RU2557343C1 - Method of determining signs and location of place of change of stressed-deformed state of buildings, structures - Google Patents

Abstract

FIELD: testing equipment.

SUBSTANCE: in implementing the method, a mathematical model of the structure is created, the adequacy of fluctuations of the real structure and its model is determined, the energy parameter for each of the elements of the structure in selected points is determined, and the change in the energy parameter of the structure is determined. At current values of change in energy parameter, different from a single value within a predetermined threshold value, the absence in the relevant registration points of the stress-deformed states is estimated, in excess of the value of change in the energy parameter of the predetermined threshold, followed by continuous growth of the value, the conclusion is made on the presence of stress-deformed states of the controlled object at such point.

EFFECT: increase in the operation speed and accuracy of determining the stress-deformed state of the controlled object, the ability of use of the method in the construction of automated systems of monitoring of engineering structures of buildings, enhanced functional capabilities, extension of the scope of application.

5 cl, 9 dwg, 1 tbl

Description

The invention relates to the field of testing structures or structures for vibration, shock loads, and in particular to methods and means for diagnosing the technical condition of designed, under construction, reconstructed construction objects, including long-span, high-rise and other unique buildings and structures.

In the manufacture of building structures, construction of industrial and civil facilities, inspection of buildings and structures to be reconstructed, quality control of building structures and products in the process of their manufacture is carried out, as well as their condition is diagnosed during operation. To control the main quality parameters of building structures characterizing their strength, rigidity and stability, selective destructive tests are currently carried out, which are ineffective during the operation of the facility, do not provide reliability of the control results, require the destruction of a large number of products (Interstate standard GOST 8829- 94 "Methods of loading tests. Rules for evaluating the strength, stiffness, crack resistance", entered into force 07/17/1997). For large-span, high-rise and other unique and responsible buildings and structures with regulatory documents (GOST P 53778-2010 "Buildings and Structures. Rules for the examination and monitoring of technical condition" and GOST 31937-2011 "Buildings and structures. Rules for the inspection and monitoring of technical condition") It is planned to create automated systems for monitoring the deformation state of load-bearing structures.

For the effective operation of automated systems for monitoring building structures, passive methods of non-destructive testing are required, which can be implemented in an automated and / or automatic mode and do not require the use of external loads (shock pulses, vibration machines). Methods based on the use of external loads (shock pulses, vibrating machines) cannot be used at the stage of operation of buildings, and their implementation in an automated and / or automatic mode is not economically justified.

Therefore, the development of new passive methods of non-destructive testing, integrally characterizing the quality of building structures, is a very relevant area of research in the theory of structures and in the field of quality management of building products. Among the promising methods of non-destructive quality control, experimental-theoretical methods occupy a special place, based on vibration technologies.

Non-destructive methods of control of building structures are known, which are based on vibration methods, including methods based on experimentally obtained by professor Korobko V.I. patterns in structural mechanics, consisting in the presence of a functional relationship between the stiffness of elastic structures and their main frequency of vibrations. The dependence obtained experimentally was used in the “Method for controlling the bending stiffness of reinforced concrete elements” protected by the copyright certificate (SU 1640595, publ. 07.04.1991, MKI A1 G01M 7/02), according to which the rigidity of the test product is determined as a function of the maximum deflection of the reference product, frequencies of the main oscillations of the reference and test products.

A disadvantage of the known analogue is that it does not solve the problem of determining the stress-strain state of an object and the places of localization of its underlying defects in the test object.

A known method of non-destructive quality control of a finished reinforced concrete product (RU patent No. 2097727, publ. 11/27/1997, G01M 7/02), according to which the controlled product is mounted on supports, mainly in accordance with operating conditions, affect the product using a source of excitation of mechanical vibrations . Oscillations of the product are converted with the help of a receiver of mechanical vibrations into an electrical signal, the magnitude of which is used to judge the amplitude of the vibrations of the product. By changing the frequency of the excited oscillations, a dependence of the amplitude of the longitudinal oscillations on the oscillation frequency is obtained. Using an electronic oscilloscope to control the shape of mechanical vibrations in the product.

