CN113295310A - Bridge damage determination method based on strain stiffness representative value - Google Patents
Bridge damage determination method based on strain stiffness representative value Download PDFInfo
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Abstract
The invention discloses a bridge damage judgment method based on a strain stiffness representative value, which comprises the following steps of: establishing a minimized bridge health monitoring system; selecting a reference section; collecting monitoring data and determining a representative value matrix (closed traffic) of the initial strain stiffness of the bridge or an expected matrix and a confidence interval (open traffic) of the representative value of the initial strain stiffness; regularly collecting and calculating a current strain stiffness representative value matrix or an initial strain stiffness representative value expectation matrix and a confidence interval; and judging whether the strain stiffness representative value matrix or the strain stiffness representative value expectation matrix changes or not, judging the damage condition of the structure according to the change condition, the confidence interval and the video image information, if no damage occurs, carrying out the next round of monitoring, and if not, correcting the strain stiffness representative value matrix or the strain stiffness representative value expectation matrix and carrying out the next round of monitoring. The method can realize the rapid and accurate judgment of the bridge damage under closed traffic and the regular online judgment of the bridge damage under open traffic.
Description
Technical Field
The invention relates to a bridge damage determination method, in particular to a bridge damage determination method based on a strain stiffness representative value, and belongs to the technical field of bridge monitoring.
Background
The method is one of the common modes for continuously and dynamically monitoring the bridge structure, and can ensure the operation safety of the bridge structure. However, the current bridge monitoring technology still has defects, is limited by the technical level of sensors and the limitation of manufacturing processes, is difficult to ensure in stability and accuracy, can generate a zero drift phenomenon along with the increase of service time, and a widely adopted single threshold mode only depends on simple mathematical statistics data, so that mass monitoring data are not fully utilized, and the technical state of the bridge cannot be scientifically and reasonably evaluated. Therefore, many scholars have studied bridge damage recognition and have achieved many results. However, these conventional damage identification methods, such as methods based on frequency, modal shape, modal strain energy, compliance matrix, etc., may achieve certain effects in closed traffic, and have low practicability in operation phase, especially random traffic.
In view of the above, how to perform deep mining analysis on massive bridge monitoring data in an operation period to realize the real value of a bridge health monitoring system, more scientifically and reasonably evaluate the safety state of a bridge structure, and has extremely important significance for guaranteeing the operation safety of the bridge structure and protecting the life and property safety of people; therefore, it is desirable to provide a bridge damage determination method using a stiffness representative value.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a bridge damage judgment method based on a strain stiffness representative value.
In order to solve the technical problems, the invention adopts the technical scheme that: a bridge damage judgment method based on a strain stiffness representative value comprises the following steps:
a. constructing a bridge health monitoring system;
b. selecting a reference section:
c. starting a health monitoring system and collecting a strain signal;
d. calculating an initial strain stiffness representative value, and dividing the calculation into calculation of an initial strain stiffness representative value matrix under closed traffic and calculation of an initial strain stiffness representative value expectation matrix and a confidence interval under open traffic;
e. regularly collecting and calculating a current strain stiffness representative value matrix of the bridge structure or a current strain stiffness representative value expectation matrix and a confidence interval;
f. and judging the damage of the bridge.
Further, in the step a, strain sensors are arranged on each key section of the bridge, and the arrangement modes of the strain sensors on each section are required to be the same; the critical sections comprise a maximum positive bending moment, a maximum negative bending moment and a section with larger response, and the section with larger response refers to the section with the strain response amplitude ratio of more than 10 under the action of a vehicle and under the action of no vehicle.
Further, in the step b, the selected reference section is a non-diseased section and a section with a larger response.
Furthermore, in the step c, a high-precision dynamic fiber grating demodulator is adopted to collect strain signals of the strain sensor, and the sampling frequency is not lower than 20 Hz.
