RU2650812C1 - Method of monitoring the technical condition of bridge structures in the process of their operation (variants) - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction in the field of nondestructive testing and is intended for monitoring the technical condition and diagnostics of span structures and supports of bridge structures of various purposes and design in the process of their operation. Method is realized by performing periodic or continuous control (monitoring) of the main elastic characteristics determining the technical condition of the spans and supports: stiffness coefficient of the cross-section of the span structure relative to the bending, stiffness coefficient relative to angular displacements in the support cross-sections of spans, stiffness coefficient of the supports relative to the transverse (vertical) shear, transverse shear stiffness coefficients of a uniform elastic base in the transverse and longitudinal directions.

EFFECT: technical result consists in increasing the reliability of monitoring the technical condition of the bridge structure to ensure its safe operation.

3 cl, 6 dwg, 7 tbl

Description

The invention relates to construction in the field of non-destructive testing and is intended to monitor the technical condition and diagnosis of spans and supports of bridge structures for various purposes and design during their operation. The proposed method allows you to control the technical condition of both bridge structures, not related to an increased level of responsibility, and especially dangerous, technically complex and unique bridge structures.

The following terms and expressions are interpreted as follows:

Series of frequencies - a sequence (array) of values of natural frequencies

Diagrams of natural vibration modes - configuration (diagram) of displacements along the measurement profile at natural vibration frequencies

Replacing analytical model - a mathematical model of vibrations of simple structures (beam, plate, etc.) that describes the object of examination as accurately as possible.

A complex transfer function is a function of converting an input signal to an output taking into account the amplitude and phase characteristics of an object.

Bridge structures are exposed to vibration, wind loads, seismic and climatic influences. Damage to spans and supports of the bridge structure is the most dangerous and requires non-destructive testing in the process of regular operation. Therefore, periodic or continuous determination of the actual technical condition of bridge structures will ensure the safety of passenger and freight traffic on railways and roads.

Known methods for testing bridge structures under the influence of static and dynamic temporary loads. The purpose of these tests is to verify the basic operational characteristics of bridge structures - permissible carrying capacity and operating mode.

A static test of a bridge structure is carried out by loading it with a temporary vertical load, at which the deflections are measured at different points and compared with the calculated ones [1] (Bondar N.G. et al. “Dynamics of railway bridges.” M., “Transport”, 1965 .) or reference.

A dynamic test of a bridge structure is carried out under the influence of dynamic loads of various types, including loaded cars that pass along the bridge at given speeds, as well as through the use of a pulse or vibration source with a varying frequency of harmonic effects [2-4] (RF Patent No. 2104508, CL G01M 7/02; RF Patent No. 2089874, CL G01N 3/32; RF Patent No. 2240626, CL G01M 7/02).

According to the known method of dynamic testing of large-scale structures [2] (RF Patent No. 2104508, class G01M 7/02), the vibrations of the tested structure at its own frequency are excited by the action of a sequence of shock pulses, which create the reactive power of the pulse exciter installed on the structure.

In the known method for diagnosing structural damage under cyclic loads [3] (RF Patent No. 2089874, class G01N 3/32), the vibrations are excited by a vibration source installed in the center of symmetry of the structure, the vibration amplitudes are measured at the frequencies of the first three natural forms of the structure by vibration sensors installed in pairs symmetrically with respect to the center of symmetry, and the degree of structural damage is determined by the distortion values or asymmetry characteristics of the corresponding vibration modes.

In another method of vibration testing of superstructures of bridge structures [4] (RF Patent No. 2240626, class G01M 7/02), a moving load is used in the form of a natural transport stream moving along the superstructure. By registering the vertical vibrations of the span at several points and calculating the mutual frequency-phase spectrum, these frequencies determine the natural frequencies and dynamic coefficients.

A known method for monitoring an automobile bridge [5] (RF Patent No. 2317534, class G01M 5/00), in which by means of periodic measurements of movements of bridge structural elements under the influence of moving vehicles, amplitude-frequency characteristics are obtained using wavelet transform, dominant frequencies are distinguished from power spectra and the residual resource of the bridge is determined by changing the frequencies. On the day of this method, it is necessary to know the limiting frequency of the stiffness loss of the reinforced concrete bridge structure, which according to the method corresponds to a four-fold loss in the stiffness of the bridge structure with respect to the stiffness at the time of acceptance tests. The method is limited in application, it cannot be used to monitor continuous reinforced concrete multi-span structures where several groups of frequencies of vertical modes of natural vibrations are observed and it is necessary to determine the lowest frequencies in the first and second groups.

In the above cases, as a result of dynamic tests of the bridge structure, the frequencies and forms of the bridge’s own vibrations, the logarithmic attenuation decrement are determined. The obtained dynamic characteristics of the oscillations of the bridge are compared with the calculated and / or reference indicators and make a conclusion about the degree of compliance of the design with the design parameters.

A significant drawback of the above methods for determining the dynamic characteristics of bridge structures [2-5] is the mandatory use of a special source of dynamic load: moving vehicles or rolling stock, vibrators, drum sets of various types, etc. In addition, the registration of vertical vibrations at several points of the structure, usually using sources of vertical dynamic loads, does not allow to identify and reliably identify the frequency groups of vertical forms of natural vibrations of the bridge structure.

These methods have insufficient resolution and low accuracy in determining the frequencies and ordinates of the diagrams of natural vibration modes. With a pulsed effect on a bridge structure, the frequencies of only the first few, prevailing in amplitude, significant forms of natural vibrations are determined, due to the short duration of the damped oscillations. During vibration exposure, the accuracy of determining the amplitude-frequency characteristics is interconnected with the step between the harmonic frequencies emitted by the vibrator. The choice of a small step between the frequencies to increase the accuracy leads to a significant increase in the observation time. The low accuracy of determining frequencies and identifying plots of natural vibrations leads to low reliability of the assessment of the technical condition of the bridge structure.

The closest analogue (prototype) to the present invention is a method for determining the physical condition of buildings and structures [6] (RF Patent No. 2140625, class G01M 7/00), which consists in the fact that measurements of spatial vibrations are carried out under the influence of a microseismic background of natural and technogenic of origin, by means of three-component vibration sensors moving around the points of the observation scheme, which ensure the recording of vibration values at the coordinates X, Y, Z at the same time, determine the individual inherent in each object dual set of parameters of dynamic characteristics of its own spatial oscillations and frequency modes of natural vibration damping rates (absorption), the transfer functions and evaluate the physical (technical) state object.

The disadvantage of this method is the low level of reliable determination of the main elastic characteristics of the bridge structure from the series of frequencies of natural spatial vibrations without the additional load on the structure: the stiffness of the span section relative to the bend, the stiffness coefficient relative to the angular displacements in the reference spans, the stiffness coefficient of the supports relative to the transverse vertical) shear, stiffness coefficients of the transverse shear of a homogeneous elastic base transverse and longitudinal directions. These elastic characteristics reflect the technical condition of the bridge structure in conventional building terms. On them you can assess the actual bearing capacity and carrying capacity of the bridge structure.