The obtained amplitude-frequency characteristic of the longitudinal vibrations of the controlled product determines the resonant frequency and the logarithmic decrement. After turning off the source of excitation of mechanical vibrations, the same parameters are determined in the mode of free damped oscillations of the product.

The obtained values of the dynamic parameters of the controlled product and / or changes in these values depending on the levels of excitation energy of longitudinal vibrations are compared with the values of the corresponding dynamic parameters and / or changes in these values depending on the level of excitation energy of the reference product obtained with the same operating parameters. Based on a comparison of the values and / or changes in the values of the dynamic parameters of the reference and controlled products, a judgment is made about the strength, stiffness, crack resistance and the prestressing value of the reinforcement of the tested product.

The disadvantages of this method: the inapplicability to the control of high-rise buildings, structures of complex configuration in the process of their operation, reconstruction, the inability to localize defects of the controlled structure.

A known method of monitoring the integral quality parameters of reinforced concrete structures in the form of flat and ribbed beam slabs (patent RU No. 2162218, publ. 01.20.2001, IPC 7 G01N 3/32, G01 L5 / 04), which includes installing the slab on a stand, fixing it to supports, excitation in the plate of oscillations at the resonant frequency, measurement of this oscillation frequency f and the logarithmic damping decrement of the oscillations δ and comparison of the obtained dynamic characteristics with the same characteristics of the reference plates, while additionally loading the plates It is concentrated load P uniformly distributed in the transverse direction of the plate and applied sequentially in predetermined sections of the span L.

Additional loading with a concentrated load of large mass applied in certain parts of the span is carried out to reduce the effect of a non-flatness defect of the lower face of a reinforced concrete flat or ribbed slabs on their dynamic characteristics in the mode of bending vibrations (due to loading, a closer fit of the lower face of the plate to the supporting devices is achieved, and for a ribbed slab - its more even bearing on corner points). Due to this, the influence of the torsional component on transverse vibrations decreases or disappears altogether, which makes it possible to more accurately determine the dynamic characteristics of the controlled plates and, accordingly, more accurately assess their quality parameters from these dynamic characteristics. For each loading stage, the corresponding dynamic characteristics are determined and the graphic dependences f-lp / L and δ-lp / L are constructed, where lp is the coordinate of the cross section to which the concentrated force P is applied, and judging by the deviation of these curves from the reference ones, the suitability of the design is controlled quality parameters for operation, and in the form of deviations - about the location of the defect.

The disadvantages of this method: the inapplicability to high-rise buildings, structures of complex configuration in the process of their operation, the need for the application of concentrated force, which complicates the use of the method in an automated mode.

The technical result, the claimed method is aimed at, is to increase the speed and accuracy of determining the deformation-stress state of the controlled object, the possibility of using the method to build automated systems for monitoring building structures, expanding the functionality due to the possibility of localizing the defect of the controlled object, determining its time occurrence, as well as in expanding the scope by spreading to high Other buildings and unique structures in the process of their design, operation, reconstruction, in the presence of both bending and torsional vibrations.

The method is based on the analysis of time series of oscillations (displacement, speed, acceleration) of building structures of buildings, structures.

The method is based on the hypothesis that when the stress-strain state of structures changes, the vibrational energy of structures changes. In this case, if there is information on the vibration parameters of structures at various points in the building, then a change in the vibration energy signals changes in the stress-strain state at the corresponding points.

According to the Fourier transform, the periodic function can be represented as the sum of individual harmonic components (sinusoids and cosines with different amplitudes A and frequencies ω).

Harmonic vibrations are movement according to the following law:

X = A sin (ωt + φ),

Where

A is the oscillation amplitude;

ω is the oscillation frequency;

φ is the oscillation phase.

