A method and system for identifying a sensor arrangement for scour dynamic identification of a beam bridge based on a scour sensitive modal set

Abstract

The application discloses a kind of based on scour sensitive modal set's beam bridge scour dynamic identification sensor arrangement method and system, including the following steps, the three-dimensional finite element structure dynamic model of the beam bridge to be monitored is established, and N discrete measuring points are set on three-dimensional finite element structure dynamic model;Extract the modal frequency and modal shape of each order modal of three-dimensional finite element structure dynamic model under multiple scour conditions, and filter scour sensitive modal, obtain scour sensitive state set;From N measuring points, target measuring point is filtered;When there is only one scour sensitive modal in scour sensitive state set, single scour sensitive modal monitoring scheme is used to arrange sensor on the bridge to be monitored;When there are two or more than two scour sensitive modals in scour sensitive state set, multiple scour sensitive modal monitoring scheme is used to arrange sensor on the bridge to be monitored.The monitoring of the application is high in reliability, and realizes the lightweight layout of sensor under the condition of meeting high-precision monitoring.

Description

Technical Field

[0001] This invention belongs to the field of bridge structural health monitoring and scour damage identification, and particularly relates to a method and system for arranging sensors for identifying scour dynamics of beam bridges based on a set of scour-sensitive modes. Background Technology

[0002] As critical infrastructure spanning rivers and waterways, beam bridges are subjected to a combination of natural and anthropogenic factors throughout their lifespan, including flood erosion, ship collisions, and vehicle loads. Among these, foundation instability caused by pile foundation erosion is a significant hidden danger leading to bridge damage and traffic disruption. Existing bridge health monitoring research largely focuses on assessing erosion depth based on static calculations or empirical formulas, lacking methods for identifying the dynamic characteristics of pile foundation erosion under environmental excitation conditions, as well as corresponding sensor optimization strategies.

[0003] In current practical engineering, bridge scour monitoring typically relies on underwater detection or a small number of empirically deployed accelerometers. This presents challenges such as the difficulty of underwater construction and high deployment costs. Furthermore, the number and location of sensors depend on manual experience, which can easily lead to sensor redundancy. Moreover, existing sensor deployment methods are mostly based on static or deterministic indicators, resulting in low measurement accuracy in practical applications. Summary of the Invention

[0004] Purpose of the invention: The first objective of this invention is to provide a method for arranging scour dynamic identification sensors for beam bridges based on a set of scour sensitive modes to achieve lightweight and high-precision identification under limited sensor conditions.

[0005] The second objective of this invention is to provide a beam bridge scour dynamic identification sensor arrangement system based on a scour sensitive mode set.

[0006] Technical solution: This invention discloses a method for arranging scour dynamic identification sensors for beam bridges based on a set of scour-sensitive modes, comprising the following steps:

[0007] A three-dimensional finite element dynamic model of the beam bridge to be monitored is established, and N discrete measuring points are set on the three-dimensional finite element dynamic model.

[0008] Excitation conditions are applied to the three-dimensional finite element dynamic model of the structure, and the modal frequencies and mode shapes of each mode under various scouring conditions are extracted. Based on the modal frequencies and mode shapes, a composite scouring sensitivity index is constructed. Scouring sensitive modes are selected from each mode according to the composite scouring sensitivity index to obtain a set of scouring sensitive states.

[0009] Based on the amplitude of the mode shape of the scour-sensitive mode at N measurement points, target measurement points are selected from the N measurement points;

[0010] When there is only one scour sensitive mode in the scour sensitive mode set, a single scour sensitive mode monitoring scheme is set based on the amplitude of the target measurement point of the scour sensitive mode, and sensors are arranged on the bridge to be monitored using the single scour sensitive mode monitoring scheme.

[0011] When there are two or more scour-sensitive modes in the scour-sensitive state set, a multi-scour-sensitive mode monitoring scheme is set up, and sensors are deployed on the bridge to be monitored using the multi-scour-sensitive mode monitoring scheme; the method of setting up the multi-scour-sensitive mode monitoring scheme is as follows:

[0012] Set a default number range for sensors, with a minimum value of 2 and a maximum value of the target measurement point. Selectively place any default number of sensors on the target measurement point to obtain a multi-sensor deployment scheme under the corresponding default number of sensors.

[0013] With any default number of sensors, for any scour-sensitive mode in the scour-sensitive state set, calculate its mode signal-to-noise ratio under different sensor deployment schemes. Combine the mode signal-to-noise ratio, the weight of the scour-sensitive mode in the scour-sensitive state set, and the composite scour sensitivity index to select the optimal sensor deployment scheme for each default number of sensors from multiple sensor deployment schemes.

[0014] Set the range of the number of sensors. The range of the number of sensors is a subset of the default range. Based on the range of the number of sensors, determine and compare the optimal layout scheme corresponding to each number of sensors. Select the minimum number of sensors from the range of the number of sensors. The optimal layout scheme corresponding to the minimum number of sensors is the multi-scour sensitive mode monitoring scheme.

[0015] Further settings The method for determining discrete measurement points is as follows: along the bridge span direction or the pier height direction, with a distance of [missing information - likely a measurement distance] from the measured point. The three-dimensional finite element structural dynamic model is discretized into several measurement points;

[0016] Multiple scour conditions refer to setting various scour depths in a three-dimensional finite element structural dynamic model; a total of [number] scour conditions are set. For the scouring condition, the range of values ​​for k is: The scouring depths corresponding to different scouring depth conditions are: ;Will The time is recorded as the no-flushing condition, and the flushing depth under the no-flushing condition is... .

[0017] Furthermore, the method for constructing the composite scour sensitivity index is as follows:

[0018] The influence of scouring conditions on modal frequencies is quantified to obtain frequency evaluation indicators.

[0019] The modal components of each mode under different scouring conditions at each measuring point are extracted from the modal vibration modes, and the influence of scouring conditions on the modal vibration modes is quantified based on the modal components to obtain the modal evaluation index.

[0020] The weights of the frequency evaluation index and the mode shape evaluation index are set, and a composite scour sensitivity index is constructed.