In the closest analogue, there is no optimal observation scheme for seismometric surveys and monitoring, which ensures the accuracy of the allocation and the necessary accuracy in determining the frequency series and ordinates of their own spatial vibrations, in the absence of vehicles moving over the bridge structure. In addition, there is no methodology for choosing replacement analytical models of a bridge structure and solving the inverse spectral problem to determine the above elastic characteristics. There is no assessment of the vibration level of the bridge structure in real time when passing vehicles to ensure the safe operation of the structure.

The technical problem that is solved when using the claimed invention is to ensure the safe operation of bridge structures reliable determination of their technical condition by a non-destructive method, without the use of any additional vibration sources.

In the proposed method for monitoring the technical condition of bridge structures during their operation (options), the technical condition of the bridge structure that is not related to the increased level of responsibility (option 1) is determined in the process of periodic detailed seismometric surveys, in the absence of vehicle traffic, by means of a mobile seismometric equipment.

In the process of monitoring the technical condition of especially dangerous, technically complex and unique bridge structures (option 2), periodically (1-2 times a month) they register spatial vibrations of bridge structures, in the absence of vehicle traffic, using stationary seismometric equipment installed on the structure.

Mathematical processing of the registration records is carried out, which determine the dynamic characteristics of the bridge structure (frequency series and diagrams of natural vibration modes) and their change during operation, including seasonal (depending on season, freezing of soil and temperature factor). Based on the series of frequencies of intrinsic spatial vibrations, analytical replacing models of the bridge structure are selected, according to which the basic elastic characteristics that reflect the technical condition of the span and supports of the bridge structure are calculated.

Using stationary seismometric monitoring equipment in real time, the overall level of vibrations is determined depending on the load on the bridge structure created by the flow of vehicles, snow and wind loads, and when vibrations are exceeded, they decide to stop the movement or limit the speed of the bridge structure.

The technical result of the claimed invention is to increase the reliability of monitoring the technical condition of the bridge structure in order to ensure its safe operation, timely appointment of terms for restoration work, reconstruction or decommissioning of the bridge structure. The claimed technical result is achieved by periodically or continuously monitoring (monitoring) the main elastic characteristics that determine the technical condition of the spans and supports: the stiffness coefficient of the span section relative to the bend, the stiffness coefficient relative to the angular displacements in the supporting sections of the spans, the stiffness coefficient of the supports relative to the transverse (vertical) shear, stiffness coefficients to the transverse shear of a homogeneous elastic base in the transverse and longitudinal directions.

Periodic detailed examinations and seismometric monitoring of the bridge structure are carried out in the absence of vehicle traffic according to optimal observation schemes, which allow reliably with a relative error of no more than 3% to select frequency series and obtain ordinates of the diagrams of their own forms of vertical, transverse and longitudinal vibrations. Using frequency series, substitute analytical models are selected and the inverse spectral problem is solved to determine the basic elastic characteristics of the bridge structure, which reflect its technical condition in generally accepted building terms. The values of the elastic characteristics allow us to evaluate the main actual parameters of the bridge structure: bearing capacity and load capacity.

The present invention allows to control in real time the overall level of vibration of the bridge structure, depending on the magnitude of the load created by the flow of vehicles, snow and wind loads and to decide on the restriction of movement when exceeding the set vibration level. Thus, periodic monitoring of the technical condition and safety of operation of the bridge structure throughout the entire life cycle is ensured.

The technical result is achieved in that in a method for monitoring the technical condition of bridge structures during their operation (options), according to the invention:

According to option 1 of the claimed invention, the monitoring of the technical condition of bridge structures, not related to an increased level of responsibility, is carried out in the absence of vehicle traffic, through periodic detailed inspections using mobile recording equipment, according to the observation scheme, which includes at least 8 observation points at each passage with mandatory observation points on all the supports of the bridge structure. Such a scheme makes it possible to reliably select frequencies with a relative error of no more than 3% and obtain the ordinates of the diagrams of the first and second groups of eigenfrequencies of vertical vibrations, eigenfrequencies of transverse and longitudinal vibrations. From the complex spectra of the transfer functions, the spectra (series) of frequencies (p _zi , p _yi p _xi, ) and the ordinates of the diagrams z _i (x), y _i (x), x _i (x) of the natural forms of vertical, transverse and longitudinal vibrations are determined. Using the diagrams of slices of the spectra of the transfer functions, the forms of natural spatial vibrations of the span structure are reliably identified and the lowest frequencies of the first two groups of natural vertical vibrations, the series of natural frequencies of transverse and longitudinal vibrations are determined.

By the nature of the dependence of the frequencies of natural vibrations on the number of forms, substitute analytical models are chosen:

- for vertical vibrations - a multi-span continuous beam, elastically fixed in the reference sections, determine the ratio of the lowest frequency of the second group of natural vibrations to the lowest frequency of the first group (p ₂ , ₁ / p _1,1 ), according to the analytical model, calculate the characteristic numbers (λ _n ) by solving the frequency equation of oscillations of a multi-span continuous beam and determine the elastic characteristics of the span: the value of the stiffness of the section relative to bending (EI), which characterizes the bearing capacity of the span, the stiffness coefficient relative to angular displacements in the reference sections of the spans μ, the stiffness coefficient of the supports relative to the transverse (vertical) shift K _Z ;

- for transverse and longitudinal vibrations - a multi-span continuous beam is considered as a single-span beam on a homogeneous elastic base, according to this analytical model, the stiffness coefficients of the transverse shear of a homogeneous elastic base in the transverse and longitudinal directions K _SH⊥ and K _{SH ||} .

The obtained values of the main elastic characteristics of the span and supports are compared with those obtained earlier in the process of initial and subsequent detailed examinations, the change in the technical condition of the span and supports of the bridge structure during operation is evaluated, and the time of the next examination is assigned.

According to option 2 of the claimed invention, in the process of monitoring the technical condition of especially dangerous, technically complex and unique bridge structures, periodically (1-2 times a month), the vibrations of the bridge structure are recorded taking into account the temperature factor at the time of registration of vibrations, in the absence of vehicle traffic, stationary observation points located according to the observation scheme, including at least two observation points on each span of the bridge structure. Such a scheme, after obtaining (rows) of frequencies (p _zi , p _yi , p _xi ) and ordinates of the diagrams z _i (x), y _i (x), x _i (x) of the eigenmodes of vertical, transverse and longitudinal vibrations according to the data a detailed initial survey of the bridge structure allows reliably with a relative error of not more than 3% to periodically identify and reliably identify the frequencies of the first and second groups of natural frequencies of vertical, natural frequencies of transverse and longitudinal vibrations. Periodically during operation, the change in the lower frequencies of the first two groups of natural vertical vibrations, the series of natural frequencies of transverse and longitudinal vibrations is determined. The basic elastic characteristics of the bridge structure are calculated according to the selected replacement analytical models, the change in the elastic characteristics over time during the operation of the structure is estimated, including taking into account their seasonal changes due to the temperature factor. The technical condition of the span and supports, the regulatory, permissible, ultimate and destructive loads, as well as the wear and safety of further operation of the bridge structure, the possibility of repair, reconstruction or the need for decommissioning are assessed.