Further, the calculation process of the initial strain stiffness representative value matrix under closed traffic is as follows:
1) the method comprises the following steps that a standard vehicle sequentially passes through each lane at the same speed, the vehicle keeps running at a constant speed in a straight line, and the lane cannot be changed in the test process; recording the dynamic response conditions of each strain sensor of each key section and each reference section, wherein the signal acquisition time is at least 300 s;
2) processing strain time-course signals in an acquisition time period by adopting a Fourier transform technology and an inverse Fourier transform technology to obtain vehicle load static strain signals;
3) and calculating to obtain an initial strain stiffness representative value matrix.
Further, the acquired strain time-course signals are subjected to fast Fourier transform to obtain frequency-domain signals of the strain time-course signals; setting the amplitude of high frequency and low amplitude in the frequency domain signal as zero, and obtaining a vehicle load static strain signal by adopting inverse Fourier transform;
and taking the ratio of the strain peak value of the reference section to the strain peak value corresponding to the monitored section as a stiffness representative value to form a stiffness representative value matrix of each section.
Further, in the step f, the judgment process of the bridge damage under the closed traffic comprises the following steps: comparing the current strain stiffness representative value matrix with the initial strain stiffness representative value matrix, if the current strain stiffness representative value matrix changes, indicating that the bridge structure stiffness has damage, identifying and evaluating, correcting the initial strain stiffness representative value matrix, and entering the next period for monitoring; if the bridge structure is not changed, the bridge structure is not damaged, and the next period of monitoring is directly carried out.
Further, the calculation process of the initial strain stiffness representative value expectation matrix and the confidence interval under open traffic comprises the following steps:
1) collecting monitoring data under the condition of open traffic;
2) carrying out zero correction on the strain signal by adopting a moving average filtering technology, and eliminating environmental influence to obtain a vehicle load strain signal;
3) further processing the vehicle load strain signal by adopting a Fourier transform technology and an inverse Fourier transform technology to obtain a vehicle load static strain signal;
4) effective data screening is carried out on the obtained vehicle load static strain signal by utilizing an automatic program, and a strain stiffness representative value sample of each measuring point is obtained;
5) and obtaining a strain stiffness representative value expectation matrix and a strain stiffness representative value confidence interval by using nonparametric estimation.
Further, the method for processing the strain signal under open traffic specifically comprises the following steps:
1) under open traffic, data acquired by the health monitoring system for a long time comprise environmental effect data and vehicle load effect data, the acquired strain signals are processed by adopting a moving average filtering technology, the window width is set to be 900s, and strain signals of the environmental effect are obtained;
calculating a vehicle load strain signal CY:
in the CY ═ ZY-HY formula, ZY is the acquired strain signal, i.e. the total strain; HY is strain signal of environmental effect; the vehicle load strain signal CY is the difference between the total strain ZY and the environmental effect strain HY;
2) the vehicle load static strain signal adopts a rolling time window of 300s and utilizes Fourier transform and inverse Fourier transform technology to obtain an accurate static strain signal;
3) ensuring that only one vehicle passes through the bridge in a fixed time period, and screening data by adopting an automatic program;
4) setting the ascending direction and the descending direction of the bridge as two nominal lanes, and calculating all strain stiffness representative value samples R of each measuring point in the time interval by referring to the calculation mode of stiffness representative values under closed traffic for the screened data meeting the conditions;
5) and calculating the expected value of R and a 95% confidence interval to obtain a strain stiffness representative value expected matrix and a strain stiffness representative value confidence interval.
Further, in step f, the determination process of the bridge damage under open traffic is as follows:
comparing the current strain stiffness representative value expected matrix with the initial strain stiffness representative value expected matrix, if the current strain stiffness representative value expected matrix changes, performing combined investigation on the strain stiffness representative value confidence interval and the video image, judging damage after traffic guidance interference is eliminated, if damage occurs, taking the damaged strain stiffness representative value expected matrix as the initial matrix, and performing subsequent monitoring by taking the current state as a reference; if the bridge structure is not changed, the bridge structure is not damaged, and the next period of monitoring is directly carried out.
