CN114993835A - Reinforced concrete beam damage identification method based on static and dynamic response - Google Patents
Reinforced concrete beam damage identification method based on static and dynamic response Download PDFInfo
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Abstract
The invention discloses a reinforced concrete beam damage identification method based on static and dynamic response, which comprises the following steps: respectively carrying out a static loading test and a dynamic response test on the concrete structure to obtain static data and dynamic response parameters of the current concrete structure; presetting the obtained static force data and dynamic response data respectively, and performing wavelet decomposition on the processed data to obtain corresponding wavelet coefficients; substituting the obtained wavelet coefficient into a damage identification calculation formula to obtain a damage identification index; and identifying the damage identification result of the concrete structure according to the obtained indexes. The method utilizes wavelet decomposition and variance curvature to be very sensitive to abnormal signals, so that the obtained static force measurement data can identify structural damage; in the aspect of dynamic response, the measurement errors caused by incomplete observation of dynamic parameters and environmental noise can be effectively reduced by carrying out wavelet de-noising and wavelet decomposition treatment on the obtained dynamic response vibration mode parameters, so that the measurement result is more accurate.
Description
Technical Field
The invention relates to the technical field of diffusion experiments, in particular to a reinforced concrete beam damage identification method based on static and dynamic response.
Background
In recent years, with the rapid development of science and technology, modern industry is developing towards large scale and industrialization, and building structures also show the complicated trend of large span, large scale and the like. Once these large building structures are destroyed, they will have disastrous effects on human production and life. With the rapid development of the building industry, the collapse accidents of buildings at home and abroad are more and more, and a large part of reasons are that the buildings have some defects. These defects are often undetectable and cannot be easily detected, so that preventive or remedial measures cannot be taken in advance. Researches on how to ensure the health and stability of the structure, the health monitoring of the structure and the damage identification of the structure become more and more important for people to pay attention.
The static characteristic parameters of the structure mainly comprise structure static strain, deflection and the like. After the structure is damaged, the rigidity of the structure can be changed, and finally the deflection, the strain and the like are changed. Therefore, parameter data of strain, deflection and the like of the structure are measured and collected, the data before and after damage are compared and analyzed, the change rule of the data is researched, and structural damage is identified. However, the amount of information in the static measurement data is very small, so that the research of the method is still in the development stage. Structural stiffness is an important parameter in these small quantities of information, and can be derived from sufficient and comprehensive measurement data.
The dynamic response-based structural damage identification has the potential advantage of remote online monitoring in structural health monitoring, normal traffic does not need to be interrupted in the monitoring process, and particularly for large civil engineering structures such as oil platforms and large bridges, the structure can be monitored by utilizing structural vibration caused by environmental excitation, so that real-time monitoring is realized. Therefore, the monitoring technology of the whole structure with vibration mode analysis as the core is rapidly developed and widely applied in the last 30 years. Because the dynamic measurement information quantity is larger than the static measurement information quantity, the research on the damage identification method based on the structural dynamic measurement data is relatively sufficient. However, due to the different sensitivity of structural damage to different identification parameters, research into structural damage identification based on dynamic measurement data has been still active in recent years. The common damage identification indexes based on the structural dynamic test parameters mainly comprise: natural frequency, displacement mode shape, displacement/acceleration frequency response function, curvature mode shape, strain frequency response function and the like. However, the identification method based on structural dynamics still needs to solve the identification difficulties caused by incomplete observation (modality and degree of freedom) and data errors.
Disclosure of Invention
In view of the above, the present invention has been made to provide a method for identifying damage to a reinforced concrete beam based on a static-dynamic response that overcomes or at least partially solves the above-mentioned problems.
In order to solve the technical problem, the embodiment of the application discloses the following technical scheme:
a reinforced concrete beam damage identification method based on static and dynamic response is characterized by comprising the following steps:
s100, respectively carrying out a static force loading test and a dynamic response test on the concrete structure to obtain static force data and dynamic response parameters of the current concrete structure;
s200, respectively carrying out preset processing on the obtained static force data and dynamic response data, and carrying out wavelet decomposition on the processed data to obtain corresponding wavelet coefficients;
s300, substituting the obtained wavelet coefficient into a damage identification calculation formula to obtain a damage identification index;
and S400, identifying the damage identification result of the concrete structure according to the obtained indexes.