[0021] Furthermore, the frequency evaluation index is obtained in the following way:

[0022] The relative rate of change of modal frequencies for each mode under each scouring condition is calculated. The formula for calculating the relative rate of change of modal frequencies is as follows:

[0023] ,

[0024] in This represents the relative rate of change of the modal frequency of the m-th mode under the k-th scouring condition; Let m be the modal frequency of the m-th mode under the k-th scouring condition. This represents the modal frequency of the m-th mode under no-scour conditions.

[0025] The average rate of change of modal frequencies for each modal order is calculated based on the relative rate of change of modal frequencies for each modal order. The formula for calculating the average rate of change of modal frequencies is as follows:

[0026] ,

[0027] in This represents the average rate of change of the modal frequency of the m-th mode. Indicates the maximum scour depth;

[0028] The average rate of change of modal frequencies is normalized to obtain the frequency evaluation index. ;

[0029] The method for obtaining the modal evaluation index is as follows: Based on the modal components, the modal curvature of each mode at each measuring point under different scouring conditions is calculated, and the formula for calculating the modal curvature is as follows:

[0030] ,

[0031] in The modal curvature of the m-th mode at measurement point i under scour-free conditions; The modal curvature of the m-th mode at measurement point i under the k-th scouring condition; The mode shape component of the m-th mode at measurement point i under scour-free conditions; This refers to the m-th order mode at the measuring point under scour-free conditions. The mode shape components at that location; This refers to the m-th order mode at the measuring point under scour-free conditions. The mode shape components at that location; The mode shape component of the m-th mode at measurement point i under the k-th scouring condition; This refers to the m-th mode at the measuring point under the k-th scouring condition. The mode shape components at that location; This refers to the m-th mode at the measuring point under the k-th scouring condition. The mode shape components at that location;

[0032] Based on modal curvature calculation, the rate of change of modal curvature for each mode under different scouring conditions is calculated, and the formula for calculating the rate of change of modal curvature is as follows:

[0033] ,

[0034] in The rate of change of modal curvature of the m-th mode under the k-th scouring condition;

[0035] The average rate of change of modal curvature for each mode is calculated based on the rate of change of modal curvature. The formula for calculating the average rate of change of modal curvature is as follows:

[0036] ,

[0037] in This represents the average rate of change of the modal curvature of the m-th mode;

[0038] The average rate of change of modal curvature is normalized to obtain the modal evaluation index. .

[0039] Furthermore, the calculation formula for the composite scouring sensitivity index is as follows:

[0040] ,

[0041] in This refers to the composite scouring sensitivity index of the m-th mode, and The range of values ​​is ; The weight of frequency evaluation indicators. The weights of the vibration mode evaluation index;

[0042] The method for obtaining the set of scour sensitive states is as follows: sort the composite scour sensitivity indices from largest to smallest, and set a composite sensitivity threshold. Maximum number of candidate modes Before choosing The sensitivity index of composite scouring in the first mode is greater than or equal to The modes are considered as scour-sensitive modes, and all scour-sensitive modes constitute the scour-sensitive state set. .

[0043] Furthermore, the method for selecting target measurement points is as follows: if the amplitude of a certain measurement point is less than a preset value in all scour-sensitive modes, the measurement point is recorded as a common mode shape measurement point; all common mode shape measurement points are removed from the N measurement points, and the remaining measurement points are the target measurement points. The mode shape vector of the scour-sensitive mode after removing all common mode shape measurement points is recorded as the target mode shape vector. ,and ,in This refers to the number of target measurement points.

[0044] Furthermore, the single scour-sensitive mode monitoring scheme is as follows: when the scour-sensitive mode is the first-order mode, only one sensor is deployed at the target measurement point with the largest amplitude; when the scour-sensitive mode is the second-order mode, one target measurement point with the largest amplitude is selected in both the positive and negative directions of the mode shape curve, and sensors are deployed at these two target measurement points; when the mode order of the scour-sensitive mode is greater than 2, the number of sensors is consistent with the half-wave number of the mode shape of the scour-sensitive mode, and the target measurement point with the largest amplitude is selected and deployed within each half-wave segment of the mode shape.

[0045] Furthermore, the optimal deployment scheme for the corresponding default number of sensors is obtained as follows:

[0046] For a specified number of sensors I, use The vector is encoded into the sensor deployment scheme L to obtain the feasible deployment vector of sensor deployment scheme L. ,in This refers to the number of target measurement points and the feasible deployment vector. The vector expression is as follows:

[0047] , ,in Indicates at the target measurement point Sensors are deployed at the location. 0 indicates the target measurement point No sensors are deployed at this location;

[0048] With any default number of sensors, for any scour-sensitive mode in the scour-sensitive state set, calculate its mode signal-to-noise ratio (SNR) under sensor deployment scheme L, and the formula for calculating the SNR is as follows:

[0049] ,

[0050] in, This represents the signal-to-noise ratio of the nth scour-sensitive mode under sensor deployment scheme L, where S refers to the excitation power spectral density under the excitation conditions. The spectral density represents the noise level of the sensor channel. This represents the damping ratio of the nth scour-sensitive mode;

[0051] Set the upper limit of the modal signal-to-noise ratio. The modal signal-to-noise ratio (SNR) of each scour-sensitive mode under all sensor deployment schemes is truncated to obtain the final SNR of each scour-sensitive mode under each sensor deployment scheme L. ,and ;

[0052] Based on the final signal-to-noise ratio of sensor deployment scheme L, the weight of the scour-sensitive mode in the scour-sensitive state set, frequency evaluation index, and mode shape evaluation index, a comprehensive signal-to-noise ratio index is constructed, and the calculation formula of the comprehensive signal-to-noise ratio index is as follows:

[0053] ,

[0054] ;

[0055] With the goal of maximizing the overall signal-to-noise ratio, the Grey Wolf optimization algorithm is used to iteratively optimize the sensor deployment scheme L, obtaining the optimal deployment scheme after iterative optimization for each default number of sensors. .