The invention discloses a bridge damage judgment method based on a strain stiffness representative value, which can be used for quickly diagnosing and judging the bridge stiffness damage condition under closed traffic and can also be used for periodically diagnosing and judging the bridge stiffness damage condition on line under open traffic. The invention establishes a minimum health monitoring system by arranging a certain fiber bragg grating strain sensor and a high-precision dynamic fiber bragg grating demodulator on a bridge, establishes a relation between structural strain and bridge damage by establishing a strain stiffness representative value matrix, effectively eliminates the influence caused by the deviation of the sensitivity coefficients of the environment and the sensor by adopting a signal processing method, can realize the quick and accurate judgment of the bridge damage under the closed traffic condition, and deduces an expected matrix of the strain stiffness representative value and a confidence interval to carry out real-time online diagnosis on the bridge damage under the open traffic condition by combining a statistical analysis method. The invention can be widely applied to the safety condition evaluation of each bridge health monitoring system and has good practicability and applicability.
Drawings
FIG. 1 is a schematic overall flow chart of the present invention.
FIG. 2 is a flow chart illustrating a specific process of the present invention.
FIG. 3 is a schematic diagram of a four-lane bridge sensor arrangement according to the present invention.
FIG. 4 is a graph of a probability density function of a certain measuring point when a bicycle passes through a bridge.
Fig. 5 is a video image of a health monitoring system at a certain time during operation.
FIG. 6 is a graph of a bridge strain envelope for the health monitoring system.
FIG. 7 is a diagram illustrating changes in strain stiffness representative values of a damaged bridge.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
The invention discloses a bridge damage judgment method based on a strain stiffness representative value, which can be used for quickly diagnosing and judging the bridge stiffness damage condition under closed traffic and can also be used for periodically diagnosing and judging the bridge stiffness damage condition on line under open traffic. As shown in fig. 1, the overall process of the bridge damage determination method is as follows:
a. constructing a bridge health monitoring system;
b. selecting a reference section:
c. starting a health monitoring system, and acquiring a strain signal of a strain sensor;
d. calculating an initial strain stiffness representative value, and dividing the calculation into calculation of an initial strain stiffness representative value matrix under closed traffic and calculation of an initial strain stiffness representative value expectation matrix and a confidence interval under open traffic;
e. regularly collecting and calculating a current strain stiffness representative value matrix of the bridge structure or a current strain stiffness representative value expectation matrix and a confidence interval;
f. and judging the damage of the bridge.
The following will explain in detail the specific processing procedure of the beam damage determination method of the present invention with reference to fig. 2:
a. constructing a bridge health monitoring system (minimization);
when constructing a minimal bridge health monitoring system, the following requirements are met:
1) strain sensors are distributed on each key section of the bridge, and the key sections are determined according to the structural form of the bridge and generally comprise maximum positive bending moment, maximum negative bending moment and larger response sections; all strain sensors are required to be arranged in the same way on each cross section, and for example, the arrangement of the four-lane bridge sensor shown in fig. 3 is adopted, and the arrangement ways of the strain sensors on the key cross sections are the same. In order to effectively capture cracks in a certain area, the long-gauge-length FBG sensors can be selected as the strain sensors, the sensors of the same manufacturer and the same batch are selected as much as possible, the usability of good data is guaranteed, the sensors are firmly and reliably installed and well coordinated with structural deformation, and the data of the sensors can reflect the real reaction of a bridge.
2) The sampling frequency is not lower than 20Hz, and a high-precision dynamic fiber grating demodulator can be sampled to meet the requirement;
3) the constructed system can acquire and store high-frequency strain monitoring data in real time.
b. Selecting a reference section:
the beam damage judgment method needs a reference section for realization, the selection of the reference section is related to the precision of damage judgment, and the selected reference section meets the following requirements:
1) in order to ensure the effectiveness and the precision of the bridge damage judgment method, a section with good disease-free rigidity, such as a section without cracks, water stains, stripped exposed ribs, corrosion and the like which influence the structural rigidity and the durability, is selected as a reference section;
2) in order to keep the high availability of strain data with a good signal-to-noise ratio, the reference section has a larger response under the action of vehicle load, and the section with the larger response means that the ratio of the amplitude of the vehicle strain signal to the amplitude of the vehicle strain signal is larger than 10, so that the good signal-to-noise ratio is ensured.
