Piezoelectric impedance-based impacted pier axial force monitoring system and method

Abstract

The invention discloses a piezoelectric impedance-based impacted pier axial force monitoring system and method, and relates to the technical field of bridge structure health monitoring. The system comprises a piezoelectric impedance-based impacted pier axial force monitoring sensor, a piezoelectric impedance wireless measuring device, a solar panel and a temperature sensor. The piezoelectric impedance axial force monitoring sensor is embedded in the concrete pier in a sensor array mode so as to measure the specific condition of the axial force in the pier. After the pier is collided, the bearing capacity and the axial force are changed, so that a diaphragm in the piezoelectric impedance axial force monitoring sensor is deformed, and the mechanical impedance is changed. The change condition of piezoelectric impedance signals of a piezoelectric ceramic piece in an axial force monitoring sensor is collected, temperature compensation is conducted through a temperature sensor, quantitative axial force change indexes are established based on the change of the piezoelectric impedance signals, and bridge collision unbalance degree indexes are compared through a database established through a finite element model and sensor monitoring data. Therefore, rapid assessment of the collision damage condition of the pier is realized.

Description

Technical Field

[0001] This invention belongs to the field of bridge structural health monitoring, and relates to a system and method for monitoring the axial force of impacted bridge piers based on piezoresistive impedance. Background Technology

[0002] In recent years, with the advancement of large-scale bridge construction and shipping development, a pattern of "numerous ships and dense bridges" has emerged. However, the emergency response capabilities of bridges to ship collisions are significantly mismatched with the development of larger ships and denser ports and shipping networks, leading to an increasingly prominent risk of bridge-to-ship collision disasters. Furthermore, due to the low level of intelligent systems, this has resulted in substantial and unnecessary economic damage. As a crucial load-bearing component in bridge structures, the performance of bridge piers directly impacts the stability and safety of the entire transportation system when subjected to collisions with vehicles or ships. Therefore, effectively monitoring the axial force of bridge piers after impacts and conducting reasonable and rapid assessments of their load-bearing capacity is of significant guiding importance for traffic control and structural reinforcement.

[0003] Current research on axial force monitoring of concrete bridge piers has yielded numerous mature theoretical methods and applied results. Commonly used methods include the rebar gauge method, pressure sensors, ultrasonic testing, and fiber optic strain sensors. However, existing methods, due to their respective shortcomings, cannot fully meet engineering requirements. The rebar gauge method, which uses vibrating wire strain sensors to monitor rebar strain and then calculates the overall axial force of the concrete structure, suffers from the effects of concrete creep and temperature changes, causing the vibrating wire strain sensor to fail to coordinate with the deformation of the pier being measured, resulting in long-term relaxation of the vibrating wire material. Furthermore, pressure sensors are susceptible to electromagnetic interference. Ultrasonic monitoring identifies axial force changes by detecting differences in ultrasonic signals; however, the inhomogeneity of concrete materials leads to weak interpretability and low accuracy. Fiber optic grating technology is expensive and complex. While all these methods for monitoring axial force in bridge piers have been validated through practical applications, they still have some limitations and face challenges related to durability and real-time performance under the specific condition of bridge pier impact.

[0004] Piezoresistive impedance based on piezoelectric smart materials is an emerging structural health monitoring method with advantages such as high sensitivity, fast response speed, accurate measurement, and real-time online monitoring. It can achieve low-cost, large-scale structural damage monitoring and has shown broad application prospects in recent years, making it very suitable for online condition monitoring of various engineering structures under complex working conditions. Currently, research and patents on the application of piezoelectric impedance technology to bridge pier axial force have not yet achieved accurate online identification of bridge pier axial force, and methods for assessing the bearing capacity of bridge piers under special impact conditions based on piezoelectric impedance technology are still lacking. Summary of the Invention

[0005] To address the aforementioned technical problems, the purpose of this invention is to provide a system and method for monitoring the axial force of impacted bridge piers based on piezoresistive impedance, and to achieve rapid assessment of the bearing capacity of bridge piers.