[0056] Furthermore, the engineering quantity range for sensors is as follows: The method for determining the minimum number of sensors is as follows:

[0057] right Extract the number of sensors z within any interval. The optimal deployment scheme and its corresponding comprehensive signal-to-noise ratio index And calculate the modal signal-to-noise ratio of all scour-sensitive modes. ;

[0058] If the modal signal-to-noise ratio of a certain scour-sensitive mode is less than If the quantity z is less than the preset lower limit of the project, then the quantity z is recorded as an infeasible quantity.

[0059] If the number of sensors z is less than the half-wave number of the highest-order scour-sensitive mode in the scour-sensitive mode set, then the number of sensors z is recorded as an infeasible number.

[0060] Eliminate For the infeasible number within the interval, sort all remaining sensor numbers in ascending order and calculate the improvement in the combined modal signal-to-noise ratio between two adjacent numbers;

[0061] When the increase in the number of sensors z is less than the preset convergence value, and satisfies When z is the minimum number of sensors, then the quantity z is recorded as the minimum number of sensors.

[0062] Based on the same invention, this invention also discloses a beam bridge scour dynamic identification sensor arrangement system based on a scour-sensitive mode set, comprising,

[0063] The model simulation unit establishes a three-dimensional finite element dynamic model of the beam bridge to be monitored, and sets N discrete measuring points on the three-dimensional finite element dynamic model.

[0064] The modal screening unit applies excitation conditions to the three-dimensional finite element structural dynamic model, extracts the modal frequencies and mode shapes of each mode under various scouring conditions, constructs a composite scouring sensitivity index based on the modal frequencies and mode shapes, and screens scouring sensitive modes from each mode according to the composite scouring sensitivity index to obtain a set of scouring sensitive states.

[0065] The measurement point screening unit selects target measurement points from N measurement points based on the amplitude of the mode shape of the scour-sensitive mode at N measurement points;

[0066] A single-mode monitoring unit, when there is only one scour-sensitive mode in the scour-sensitive mode set, sets a single scour-sensitive mode monitoring scheme based on the amplitude of the target measurement point of the scour-sensitive mode, and arranges sensors on the bridge to be monitored using the single scour-sensitive mode monitoring scheme;

[0067] The multi-modal monitoring unit, when there are two or more scour-sensitive modes in the scour-sensitive mode set, sets up a multi-scour-sensitive mode monitoring scheme, and deploys sensors on the bridge to be monitored using the multi-scour-sensitive mode monitoring scheme; the method of setting up the multi-scour-sensitive mode monitoring scheme is as follows:

[0068] Set a default number range for sensors, with a minimum value of 2 and a maximum value of the target measurement point. Selectively place any default number of sensors on the target measurement point to obtain a multi-sensor deployment scheme under the corresponding default number of sensors.

[0069] With any default number of sensors, for any scour-sensitive mode in the scour-sensitive state set, calculate its mode signal-to-noise ratio under different sensor deployment schemes. Combine the mode signal-to-noise ratio, the weight of the scour-sensitive mode in the scour-sensitive state set, and the composite scour sensitivity index to select the optimal sensor deployment scheme for each default number of sensors from multiple sensor deployment schemes.

[0070] Set the range of the number of sensors. The range of the number of sensors is a subset of the default range. Based on the range of the number of sensors, determine and compare the optimal layout scheme corresponding to each number of sensors. Select the minimum number of sensors from the range of the number of sensors. The optimal layout scheme corresponding to the minimum number of sensors is the multi-scour sensitive mode monitoring scheme.

[0071] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The present invention simulates the dynamic characteristics of the bridge under various scour conditions, and constructs a composite scour sensitivity index by combining the modal frequency change rate and the mode shape curvature change. It screens the most sensitive scour modes and target measuring points, avoiding the reliance on experience to select the location of target modes and measuring points in traditional methods. This is conducive to improving the ability to extract scour sensitive information. Placing the sensor at the target measuring point can effectively improve the reliability and accuracy of bridge monitoring.

[0072] This invention allows for the setting of a single scour-sensitive mode monitoring scheme or a multi-scour-sensitive mode monitoring scheme based on the number of scour-sensitive modes. The single scour-sensitive mode monitoring scheme, while ensuring the matching of modal order with the number of target measurement points, concentrates a limited number of sensors in the main vibration region of the modal shape, guaranteeing that the single scour-sensitive mode has sufficient signal-to-noise ratio and identifiability under environmental excitation conditions. The multi-scour-sensitive mode monitoring scheme, by comprehensively considering the range of sensor numbers and weighted modal signal-to-noise ratio, jointly optimizes the number and placement of sensors. This allows for the determination of the minimum required number of sensors and their optimal placement while meeting the accuracy requirements for scour-sensitive mode identification, thus achieving lightweight sensor deployment while maintaining high-precision monitoring. Attached Figure Description

[0073] Figure 1 This is a flowchart of the method of the present invention;

[0074] Figure 2 This is a schematic diagram of the system structure of the present invention;

[0075] Figure 3 This is the three-dimensional finite element structural dynamic model in the embodiments of the present invention;

[0076] Figure 4 This is the first mode shape diagram of the three-dimensional finite element structural dynamic model under a certain scouring condition in an embodiment of the present invention;

[0077] Figure 5 This is the second-order mode shape diagram of the three-dimensional finite element structural dynamic model under a certain scouring condition in an embodiment of the present invention;

[0078] Figure 6 This is the third-order mode shape diagram of the three-dimensional finite element structural dynamic model under a certain scouring condition in an embodiment of the present invention;

[0079] Figure 7 This is the fourth mode shape diagram of the three-dimensional finite element structural dynamic model under a certain scouring condition in an embodiment of the present invention;

[0080] Figure 8 This is the optimal deployment scheme when the number of sensors is 4 in this embodiment of the invention;

[0081] Figure 9 A comparison diagram of the signal-to-noise ratio (SNR) of the first, second, and third modes before and after optimization in an embodiment of the present invention;

[0082] Figure 10 This is a convergence diagram showing the number of sensors required to achieve optimal accuracy for each scour-sensitive mode sensor in the embodiments of the present invention. Detailed Implementation

[0083] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0084] Example 1

[0085] like Figure 1 As shown, the present invention discloses a method for arranging scour dynamic identification sensors for beam bridges based on a set of scour-sensitive modes, comprising the following steps:

[0086] S1: Establish a three-dimensional finite element dynamic model of the beam bridge to be monitored, and set N discrete measuring points on the three-dimensional finite element dynamic model.