c. Starting a health monitoring system, and collecting strain signals of a strain sensor by adopting a high-precision dynamic fiber grating demodulator;
d. calculating an initial rigidity representative value, and dividing the initial rigidity representative value into two conditions of a closed traffic condition and an open traffic condition:
1) acquiring a representative value matrix of initial strain stiffness under closed traffic:
(1) the standard vehicles pass through the lanes at the same speed in sequence, the vehicles should keep constant-speed straight-line running, and the lanes cannot be changed in the test process. Recording the dynamic response conditions of each strain sensor of each key section and each reference section; it is advisable to choose a weight of 20-30 tons for the standard vehicle used; meanwhile, the signal acquisition time is at least 300s, and enough frequency resolution is required to be ensured.
(2) Initial stiffness representative value calculation:
and processing the strain signals in the acquisition time period by adopting Fourier transform calculation and Fourier inverse transform technology to obtain vehicle load static strain signals, and further calculating to obtain an initial strain stiffness representative value matrix. The method specifically comprises the following steps: carrying out Fourier transform processing on the collected strain time-course data to obtain a frequency domain signal, setting the amplitude of a high-frequency low-amplitude component in the frequency domain to be zero, reducing the processed frequency domain signal by utilizing an inverse Fourier transform technology to obtain a vehicle load static strain signal, and taking the ratio of static strain signal peak values of each monitored section strain sensor and a strain sensor at a position corresponding to a reference section as a strain stiffness representative value to form a strain stiffness representative value matrix of each section.
Taking fig. 3 as an example, four lanes are shown, YB is an abbreviation of strain, YB-N-x, where N denotes a section number, and x is a lane number or a strain sensor number; when the 1 st cross section is taken as a reference cross section, the strain stiffness representative value matrix F (2) of the 2 nd cross section is as follows:
wherein, E'pq(1) Showing the strain sensor response peak in the qth lane of section 1 (reference section) when the vehicle is traveling in the pth lane, Epq(2) The vehicle runs on the p-th lane, and the strain sensor response peak value under the q-th lane of the 2 nd section (test section).
2) Acquiring an initial strain stiffness representative value expectation matrix under open traffic:
collecting monitoring data for a certain time under the condition of open traffic, and calculating to obtain an initial strain stiffness representative value expectation matrix and a strain stiffness representative value confidence interval of each measuring point; and for the acquisition time, the acquisition time is determined according to the traffic volume, and the acquired sample data can show a statistical rule. The specific calculation process is as follows:
(1) zero point correction
Under open traffic, data acquired by the health monitoring system for a long time comprise environmental effect data and vehicle load effect data, the environmental effect is stripped by adopting a moving average filtering technology, namely zero point correction, and a vehicle load strain signal is obtained after environmental influence is eliminated.
Processing the acquired strain signal (total strain ZY) by adopting a moving average filtering technology (the window width is set to 900s) to obtain a strain signal (HY) with an environmental effect;
calculating a vehicle load strain signal (CY):
CY＝ZY-HY
(2) acquiring a vehicle load static strain signal:
further processing the vehicle load strain signal by adopting Fourier transform and inverse Fourier transform technology to obtain a vehicle load static strain signal; and acquiring an accurate static strain signal by adopting Fourier transform and inverse Fourier transform techniques with reference to a rolling time window of 300s under closed traffic.
(3) Efficient data screening
And carrying out effective data screening on the obtained static strain signal data by utilizing automatic forming so as to obtain a strain stiffness representative value sample of each measuring point. The strain data adopted by the method are single-vehicle strain effects, and in order to ensure that the selected data are not influenced by the multi-vehicle effects, it is required to ensure that only one vehicle passes through the bridge within a fixed time period.