Further, the static force data of the concrete structure comprises at least: deflection of the concrete structure and bar strain data.
Further, the dynamic response parameters of the concrete structure at least comprise: displacement mode and strain mode parameters of the concrete structure.
Further, the damage identification calculation formula is as follows:
wherein,
the parameters are wavelet coefficient curvature factors based on static and dynamic parameters, namely damage identification indexes, and displacement, strain and vibration mode data can be taken as the parameters;
wavelet coefficients representing static and dynamic parameters at the ith node of the beam structure; and a is the node spacing.
Further, the method of the static loading test is as follows: the method comprises the steps of carrying out 4-point loading on a test beam by adopting a jack, enabling the distance between two loading points to be l/3, enabling l to be the length of a test piece, connecting the loading points with a load sensor, loading the load on the pre-damaged beam through the load sensor, measuring vertical deflection deformation data of the beam through a shifter arranged on the test piece, measuring strain data of a tensioned steel bar through a pre-embedded steel bar strain gauge, and measuring strain change of a compression area of concrete through pasting a resistance strain gauge on the outer edge of the compression side of a span.
Further, the shifter and the steel bar strain gauge are evenly placed on the test beam, the number of the shifter is 8, the distance between the two shifters is l/10, the number of the steel bar strain gauges is 12, the distance between the two strain gauges is l/15, and l is the length of the test piece.
Further, the method of the dynamic response test is as follows: the surface of a test beam is polished to be flat, after acetone is carefully cleaned, the acceleration sensor is firmly bonded by using clay, the beam structure is excited by a hammering method on the central line of the upper section of the beam, the data of the sensor is recorded, and the frequency response function curve measured by each measuring point is normalized to obtain the modal shape data.
Further, the method for normalizing the frequency response function curve measured at each measuring point comprises the following steps: and taking the maximum value of the amplitude of the measuring point corresponding to each order mode as a normalization factor, determining the positive and negative of the mode shape of each measuring point by using the phase angle, and comparing the value field normalization factor values of each measuring point to obtain the mode shape of the beam.
The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:
in the static response aspect, firstly, wavelet decomposition and variance curvature processing are carried out on static data obtained by loading to obtain corresponding damage identification indexes, then whether damage occurs or not, where damage positions are located and the relative size of damage degrees can be judged by analyzing the indexes, and only displacement and strain data of a structure need to be measured in a static loading test, so that a measuring instrument is simple. Compared with the existing damage identification based on static parameters, the method has the advantages that the static measurement data can identify the damage of the structure by performing wavelet decomposition and variance curvature processing on the displacement and strain data which can not completely reflect the damage information of the structure and utilizing the wavelet decomposition and the variance curvature to be very sensitive to abnormal signals; in the aspect of dynamic response, the obtained dynamic response vibration mode parameters are subjected to wavelet de-noising and wavelet decomposition processing, so that incomplete observation of the dynamic parameters and environmental noise can be effectively reduced
And the measurement error generated by the sound enables the measurement result to reflect the damage information of the structure more accurately.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
fig. 1 is a flowchart of a reinforced concrete beam damage identification method based on static and dynamic response in embodiment 1 of the present invention;
FIG. 2 is a schematic diagram of the static loading of the test beam in embodiment 1 of the present invention;
FIG. 3 is a schematic view showing the installation position of a displacement gauge in embodiment 2 of the present invention;
FIG. 4 is a schematic diagram of a position of a steel bar strain gauge in embodiment 2 of the present invention;
fig. 5 is a schematic view of an installation position of an acceleration sensor in embodiment 2 of the present invention;
FIG. 6 is a power test hammer point in example 2 of the present invention;
FIG. 7(a) is a graph of the absence of damage in a static damage indicator in example 1 of the present invention;
FIG. 7(b) is a graph showing a single lesion in a static lesion indicator in example 1 of the present invention;
FIG. 7(c) is a graph of multiple lesions in the indication of static damage in example 1 of the present invention;
FIG. 8(a) is a schematic diagram of the dynamic damage index in example 1 of the present invention;
FIG. 8(b) is a schematic diagram of a dynamic damage index showing a single damage in example 1 of the present invention;
FIG. 8(c) is a schematic diagram of a dynamic damage index showing multiple damages in example 1 of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
In order to solve the problems in the prior art, the embodiment of the invention provides a reinforced concrete beam damage identification method based on static and dynamic response.