The kinetic energy of harmonic oscillations is calculated by the following formula:

, $$X=\frac{m{v}^2}{2}$$

,

Where

m - mass of the oscillating body (points)

v is the speed of the oscillating body (points)

The speed of harmonic oscillations is the derivative of the movement of harmonic oscillations in time:

Accordingly, the formula for calculating the kinetic energy of vibration takes the following form:

The potential energy of harmonic oscillations when the oscillating point deviates at a distance x from the equilibrium position is calculated by the formula:

F is the force equal to the product of mass and acceleration:

,

,

then the potential energy takes the form:

The total energy of harmonic oscillations takes the form:

Thus, the total energy of the oscillation is directly proportional to the mass, squared amplitude and frequency of the oscillation.

It is known that the values of the natural frequencies of oscillations are associated with the mass and rigidity of the structure by the following dependence:

,

,

Where

m is the mass;

k is the stiffness.

If we fix the mass of structures as an unchanged value (during the operation of the building, changes in mass compared to the mass of the entire building are insignificant) and the occurrence of defects is considered as a change in stiffness, then a change in A ² · ω ² indicates the occurrence of defects in the building structures.

, где n - количество точек (частот) в спектре, которое определяется длиной записи колебаний dT (временного окна). Для вычисления суммарного энергетического параметра в точке осуществляется суммирование энергетических параметров по осям S=S_x+S_y+S_z.The calculation of these parameters can be carried out by recording the accelerations (velocities, displacements) of the oscillations along one or several axes X, Y, Z of the coordinate system associated with the building with a given time window (dT) at different points of the building, calculating the spectral characteristics of the oscillations in each such point, the calculation of the energy parameters A ² · ω ² at each point and along each axis in the form of the sum of the square of the products of the amplitudes at the corresponding frequencies - $$S={\displaystyle {\sum }_i^{\mathrm{<figure-callout\; id="2"\; label="n\; A\; i"\; filenames="00000026.png,00000027.png"\; state="\{\{state\}\}">n\; </figure-callout>}}{A}_i^{}{}_2^{}\cdot {\mathrm{<figure-callout\; id="2"\; label="\omega \; i"\; filenames="00000026.png,00000027.png"\; state="\{\{state\}\}">\omega \; </figure-callout>}}_i^{}}$$

, where n is the number of points (frequencies) in the spectrum, which is determined by the length of the recording of vibrations dT (time window). To calculate the total energy parameter at a point, the energy parameters are summed along the axes S = S _x + S _y + S _z .

The change in energy parameters over time can be defined as the ratio of S _t - the value of the energy parameter at the current time t - to the value of S ₀ at the previous time, relative to which the change in the stress-strain state of building structures for each measurement point is determined.

In accordance with the above, the value of the change in the energy parameter for time t is determined by the formula:

,

,

Where

K is the change in the energy parameter,

S _t is the value of the parameter at time t,

S ₀ - parameter value at the previous moment.

The feasibility of the claimed method with the achievement of the claimed technical result was tested on the example of a high-rise 40-story building, the design height of which is 138 m. The building structures are made of reinforced concrete. The height of the typical floor is 3.3 m. On the first and second floors, under the entire area of the courtyard, there is an underground parking lot, which is separated by a deformation seam from the high-rise part of the building. The cross-section (plan) of the high-rise part of the building is characterized by a cross-wall diagram of load-bearing structures with a stiffness core located in the center.

To study the operation of the method, a mathematical model of this building was implemented using the finite element method (Gallager R. Finite Element Method. Basics: Translated from English - M .: Mir, 1984) and its adequacy was checked for the corresponding characteristics of a real building (see above) ) Using a mathematical model, a dynamic analysis was performed (the input vibrational impact was set and vibrations were recorded at given points in the model) and a modal analysis (vibration modes were calculated from the natural frequencies of the building).