(4) Obtaining a strain stiffness representative value expectation matrix and strain stiffness representative value confidence intervals of the measuring points by nonparametric calculation:
for bridges in the operation period of open traffic, the vehicle load size and lane distribution are random, and the exact vehicle distribution rule at each moment cannot be known. Therefore, the vehicle running direction is determined according to the strain response time of each section, so that effective data can be divided into two groups according to the vehicle running direction. At this time, the bridge can be considered to have two nominal lanes, namely an ascending lane and a descending lane.
And for the screened data meeting the conditions, calculating all strain stiffness representative value samples R of each measuring point in the period by referring to a calculation mode of the strain stiffness representative value in closed traffic.
And calculating expected values of R and 95% confidence intervals, and forming an initial strain stiffness representative value expected matrix by using the expected values. Also taking fig. 3 as an example, if the 1 st cross section is the reference cross section, the 2 nd cross section initial strain stiffness representative value expected matrix F (2) becomes:
in the same formula, E'pq(1) Showing the strain sensor response peak in the qth lane of section 1 (reference section) when the vehicle is traveling in the pth lane, Epq(2) The vehicle is in the p-th vehicleOn-road driving, section 2 (test section) q-th under-lane strain sensor response peak.
Although the lane and the vehicle speed when the vehicle is running cannot be obtained, the statistical law shows that, in the case of no traffic control measure, each measurement point follows a certain distribution relation when the vehicle passes through a bridge, and the probability density function can be obtained by non-parametric estimation, as shown in fig. 4, where f ═ λ (μ, σ) represents the probability density function, μ represents an expected value, σ represents a standard deviation, and λ (μ, σ) represents the distribution of μ and σ following λ.
And monitoring the variable stiffness representative value expectation matrix and the confidence interval, so that the damage condition of the bridge can be evaluated.
e. And (3) regularly acquiring and calculating a current strain stiffness representative value matrix (under closed traffic) or a current strain stiffness representative value expectation matrix and a confidence interval (under open traffic) of the bridge structure, wherein the calculation method is consistent with the determination of the initial strain stiffness representative value.
f. Bridge damage judgment:
the judgment under the closed traffic condition and the judgment under the open traffic condition are also divided;
1) judging the damage of the bridge under the closed traffic condition:
comparing the current strain stiffness representative value matrix with the initial strain stiffness representative value matrix, if the current strain stiffness representative value matrix changes, identifying and evaluating, correcting the initial strain stiffness representative value matrix, and entering the next period for monitoring; the strain stiffness representative value matrix is changed, the stiffness of the surface bridge structure is damaged, and the damaged strain stiffness representative value is used as an initial matrix and is subjected to subsequent monitoring on the basis of the current state; if a repairing measure is taken, a matrix for representing the strain stiffness value after repairing is acquired and calculated to be used as an initial matrix.
And (4) comparing and not changing, and directly entering the next period for monitoring without damaging the surface bridge structure.
2) Judging the damage of the bridge under open traffic:
comparing the current strain stiffness representative value expected matrix with the initial strain stiffness representative value expected matrix, if the current strain stiffness representative value expected matrix changes, performing combined examination on a strain stiffness representative value confidence interval and a video image, and if the change occurs, performing damage judgment after traffic steering interference is eliminated, if the damage occurs, taking the damaged strain stiffness representative value expected matrix as the initial matrix, and performing subsequent monitoring by taking the current state as a reference; if a repairing measure is adopted, acquiring and calculating a strain stiffness representative value expected matrix after repairing as an initial matrix;
if the structure is not changed, the structure is not damaged, and the next period of monitoring is directly carried out.
The bridge damage determination under the open traffic condition of the invention is further described below with reference to specific embodiments.
Firstly, as shown in fig. 6, only the strain envelope diagram of a certain bridge monitored by the health monitoring system is intercepted, and the strain envelope diagram is displayed between 3 and 15 days in 2020 and 06 days in 08 and 2020, so that the monitoring system can be seen to be stable for a long time and can capture a large amount of strain data; the method for judging the damage condition of the bridge based on the representative value of the strain stiffness is applied, for example, as shown in fig. 5, a video image at a certain time in an operating monitoring system is shown, the damage judgment is carried out after traffic steering interference is eliminated by carrying out combined investigation on a confidence interval of the representative value of the strain stiffness and the video image, fig. 7 is a change condition of the representative value of the strain stiffness of the damaged bridge monitored by the method, the change condition of the representative value of the strain stiffness of the bridge in units of years is shown, and the damage of the monitored section is found through on-site rechecking, so that the effectiveness of the method is proved.