[0006] The technical solution of the present invention:

[0007] A piezoresistive impedance-based axial force monitoring system for impacted bridge piers includes a piezoresistive impedance-based axial force monitoring sensor for impacted bridge piers, a piezoresistive impedance wireless measurement device, a solar panel, and a temperature sensor.

[0008] The piezoelectric impedance-based axial force monitoring sensor for impacted bridge piers includes a piezoelectric ceramic sheet 1 and a metal diaphragm 2, an upper stainless steel shell 5, a lower stainless steel shell 6, a force transmission rod 3, a 3D-printed ABS waterproof plastic cap 4, a shielded wire 7, and bolts 8. The piezoelectric ceramic sheet 1 is attached to the upper surface of the metal diaphragm 2, and the metal diaphragm 2 is attached to the top of the force transmission rod 3. The 3D-printed ABS waterproof plastic cap 4 covers the piezoelectric ceramic sheet 1. The upper stainless steel shell 5 has a hollow structure with an open bottom and a closed top. The 3D-printed ABS waterproof plastic cap 4 and the piezoelectric ceramic sheet 1 are located inside the hollow structure, which facilitates the deformation of the metal diaphragm 2. The lower stainless steel shell 6 has a through hole in its center, and the force transmission rod 3 is located inside the through hole. The upper stainless steel shell 5 and the lower stainless steel shell 6 have corresponding screw holes, and the upper stainless steel shell 5 and the lower stainless steel shell 6 are fixed together by bolts 8.

[0009] The lower surface electrode of the piezoelectric ceramic sheet 1 is led out to the upper surface through one side end and separated from the original upper surface electrode to form a flanged electrode, and a shielded wire 7 is led out; the 3D printed ABS waterproof plastic cap and stainless steel shell have holes to provide a channel for the shielded wire to connect to the piezoelectric impedance wireless measurement device.

[0010] The piezoelectric impedance wireless measurement device includes a microprocessor module and a piezoelectric impedance measurement module, a wireless communication module, and a power supply module connected to the microprocessor module. The piezoelectric impedance measurement module is controlled by a microprocessor as an integrated control module to perform measurement commands and is connected to the axial force monitoring sensor via a shielded wire 7. The axial force monitoring system is powered by the power supply module, which is connected to the solar panel to meet the power supply requirements for long-term remote monitoring. The axial force monitoring system accesses the Internet of Things through the wireless communication module to input data into a cloud database and remotely wirelessly excites the piezoelectric ceramic sheet 1 to obtain signals characterizing the axial force, such as the impedance spectrum and peak frequency, from the axial force monitoring sensor of the impacted bridge pier.

[0011] The temperature sensor is connected to the microprocessor module and transmits the measured temperature of the environment where the axial force monitoring sensor is located to the piezoresistive impedance wireless measurement device.

[0012] A method for monitoring the axial force of a bridge pier under impact based on piezoresistive impedance, using the aforementioned monitoring system, is employed to assess the bearing capacity of the bridge pier under impact. The specific steps are as follows:

[0013] Step (1) Under laboratory conditions, the packaged axial force monitoring sensor was subjected to a load test, and the piezoresistive impedance signal was monitored at the same time to establish a linear relationship between axial force, temperature and peak frequency of axial force monitoring sensor;

[0014] Step (2) Embed the axial force monitoring sensor into the concrete pier column to establish baseline data.

[0015] Step (3) Based on the finite element model of bridge pier collapse under impact, establish the skewness imbalance index under different working conditions. and database.

[0016] Step (4) Set up a triggering mechanism to determine whether a collision event has occurred.

[0017] Step (5) Filter and temperature compensation are applied to the original signal recorded after the trigger to obtain the axial force value at the location.

[0018] Step (6) Calculate the actual bridge impact imbalance index based on the axial force value obtained in step (5). Compared with the unbalance index based on section bending moment And quickly retrieve the corresponding working conditions from the database established in step (3).