The adequacy of the mathematical model was verified by comparing the characteristics of the building’s vibrations obtained from the results of experimental measurements and the results of mathematical modeling.

Experimental measurements were carried out during the construction of the building. The first measurements were made on the 12th, 18th and 22nd floors, when the building was erected with a height of 25 floors (~ 83 m). According to the results of the first measurements, convergence with the results of mathematical modeling was carried out and the adequacy of the developed mathematical model was shown. The second series of measurements was carried out when the frame of the building was already fully erected (40 floors), and work was carried out on the arrangement of the facades. Based on the results of the second series of measurements, the calculated data (frequencies and waveforms) obtained from the simulation results were checked, the adequacy of the mathematical model developed for the constructed building with the aim of further calculations on modeling and forecasting the technical condition of the object was shown.

Experimental vibrational spectra for an unfinished building were obtained by recording vibrational velocities with a sampling frequency of 0.001 seconds using cycle meters. To compare the results of field measurements with the results of mathematical modeling, various measurement schemes can be used: measurements can be carried out on floors with serial numbers, where each subsequent one differs from the previous one by a constant or variable value, measurements can be carried out by sensors installed on the corresponding floor along all three axes of the building or along one of its axes - from the point of view of the problem being solved and the declared technical result, only the coincidence of the real schemes is essential measurements with the scheme for which the building model was built.

To determine the input vibrational impact, an experimental recording of the oscillation speed was carried out at the level of the foundation slab (2nd floor) of the building under construction, which was then used as the input impact in calculating the dynamic characteristics on the mathematical model.

The cycle diagrams obtained for the experimental and calculated records of vibration velocities for the 22th, 18th and 12th floors of the building are shown in FIG. 1. On the abscissa axis of each of the graphs in FIG. 1, time in seconds is plotted, along the ordinate axis - speed in m / s.

In the left column of FIG. 1, positions a, c, and e denote cycle diagrams obtained for experimental records of vibration velocities for the 22, 18, and 12 floors of a building, respectively. In the right column of FIG. 1, positions b, d, and f denote cycle diagrams obtained for calculating records of vibration velocities for the 22nd, 18th, and 12th floors of the building model, respectively.

In the left column of FIG. 2, positions a, c, and e denote the graphs of the velocity spectra obtained for experimental records of vibrational velocities for the 22nd, 18th, and 12th floors of the building, respectively. In the right column of FIG. 2, b, d and f indicate the graphs of the velocity spectra obtained for the calculated records of the vibrational velocities for the 22nd, 18th and 12th floors of the building model, respectively. The frequency in Hz is plotted on the abscissa axis of each graph, and the amplitude in m / s on the ordinate axis.

From the analysis of experimental data and data obtained by calculation, good convergence of the results is visible. From the experimental and calculated spectra, two close frequencies are seen in the region of 1.1–1.2 Hz. Based on the results of mathematical modeling, the forms of vibration are determined. The first waveform is torsional at a frequency of 1.113 Hz, the second waveform is bending at a frequency of 1.248 Hz.

The second series of measurements was already carried out for the constructed building (40 floors). The oscillations were recorded by GeoSIG GMS-18 accelerometers in the basement (-2 floor), on the 10th, 20th, 30th and 40th floors. The results of experimental and calculated records of accelerations (change in acceleration values over time) are presented in FIG. 3. On the abscissa axis of each of the graphs in FIG. 3 the time in seconds is plotted, along the ordinate axis - acceleration in m / s ² .

In the left column of FIG. 3, positions a, c, e, and g denote acceleration graphs obtained for experimental records of vibration accelerations for the 40th, 30th, 20th, and 10th floors of the building, respectively. In the right column of FIG. 3, b, d, f, and h indicate the acceleration graphs obtained for the calculated records of vibration accelerations for the 40th, 30th, 20th, and 10th floors of the building model, respectively.