In addition, the monitoring of the technical condition of especially dangerous, technically complex and unique bridge structures is carried out in the conditions of passage of vehicles, by means of a stationary located recording monitoring equipment. Real-time continuous stack recordings determine the overall vibration level of the span in the ranges of significant frequencies of natural spatial vibrations of the bridge structure and frequencies excited by moving vehicles, depending on the magnitude of the load on the bridge structure created by the stream of vehicles, snow and wind loads. The vibration level is compared with the settings given by the designers of the bridge structure for the amplitude of the vibrations, if the settings are exceeded, the vibration signal is recorded and, if necessary, a decision is made to stop the movement or limit the speed of the bridge structure, send a message to the addresses of the controlling organizations and provide, thus , safety of operation of the facility in terms of vibration.

The list of tables explaining the essence of the claimed invention:

Table 1. Common-mode forms of intrinsic vertical vibrations of continuous continuous span.

Table 2. Common-mode forms of their own transverse vibrations of continuous continuous span.

Table 3. Common-mode forms of intrinsic longitudinal vibrations of continuous continuous span.

Table 4. Frequencies of horizontal and vertical vibrations of the bridge.

Table 5. The propagation velocity of a bending pulse wave, carrier frequencies and structural stiffness of a bending section.

Table 6. The values of the dynamic stiffness of the supports for vertical shear at a frequency of 1.24 Hz.

Table 7. Seasonal changes in the frequencies of natural vertical vibrations.

The list of graphic images explaining the essence of the claimed invention:

FIG. 1. Span structure and observation system.

; б) приведенный спектр

; в) спектр когерентности

; г) спектр коэффициента бегучести волны К_КБВ,_[z](f).FIG. 2. Normalized spectra of parameters of vertical vibrations of the span: a) acceleration spectrum

; b) reduced spectrum

; c) coherence spectrum

; g) the spectrum of the coefficient of wave conductivity K _KBM , _[z] (f).

FIG. 3. Transfer function (two-dimensional spectrum): a) two-dimensional spectrum of amplitudes; b) two-dimensional spectrum of the initial phases.

FIG. 4. Functions for determining the minimum characteristic number λ _{1,1, L2} , referred to the length of the middle span (L ₂ ) of a six-span beam, elastically supported relative to angular and rigidly relative to transverse movements with spans L ₁ = L ₆ , L ₂ = L ₃ = L ₄ = L ₅ and L ₂ / L ₁ = 1.5: a) function p _2.1 / p _1.1 = Ф (μ); b) the function λ _{1,1, L2} (μ).

FIG. 5. Speed hodographs of the propagation of elastic waves: a) X - component; b) the Y component; c) Z is a component.

FIG. 6. Normalized amplitude spectra of acceleration of vertical vibrations of the bridge structure averaged over all observation points obtained from surveys in 2006 and 2008

The inventive method is as follows.

In the absence of vehicles moving across the bridge, a detailed seismometric survey of the bridge structure is carried out by registering vibrations of the multi-span structure at all points of the monitoring system (tens, hundreds of points) simultaneously using specialized multichannel seismometric equipment, or simultaneously at the reference point and several observation points sequentially moved in accordance with an observation circuit using low-channel seismometric equipment (channel 9-12 ) and three-component sensors, providing registration of the values of the fluctuations of the span along the coordinates X, Y and Z. The entries in the reference point are used to linearly bring all the multi-time records to a single recording time [7] (RF Patent No. 2150684, class G01M 7/00) . This method allows the inspection of any object using a seismometric station with a minimum number of channels.

The optimal observation scheme for a detailed seismometric survey of bridge structures is a scheme that includes at least 8 observation points on each span with mandatory observation points on all supports of the bridge structure. Such a scheme, in accordance with Kotelnikov’s theorem (at least 4 observation points per half-wave), allows one to reliably isolate frequencies with a relative error of not more than 3% and obtain ordinates of the diagrams of the first and second groups of eigenfrequencies of vertical, eigenfrequencies of transverse and longitudinal vibrations of the structure . The frequency of detailed seismometric surveys (without installing stationary monitoring equipment) is determined by the degradation rate of the structure and regulatory documents (usually about 3-5 years). To exclude the influence of seasonal changes (mainly the temperature factor) on the data of periodic surveys, surveys should be carried out in the same climatic conditions. The temperature factor is the temperature of the surrounding air, water, structure for a certain period of time (day, week, month).

As a result of a detailed seismometric survey (option 1) receive:

- while registering at all observation points

S _[V] (x _i , y _i , z _i , t) - an array of registration records (seismograms) recorded at observation points with coordinates [x _i , y _i , z _i ], where the observation vector [V] denotes X, Y, Z — direction of the main axes of the structure, X — longitudinal vibrations directed along the longitudinal axis of the structure, Y — transverse vibrations — perpendicular to the longitudinal axis, Z — vertical;

- during sequential registration of vibrations at observation points and reference point S _[V] (x _i , y _i , z _i , t) - an array of seismograms recorded at observation points with coordinates [x _i , y _i , z _i ] and S _{[ V]} (x _0i , y _0i , z _0i , t) - an array of seismograms recorded at the reference observation point with coordinates [x ₀ , y ₀ , z ₀ ] corresponding to synchronous records obtained at the i-th observation point.

When monitoring especially dangerous, technically complex and unique structures (option 2), registration at all stationary observation points is carried out simultaneously, therefore S _[V] (x _i , y _i , z _i , t) is obtained - an array of registration records (seismograms) recorded at stationary observation points with coordinates [x _i , y _i , z _i ]. Moreover, any of the stationary observation points can be chosen as a reference point. At the first stage, before installing a stationary monitoring system, it is necessary to carry out an initial detailed examination of the bridge structure in order to determine the series of frequencies and ordinates of the diagrams of the spatial vibrations of the bridge structure. Based on the results of the initial examination, the optimal location scheme of observation points for monitoring is assigned, analytical replacement models are selected, and the elastic characteristics of the spans and supports of the bridge structure are evaluated. The scheme includes at least two observation points on the span (one in the middle of the span, the second 1/4 of the span), which makes it possible to distinguish the main frequencies of natural modes of vibration for the three components, taking into account the series of frequencies and diagrams obtained and identified earlier in the detailed examination own spatial vibrations. According to this scheme, stationary recording equipment is installed to periodically monitor bridge structures.

Micro vibrations of the bridge structure are recorded using stationary seismometric equipment, in the absence of vehicles moving along the bridge, periodically (for example, 1-2 times a month), with the temperature factor taken into account at the time of the oscillation recording. In this case, it is necessary to stop the movement of vehicles or rolling stock along the bridge structure at the time of registration of vibrations (5-7 minutes). On railway bridges, registration can be done more often given the presence of "windows" in the movement of trains.

According to the registration records obtained during periodic detailed examinations or monitoring, the complex transfer functions are calculated. When simultaneously registering at all observation points, one of the observation points is designated as a reference point and the transfer functions are calculated, the reference point is an observation point, and when working with a reference point, complex transfer functions between a fixed reference point and observation points are calculated in accordance with the method [7] (RF patent No. 2150684, class G01M 7/00).