Example 1
The embodiment discloses a reinforced concrete beam damage identification method based on static and dynamic response, as shown in fig. 1, including:
s100, respectively carrying out a static force loading test and a dynamic response test on the concrete structure to obtain static force data and dynamic response parameters of the current concrete structure.
In this embodiment, the static data of the concrete structure comprises at least: deflection of the concrete structure and rebar strain data. The dynamic response parameters of the concrete structure include at least: displacement mode and strain mode parameters of the concrete structure.
Specifically, in this embodiment, the method of the static loading test is as shown in fig. 2, and the test uses a jack to perform 4-minute point loading on the test beam. The test piece has a size of l × b × h and has a rectangular cross section. The distance between the two loading points is l/3, and the loading points are both connected with the load sensor. And the load of the pre-damaged beam cannot exceed the cracking load, and the cracking load is determined according to the bearing capacity calculation. The loading grade is controlled by a pressure sensor, and the magnitude of the external load is measured by a load sensor connected with the hydraulic jack.
The vertical deflection deformation of the beam is measured through a dial indicator arranged on a test piece, the strain of a tensile steel bar is measured through a pre-buried resistance strain gauge, the strain change of a compression area of concrete is measured by attaching the resistance strain gauge to the outer edge of the middle compression side, all data are automatically collected by an IMP data acquisition system, a shifter and the steel bar strain gauge are evenly placed on the test beam, the number of the shifters is 8, the distance between the two shifters is l/10, the number of the steel bar strain gauges is 12, the distance between the two strain gauges is l/15, and l is the length of the test piece. The arrangement conditions of the displacement and the strain gauge of each test piece are respectively shown in fig. 3 and fig. 4, wherein the serial numbers of the displacers are from left to right: w1, W2, W3, W4, W5, W6, W7, W8 and W9. The serial number of the steel bar strain gauge is sequentially as follows from left to right: e1, E2, E3, E4, E5, E6, E7, E8, E9, E10, E11, E12, E13. Loading force to a cracking load, and recording displacement meter data obtained by the test: w1, w2, w3, w4, w5, w6, w7, w8, w 9; and steel bar strain data: e1, e2, e3, e4, e5, e6, e7, e8, e9, e10, e11, e12, e 13.
In this embodiment, the method of the dynamic response test is as follows: the surface of the test beam is polished to be flat, and after acetone is carefully cleaned, the sensor is firmly bonded by using clay. When the acceleration sensor is installed, the sensor must be installed in the direction to be measured of a measurement vibration point, the influence of the lateral sensitivity of the sensor is reduced as much as possible, when the beam is knocked, the sensor is kept away from the sensor, the signal overload is prevented, and the specific installation position of the sensor is shown in fig. 5. The beam structure was excited by hammering, the dynamic test hammer point was as shown in fig. 6, and the sensor data was recorded. Normalizing the frequency response function curve measured by each measuring point, which comprises the following specific steps: using the maximum value of the amplitude of the measuring point corresponding to each order mode as a normalization factor, and determining the positive and negative of the mode shape of each measuring point by the phase angle (
Taking positive, and taking positive from-180-0). The phase angle only determines the positive and negative problems of the vibration mode of the measuring point, and the numerical value of the phase angle does not play a substantial role in judging the positive and negative of the vibration mode, so that the error of the phase measurement numerical value does not need to be considered too much in the measuring process. Comparing the value domain normalization factor values of the measuring points to obtain the vibration mode of the beam
S200, respectively carrying out preset processing on the obtained static force data and dynamic response data, and carrying out wavelet decomposition on the processed data to obtain corresponding wavelet coefficients;
specifically, the displacement, strain data and modal shape data obtained by the test are respectively converted into the following determinant:
W＝{wl w2 w3 w4 w5 w6 w7 w8 w9}
E＝{e1 e2 e3 e4 e5 e6 e7 e8 e9 e10 e11 e12 e13}
substituting the obtained displacement determinant into a wavelet decomposition program in MATLAB to obtain a wavelet decomposition coefficient determinant D of displacement data cwt And outputting the wavelet decomposition coefficient of the displacement data. Similarly, the wavelet decomposition coefficient E of the strain data is calculated cwt In the present example, the displacement data is wavelet decomposed by a coefficient W cwt Wavelet decomposition coefficient E of strain data cwt Wavelet decomposition coefficient of modal shape data
Respectively as follows:
s300, substituting the obtained wavelet coefficient into a damage identification calculation formula to obtain a damage identification index; in this embodiment, the damage identification calculation formula is:
wherein,
the parameter is a wavelet coefficient curvature factor based on static and dynamic parameters, namely a damage identification index, and the parameter can be displacement, strain and vibration mode data;
wavelet coefficients representing static and dynamic parameters at the ith node of the beam structure; and a is the node spacing.