The results of the experimental (left) and calculated (right) vibrational acceleration spectra are shown in FIG. 4, where the positions a, c, e, and g denote the graphs of acceleration spectra obtained for experimental records of vibration accelerations for the 40th, 30th, 20th, and 10th floors of the building, respectively. In the right column of FIG. 4, the positions b, d, f and h indicate the acceleration spectra obtained for the calculated records of vibration accelerations for the 40th, 30th, 20th and 10th floors of the building, respectively.

An analysis of the graphs allows us to see that the constructed building also has two frequencies that are close in frequency at the frequencies of 0.5 Hz and 0.54 Hz (according to the results of the experiment) and 0.52 Hz and 0.57 Hz (according to the results of mathematical modeling). The difference in hundredths of Hz between the experimental and calculated frequencies is explained by the fact that when constructing the mathematical model, the weight of the building facades, which were already half equipped during experimental measurements, was not taken into account. Accordingly, the experimental measurements show the vibration parameters of a heavier building compared to the one that was simulated.

The results of comparison of experimental measurements with the results of mathematical modeling show the adequacy of the developed model.

Modeling defects and verifying the operation of the method

To test the possibility of identifying signs and localizing places of change in the stress-strain state of structures using the proposed method, hypothetical defects were introduced into the building model.

The original model of the building (without defects) is accepted as a model of the building, which reflects its initial state (at the previous moment in time).

A defective building model is accepted as a building model that reflects its current state (at the current time).

To ensure the reliability of the verification of the method, 3 different locations of the defect on the 20th, 22nd and 25th floors were considered. Each option corresponds to the current point in time.

To do this, the following changes were made to the mathematical model (sequentially for each option):

- Decrease in the modulus of elasticity of concrete (grade B30) from 3.25 * 10 ¹⁰ Pa to 1.8 * 10 ¹⁰ Pa (which corresponds to concrete grade B10) for structures on the 20th floor.

- Reducing the modulus of elasticity of concrete (grade B30) from 3.25 * 10 ¹⁰ Pa to 1.8 * 10 ¹⁰ Pa (which corresponds to concrete grade B10) for structures on the 22nd floor.

- Decrease in the modulus of elasticity of concrete (grade B30) from 3.25 * 10 ¹⁰ Pa to 1.8 * 10 ¹⁰ Pa (which corresponds to concrete of grade B10) at the walls of the 25th floor and with a decrease in the modulus of elasticity of concrete (grade B40) from 3.6 * 10 ¹⁰ Pa up to 1.8 * 10 ¹⁰ Pa (which corresponds to concrete of grade B10) at the ceiling of the 25th floor.

The claimed method for each of the options was as follows:

At the input of the base of each mathematical model, a three-component vibrational impact in the form of generated normal noise was set (Fig. 5).

For the initial model (without a defect) and for each model with a defect, acceleration records along the X, Y, Z axes of 120 seconds (dT) length for each floor (from the 1st to the 40th) were obtained.

(где n - количество точек в спектре, m - номер точки измерения (этажа), значения m изменяются от 1 до 40).For the initial model (without defect), based on the obtained records of accelerations for each measurement point (floor), the vibration spectrum (dependence of the amplitude of the oscillations on frequency) was calculated, then for each measurement point (floor) the energy parameter was calculated $$S_{0m}={\displaystyle \sum {}_i^n}{A}_{im}^2\cdot w_{im}^2$$

(where n is the number of points in the spectrum, m is the number of the measurement point (floor), the values of m vary from 1 to 40).

(где n - количество точек в спектре, m - номер этажа, значения m изменяются от 1 до 40).For each model with a defect, based on the obtained records of accelerations according to the same algorithm as for the defect-free model, a separate energy parameter was also calculated for each floor $$S_{tm}={\displaystyle \sum {}_i^n}{A}_{im}^2\cdot w_{im}^2$$

(where n is the number of points in the spectrum, m is the floor number, m values vary from 1 to 40).