As a result of processing three-component records of micro-vibrations, in the absence of movement of vehicles on a bridge structure, it is determined:

- spectra (rows) of frequencies (p _i ) and the ordinates of the diagrams z _i (x) of the eigenmodes of vertical, transverse and longitudinal vibrations. Frequency spectra and natural vibration diagrams are determined using complex spectra of the vibration transfer functions “reference point is the kth observation point” (i - the index determines the continuous numbering of frequencies and natural vibration modes) [6, 7] (RF Patent No. 2140625, cl. G01M 7/00, RF Patent No. 2150684, CL G01M 7/00);

- from the diagrams of slices of the spectra of complex transfer functions, the forms of intrinsic vertical, transverse and longitudinal vibrations of the span structure are identified and the frequencies of the first two groups of intrinsic vertical vibrations and transverse vibrations and the frequencies of intrinsic transverse and longitudinal vibrations are determined;

- the ratio of the lowest frequency of the second group to the lowest frequency of the first group of natural vertical vibrations (p _2,1 / _1,1 - the first index is the group number, the second frequency number in the frequency group of the natural modes of spans) in the case of continuous spans or the ratio of frequencies to the frequency of the first form of natural vertical, transverse and longitudinal vibrations, in the case when the spectra of the natural frequencies of the structure correspond to the spectrum of a single-span beam on an elastic homogeneous half-space;

- impulse characteristics at observation points, by applying the inverse Fourier transform of the complex spectrum of the transfer function. Using them, speed hodographs are constructed for all observation components and the propagation velocities of elastic waves in a bridge structure are determined;

In addition, with the help of stationary monitoring equipment, the vibration level of the bridge structure is estimated depending on the magnitude of the load on the bridge structure created by the flow of vehicles, snow and wind loads. The values of the standard deviation in the ranges of significant frequencies of the natural spatial vibrations of the bridge structure and the frequencies excited by moving vehicles are determined.

The frequencies and forms of natural vibrations are determined from the three main axes of the bridge structure using the complex spectra of transfer functions, which are calculated as the optimal Kolmogorov – Wiener filter [8] (G. Korn and T. Korn, Handbook of Mathematics for scientists and engineers. Moscow 1974 . - 760 p.).

The transfer function for the k-th observation point, at an arbitrary frequency f _j , for a given observation vector is determined by the well-known expression:

where C _ol (f _j ) and C _kl (f _j ) are the complex Fourier spectra of realizations (fragments of simultaneous recording of oscillations of the same duration) at the reference point and observation point, respectively;

n is the number of recording fragments (implementations) in one observation session;

* conjugation sign of a complex number.

For example, at a sampling frequency of 128 Hz, the recording length is usually selected at 64 K (K = 1024), and the number of fragments is 8; four; 2; 1, the length of the fragments, respectively, 8 K; 4K; 2 K; K. The accuracy of determining the frequencies of natural vibrations depends on the length of the fragment, and the signal-to-noise ratio depends on the number of fragments.

The transfer function for a given observation vector is defined as the set of transfer functions assigned to individual observation points and represents a two-dimensional spectrum in coordinates: observation point number - frequency - module / phase of the transfer function. The relative error in determining the values of the frequencies of spatial vibrations of the bridge structure depends on the length of the fragments of the records 2 K or 4 K samples, according to which the transfer function is calculated and is respectively ± 0.03125 Hz or ± 0.0156 Hz.

The spectrum that is obtained as a result of multiplying the transfer function by the amplitude spectrum of vibrations averaged over all observation sessions at the reference point (the characteristic effect at the reference point during the examination) is called the reduced vibration spectrum. As a rule, the presented spectrum of vibrations has more pronounced spectral peaks than the spectrum of the transfer function.

The values (spectrum) of frequencies p _i of the natural modes of the spans of the bridge structure are determined according to the spatio-temporal resonance conditions [9] (Saburov BC, Kuzmenko A.P. Survey of high-rise buildings. Engineering-seismometric method. LAMBERT Academic Publishing, 2013. - 175 s):

where K _KBV (f) is the spectrum of the coefficient of solvency of a spatial wave;

P (f) is the amplitude spectrum of the transfer function.

The spectrum of the spatial wave coefficient of transmittance is a dependence of the ratio of the amplitude of the traveling wave to the sum of the amplitudes of the standing and traveling waves recorded on the observation profile, and varies from zero to unity. If at the frequency f _i К _КБВ (f _i ) → 0, then resonant oscillations are observed in the mechanical system. If at the frequency f _i К _КБВ (f _i ) → 1, then antiresonance oscillations are observed in the mechanical system.

In addition, the spectrum of the coherence coefficient of oscillation is used to identify the eigenmodes.

в диапазоне [0÷1]. Единица соответствует линейной зависимости колебаний в двух пунктах, между которыми определяется коэффициент. Высокий коэффициент когерентности наблюдается на частотах собственных форм. При нулевом значении коэффициента колебания в двух пунктах независимы.The spectrum of the coherence coefficient of oscillation is a measure of assessing the correctness of a linear model when recalculating seismograms [7] (RF Patent No. 2150684, class G01M 7/00). Limits of change

in the range [0 ÷ 1]. The unit corresponds to a linear dependence of the oscillations at two points, between which the coefficient is determined. A high coherence coefficient is observed at the frequencies of the eigenmodes. With a zero value of the coefficient of oscillation in two points are independent.

Plots of in-phase modes of natural oscillations ξ _i (x) in the vertical or horizontal plane at the oscillation frequency p _{i are} determined according to the expression (slice of the transfer function at the frequency p _i ):

where ξ _{k, i} is the ordinate of the plot at the frequency of the i-th spectral component in the k-th observation point located at a distance x _k from the beginning of the span;

p _i is the frequency of the natural form of elastic vibrations;

P _k (p _i ) - a complex transfer function "strong point - k-th observation point."

Considering that the initial phases at observation points at frequencies of natural modes of vibration can differ by a factor of π, for a multi-span beam, the plot of the in-phase mode of natural modes is defined as a plot at the time when the rms value of the ordinates of the chart reaches its maximum differs, the minimum error of the order of 3-5% is observed for the frequencies of vertical vibrations, and the maximum for the first frequencies of transverse and longitudinal vibrations (see example ABLE 1, 2, 3). The large error in determining the diagrams of transverse and longitudinal vibrations is due to the influence of supports during the movement of the span according to the first forms of vibrations of the entire continuous span.

To determine the propagation velocity of elastic waves along the three main axes of a bridge structure, the impulse characteristics are calculated at all observation points by applying the inverse Fourier transform to the complex spectra of the transfer function. As a result, a high-speed hodograph is built, which determines the propagation velocity of elastic waves. The values of the elastic wave velocities also make it possible to evaluate individual elastic characteristics of the structure.

To calculate the elastic characteristics of the bridge structure, analytical replacement models are chosen that are most closely related to the spectra (rows) of frequencies of natural vertical, transverse and longitudinal vibrations. The frequency spectra of the modes of natural vibrations in the vertical, transverse and longitudinal directions are mainly determined by the following elastic characteristics:

- stiffness of the span section relative to bending (EI);

- the stiffness coefficient of the supports relative to the angular displacements in the supporting sections of the spans (μ);

- the stiffness coefficient of the supports relative to the transverse and vertical shear (K _Z );

- the stiffness coefficients of the transverse shear of a homogeneous elastic base in the transverse and longitudinal directions, respectively, K _SH⊥ , K _{SH ||} .