[0087] Based on the design drawings, construction data, and geological survey report of the beam bridge to be monitored, the geometric dimensions, material parameters, and foundation types of the main beams, piers, abutments, and pile foundations are determined, and a three-dimensional finite element structural dynamic model of the beam bridge to be monitored is established. The three-dimensional finite element structural dynamic model includes the main beams, piers, abutments, and pile foundations of the beam bridge to be monitored. In this embodiment, the three-dimensional finite element structural dynamic model is as follows: Figure 3 As shown, Figure 3 In the figure, X, Y, and Z are the three-dimensional coordinate system of the three-dimensional finite element structural dynamic model.

[0088] A Winkler foundation model is placed at the interface between the pile foundation and the soil in the three-dimensional finite element structural dynamic model. The Winkler foundation model is used to simulate the lateral reaction force of the soil around the pile foundation.

[0089] Among the settings The method for determining discrete measurement points is as follows: along the bridge span direction or the pier height direction, with a distance of [missing information - likely a measurement distance] from the measured point. The three-dimensional finite element dynamic model of the structure is discretized into several measurement points. The coordinates of the i-th measurement point are denoted as follows: .

[0090] Preferably, key monitoring areas are set on the three-dimensional finite element structural dynamic model. In key monitoring areas Discrete points are set inside. And the value of i ranges from [1, N]. Among them, the key monitoring areas are... The preferred method is to use the key sections of the pile foundation, pier, and superstructure in a three-dimensional finite element structural dynamic model.

[0091] S2: Apply excitation conditions to the three-dimensional finite element dynamic model of the structure, and extract the modal frequencies and mode shapes of each mode under various scouring conditions. Construct a composite scouring sensitivity index based on the modal frequencies and mode shapes, and select scouring-sensitive modes from each mode according to the composite scouring sensitivity index to obtain the set of scouring-sensitive modes. .

[0092] In this embodiment, the first-order mode shape under a certain scouring condition is as follows: Figure 4 As shown, the second-order mode shape is as follows: Figure 5 As shown, the third-order mode shape is as follows: Figure 6 As shown, the fourth-order mode shape is as follows: Figure 7 As shown, Figures 4 to 7 In the figure, X, Y, and Z are the three-dimensional coordinate system of the three-dimensional finite element structural dynamic model.

[0093] Preferably, a standardized excitation is applied to the three-dimensional finite element structural dynamic model; that is, the initial displacement of free vibration or unit pulse load of the three-dimensional finite element structural dynamic model is set to ensure the effectiveness and accuracy of subsequent modal analysis and dynamic response extraction.

[0094] Multiple scour conditions refer to setting various scour depths in a three-dimensional finite element structural dynamic model. The spring stiffness of the Winkler foundation model is proportional to the bearing capacity of the beam bridge pile foundation. When simulating multiple scour conditions, different scour depths are set by adjusting the spring stiffness.

[0095] This embodiment sets a total of A series of scouring conditions, where the value of k ranges from... ;Will The time is recorded as the no-scouring condition, at which point the scouring depth is... ;Will These are denoted as different scour depth conditions, and the corresponding scour depths are: Let the modal frequency of the m-th mode under the k-th scouring condition be denoted as . Let the mode shape of the m-th mode under k scouring conditions be denoted as The no-scour condition is taken as the reference condition, and the modal frequency under the reference condition is denoted as the reference frequency. The modal shape under the reference operating condition is denoted as the reference mode shape, and .

[0096] Preferably, after obtaining the mode shapes of each mode under various scouring conditions, the mode shapes of each mode can be mass normalized to eliminate the influence of numerical scale differences.

[0097] S21: Quantify the degree of influence of scouring conditions on modal frequencies to obtain frequency evaluation indicators.

[0098] S211: Calculate the relative rate of change of modal frequencies for each mode under each scouring condition. The formula for calculating the relative rate of change of modal frequencies is as follows:

[0099] ,

[0100] in This represents the relative rate of change of the modal frequency of the m-th mode under the k-th scouring condition; Let m be the modal frequency of the m-th mode under the k-th scouring condition. Indicates the reference frequency.

[0101] relative rate of change of modal frequencies This reflects the fact that at a scouring depth of At that time, the relative variation of the m-th natural frequency of the three-dimensional finite element structural dynamic model with respect to the scour-free condition is... The larger the value, the more sensitive the modal frequency of that mode is to the scouring condition.

[0102] S212: Calculate the average rate of change of the modal frequencies of the corresponding order modes based on the relative rate of change of the modal frequencies of each order, and the formula for calculating the average rate of change of the modal frequencies is as follows:

[0103] ,

[0104] in This represents the average rate of change of the modal frequency of the m-th mode. Indicates the maximum scour depth. This indicates the scouring depth under no-scouring conditions, and , .

[0105] S213: Normalize the average rate of change of modal frequencies to obtain frequency evaluation indices. .

[0106] The average rate of change of the modal frequency can be normalized using linear normalization, and the formula for linear normalization is as follows:

[0107] ,

[0108] in The normalized average rate of change of the modal frequencies of the m-th mode is the frequency evaluation index of the m-th mode. ; The normalized average rate of change of modal curvature; .

[0109] S22: Extract the mode shape components of each mode under different scouring conditions at each measuring point from the mode shape, and quantify the influence of scouring conditions on the mode shape based on the mode shape components to obtain the mode shape evaluation index.

[0110] S221: Based on modal components, calculate the modal curvature of each mode at each measuring point under different scouring conditions, and the formula for calculating the modal curvature is as follows:

[0111]

[0112] in The modal curvature of the m-th order mode at measurement point i under scour-free conditions; The modal curvature of the m-th mode at measurement point i under the k-th scouring condition; The mode shape component of the m-th order mode at measurement point i under scour-free conditions; The m-th order mode at the measuring point under scour-free conditions. The mode shape components at that location; The m-th order mode at the measuring point under scour-free conditions. The mode shape components at that location; The mode shape component of the m-th mode at measurement point i under the k-th scouring condition; This refers to the m-th mode at the measuring point under the k-th scouring condition. The mode shape components at that location; This refers to the m-th mode at the measuring point under the k-th scouring condition. The mode shape components at that location.