Therefore, according to the bridge damage judgment method based on the representative value of the strain stiffness disclosed by the invention, firstly, a minimized bridge health monitoring system is constructed on a bridge, namely strain sensors are arranged on each key section and each reference section, strain monitoring data of the positions corresponding to the reference section and the monitored section under closed traffic are collected, the technologies such as Fourier transform, inverse Fourier transform and the like are adopted for processing, an accurate stiffness representative value matrix is obtained through calculation, and then the bridge damage condition is judged. Meanwhile, under the condition of open traffic, the method is improved by adopting a statistical technology, so that the online damage judgment of the bridge can be carried out according to the change conditions of the strain stiffness representative value expectation matrix and the confidence interval. The method can eliminate the influence caused by the sensitivity system error of the sensor and the environment, and can accurately judge the damage condition of the bridge.
The above embodiments are not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make variations, modifications, additions or substitutions within the technical scope of the present invention.
Claims (10)
1. A bridge damage judgment method based on a strain stiffness representative value is characterized by comprising the following steps: the method comprises the following steps:
a. constructing a bridge health monitoring system;
b. selecting a reference section;
c. starting a health monitoring system, and collecting a strain signal;
d. calculating an initial strain stiffness representative value, and dividing the calculation into calculation of an initial strain stiffness representative value matrix under closed traffic and calculation of an initial strain stiffness representative value expectation matrix and a confidence interval under open traffic;
e. regularly collecting and calculating a current strain stiffness representative value matrix of the bridge structure or a current strain stiffness representative value expectation matrix and a confidence interval;
f. and judging the damage of the bridge.
2. The bridge damage determination method based on the representative value of strain stiffness according to claim 1, wherein: in the step a, strain sensors are arranged on each key section of the bridge, and the arrangement modes of the strain sensors on each section are required to be the same; the critical sections comprise a maximum positive bending moment, a maximum negative bending moment and a section with larger response, and the section with larger response refers to the section with the strain response amplitude ratio of more than 10 under the action of a vehicle and under the action of no vehicle.
3. The bridge damage determination method based on the representative value of strain stiffness according to claim 2, wherein: in the step b, the selected reference section is a section which is free of diseases and has large strain response.
4. The bridge damage determination method based on the strain stiffness representative value according to claim 3, wherein: and c, acquiring the strain signal of the strain sensor by using a high-precision dynamic fiber grating demodulator, wherein the frequency is not lower than 20 Hz.
5. The bridge damage determination method based on the strain stiffness representative value according to claim 1 or 4, wherein: the calculation process of the initial strain stiffness representative value matrix under closed traffic comprises the following steps:
1) the method comprises the following steps that a standard vehicle sequentially passes through each lane at the same speed, the vehicle keeps running at a constant speed in a straight line, and the lane cannot be changed in the test process; recording the dynamic response conditions of each strain sensor of each key section and each reference section, wherein the signal acquisition time is at least 300 s;
2) processing strain time-course signals in an acquisition time period by adopting a Fourier transform technology and an inverse Fourier transform technology to obtain vehicle load static strain signals;
3) and calculating to obtain an initial strain stiffness representative value matrix.
6. The bridge damage determination method based on the representative value of strain stiffness according to claim 5, wherein: the acquired strain time-course signals are subjected to fast Fourier transform to obtain frequency-domain signals of the strain time-course signals; setting the amplitude of high frequency and low amplitude in the frequency domain signal as zero, and obtaining a vehicle load static strain signal by adopting inverse Fourier transform;
and taking the ratio of the strain peak value of the reference section to the strain peak value corresponding to the monitored section as a stiffness representative value to form a stiffness representative value matrix of each section.