The aforementioned elastic characteristics of the bridge structure are determined within the framework of analytical replacement models, which are selected depending on the nature of the spectrum of natural frequencies and taking into account the design of the bridge structures.

The simplest construction of a bridge structure is a single-span bridge structure, the analytical replacing model of which in the general case is a model of a single-span beam elastically fixed in supporting sections relative to transverse and angular movements.

The frequencies of the natural vibration modes of a single-span beam are determined by the well-known expression:

where EI is the stiffness of the span section relative to bending in a given direction.

For example, to quickly assess the stiffness of a section of a single-span structure with respect to bending EI (vertical and transverse direction), a model of bending vibrations of a single-span beam rigidly fixed in supporting sections with respect to transverse and elastically relative to angular displacements can be chosen as a replacement model. In this case, the characteristic numbers λ _n are the roots of the frequency equation:

- значения функций Крылова при х=L,

- безразмерная координата;Where

are the values of the Krylov functions at x = L,

- dimensionless coordinate;

λ _n - characteristic numbers (roots of the frequency equation (5));

- коэффициент жесткости относительно угловых перемещений в опорных сечениях;

- stiffness coefficient relative to angular displacements in the reference sections;

To _ϕ - the rigidity of the nodes of the spans with supports relative to angular displacements;

K _Z = ∞ is the stiffness coefficient of the supports relative to the transverse (vertical) shift.

To determine the stiffness of the span section relative to compression-tension in the longitudinal direction EF and the condition of fixing in the reference sections, the equation of longitudinal vibrations is used. The options for finding λ _{n the} frequency equations of the bending, shear, and longitudinal vibrations of the beam, for which the given ratios of the measured eigenfrequency frequencies are satisfied, the elastic characteristics EI and μ of the span are calculated, and the conditions for the uniqueness of solving the inverse spectral problem are given in [10] (Saburov BC, Kuzmenko AP Theory of beam oscillations. [Electronic resource]: Textbook for the course "Dynamics of building structures and structures. Novosibirsk, 2015. - 179 s).

The most difficult to assess the technical condition are continuous spans.

As is known [11] (Sorokin ES, Dynamics of interfloor overlap. - M., 1941. - 240 p.), In contrast to single-span beams (for a split span) having only one main frequency of vertical vibrations, one first harmonic , one second harmonic, etc., multi-span continuous beams have a group of fundamental frequencies of vertical vibrations, a group of first harmonics, a group of second harmonics, etc. In this case, the number of frequencies of vertical vibrations in the group of a multi-span continuous beam is equal to the number of spans of the beam. The lowest frequency group is called the lowest frequency, the highest - the highest frequency. In each frequency group, the difference between adjacent frequencies is less than between the last frequency of one group and the first frequency of the subsequent group.

It is proposed to use the model of vibrations of a multi-span (or single-span) continuous beam, elastically fixed relative to angular and rigidly relative to transverse displacements in the supporting sections, as an analytical model of the n bridge span for vibrations in the vertical direction. The frequency equation of oscillations of a multi-span continuous beam is compiled according to the rules for the correspondence of boundary conditions [12] (Timoshenko SP, Young D.Kh., Weaver I. Oscillations in engineering. - M .: Mashinostroenie, 1985. - 344 p.).

If we assume in the model that the stiffnesses of the angular displacements in the reference sections of the spans μ _i are equal and the bearing conditions are the same, the characteristic numbers (the roots of the frequency equation (λ _n )) are determined by solving the frequency equation of oscillations of a multi-span continuous beam recorded in the form of a determinant ( n> 1):

- значения функций Крылова при х=L_n и определенных для n-го пролета длиной L_n,

- безразмерная координата;Where

- the values of the Krylov functions at x = L _n and defined for the nth span of length L _n ,

- dimensionless coordinate;

λ _n - characteristic numbers (roots of the frequency equation (6)), referred to the n-th span;

- коэффициент жесткости относительно угловых перемещений в опорных сечениях;

- stiffness coefficient relative to angular displacements in the reference sections;

To _ϕ - the rigidity of the nodes of the spans with supports relative to angular displacements;

K _Z = ∞ is the stiffness coefficient of the supports relative to the transverse (vertical) shift.

In the general case, when the stiffness of the angular displacements in the reference sections of the spans is different and the support conditions are not the same, the frequency equation of type (6) contains (3⋅N + 2) unknowns. Therefore, to solve the inverse spectral problem, it is necessary to compose a system of (3⋅N + 2) equations, each of which is a frequency equation written in relation to (3⋅N + 2) measured frequencies of natural vertical oscillations. It is practically impossible to measure such a number of natural frequencies because of the extremely small amplitudes of oscillations at high frequencies. Therefore, at the nerve stage of monitoring, we accept that the stiffnesses of the angular displacements in the reference sections of the spans are equal and the conditions of the spans of bearing are the same. In this case, only two values of the natural frequencies are sufficient. At the lower (or higher) frequencies of the first and second groups of vertical vibrations, the condition for the equality of the coefficient μ is fulfilled and therefore these frequencies are used for calculations.

The stiffness is found for angular displacements in the reference sections of the spans and the abutment conditions as a result of solving the frequency equation (6) with respect to λ _n for a fixed value of μ. In this case, the function of the ratio of the lower frequencies of the second and first frequency groups of the natural forms of vertical vibrations of the multi-span continuous beam is determined depending on the stiffness coefficient relative to the angular displacements K _ϕ in the reference sections p _2.1 / p _1.1 = Ф (μ) and the function λ _1.1 (μ), which determines the dependence of the minimum characteristic number on the stiffness coefficient μ.

This model satisfactorily describes the vibrations of bridge structures at known low frequencies of the first and second groups of natural forms of vertical vibrations, which are determined with the maximum accuracy during the examination.

For transverse and longitudinal vibrations, a continuous multi-span beam has only one main frequency of transverse and longitudinal vibrations, one first harmonic, one second harmonic, etc. That is, a continuous multi-span beam oscillates in the transverse and longitudinal directions as a beam on a uniform elastic base (beam on elastic supports) with some integral stiffness coefficients for the transverse shear of the base in the transverse and longitudinal directions, respectively, K _SH⊥ , K _{SH ||} . The solutions of direct and inverse spectral problems on beam vibrations on an elastic base are also given in [10] (Saburov BC, Kuzmenko AP The theory of beam vibrations. [Electronic resource]: Training manual for the course “Dynamics of building structures and structures.” Novosibirsk , 2015 .-- 179 s).

Further, the monitoring of the technical condition of especially dangerous, technically complex and unique bridge structures is carried out in the conditions of passage of vehicles by means of stationary monitoring equipment. Real-time continuous stack recordings determine the overall vibration level of the span in the ranges of significant frequencies of natural spatial vibrations of the bridge structure and frequencies excited by moving vehicles, depending on the magnitude of the load on the bridge structure created by the stream of vehicles, snow and wind loads.

The ranges of significant frequencies of natural vibrations of a particular bridge structure along the main axes of the structure are determined according to a detailed survey. The frequencies of natural vibrations depend on the length of the spans and the structure of the structure.

