damping ratio and mode shape extracted by the TDD unit. Monitoring system.

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