[0019] Step (7) Quickly assess the load-bearing capacity of the impacted bridge pier, make a decision, and promptly implement traffic control and reinforcement measures.

[0020] The piezoresistive impedance signal acquisition in step (1) should be performed using the piezoresistive impedance-based impact pier axial force monitoring system, and simultaneously using a precision impedance analyzer to verify the correctness of the system's acquired signal.

[0021] The piezoresistive impedance signal in step (1) includes: impedance Real part of impedance Imaginary part of impedance Admittance Admittance Real Part and the imaginary part of admittance The relationship between them is as follows:

[0022]

[0023] in, The imaginary unit, .

[0024] In step (2), the baseline data is established by continuously monitoring the measured peak frequency under normal conditions without collisions, recording its average value and fluctuation range, and establishing a dynamic baseline.

[0025] The imbalance index in step (3) and The calculation formula is as follows:

[0026]

[0027] in, The skewness imbalance index characterizes the degree of asymmetry in the distribution of axial forces on the interface. It is an index of imbalance based on the bending moment of the cross section; This represents the total number of sensors on the same cross-section. For the first The axial force value of each axial force monitoring sensor. This is the average of the axial force values ​​from all axial force monitoring sensors at this cross section. For equivalent bending moment, For the first The distance transmitted from each axial force monitoring sensor to the center axis of the cross section.

[0028] The triggering mechanism in step (4) is that if the change in the peak frequency of a certain axial force monitoring sensor exceeds three times or more the standard deviation of the dynamic baseline noise in two consecutive monitoring sessions, it is immediately determined that a collision event has occurred.

[0029] Compared with currently applied technologies, the beneficial effects of this invention are:

[0030] This invention utilizes a piezoresistive impedance-based axial force monitoring system for impact-affected bridge piers. The peak frequency of the piezoresistive conductivity spectrum reflects the axial force at the sensor's location. Furthermore, the change in axial force exhibits a strong linear relationship with the bending resonant frequency of the diaphragm within the sensor, enabling quantitative monitoring of axial force changes in the bridge pier. By analyzing and transmitting the measured data through this system, long-distance online monitoring of axial force is achieved. Finally, a monitoring method is proposed for rapid assessment of the load-bearing capacity of impact-affected bridge piers. An array of piezoresistive impedance-based axial force monitoring sensors can roughly determine the location and severity of the impact. A database is established by combining a finite element model with the monitoring data, and a rapid assessment is achieved through simple calculations using an imbalance index. Compared to existing technologies and methods, this invention offers advantages such as simple principle, clear mechanism, low cost, and real-time online operation. It also meets the needs of bridges under special impact conditions and has broad application prospects. Attached Figure Description

[0031] Figure 1This is a schematic diagram of the axial force monitoring sensor for impacted bridge piers based on piezoresistive impedance according to the present invention;

[0032] Figure 2 This is a cross-sectional view of the axial force monitoring sensor for impacted bridge piers based on piezoresistive impedance of the present invention;

[0033] Figure 3 This invention provides a system for monitoring the axial force of a bridge pier under impact based on piezoresistive impedance.

[0034] Figure 4 It is the array distribution of axial force monitoring sensors for impacted bridge piers embedded in concrete pier columns based on piezoresistive impedance;

[0035] Figure 5 This is a flowchart of a method for monitoring the axial force of a bridge pier under impact based on piezoresistive impedance, provided by the present invention.