[0113] S222: Based on modal curvature calculation, the rate of change of modal curvature for each mode under different scouring conditions is calculated, and the formula for calculating the rate of change of modal curvature is as follows:

[0114] ,

[0115] in It refers to the rate of change of the modal curvature of the m-th mode under the k-th scouring condition.

[0116] The numerator in the formula for calculating the rate of change of modal curvature The denominator represents the total absolute change in modal curvature of the m-th mode. Represents the curvature of the m-th mode relative to the reference mode. The absolute total amount is used for dimensionless transformation. The larger the value, the more significant the change in the bending mode of the m-th mode under the k-th scouring condition.

[0117] S223: Calculate the average rate of change of modal curvature for each mode based on the rate of change of modal curvature. The formula for calculating the average rate of change of modal curvature is as follows:

[0118] ,

[0119] in This represents the average rate of change of the mode curvature of the m-th mode.

[0120] S224: Normalize the average rate of change of mode curvature to obtain the mode evaluation index. .

[0121] The average rate of change of mode curvature can be normalized using linear normalization, and the formula for linear normalization is as follows:

[0122] ,

[0123] in The normalized average rate of change of modal curvature; .

[0124] S23: Set the weights of the frequency evaluation index and the mode evaluation index, and construct a composite scour sensitivity index.

[0125] Set the weight of the frequency evaluation index to The weights of the mode shape evaluation index are set as follows: The formula for calculating the composite scouring sensitivity index is as follows:

[0126] ,

[0127] in This refers to the composite scouring sensitivity index of the m-th mode, and The range of values ​​is . The larger the value, the stronger the overall sensitivity of the m-th mode to the scour depth.

[0128] In practical applications, the weights of the average rate of change of modal frequencies and the average rate of change of modal curvature can be set according to requirements. When more attention is paid to modal frequency changes, a weight of 100% can be used. The value is relatively large; when more attention is paid to local stiffness variations in the foundation (such as in the pile-pier region), it can be increased. .

[0129] S24: Sort the composite scouring sensitivity indices from largest to smallest, and set the composite sensitivity threshold. Maximum number of candidate modes Before choosing The sensitivity index of composite scouring in the first mode is greater than or equal to The modes are considered as scour-sensitive modes, and all scour-sensitive modes constitute the scour-sensitive state set. .

[0130] like Figures 8 to 10 As shown, in this embodiment, a total of 3 scour-sensitive modes were selected, namely Mode 1 (first-order mode), Mode 2 (second-order mode), and Mode 3 (third-order mode).

[0131] For the set of scour-sensitive states Any nth scour-sensitive mode in the data, The mode shape vectors of the scour-sensitive mode at all measuring points are denoted as... .

[0132] The resulting set of scour-sensitive states This will be used for subsequent sensor deployment optimization to ensure that sensor resources are prioritized for the modes that are most sensitive to scour and have the highest identification value.

[0133] In practical applications, the composite sensitivity threshold The maximum number of candidate modes is set according to engineering requirements and subsequent modality recognition capabilities. Configured according to project requirements. The preferred value range is 3 to 5.

[0134] S3: Based on the amplitude of the mode shape of the scour-sensitive mode at N measurement points, select target measurement points from the N measurement points.

[0135] like Figure 8 As shown, in this embodiment, a total of 140 measurement points (degrees of freedom) are set, and 15 target measurement points are selected. These 15 target measurement points are... Figure 10 The 11 candidate sensor measurement points (target measurement points where no sensors are deployed in this embodiment) and 4 preferred sensor measurement points (target measurement points where sensors are actually deployed).

[0136] For each measuring point i, if the mode amplitude of measuring point i is less than the preset value in all scour-sensitive modes... That is, satisfying If we denote these measurement points as common mode shape measurement points, then we remove all common mode shape measurement points from the N measurement points, and the remaining measurement points are the target measurement points. The modal shape vector of the scour-sensitive mode after removing all common mode shape measurement points is denoted as the target mode shape vector. ,and ,in This refers to the number of target measurement points.

[0137] By eliminating common mode measurement points, it is possible to avoid placing sensors at measurement points with weak response and low signal-to-noise ratio.

[0138] Preferably, in practical applications, the feasible locations for sensor deployment are screened by comprehensively considering the accessibility of construction and maintenance as well as the engineering constraints of response significance, and measuring points that are inconvenient for construction and maintenance among non-common mode measuring points are eliminated.

[0139] Preferably, before screening target measurement points, the mode shape vectors of all scour-sensitive modes are normalized to make the maximum mode shape amplitude normalized to 1, and only the relative magnitude relationship between each measurement point is retained, which is convenient for comparing the response strength of different measurement points and different modes.

[0140] S4: When the set of sensitive states is flushed When there is only one scour-sensitive mode, a single scour-sensitive mode monitoring scheme is set up based on the amplitude of the target measurement point of the scour-sensitive mode, and sensors are arranged on the bridge to be monitored using the single scour-sensitive mode monitoring scheme.

[0141] The single scour-sensitive mode monitoring scheme is as follows: when the scour-sensitive mode is the first-order mode, only one sensor is deployed at the target measurement point with the largest amplitude; when the scour-sensitive mode is the second-order mode, one target measurement point with the largest amplitude is selected in both the positive and negative directions of the mode shape curve, and sensors are deployed at these two target measurement points; when the mode order of the scour-sensitive mode is greater than 2, the number of sensors is consistent with the half-wave number of the mode shape of the scour-sensitive mode, and the target measurement point with the largest amplitude is selected and deployed within each half-wave segment of the mode shape.

[0142] The single scour-sensitive mode monitoring scheme, under the premise of matching the modal order with the number of target measurement points, concentrates a limited number of sensors in the main vibration region of the modal shape, ensuring that the single scour-sensitive mode has sufficient signal-to-noise ratio and identifiability under environmental excitation conditions.