Thus, we obtained a one-dimensional array (dimension 40) of the energy parameter values for a defect-free model and three one-dimensional array (dimension 40) for the energy parameters of the corresponding models with defects (Table 1).

Table 1 Floor Number (m) The value of the energy parameter of a defect-free model S ₀ (previous time) The value of the energy parameter of the defective model S _t Defective model on the 20th floor (Current time. Option 1) Defective model on the 22nd floor (Current time. Option 2) Defective model on the 25th floor (Current time Option 3) one S ₀₁ S _t1 S _t1 S _t1 2 S ₀₂ S _t2 S _t2 S _t2 ... ... ... ... ... 40 S ₀₄₀ S _t40 S _t40 S _t40

For each variant of the defective model, the change in the energy parameter K was calculated in accordance with the following dependence:

For this, it is necessary to obtain integral energy (in all directions of X, Y, Z) at the current moment of time (S _t ) for each measurement point (points from 1 to 40) and integral energy (in all directions of X, Y, Z) in the previous point in time (S ₀ ) for each measurement point (points from 1 to 40). Then follows the operation of element-wise division - i.e. dividing the parameter S obtained for each point at the current time t by the value of the same parameter for the same point at the previous time. That is, S _t at point No. 1 is divided by S ₀ at point No. 1, S _t at point No. 2 is divided by S ₀ at point No. 2 and such division operations, taking into account that m varies from 1 to 40, respectively, should be 40 (according to the number of floors in the building).

The block diagram of the algorithm for calculating the energy parameters (S _0m and S _tm ) and changes in the energy parameter K is shown in Fig.6, where the following notation:

1. The unit for recording acceleration of oscillations along the X axis of the model without a defect;

2. Block for calculating the spectrum of oscillations along the X axis of the model without a defect;

, где n - количество точек (частот) в спектре, j=х, m - номер точки измерения;3. The unit for calculating the sum of the element-wise square of the product of the amplitude and frequency in accordance with the following dependence: $$S_{0mj}={\displaystyle {\sum }_i^n{A}_{im}^2\cdot w_{im}^2}$$

where n is the number of points (frequencies) in the spectrum, j = x, m is the number of the measurement point;

4. The unit for recording acceleration of oscillations along the Y axis of the model without a defect;

5. Block for calculating the spectrum of oscillations along the Y axis of the model without a defect;

, где n - количество точек (частот) в спектре, j=y, m - номер точки измерения;6. The unit for calculating the sum of the element-wise square of the product of the amplitude and frequency in accordance with the following dependence: $$S_{0mj}={\displaystyle {\sum }_i^n{A}_{im}^2\cdot w_{im}^2}$$

where n is the number of points (frequencies) in the spectrum, j = y, m is the number of the measurement point;

7. The unit for recording acceleration of oscillations along the Z axis of the model without a defect;

8. Block for calculating the spectrum of oscillations along the Z axis of the model without a defect;

, где n - количество точек (частот) в спектре, j=z, m - номер точки измерения;9. The unit for calculating the sum of the element-wise square of the product of the amplitude and frequency in accordance with the following dependence: $$S_{0mj}={\displaystyle {\sum }_i^n{A}_{im}^2\cdot w_{im}^2}$$

where n is the number of points (frequencies) in the spectrum, j = z, m is the number of the measurement point;

10. Block for generating energy parameters S _{0m by} element-wise summation of S _0mx , S _0my and S _0mz , where m is the number of the measurement point;

11. The unit for recording acceleration of oscillations along the X axis of the defective model;

12. Block for calculating the spectrum of oscillations along the X axis of the defective model;

, где n - количество точек (частот) в спектре, j=х, m - номер точки измерения;13. The unit for calculating the sum of the element-wise square of the product of the amplitude and frequency for a model with a defect in accordance with the following dependence: $$S_{tmj}={\displaystyle {\sum }_i^n{A}_{im}^2\cdot w_{im}^2}$$

where n is the number of points (frequencies) in the spectrum, j = x, m is the number of the measurement point;