Specifically, in this embodiment, the specific formula of the damage identification index of the static and dynamic parameters is as follows:
in the formula, W i wt At node i of the beam structureDisplacement wavelet coefficient curvature damage index size; e i wt The strain wavelet coefficient curvature damage index size at the beam structure node i is shown;
the size of the index of the vibration mode wavelet coefficient curvature damage at the node i of the beam structure is shown.
And S400, identifying the damage identification result of the concrete structure according to the obtained indexes. Specifically, when the displacement wavelet coefficient curvature index is processed, and when the node number-damage index is as shown in fig. 7(a), the damage index is 0 at each node, it can be considered that the beam structure is not damaged basically; when the node number-damage index is as shown in fig. 7(b), it can be considered that the beam structure is damaged near the node 4, i.e., the displacement meter W4, and the indexes at other undamaged nodes are 0, and the larger the damage degree is, the larger the value of the index at the damaged node is; when the node number-damage index is as shown in fig. 7(c), it can be considered that the beam structure is damaged in the vicinity of the displacement meter W2 and the vicinity of the displacement meter W6, respectively, and similarly to the single damage case, the damage index is not 0 at the 2 and 6 nodes, the index values at the remaining undamaged nodes are 0, and the value of the damage index under 20% damage is larger than the damage index value under 10% damage at the node.
Similarly, the strain coefficient curvature index is treated in the same manner, but the change in the beam structure position corresponding to each node number is noted.
And (5) processing the curvature index of the vibration mode wavelet coefficient, and drawing a first-order vibration mode damage index obtained by the test. When the node number-damage index is as shown in fig. 8(a), it can be considered that the beam structure is not substantially damaged; when the node number-damage index is as shown in fig. 8(b), it can be considered that the beam structure is damaged in the vicinity of the node 2, i.e., the acceleration sensor 2#, and the damage index value is larger as the degree of damage is larger; when the node number and the damage index are as shown in fig. 8(c), it is considered that the beam structure is damaged in the vicinity of the acceleration sensor 2# and the acceleration sensor 4# respectively, and the degree of damage is large and small, which impairs the determination of the damage index value.
In the static and dynamic response-based reinforced concrete beam damage identification method provided by the embodiment, in the aspect of static response, wavelet decomposition and variance curvature processing are firstly carried out on static data obtained by loading to obtain corresponding damage identification indexes, then whether damage occurs or not, where the damage position is and the relative size of the damage degree can be judged by analyzing the indexes, and in a static loading test, only displacement and strain data of a structure need to be measured, and a measuring instrument is simple. Compared with the existing damage identification based on static parameters, the method has the advantages that the static measurement data can identify the damage of the structure by performing wavelet decomposition and variance curvature processing on the displacement and strain data which can not completely reflect the damage information of the structure and utilizing the wavelet decomposition and the variance curvature to be very sensitive to abnormal signals; in the aspect of dynamic response, the measurement errors caused by incomplete observation of dynamic parameters and environmental noise can be effectively reduced by performing wavelet de-noising and wavelet decomposition on the obtained dynamic response mode parameters, so that the measurement results can more accurately reflect the damage information of the structure.