[0143] S5: When there are two or more scour-sensitive modes in the scour-sensitive state set, a multi-scour-sensitive mode monitoring scheme is set up, and sensors are arranged on the bridge to be monitored using the multi-scour-sensitive mode monitoring scheme.

[0144] S51: Set the default number range of sensors. The minimum value of the default number range is 2 and the maximum value is the number of target measurement points. Selectively arrange any default number of sensors on the target measurement points to obtain a multiple sensor layout scheme under the corresponding default number of sensors.

[0145] Let the arrangement of sensors selectively placed on the target measurement points be denoted as sensor layout scheme L, and let C be the set corresponding to the default quantity range. .

[0146] S52: Under any default number of sensors, for any scour-sensitive mode in the scour-sensitive state set, calculate its mode signal-to-noise ratio under different sensor deployment schemes. Combine the mode signal-to-noise ratio, the weight of the scour-sensitive mode in the scour-sensitive state set, and the composite scour sensitivity index to select the optimal deployment scheme under each default number of sensors from multiple sensor deployment schemes.

[0147] S521: For a specified number of sensors I, use... The vector is encoded into the sensor deployment scheme L to obtain the feasible deployment vector of sensor deployment scheme L. ,in This refers to the number of target measurement points and the feasible deployment vector. The vector expression is as follows:

[0148] , ,in Indicates at the target measurement point Sensors are deployed at the location. 0 indicates the target measurement point No sensors are installed at the location.

[0149] S522: With any default number of sensors, for any scour-sensitive mode in the scour-sensitive state set, calculate its mode signal-to-noise ratio (SNR) under sensor deployment scheme L, and the formula for calculating the SNR is as follows:

[0150] ,

[0151] in, Let S represent the signal-to-noise ratio of the nth scour-sensitive mode under sensor deployment scheme L, and let S refer to the excitation power spectral density of the excitation condition applied in step S2. The spectral density represents the noise level of the sensor channel. This represents the damping ratio of the nth scour-sensitive mode.

[0152] in This represents the mode shape energy of the nth scour-sensitive mode at all target measurement points. This is the damping correction term for the amplification factor at resonance in a single-degree-of-freedom system. Given the excitation condition S and the noise spectral density... and damping ratio Under the conditions, The changes in sensor deployment scheme L are mainly due to The determination refers to the degree of mode energy concentration of the scour-sensitive mode at the selected target measurement point. The more concentrated the mode energy is at the target measurement point where the sensor is deployed, the better. The larger the value, the higher the corresponding modal signal-to-noise ratio. The higher.

[0153] S523: Set the upper limit of the modal signal-to-noise ratio. The modal signal-to-noise ratio (SNR) of each scour-sensitive mode under all sensor deployment schemes is truncated to obtain the final SNR of each scour-sensitive mode under each sensor deployment scheme L. ,and .

[0154] In other words, the modal signal-to-noise ratio (SNR) of each scour-sensitive mode under all sensor deployment schemes is truncated using the above method to obtain the final SNR of each scour-sensitive mode under each sensor deployment scheme L. .

[0155] S524: Based on the final signal-to-noise ratio of sensor deployment scheme L, the weight of the scour-sensitive mode in the scour-sensitive state set, frequency evaluation index, and mode shape evaluation index, a comprehensive signal-to-noise ratio index is constructed, and the calculation formula of the comprehensive signal-to-noise ratio index is as follows:

[0156] ,

[0157] .

[0158] This is a tradeoff factor used to balance improving the overall signal-to-noise ratio of all modes with raising the baseline of the weakest mode. To ensure the highest possible overall recognition capability for scour-sensitive modes, Ensure that the signal-to-noise ratio of the most unfavorable mode is not too low, thereby avoiding extreme sensor deployment schemes where some modes are very clear while others are almost invisible.

[0159] S525: With the goal of maximizing the overall signal-to-noise ratio, the Grey Wolf optimization algorithm is used to iteratively optimize the sensor deployment scheme L, obtaining the optimal deployment scheme after iterative optimization for each default number of sensors. .

[0160] The method for iteratively optimizing the sensor deployment scheme L using the Grey Wolf optimization algorithm is as follows:

[0161] Population initialization. Under the constraint conditions... Given the premise of randomly generating several feasible deployment vectors The feasible deployment vector Let each individual be a target function, and calculate the corresponding objective function value for each individual. and the modal signal-to-noise ratio of each scour-sensitive mode. Individuals that do not meet the constraints are considered infeasible. The "wolf pack" position parameters are updated in the continuous space according to the update rules of the gray wolf optimization algorithm, which means updating the target measurement point positions selected by the sensor. Then, the continuous variables (target measurement points) are transformed into... The form is adjusted by adding or removing some measuring points to ensure that each individual continues to meet the sensor number constraint. ;

[0162] Recalculate the objective function for the updated individuals. and modal signal-to-noise ratio Eliminate individuals that do not meet the objective function, and retain the individual with the largest objective function value as the elite solution for the current iteration.

[0163] When the objective function If the improvement rate falls below a preset threshold or the maximum number of iterations is reached after several consecutive iterations, the search is terminated, and the deployment scheme with the highest current objective function value is recorded as the optimal deployment scheme with I sensors, denoted as... .

[0164] In this embodiment, the optimal deployment scheme when the number of sensors is 4 is as follows: Figure 8 As shown, the locations of the four sensors (sensor 1, sensor 2, sensor 3, and sensor 4) are as follows: Figure 8 The preferred sensor measurement points (the target measurement points where the sensors are actually deployed) are shown in the figure. Four sensors monitor the first mode (mode 1), the second mode (mode 2), and the third mode (mode 3).

[0165] In this embodiment, the modal signal-to-noise ratios (SNRs) before and after optimization for the first mode (mode 1), the second mode (mode 2), and the third mode (mode 3) are as follows: Figure 9 As shown, Figure 9 The minimum threshold of modal signal-to-noise ratio refers to .