14. The unit for recording acceleration of oscillations along the Y axis of the defective model;

15. The unit for calculating the spectrum of oscillations along the Y axis of the defective model;

, где n - количество точек (частот) в спектре, j=у, m - номер точки измерения;16. The unit for calculating the sum of the element-wise square of the product of the amplitude and frequency for a model with a defect in accordance with the following dependence: $$S_{tmj}={\displaystyle {\sum }_i^n{A}_{im}^2\cdot w_{im}^2}$$

where n is the number of points (frequencies) in the spectrum, j = y, m is the number of the measurement point;

17. A unit for recording acceleration of oscillations along the Z axis of a defective model;

18. The unit for calculating the spectrum of oscillations along the Z axis of the defective model;

, где n - количество точек (частот) в спектре, j=z, m - номер точки измерения;19. The unit for calculating the sum of the element-wise square of the product of the amplitude and frequency for a model with a defect in accordance with the following dependence: $$S_{tmj}={\displaystyle {\sum }_i^n{A}_{im}^2\cdot w_{im}^2}$$

where n is the number of points (frequencies) in the spectrum, j = z, m is the number of the measurement point;

20. The unit for generating energy parameters S _{tm by} elementwise summation of the parameters S _tmx , S _tmy and S _tmz obtained in blocks 13, 16 and 19, respectively, for a model with a defect, where m is the number of the measurement point;

.21. The unit for calculating the change in the energy parameter K _m in accordance with the following dependence: $$K_m=\frac{S_{tm}}{S_{0m}}$$

.

22. The unit for calculating the maximum deviations of the values of K from 1 in accordance with a predetermined threshold value.

The algorithm was tested for three options for the location of defects: on the 20th floor, on the 22nd floor, on the 25th floor. To calculate the energy criterion Ktm in each variant according to the above algorithm, the energy parameters for each measurement point Stm were calculated, the values of which were divided by the corresponding energy parameters of the measurement points S _{0m of the} model without a defect.

The results of calculating the criterion K according to the above algorithm for a model with a defect on the 20th floor are presented in FIG. 7, with a defect on the 22nd floor - in FIG. 8, with a defect on the 25th floor - in FIG. 9.

The given graphic materials show that at the points where K has the greatest deviations from 1, the greatest changes in the stress-strain state of structures take place. Accordingly, by the value of the change in the energy parameter obtained by dividing its value at the current time by the value at the previous time, we can judge both the occurrence of strain-strain states of structures of buildings / structures and the place in which such states arose.

When registering with the sensors of speeds, accelerations, linear displacements, etc., installed continuously on the building / structure, or with certain discrete parameters, analyzing the values of the energy spectra over time, you can get a complete picture of when and in what place of the building / structure the deformation -stress state of the building / structure and how it developed.

The choice of the number and places of the points of registration of fluctuations is made from the following considerations. On the one hand, the larger the number of registration points, the more accurately you can determine the place of change in the stress-strain state of structures. But on the other hand, economic considerations, the amount of computing, etc. limit the number of registration points. The minimum of such points, at which the necessary accuracy of determination of deformation stresses, their localization is ensured, depends on the building structure. For example, in high-rise buildings, registration points can be located over one or several floors, thus, it is possible to localize the occurrence of defects to one or several floors, for extended objects, registration points can be located on each individual span, supported by supports, thus, localization will be it is provided with accuracy to flight.

Acceleration sensors (speed, displacement), necessary recording equipment and materials (cable networks, analog-to-digital converters, switches) are installed at selected points of the building / structure based on the indicated considerations.

Based on the measured vibration parameters, the spectral characteristics of the vibrations are calculated at each recording point in accordance with the circuit shown in FIG. 6.