It should be understood that the specific order or hierarchy of steps in the processes disclosed is an example of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged without departing from the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not intended to be limited to the specific order or hierarchy presented.
In the foregoing detailed description, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the subject matter require more features than are expressly recited in each claim. Rather, as the following claims reflect, invention lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.
Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. Of course, the storage medium may also be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. Of course, the processor and the storage medium may reside as discrete components in a user terminal.
For a software implementation, the techniques described herein may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in memory units and executed by processors. The memory unit may be implemented within the processor or external to the processor, in which case it can be communicatively coupled to the processor via various means as is known in the art.
What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the embodiments described herein are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim. Furthermore, any use of the term "or" in the specification of the claims is intended to mean a "non-exclusive or".
Claims (8)
1. A reinforced concrete beam damage identification method based on static and dynamic response is characterized by comprising the following steps:
s100, respectively carrying out a static force loading test and a dynamic response test on the concrete structure to obtain static force data and dynamic response parameters of the current concrete structure;
s200, respectively carrying out preset processing on the obtained static force data and dynamic response data, and carrying out wavelet decomposition on the processed data to obtain corresponding wavelet coefficients;
s300, substituting the obtained wavelet coefficient into a damage identification calculation formula to obtain a damage identification index;
and S400, identifying the damage identification result of the concrete structure according to the obtained indexes.
2. The reinforced concrete beam damage identification method based on static-dynamic response of claim 1, wherein the static data of the concrete structure at least comprises the following steps: deflection of the concrete structure and bar strain data.
3. The method for identifying the damage of the reinforced concrete beam based on the static-dynamic response as claimed in claim 1, wherein the dynamic response parameters of the concrete structure at least comprise: displacement mode and strain mode parameters of the concrete structure.
4. The reinforced concrete beam damage identification method based on the static-dynamic response, as claimed in claim 1, wherein the damage identification calculation formula is:
wherein,
the parameter is a wavelet coefficient curvature factor based on static and dynamic parameters, namely a damage identification index, and the parameter can be displacement, strain and vibration mode data;
wavelet coefficients representing static and dynamic parameters at the ith node of the beam structure; and a is the node spacing.
5. The reinforced concrete beam damage identification method based on static-dynamic response of claim 1, wherein the static loading test method comprises the following steps: the method comprises the steps of carrying out 4-point loading on a test beam by adopting a jack, enabling the distance between two loading points to be l/3, enabling the loading points to be connected with a load sensor, loading a load on a pre-damaged beam through the load sensor, measuring vertical deflection deformation data of the beam through a shifter arranged on the test piece, measuring strain data of a tensioned steel bar through a pre-embedded steel bar strain gauge, and measuring strain change of a compression area of concrete through pasting a resistance strain gauge on the outer edge of a mid-span compression side.
6. The method for identifying the damage of the reinforced concrete beam based on the static and dynamic response is characterized in that the displacers and the steel bar strain gauges are evenly arranged on the test beam, the number of the displacers is 8, the distance between the two displacers is l/10, the number of the steel bar strain gauges is 12, and the distance between the two strain gauges is l/15, wherein l is the length of the test piece.
7. The reinforced concrete beam damage identification method based on static and dynamic response of claim 1, wherein the dynamic response test method comprises the following steps: the surface of a test beam is polished to be flat, after acetone is carefully cleaned, the acceleration sensor is firmly bonded by using clay, the beam structure is excited by a hammering method at the center line of the upper section of the beam, the data of the sensor is recorded, and the frequency response function curve measured by each measuring point is normalized to obtain the modal shape data.
8. The reinforced concrete beam damage identification method based on static and dynamic response of claim 7, wherein the method for normalizing the frequency response function curve measured at each measuring point comprises the following steps: and taking the maximum value of the amplitude of the measuring point corresponding to each order mode as a normalization factor, determining the positive and negative of the mode shape of each measuring point by using the phase angle, and comparing the value field normalization factor values of each measuring point to obtain the mode shape of the beam.
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