[0166] Under the given constraint of the number of sensors, this invention can automatically search for and obtain a deployment scheme that maximizes the overall modal signal-to-noise ratio of the scour-sensitive mode while ensuring the identifiability of the weakest mode within a default quantity range where target measurement point locations have been eliminated and engineering feasibility constraints have been met. .

[0167] S53: Set the range of the number of sensors. The range of the number of sensors is a subset of the default range. Based on the range of the number of sensors, determine and compare the optimal layout scheme corresponding to each number of sensors. Select the minimum number of sensors from the range of the number of sensors. The optimal layout scheme corresponding to the minimum number of sensors is the multi-scour sensitive mode monitoring scheme.

[0168] The range of engineering quantities for sensors is: In practical applications, the range of sensor quantities should be determined by considering both the engineering requirements and the channel conditions of the monitoring system. Where: lower limit The upper limit is determined jointly by the on-site deployment capacity and the minimum coverage requirements for key parts of the bridge structure to be monitored; The number of data acquisition system channels, cabling conditions, and economic costs are all factors that determine the outcome; and , All belong to set C, meaning the project quantity range is a subset of the default quantity range.

[0169] The minimum number of sensors is determined as follows:

[0170] S541: Yes Extract the number of sensors z within any interval. The optimal deployment scheme and its corresponding comprehensive signal-to-noise ratio index And calculate the modal signal-to-noise ratio for each scouring mode. .

[0171] Modal signal-to-noise ratio The calculation formula is: .

[0172] S542: If the modal signal-to-noise ratio of a certain scour-sensitive mode is less than... If the number of sensors z is less than the preset lower limit of the engineering, then the number of sensors z is recorded as an infeasible number; if the number of sensors z is less than the half-wave number of the highest order scour sensitive mode in the scour sensitive mode set, then the number of sensors z is recorded as an infeasible number.

[0173] The preset lower limit value for the project is preferably 1. or When z is infeasible, denote the quantity z as an infeasible quantity.

[0174] S543: Removal For the infeasible number within the interval, sort all remaining sensor numbers in ascending order and calculate the improvement in the combined modal signal-to-noise ratio between adjacent numbers.

[0175] The formula for calculating the increase is as follows: ,in The optimal deployment scheme is given by the number of sensors z. The corresponding overall signal-to-noise ratio (SNR) index.

[0176] S544: When the improvement in the number of sensors z is less than the preset convergence value, and satisfies When z is the minimum number of sensors, then the quantity z is recorded as the minimum number of sensors.

[0177] Preset convergence value Preferred The improvement in the number of sensors z is less than the preset convergence value, which means it satisfies... .

[0178] Simultaneously satisfy and At that time, Adding another sensor to the existing setup offers limited improvement to the overall modal signal-to-noise ratio. Therefore, it is assumed that at the given sensor count z, the overall recognition capability of the scour-sensitive mode has entered a convergence range with diminishing returns; further additions of sensors will lead to a significant increase in cost with limited improvement in recognition accuracy.

[0179] All conditions are met simultaneously and Among the feasible number of sensors, this invention selects the smallest number as the minimum number of sensors required for identifying the scour dynamics of the bridge to be monitored, denoted as . The corresponding optimal deployment scheme This is the multi-scour-sensitive mode monitoring scheme that is the final output of this invention.

[0180] Preferred, in All within the scope None of them can be satisfied When (e.g., the signal-to-noise ratio of certain key modes is consistently lower than) ), then can As a security-side configuration option, the manual suggests that it is necessary to increase the data acquisition time, improve the excitation conditions, or use a higher-performance sensor to meet the recognition accuracy requirements.

[0181] In this embodiment, the minimum number of sensors is determined to be 17, such as Figure 10 As shown, the modal signal-to-noise ratio of the first mode (mode 1), the second mode (mode 2), and the third mode (mode 3) converges when the number of sensors is 17, that is, the sensor convergence inflection point is 17.

[0182] Example 2

[0183] like Figure 3 As shown, the present invention discloses a beam bridge scour dynamic identification sensor arrangement system based on a scour sensitive mode set, including a model simulation unit, a mode screening unit, a measurement point screening unit, a single mode monitoring unit, and a multi-mode monitoring unit.

[0184] The model simulation unit establishes a three-dimensional finite element dynamic model of the beam bridge to be monitored, and sets N discrete measuring points on the three-dimensional finite element dynamic model. The model simulation unit executes step S1 in Example 1.

[0185] The modal screening unit applies excitation conditions to the three-dimensional finite element structural dynamic model, extracts the modal frequencies and mode shapes of each mode under various scouring conditions, constructs a composite scouring sensitivity index based on the modal frequencies and mode shapes, and filters scouring-sensitive modes from each mode according to the composite scouring sensitivity index to obtain a set of scouring-sensitive modes. The modal screening unit executes step S2 in Example 1.

[0186] The measurement point selection unit selects target measurement points from N measurement points based on the amplitude of the mode shape of the scour-sensitive mode at N measurement points. The measurement point selection unit executes step S3 in Example 1.

[0187] The single-mode monitoring unit, when there is only one scour-sensitive mode in the scour-sensitive mode set, sets up a single scour-sensitive mode monitoring scheme based on the amplitude of the target measurement point of that scour-sensitive mode, and deploys sensors on the bridge to be monitored using the single scour-sensitive mode monitoring scheme. The single-mode monitoring unit executes step S4 in Example 1.

[0188] The multi-modal monitoring unit, when there are two or more scour-sensitive modes in the scour-sensitive mode set, sets up a multi-scour-sensitive mode monitoring scheme, and deploys sensors on the bridge to be monitored using the multi-scour-sensitive mode monitoring scheme; the method of setting up the multi-scour-sensitive mode monitoring scheme is as follows:

[0189] Set a default number range for sensors, with a minimum value of 2 and a maximum value of the target measurement point. Selectively place any default number of sensors on the target measurement point to obtain a multi-sensor deployment scheme under the corresponding default number of sensors.