, где n - количество точек (частот) в спектре, j - направление (x, y, z).The energy parameter S is calculated at each point along each axis (X, Y, Z) in the form of the sum of the square of the products of amplitudes at the corresponding frequencies - $$S_j={\displaystyle {\sum }_i^n{A}_i^2\cdot {\mathrm{<figure-callout\; id="2"\; label="w\; i"\; filenames="00000026.png,00000027.png"\; state="\{\{state\}\}">w\; </figure-callout>}}_i^{}}$$

, where n is the number of points (frequencies) in the spectrum, j is the direction (x, y, z).

The total energy parameter at each point S = S _x + S _y + S _{z is} calculated.

, где K - изменение энергетического параметра S_o, S_t - значение энергетического параметра в момент времени t, S_o - значение энергетического параметра в предшествующий момент.The change in the K criterion over time is calculated as the ratio of the energy parameters S at the current time to the energy parameters S at the previous time for each registration point - $$K=\frac{S_t}{S_o}$$

where K is the change in the energy parameter S _o , S _t is the value of the energy parameter at time t, S _o is the value of the energy parameter at the previous moment.

The current values of K obtained for each registration point are compared with a single value. At current values of K that differ from a single value by a predetermined threshold value, a judgment is made about the absence of stress-strain states of the building / structure being monitored at the corresponding registration points. If the current value K exceeds a predetermined threshold and the subsequent continuous growth of its value according to several measurements in a row for the same registration point, it is concluded that there are stress-strain states of the controlled object at that point.

The specific value of the threshold value K is determined for each building, structure depending on design decisions and design features, on the given accuracy of control of changes in the stress-strain state of structures, on the allowable range of changes in the stress-strain state of structures, which is set by the designers of buildings and structures.

An analysis of the energy parameter S with further calculation of the K criterion using the above formula separately but for the X, Y, Z directions allows us to determine the direction in which a change in the stress-strain state was formed at the registration point.

By changing the previous moment of time (relative to which the change in the stress-strain state is determined), it is possible to determine at what point in time and where the defect occurred.

Claims (5)

1. A method for determining the signs and localization of the place of change of the stress-strain state of buildings, structures, including building a mathematical model of the building, structure, establishing the adequacy of the constructed model for a real building, building by comparing the values of the vibration parameters of the real building, building and its model, for the same the same points, the definition for each floor of the mathematical model of the building, the span of the construction of the energy parameter S as a function of the products of the squares of the amplitudes A and frequencies ω s oscillation spectrum for each axis associated with the building, structure, determining the energy parameter at a point by summing its components obtained for each axis, determining the change in the energy parameter of the building, structure from the following relationship

where
K is the change in the energy parameter,
S _t is the value of the energy parameter at time t,
S _o - the value of the energy parameter at the previous moment,
comparing the value of K with a unit value and for values of K differing from a unit value by an amount not exceeding a predetermined threshold value, making a judgment on the absence of stress-strain states of the monitored building, structure at the corresponding registration points, when the current K value exceeds a predetermined threshold and the subsequent continuous growth of its value according to several measurements in a row for the same registration point, a judgment is made on the presence of stress-strain states controlled object at that point. 2. The method according to claim 1, characterized in that the amplitudes and frequencies of the oscillations are determined based on the displacement, speed or acceleration of the oscillations. 3. The method according to claim 1, characterized in that the displacement, velocity or acceleration of oscillations is measured at points that are located in one or several floors in high-rise buildings, and in long structures — on each individual span, based on supports. 4. The method according to claim 1, characterized in that the localization of the direction in which the stress-strain state of the building, structure is changed, is determined by comparing the value of the energy parameter S at the current time in the selected direction X, Y or Z with the value of the same parameter in the same direction defined for the same registration point for the previous point in time. 5. The method according to claim 1, characterized in that in order to determine the development of the stress-strain state of the building, structure in time, several points in time are selected as the previous points in time, separating the current time from the point in time at which the building, structures were absent -deformed states in a point or direction, for which the change in the stress-strain state in time is determined, and for each of them determine the change in the energy parameter K.

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