[0036] Figure 6 This is a schematic diagram of the impedance spectrum of the piezoresistive impedance axial force monitoring sensor under different axial forces in an embodiment of the present invention;

[0037] Figure 7 This is a schematic diagram illustrating the linear relationship between the resonant frequency of the axial force monitoring sensor and the change in axial force in an embodiment of the present invention;

[0038] In the diagram: 1. Piezoelectric ceramic sheet; 2. Metal diaphragm; 3. Force transmission rod; 4. 3D printed ABS waterproof plastic cap; 5. Upper stainless steel shell; 6. Lower stainless steel shell; 7. Shielded wire; 8. Bolt. Detailed Implementation

[0039] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0040] The present invention discloses a piercing axial force monitoring system based on piezoresistive impedance, comprising a piercing axial force monitoring sensor based on piezoresistive impedance, a wireless piezoresistive impedance measuring device, a solar panel, and a temperature sensor.

[0041] like Figure 1 and Figure 2As shown, the axial force monitoring sensor for impacted bridge piers based on piezoelectric impedance includes a piezoelectric ceramic sheet 1 and a metal diaphragm 2, an upper stainless steel shell 5, a lower stainless steel shell 6, a force transmission rod 3, a 3D-printed ABS waterproof plastic cap 4, and bolts 8. The piezoelectric ceramic sheet 1 is attached to the upper surface of the metal diaphragm 2, and the metal diaphragm 2 is attached to the top of the force transmission rod 3. The 3D-printed ABS waterproof plastic cap 4 covers the piezoelectric ceramic sheet 1. The upper stainless steel shell 5 has a hollow structure with an open bottom and a closed top. The 3D-printed ABS waterproof plastic cap 4 and the piezoelectric ceramic sheet 1 are located inside the hollow structure, which facilitates the deformation of the metal diaphragm 2. The lower stainless steel shell 6 has a through hole in its center, and the force transmission rod 3 is located inside the through hole. The upper stainless steel shell 5 and the lower stainless steel shell 6 have corresponding screw holes, and the upper stainless steel shell 5 and the lower stainless steel shell 6 are fixed together by bolts 8.

[0042] The axial force monitoring sensor for impacted bridge piers based on piezoelectric impedance is fabricated by attaching a piezoelectric ceramic sheet 1 to the surface of a metal diaphragm 2. One end of a shielding wire 7 is welded to the two electrodes of the piezoelectric ceramic sheet. A 3D-printed ABS waterproof plastic cap 4 and an upper stainless steel outer shell 5 have holes to provide a channel for the shielding wire to connect to the wireless piezoelectric impedance measuring device. Its basic principle is as follows: when the axial force changes, the force transmission rod 3 transmits the axial force, causing changes in the morphology, stiffness, and other physical properties of the metal diaphragm 2, which in turn changes its mechanical impedance. This change is reflected in the piezoelectric impedance signal measured by the piezoelectric ceramic sheet 1 coupled to the metal diaphragm 2, thereby achieving axial force monitoring.

[0043] Furthermore, the diameter of the metal diaphragm 2 is slightly larger than the inner diameter of the lower stainless steel outer shell 6, so that the outer shell has a fixing effect on the diaphragm.

[0044] Furthermore, the bottom of the force transmission rod 3 is located outside the lower stainless steel housing 6, which can transfer the stress in the concrete to the metal diaphragm 2.

[0045] Furthermore, the force transmission rod 3 and the metal diaphragm 2 can be made of different metals, such as brass, stainless steel, aluminum alloy, etc., depending on the range of axial force to be measured.

[0046] Furthermore, the cross-sectional shape and cross-sectional area of ​​the force transmission rod 3 are selected based on the range of axial force measured.

[0047] Furthermore, the piezoelectric ceramic sheet 1 has the same shape as the force transmission rod 3, and the area of ​​the piezoelectric ceramic sheet 1 is slightly smaller than the cross-sectional area of ​​the force transmission rod 3. It is tightly bonded to the metal diaphragm 2 with epoxy resin. The force transmission rod 3 is tightly bonded to the metal diaphragm 2 with epoxy resin. Epoxy resin is coated between the pores of the encapsulated sensor to achieve a waterproof effect.

[0048] Furthermore, the bolts of the same batch of axial force sensors should be subjected to equal prestress during packaging.