The impact of vehicles on spans is determined by the frequency spectrum of natural vibrations of the frames and bodies of cars, railway rolling stock, with the masses of aggregates and devices fixed to them, the masses of goods and the stiffness characteristics of springs, springs and air suspensions, as well as the technical condition of the surface of the carriageway or railway track . For vehicles, for example, there are two main frequency bands of exposure: the first in the range of 1 ÷ 4 Hz, the second 6 ÷ 10 Hz.

To assess the impact of wind loads, it is necessary to record the direction and speed of the wind, which is especially important for cable-stayed and arched bridge structures.

The vibration level is defined as the rms value in the given frequency ranges. The vibration level is compared with the settings given by the designers of the bridge structure for the amplitude of the vibrations. If the settings are exceeded, the vibration signal is recorded and, if necessary, a decision is made to stop the movement or to limit the speed of movement along the bridge structure, send a message to the addresses of the controlling organizations and, thus, ensure the safety of the operation of the structure by vibration level.

An example implementation of the claimed invention

The inventive method for monitoring the technical condition of bridge structures during their operation using periodic surveys of bridge structures and monitoring was used to process the results of two detailed seismometric surveys of the bridge structure through the Baibalakovsky channel for 17 km of the Khanty-Mansiysk - Nyagan road.

Specifications. The bridge span is all-metal with an orthotropic plate of the roadway. The continuous beam of the bridge has a total length of 346 m and six spans (longitudinal scheme 42.0 + 4 × 63.0 + 42.0 m). The total width of the bridge is 14.54 meters. The weight of a running meter of the superstructure is - 8.25 tf / m. Supports No. 1.7 of the bridge abutment - bezverstverkovye, precast-monolithic, reinforced concrete with a height of 3.754 meters, intermediate supports No. 2, 3, 4, 5, 6 of the bridge reinforced concrete from contour blocks on pile piles with a diameter of 1420 mm and a length of 14 m. the structure rests on the upper part of the supports at two points.

The span diagram and observation system during the examination are presented in FIG. 1. The points show the observation points (with a step of 5.25 m) on the profile along the longitudinal axis of the bridge with a mandatory observation point in the center of each support. Observation points 4-68 are located on the span, observation points 1-3 and 69-72 on the soil base of the coastal abutments of the bridge. Directions of coordinates during the examination: component X - along the longitudinal axis of the bridge; component Y - perpendicular to the longitudinal axis; component Z - vertically.

The oscillations of the bridge span under the influence of the microseismic background were recorded in separate sessions lasting 384 seconds (at a sampling frequency of 128 Hz) with simultaneous recording by three sensors on the bridge span. One of the sensors was used as a reference (its position remained unchanged during the entire inspection of the bridge - observation point No. 27), and the other two moved along the object being examined in accordance with the observation scheme.

According to paragraph 1 of the formula (option 1), an initial detailed seismometric survey of the bridge structure was carried out. Below are the dynamic and elastic characteristics that can be determined based on the proposed monitoring method.

приведенный амплитудный спектр колебаний

спектр параметра бегучести волны К_КБВ,[z](f) и спектр коэффициента когерентности колебания опорный пункт - пункт наблюдения

представлены на фиг. 2.Dynamic spectral characteristics of vertical oscillations (Z - component). The normalized amplitude acceleration spectrum averaged over all observation points

reduced amplitude spectrum of vibrations

spectrum of the wave run-time parameter of the KBM wave _{, [z]} (f) and the spectrum of the coherence coefficient of the vibration reference point - observation point

presented in FIG. 2.

On the spectra of vertical oscillations, two groups of spectral peaks are pronounced: 1.26–2.9 Hz — the first group; 3.47-5.6 Hz - the second group. Between the frequency ranges of the first and second groups, the frequency range of the minimum oscillation amplitudes is pronounced. The spectra of the transfer functions and the spectra in the frequency band 1.26-2.9 Hz clearly distinguish six spectral peaks corresponding to the frequencies of the first group of vertical vibrations of a six-span continuous beam on supports. In the frequency band of 3.47-5.6 Hz, six spectral peaks of the second group are distinguished, but less pronounced, there are practically no vibrations of the higher groups in the spectra. Minimum (0.1–0.2) values are observed on the runoff coefficient spectra in the indicated ranges, and maximum (0.8–0.9) values on the coherence coefficient spectra confirm the presence of intrinsic vibrations of the structure.

Frequency values that have the maximum coincidence for the frequencies of the spectral peaks of the reduced spectra (acceleration), spectra of the transfer function, coherence coefficient, and spectral minima for the spectrum of the wave coefficient K of the _{KBV, [z]} (f) along the main axes of the bridge structure (vertical, transverse and longitudinal) are presented in table 4.

, определенного по записям колебаний в пунктах наблюдения.Forms of own vertical vibrations. The identification of the number of natural forms of vertical vibrations was carried out using the transfer function, presented in the form of a two-dimensional spectrum of amplitudes and the initial phases of the oscillations in the form of a color map in the axes: amplitude spectrum module (phase) - oscillation frequency - distance along the observation profile. In FIG. 3 presents maps of the amplitude and phase reduced spectrum

determined by the records of fluctuations in the observation points.

The natural vibrations in the two-dimensional spectra are parallel to the axis of the number of line points from ellipsoid spots, the color of which corresponds to amplitudes of oscillations increased in relation to the general background. The number of ellipsoidal spots corresponds to the shape number in the case of a single-span or split beam model and the number of spans for a continuous multi-span structure (6 spots - 6 spans) for the first frequency group. For the second group of 6 spans - 12 spots, two on each span. In order to distinguish frequencies and plots of the second group of vertical oscillations, it is necessary to provide a monitoring scheme of at least 8 observation points on each span (in accordance with Kotelnikov’s theorem, four points for each half-wave). The greater detail of the observations allows one to determine the diagrams of their own forms with a smaller error.

After constructing “slices” of the diagrams of amplitude variation at a given frequency, depending on the observation point, taking into account the initial phases of the oscillations at the frequencies indicated in Table 4, diagrams of the first and second groups of common-mode forms of intrinsic vertical vibrations of the bridge structure were determined and identified (Table 1).

As can be seen from table 1, the lowest frequency (p _1.1 = 1.24 Hz) of the 1st group of vertical vibrations is characterized by a change in the sign of the amplitude of movement during the transition from one span to another, and the maximum (p _1.6 = 2.719 Hz) - by the movement of one sign.

Plots of common-mode forms of their own transverse (Y-component) and longitudinal (X-component) vibrations are shown in Table 2 and Table 3.

From tables 2 and 3 it can be seen that in the transverse and longitudinal direction, the bridge structure oscillates at the frequencies of its own forms as a continuous beam on an elastic homogeneous base - the forms of natural vibrations for the entire continuous span are distinguished: first, second, third, etc.

Assessment of the stiffness of the bending section of a continuous beam of a bridge structure by the ratio of the lowest natural frequencies of the second and first groups of vertical vibrations.