7. The bridge damage determination method based on the strain stiffness representative value according to claim 6, wherein: in the step f, the judgment process of the bridge damage under the closed traffic comprises the following steps: comparing the current strain stiffness representative value matrix with the initial strain stiffness representative value matrix, if the current strain stiffness representative value matrix changes, indicating that the bridge structure stiffness has damage, identifying and evaluating, correcting the initial strain stiffness representative value matrix, and entering the next period for monitoring; if the bridge structure is not changed, the bridge structure is not damaged, and the next period of monitoring is directly carried out.
8. The bridge damage determination method based on the strain stiffness representative value according to claim 1 or 4, wherein: the calculation process of the initial strain stiffness representative value expectation matrix and the confidence interval under open traffic comprises the following steps:
1) collecting monitoring data under the condition of open traffic;
2) carrying out zero correction on the strain signal by adopting a moving average filtering technology, and eliminating environmental influence to obtain a vehicle load strain signal;
3) further processing the vehicle load strain signal by adopting a Fourier transform technology and an inverse Fourier transform technology to obtain a vehicle load static strain signal;
4) effective data screening is carried out on the obtained vehicle load static strain signal by utilizing an automatic program, and a strain stiffness representative value sample of each measuring point is obtained;
5) and obtaining a strain stiffness representative value expectation matrix and a strain stiffness representative value confidence interval by using nonparametric estimation.
9. The bridge damage determination method based on the strain stiffness representative value according to claim 8, wherein: the method for processing the strain signal under open traffic specifically comprises the following steps:
1) under open traffic, data acquired by the health monitoring system for a long time comprise environmental effect data and vehicle load effect data, the acquired strain signals are processed by adopting a moving average filtering technology, the window width is set to be 900s, and strain signals of the environmental effect are obtained;
calculating a vehicle load strain signal CY:
CY＝ZY-HY
in the formula, ZY is an acquired strain signal, namely total strain; HY is strain signal of environmental effect; the vehicle load strain signal CY is the difference between the total strain ZY and the environmental effect strain HY;
2) the vehicle load static strain signal adopts a rolling time window of 300s and utilizes Fourier transform and inverse Fourier transform technology to obtain an accurate static strain signal;
3) ensuring that only one vehicle passes through the bridge in a fixed time period, and screening data by adopting an automatic program;
4) setting the ascending direction and the descending direction of the bridge as two nominal lanes, and calculating all strain stiffness representative value samples R of each measuring point in the time interval by referring to the calculation mode of stiffness representative values under closed traffic for the screened data meeting the conditions;
5) and calculating the expected value of R and a 95% confidence interval to obtain a strain stiffness representative value expected matrix and a strain stiffness representative value confidence interval.
10. The bridge damage determination method based on the strain stiffness representative value according to claim 9, wherein: in the step f, the judgment process of the bridge damage under open traffic comprises the following steps:
comparing the current strain stiffness representative value expected matrix with the initial strain stiffness representative value expected matrix, if the current strain stiffness representative value expected matrix changes, performing combined investigation on the strain stiffness representative value confidence interval and the video image, judging damage after traffic guidance interference is eliminated, if damage occurs, taking the damaged strain stiffness representative value expected matrix as the initial matrix, and performing subsequent monitoring by taking the current state as a reference; if the bridge structure is not changed, the bridge structure is not damaged, and the next period of monitoring is directly carried out.
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| CN116228761A (en) * | 2023-05-08 | 2023-06-06 | 中交四公局第一工程有限公司 | Steel structure rigidity damage evaluation method and system |
| CN116680646A (en) * | 2023-07-31 | 2023-09-01 | 民航机场规划设计研究总院有限公司 | Method and device for identifying damage of aircraft load bridge, electronic equipment and storage medium |
| CN117076928A (en) * | 2023-08-25 | 2023-11-17 | 中交路桥科技有限公司 | Bridge health state monitoring method, device and system and electronic equipment |
| CN117554006A (en) * | 2024-01-09 | 2024-02-13 | 北京云庐科技有限公司 | Bridge health assessment method and system based on dynamic strain monitoring |
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