[0049] like Figure 3 As shown, the piezoelectric impedance wireless measurement device includes a microprocessor module, a piezoelectric impedance measurement module, a wireless communication module, and a power supply module. The piezoelectric impedance measurement module is connected to the piezoelectric ceramic sheet 1 via a shielded wire 7, and can remotely and wirelessly excite the piezoelectric ceramic sheet 1 to obtain signals that characterize the axial force, such as the impedance spectrum and peak frequency, from the axial force monitoring sensor of the impacted bridge pier.

[0050] The microprocessor module uses a development board based on the ESP32-WROOM-32 module; the core component of the piezoresistive impedance measurement module is the AD5933 chip; the wireless communication module uses a 4G DTU module connected to the ESP32 main control chip via a UART serial port.

[0051] The wireless piezoresistive impedance measuring device should be placed in a distribution box to achieve waterproofing, protection, and ease of maintenance.

[0052] The piezoresistive impedance wireless measurement device has a power supply module that connects to a solar panel to achieve self-powering.

[0053] The piezoresistive impedance wireless measurement device is equipped with a wireless communication module that connects to the user's computer via 4G signal to transmit the monitored sensor data, temperature data, etc. back in a timely manner.

[0054] The temperature sensor selected is the DS18B20 temperature sensor probe, which is controlled by a microprocessor as an integrated control module to perform measurement command control, and ensures that the temperature sensor and the axial force monitoring sensor are located in the same environment.

[0055] The temperature sensor should be embedded in the concrete pier along with the axial force monitoring sensor for impacted bridge piers based on piezoresistive impedance, facilitating temperature compensation of the sensor data. This system is easy to install, has low maintenance costs, low power requirements, and can be self-powered by solar energy, thus enabling long-term wireless monitoring.

[0056] like Figure 4 The image shows the array distribution of the axial force monitoring sensor for impact-affected bridge piers embedded in the concrete pier column. To facilitate rapid subsequent evaluation, the sensor array is symmetrically distributed in a circular pattern at equal angles, and the appropriate number can be selected according to monitoring requirements and the cross-sectional area of ​​the pier column.

[0057] like Figure 5 As shown, a method for monitoring the axial force of a bridge pier under impact based on piezoresistive impedance, using the aforementioned monitoring system, comprises the following specific steps:

[0058] Step 401: Under laboratory conditions, load tests are performed on the packaged axial force monitoring sensor, and the piezoresistive impedance signal is monitored simultaneously to establish a linear relationship between axial force, temperature and the peak frequency of the axial force monitoring sensor.

[0059] Step 402: Embed the axial force monitoring sensor into the concrete pier column to establish baseline data.

[0060] Step 403: Based on the finite element model of bridge pier collapse due to impact, establish imbalance indices under different working conditions. and database.

[0061] Step 404: Set up a trigger mechanism to determine whether a collision event has occurred.

[0062] Step 405: Filter and process the original signal recorded after triggering to obtain the axial force value at the current location.

[0063] Step 406: Calculate the actual bridge impact imbalance index. and And quickly retrieve the corresponding operating conditions from the database.

[0064] Step 407: Quickly assess, make decisions, and implement timely traffic control and reinforcement measures.

[0065] The piezoresistive impedance signal acquisition in step 401 should be performed using the piezoresistive impedance-based impact pier axial force monitoring system, and the system should be verified using a precision impedance analyzer.

[0066] The piezoresistive impedance signal in step 401 includes: impedance Real part of impedance Imaginary part of impedance Admittance Admittance Real Part Imaginary part of admittance The relationship between them is as follows:

[0067]

[0068] in, The imaginary unit, .

[0069] In step 402, the baseline data is established by continuously monitoring the measured peak frequency under normal conditions without collisions, recording its average value and fluctuation range, and establishing a dynamic baseline.

[0070] The finite element model of the bridge pier collapse in step 403 should be determined based on the specific project being monitored.