The analytical model of the bridge structure is represented by a six-span continuous beam elastically fixed relative to angular and rigidly relative to transverse movements (K _Z = ∞) with spans L ₁ = L ₆ , L ₂ = L ₃ = L ₄ = L ₅ and L ₂ / L ₁ = 1 ,5.

In general, the frequency equation of a 6-span beam, elastically fixed relative to angular displacements in the reference sections, according to expression (6) for N = 6, can be written in the form:

Where

To _ϕ - the rigidity of the nodes of the spans with supports relative to angular displacement.

Experimentally determined:

- the lowest frequency of the natural form of vertical vibrations of the first group (Z-component) is p _1.1 = 1.24 Hz;

- the lowest frequency of the second group - p _2.1 = 4.06 Hz.

In FIG. 4a shows the function Ф (μ) for a six-span beam with the above spans defined according to the frequency equation (6), and in FIG. 4b is a diagram of the function λ _1,1 (μ) related to the span length L ₂ .

The sequence for determining λ _1.1 from a given frequency ratio p ₂₁ / p _{11 is} shown in FIG. 4a, b. First, at a predetermined ratio of frequencies p ₂₁ / p ₁₁ according to the dependence Ф (μ) shown in FIG. 4a (arrows 1-2), the value of the coefficient μ (p ₂₁ / p ₁₁ ) is determined, then at a given value of μ the coefficient λ _1.1 is determined (Fig. 4b, arrows 3-4).

The calculation of the mean cross section stiffness (EI) of a multi-span continuous beam is made according to the well-known formula [12] (Timoshenko SP, Young D.Kh., Weaver I. Oscillations in engineering. - M .: Mashinostroenie, 1985. - 344 s .):

where λ _i - characteristic numbers (roots of the frequency equation), reduced to the total length or length (L) of a separately specified span of a multi-span beam;

L is the total length of the spans or the length of a separately specified span;

m is the linear mass;

EI is the stiffness of the span section relative to bending;

p _i [Hz] - the value of the frequency of the i-th form of natural oscillations, determined as a result of the survey.

The value of p _2.1 / p _1.1 = 3.28 corresponds to the stiffness value of the angular displacements μ = 2.1 (Fig. 4a) and λ _{1.1, L2} = 3.893 (Fig. 4b), referred to the span of length L = 63 m. The bending stiffness of the section is (design value - 4.2 410 ⁶ ts⋅m ² ):

Determination of the propagation velocity of elastic waves along spans. According to the definition of the transfer function, the inverse Fourier transform of the complex spectrum of the transfer function determines the impulse response of the object at the observation points, which makes it possible to construct velocity hodographs (seismograms) and determine the propagation velocity of elastic waves for the three observation components along the span [9] (Saburov BC, Kuzmenko A .P. Inspection of buildings with increased number of storeys. Engineering-seismometric method. LAMBERT Academic Publishing, 2013. - 175 s). An example of high-speed travel time curves for elastic waves with polarization along the components X, Y, Z (pulse action point - reference point No. 27) is shown in FIG. 5.

Evaluation of the stiffness of the bending section by the propagation velocity of the bending will. The group velocity of a flexural wave (pulse propagation velocity) along a continuous span is [13] (Landau LD, Lifshits EM Theory of elasticity. - M.: Nauka, 1987. - 248 p.):

where m is the linear mass [(tf / m) / (m / s ² )].

The propagation velocity of a bending wave of a pulse with vertical polarization, the carrier frequency of the pulse and the structural stiffness of the cross section of the bending of individual spans are shown in table 5.

The average speed of propagation of bending waves along a continuous span with vertical polarization (Z - component) is V _Z = 430 ± 10 m / s ² (Fig. 5c). The average frequency of the propagating pulse is f _Z = 7.2 Hz. According to expression (10), the stiffness of the cross section for bending in the vertical direction is equal to (design value 4.2⋅10 ⁶ ts⋅m ² ):

where m = 0.841 tf⋅c ² / m ² - linear mass.

As can be seen, the stiffness of the bending cross section in the vertical direction, obtained from the velocities of bending waves (11) and calculated from the natural frequencies in the replacement model (9), practically coincides.

Stiffness of the span in the transverse direction. The average speed of propagation of bending waves along a structure with polarization in the transverse direction (Y - component) is V _Y = 1250 ± 30 m / s ² . The average value of the carrier frequency of the pulse f _Y = 27.2 Hz. According to the expression (11), the stiffness of the cross section to bending in the transverse direction is equal to:

The magnitude of the dynamic stiffness of the supports for vertical shear is estimated by the amplitudes of the vertical displacements at the observation points located in the reference sections of the spans (above the bridge supports), at the lowest frequency of the first group of natural vertical vibrations in accordance with the theory of resistance of materials. The task is reduced to finding the stiffness of the supports with a known deflection diagram and distributed static load equal to the inertial load. The values of the dynamic stiffness of the supports for vertical shear at the lowest frequency of natural vertical vibrations are given in table 6.

The calculation results show that the dynamic stiffness of the vertical shear on the support No. 4 is significantly less than the rest of the supports, which indicates the need for additional studies of the conditions for pairing the support No. 4 with the span and the soil base to determine the reasons for the increased mobility of the support.

According to paragraph 2 of the formula (option 2), taking into account the life cycle of bridge structures (30-50 years), it is impossible to present data on the change over several years of the frequencies of natural vibrations and elastic characteristics during operation, exceeding the error of their determination. For reliability, observation periods of at least 5-10 years are required. However, seasonal changes from the temperature factor were recorded.

Since it is not economically feasible to install a stationary monitoring system on a bridge structure across the Baibalakovsky Canal, a second detailed seismometric survey was carried out to isolate seasonal changes in dynamic characteristics from the temperature factor.

According to the data of two surveys, it is possible to compare the natural frequencies of vertical oscillations during the survey in April 2006 and March 2008 at different ambient temperatures. In March, the average daily temperature was 10-15 ° C lower than in April.

In FIG. Figure 6 shows the normalized amplitude spectra of acceleration of vertical vibrations of the bridge structure averaged over all observation points obtained during surveys of 2006 and 2008.

As you know, with increasing temperature, due to the expansion of spans along the longitudinal axis of the bridge, compressive axial stresses increase, which leads to a decrease in the frequencies of natural vertical vibrations.

Table 7 shows the frequencies of the first group of intrinsic vertical vibrations of the bridge structure for two surveys. The frequencies of natural vertical oscillations are measured with an accuracy of ÷ 0.015 (1/64) Hz.

The frequency groups in FIG. 6 correspond to the same forms of vertical vibrations, the spectra differ in amplitude. A pronounced spectral peak with a central frequency of about 3.5 Hz is caused by vibrations at the frequency of the first form of transverse vibrations of the bridge structure (see table 2). The lowest frequency values of the second group are 3.85 Hz. The ratio of frequencies for April and March are equal to p _2.1 / p _1.1 = 3.243, respectively; p _2.1 / p _1.1 = 3.274.

According to paragraph 3 of the formula, the ranges of significant frequencies of vertical, transverse and longitudinal natural vibrations are determined, respectively: 1.2 ÷ 6 Hz; 3 ÷ 8 Hz; 9 ÷ 30 Hz. The impact of vehicles for the road bridge in the vertical direction is in the ranges of 1 ÷ 4 Hz and 6 ÷ 10 Hz.