[0071] In step 403, the imbalance of axial force distribution in the cross section is calculated. and It can be considered by combining the following two formulas:

[0072]

[0073] in, The skewness imbalance index characterizes the degree of asymmetry in the distribution of axial forces on the interface. It is an index of imbalance based on the bending moment of the cross section; This represents the total number of sensors on the same cross-section. For the first The axial force value of each axial force monitoring sensor. This is the average of the axial force values ​​from all axial force monitoring sensors at this cross section. For equivalent bending moment, For the first The distance transmitted from each axial force monitoring sensor to the center axis of the cross section.

[0074] The triggering mechanism in step 404 is that if the change in the peak frequency of a certain axial force monitoring sensor exceeds several times the standard deviation of the dynamic baseline noise in two consecutive monitoring sessions, a collision event is immediately determined to have occurred.

[0075] Taking the real part of the admittance signal in the impedance signal as an example, such as Figure 6 As shown, the resonant peak frequency of the axial force monitoring sensor for impacted bridge piers based on piezoresistive impedance decreases as the axial force increases, such as... Figure 7 As shown, the two have an excellent linear fit, so the magnitude of the axial force on the dowel bar can be accurately determined based on the measured peak frequency, thus reflecting the axial force at each measuring point in the concrete.

Claims

1. A system for monitoring the axial force of a bridge pier under impact based on piezoresistive impedance, characterized in that, The monitoring system includes a piezoelectric impedance-based axial force monitoring sensor for impacted bridge piers, a piezoelectric impedance wireless measurement device, a solar panel, and a temperature sensor. The piezoelectric impedance-based axial force monitoring sensor for impacted bridge piers includes a piezoelectric ceramic sheet (1) and a metal diaphragm (2), an upper stainless steel shell (5), a lower stainless steel shell (6), a force transmission rod (3), a 3D-printed ABS waterproof plastic cap (4), a shielded wire (7), and bolts (8); the piezoelectric ceramic sheet (1) is attached to the upper surface of the metal diaphragm (2), and the metal diaphragm (2) is attached to the top of the force transmission rod (3); the 3D-printed ABS waterproof plastic cap (4) covers the piezoelectric ceramic sheet (1); The upper stainless steel shell 5 has a hollow structure inside, with an open bottom and a closed top. The 3D printed ABS waterproof plastic cap (4) and the piezoelectric ceramic sheet (1) are located inside the hollow structure, which facilitates the deformation of the metal diaphragm (2). The lower stainless steel shell (6) has a through hole in the center, and the force transmission rod (3) is located inside the through hole. The upper stainless steel shell (5) and the lower stainless steel shell (6) have corresponding screw holes, and the upper stainless steel shell (5) and the lower stainless steel shell (6) are fixed together by bolts (8). The lower surface electrode of the piezoelectric ceramic sheet (1) is led out to the upper surface through one side end and separated from the original upper surface electrode to form a flanged electrode, and a shielded wire (7) is led out; the 3D printed ABS waterproof plastic cap and stainless steel shell have holes to provide a channel for the shielded wire to connect with the piezoelectric impedance wireless measurement device. The piezoelectric impedance wireless measurement device includes a microprocessor module and a piezoelectric impedance measurement module, a wireless communication module, and a power supply module connected to the microprocessor module. The piezoelectric impedance measurement module is controlled by a microprocessor as an integrated control module to perform measurement commands and is connected to the axial force monitoring sensor through a shielded wire (7). The axial force monitoring system is powered by the power supply module, which is connected to the solar panel. The axial force monitoring system accesses the Internet of Things through the wireless communication module to realize data entry into the cloud database and remotely wirelessly excites the piezoelectric ceramic sheet (1) to obtain the impedance spectrum and peak frequency of the impacted bridge pier axial force monitoring sensor. The temperature sensor is connected to the microprocessor module and transmits the measured temperature of the environment where the axial force monitoring sensor is located to the piezoresistive impedance wireless measurement device.