Thus, for a road bridge, it is necessary to determine the overall level of vibration along the main axes of the structure in the above frequency ranges. The level of vibration, as you know, can be estimated by calculating the rms values of displacements, speeds or accelerations in the given frequency ranges. Similarly, designers of bridge structures set the settings in the form of rms values (usually acceleration) in the above frequency ranges, which are compared with the actual ones depending on the loads on the bridge structure.

Literature.

1. Cooper N.G. and others. "Dynamics of railway bridges." M., "Transport", 1965.

2. The method of dynamic testing of large-scale structures. RF patent No. 2104508, cl. G01M 7 / 02.1998.

3. A method for diagnosing structural damage during cyclic loads. RF patent No. 2089874, cl. G01N 3 / 32,1997.

4. The method of vibration testing of spans of bridge structures. RF patent No. 2240626, cl. G01M 7 / 02.1999.

5. A method for monitoring an automobile bridge. RF patent No. 2317534, cl. G01M 5/00, 2008.

6. RF patent No. 2140625. A method for determining the physical condition of buildings and structures. Kuzmenko A.P., Baryshev V.T. and other class G01M 7/00.

7. RF patent No. 2150684. A way to bring to a single time registration of multi-time measurement records. Kuzmenko A.P., Saburov V.S. and others. Bulletin of inventions. 2000. No. 16.

8. G. Korn and T. Korn, A Handbook of Mathematics for Scientists and Engineers. Moscow 1974.- 760 p.

9. Saburov B.C., Kuzmenko A.P. Inspection of buildings with high floors. Engineering seismometric method. LAMBERT Academic Publishing, 2013 .-- 175 p.

10. Saburov B.C., Kuzmenko A.P. Theory of beam vibrations. [Electronic resource]: Textbook. allowance for the course "Dynamics of building structures and structures." Novosibirsk, 2015 .-- 179 p. (ISBN 978-5-9905791-3-2)

11. Sorokin E.S. The dynamics of floors. - M., 1941 .-- 240 p.

12. Timoshenko S.P. Young D.H., Weaver I. Fluctuations in engineering. - M.: Mechanical Engineering, 1985 .-- 344 p.

13. Landau L.D., Lifshits E.M. Theory of elasticity. - M .: Nauka, 1987 .-- 248 p.

Claims (9)

1. A method for monitoring the technical condition of bridge structures during their operation, which consists in monitoring the bridge structure by registering the spatial vibrations of the span under the influence of a microseismic background of natural and technogenic origin, determine the dynamic characteristics of the spatial vibrations of the bridge structure from the survey, evaluate the technical the state of the object, characterized in that monitoring the technical condition of the bridge with armaments that are not related to an increased level of responsibility are carried out in the absence of vehicle traffic through periodic detailed examinations using mobile recording equipment, according to the observation scheme, which includes at least eight observation points on each passage with mandatory observation points on all the supports of the bridge structure, which allows reliably with a relative error of no more than 3% to select frequencies and obtain ordinates of diagrams of the first and second groups of eigenfrequencies vertical oscillation eigenfrequencies transverse and longitudinal vibrations; through mathematical processing, the spectra (rows) of frequencies (p _zi , p _yi , p _xi ) and the ordinates of the diagrams z _i (x), y _i (x), x _i (x) of the eigenvalues of vertical, transverse and longitudinal vibrations, from the diagrams of sections of the spectra of the transfer functions, they identify the forms of their own vertical, transverse and longitudinal vibrations of the span structure and determine the lower frequencies of the first two groups of natural vertical vibrations, the series of natural frequencies of transverse and longitudinal vibrations, choose Depending on the nature of the series of natural frequencies of the form of numbers replacing analytical models: - for vertical vibrations - multi-span continuous beam, elastically fixed in the reference sections, determine the ratio of the lowest the frequencies of the second group of natural vibrations to the lowest frequency of the first group (p _2.1 / p _1.1 ), according to the analytical model, calculate the characteristic numbers (λ _n ) by solving the frequency equation of the vibrations of a multi-span continuous beam and determine the elastic characteristics of the span: the value of the cross-section stiffness relative to bending (EI), characterizing the bearing capacity of the span, the stiffness coefficient relative to angular displacements in the reference sections of the spans μ, the stiffness coefficient of the supports relative to the transverse Nogo (vertical) shift K _Z ; - for transverse and longitudinal vibrations - a multi-span continuous beam is considered as a single-span beam on an elastic homogeneous base, according to this analytical substitution model, the stiffness coefficients of the transverse shear of a homogeneous elastic base in the transverse and longitudinal directions are _determined : K _SH⊥ and K _{SH ||} .; using substitute models and frequency series, the basic elastic characteristics of the bridge structure are calculated, the elastic characteristics are compared with those obtained earlier in the process of initial and subsequent detailed examinations, and the change in the technical condition of the span and supports of the bridge structure during operation is evaluated. 2. A method for monitoring the technical condition of bridge structures during their operation, which consists in monitoring the bridge structure by registering the spatial vibrations of the span under the influence of a microseismic background of natural and man-made origin, determine the dynamic characteristics of the spatial vibrations of the bridge structure from the survey, evaluate the technical the state of the object, characterized in that in the process of monitoring the technical condition I especially dangerous, technically complex and unique bridge structures periodically (1-2 times a month) carry out registration of fluctuations of the bridge structure, taking into account the temperature factor at the time registration of fluctuations, in the absence of movement of vehicles through stationary observation points, located according to the scheme, which includes at least two observation points on each span of the bridge structure, allowing after receiving (rows) of frequencies (p _zi , p _yi , p _xi ) and ordinates diagrams z _i (x), y _i (x), x _i (x) eigenmodes of vertical, transverse and longitudinal oscillations of the results of detailed data of the primary examination of bridge structures reliably with a relative error less than 3% and periodically allocate ide To identify the frequencies of the first and second groups of natural frequencies of vertical vibrations, natural frequencies of transverse and longitudinal vibrations, periodically during operation, determine the change in the lower frequencies of the first two groups of natural vertical vibrations, the series of natural frequencies of transverse and longitudinal vibrations and calculate the basic elastic characteristics using selected replacement analytical models bridge structures, evaluate the change in elastic characteristics over time during the operation of the structure, including including taking into account their seasonal changes due to the temperature factor, the technical condition of the span and supports, the regulatory, permissible, ultimate and destructive loads, as well as the wear and safety of the further operation of the bridge structure are evaluated. 3. The method according to p. 2, characterized in that the monitoring of the technical condition of especially dangerous, technically complex and unique bridge structures is carried out in the conditions of passage of vehicles, by means of stationary monitoring equipment for monitoring continuous stack records obtained in real time, determine the general vibration level of the span in the ranges of significant frequencies of natural spatial vibrations of the bridge structure and frequencies excited by the driving camping vehicles, depending on the load on the bridge construction produced transport stream means, snow and wind loads, compare the vibration level with the settings given by the designers of the bridge structure for the amplitude of the vibrations and, if the settings are exceeded, record the vibration signal and, if necessary, make a decision to stop the movement or limit the speed of the bridge structure.

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