2. The axial force monitoring system for impacted bridge piers based on piezoresistive impedance according to claim 1, characterized in that, The diameter of the metal diaphragm (2) is larger than the inner diameter of the lower stainless steel shell (5); the bottom of the force transmission rod (3) is located outside the lower stainless steel shell (5); the shape of the piezoelectric ceramic sheet (1) is consistent with that of the force transmission rod (3), and the area of ​​the piezoelectric ceramic sheet (1) is smaller than the cross-sectional area of ​​the force transmission rod (3).

3. The axial force monitoring system for impacted bridge piers based on piezoresistive impedance according to claim 1, characterized in that, The force transmission rod (3) and the metal diaphragm (2) are made of different metals selected based on the range of axial force to be measured.

4. The axial force monitoring system for impacted bridge piers based on piezoresistive impedance according to claim 1, characterized in that, The piezoelectric ceramic sheet (1) and the metal diaphragm (2) are tightly bonded together with epoxy resin; the force transmission rod (3) and the metal diaphragm (2) are tightly bonded together with epoxy resin; epoxy resin is coated between the pores of the encapsulated sensor to achieve a waterproof effect.

5. A method for monitoring the axial force of a bridge pier under impact based on piezoresistive impedance, characterized in that, The monitoring system described in any one of claims 1-4 is used to assess the bearing capacity of a bridge pier subjected to impact, and the specific steps are as follows: Step (1) Under laboratory conditions, the packaged axial force monitoring sensor was subjected to a load test, and the piezoresistive impedance signal was monitored at the same time to establish a linear relationship between axial force, temperature and peak frequency of axial force monitoring sensor; Step (2) Embed the axial force monitoring sensor into the concrete pier column to establish baseline data; Step (3) Based on the finite element model of bridge pier collapse due to impact, establish the skewness imbalance index under different working conditions. and database; Step (4) Set up a triggering mechanism to determine whether a collision event has occurred; Step (5) The original signal recorded after the trigger is processed by filtering, temperature compensation and other methods to obtain the axial force value at the current position; Step (6) Calculate the actual bridge impact imbalance index based on the axial force value obtained in step (5). Compared with the unbalance index based on section bending moment And quickly retrieve the corresponding working conditions from the database established in step (3); Step (7) Quickly assess the load-bearing capacity of the impacted bridge pier, make a decision, and promptly implement traffic control and reinforcement measures.

6. The method for monitoring the axial force of a bridge pier under impact based on piezoresistive impedance according to claim 5, characterized in that, The piezoresistive impedance signal in step (1) includes: impedance Real part of impedance Imaginary part of impedance Admittance Admittance Real Part and the imaginary part of admittance The relationship between them is as follows: ； in, The imaginary unit, .

7. The method for monitoring axial force on impacted bridge piers based on piezoresistive impedance according to claim 5, characterized in that, In step (2), the baseline data is established by continuously monitoring the measured peak frequency under normal conditions without collisions, recording its average value and fluctuation range, and establishing a dynamic baseline.

8. The method for monitoring the axial force of a bridge pier under impact based on piezoresistive impedance according to claim 5, characterized in that, The imbalance index in step (3) and The calculation formula is as follows: ； in, The skewness imbalance index characterizes the degree of asymmetry in the distribution of axial forces on the interface. It is an index of imbalance based on the bending moment of the cross section; The total number of sensors on the same cross-section. For the first The axial force value of each axial force monitoring sensor. This is the average of the axial force values ​​from all axial force monitoring sensors at this cross section. For equivalent bending moment, For the first The distance transmitted from each axial force monitoring sensor to the center axis of the cross section.

9. The method for monitoring axial force on a bridge pier under impact based on piezoresistive impedance according to claim 5, characterized in that, The triggering mechanism in step (4) is that if the change in the peak frequency of a certain axial force monitoring sensor exceeds three times or more the standard deviation of the dynamic baseline noise in two consecutive monitoring sessions, it is immediately determined that a collision event has occurred.

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