[0190] With any default number of sensors, for any scour-sensitive mode in the scour-sensitive state set, calculate its mode signal-to-noise ratio under different sensor deployment schemes. Combine the mode signal-to-noise ratio, the weight of the scour-sensitive mode in the scour-sensitive state set, and the composite scour sensitivity index to select the optimal sensor deployment scheme for each default number of sensors from multiple sensor deployment schemes.

[0191] The range of sensor quantities is set, which is a subset of the default quantity range. Based on the range of sensor quantities, the optimal deployment scheme corresponding to each quantity of sensors is determined and compared. The minimum number of sensors is selected from the range of sensor quantities, and the optimal deployment scheme corresponding to the minimum number of sensors is the multi-flushing sensitive mode monitoring scheme. The multi-modal monitoring unit executes step S5 in Example 1.

Claims

1. A method for arranging scour dynamic identification sensors for beam bridges based on a set of scour-sensitive modes, characterized in that: Includes the following steps, A three-dimensional finite element dynamic model of the beam bridge to be monitored is established, and N discrete measuring points are set on the three-dimensional finite element dynamic model. Excitation conditions were applied to a three-dimensional finite element dynamic model of a structure, and the modal frequencies and mode shapes of each mode under various scouring conditions were extracted. A composite scouring sensitivity index was constructed based on the modal frequencies and mode shapes. Scouring-sensitive modes were then selected from each mode based on the composite scouring sensitivity index to obtain a set of scouring-sensitive states. The method for constructing the composite scouring sensitivity index is as follows: The influence of scouring conditions on modal frequencies is quantified to obtain frequency evaluation indicators. The modal components of each mode under different scouring conditions at each measuring point are extracted from the modal vibration modes, and the influence of scouring conditions on the modal vibration modes is quantified based on the modal components to obtain the modal evaluation index. Set the weights of frequency evaluation index and mode evaluation index, and construct a composite scour sensitivity index; Based on the amplitude of the mode shape of the scour-sensitive mode at N measurement points, target measurement points are selected from the N measurement points; When there is only one scour sensitive mode in the scour sensitive mode set, a single scour sensitive mode monitoring scheme is set based on the amplitude of the target measurement point of the scour sensitive mode, and sensors are arranged on the bridge to be monitored using the single scour sensitive mode monitoring scheme. When there are two or more scour-sensitive modes in the scour-sensitive state set, a multi-scour-sensitive mode monitoring scheme is set up, and sensors are deployed on the bridge to be monitored using the multi-scour-sensitive mode monitoring scheme; the method of setting up the multi-scour-sensitive mode monitoring scheme is as follows: Set a default number range for sensors, with a minimum value of 2 and a maximum value of the target measurement point. Selectively place any default number of sensors on the target measurement point to obtain a multi-sensor deployment scheme under the corresponding default number of sensors. With any default number of sensors, for any scour-sensitive mode in the scour-sensitive state set, calculate its mode signal-to-noise ratio (MSNR) under different sensor deployment schemes. Combine the MSNR, the weight of the scour-sensitive mode in the scour-sensitive state set, and the composite scour sensitivity index to select the optimal deployment scheme under each default number of sensors from multiple sensor deployment schemes. Set the range of the number of sensors. The range of the number of sensors is a subset of the default range. Based on the range of the number of sensors, determine and compare the optimal layout scheme corresponding to each number of sensors. Select the minimum number of sensors from the range of the number of sensors. The optimal layout scheme corresponding to the minimum number of sensors is the multi-scour sensitive mode monitoring scheme.

2. The method for arranging scour dynamic identification sensors for beam bridges based on a set of scour-sensitive modes according to claim 1, characterized in that: set up The method for determining discrete measurement points is as follows: along the bridge span direction or the pier height direction, with a distance of [missing information - likely a measurement distance] from the measurement point. The three-dimensional finite element structural dynamic model is discretized into several measurement points; Multiple scour conditions refer to setting various scour depths in a three-dimensional finite element structural dynamic model; a total of [number] scour conditions are set. For the scouring condition, the range of values ​​for k is: The scouring depths corresponding to different scouring depth conditions are: ;Will The time is recorded as the no-flushing condition, and the flushing depth under the no-flushing condition is... .

3. The method for arranging scour dynamic identification sensors for beam bridges based on a set of scour-sensitive modes according to claim 2, characterized in that: The frequency evaluation index is obtained in the following ways: The relative rate of change of modal frequencies for each mode under each scouring condition is calculated. The formula for calculating the relative rate of change of modal frequencies is as follows: ， in This represents the relative rate of change of the modal frequency of the m-th mode under the k-th scouring condition; Let m be the modal frequency of the m-th mode under the k-th scouring condition. This represents the modal frequency of the m-th mode under no-scour conditions. The average rate of change of modal frequencies for each modal order is calculated based on the relative rate of change of modal frequencies for each modal order. The formula for calculating the average rate of change of modal frequencies is as follows: ， in This represents the average rate of change of the modal frequency of the m-th mode. Indicates the maximum scour depth; The average rate of change of modal frequencies is normalized to obtain the frequency evaluation index. ; The method for obtaining the modal evaluation index is as follows: Based on the modal components, the modal curvature of each mode at each measuring point under different scouring conditions is calculated, and the formula for calculating the modal curvature is as follows: ， in The modal curvature of the m-th mode at measurement point i under scour-free conditions; The modal curvature of the m-th mode at measurement point i under the k-th scouring condition; The mode shape component of the m-th mode at measurement point i under scour-free conditions; This refers to the m-th order mode at the measuring point under scour-free conditions. The mode shape components at that location; This refers to the m-th order mode at the measuring point under scour-free conditions. The mode shape components at that location; The mode shape component of the m-th mode at measurement point i under the k-th scouring condition; This refers to the m-th mode at the measuring point under the k-th scouring condition. The mode shape components at that location; This refers to the m-th mode at the measuring point under the k-th scouring condition. The mode shape components at that location; Based on modal curvature calculation, the rate of change of modal curvature for each mode under different scouring conditions is calculated, and the formula for calculating the rate of change of modal curvature is as follows: ， in The rate of change of modal curvature of the m-th mode under the k-th scouring condition; The average rate of change of modal curvature for each mode is calculated based on the rate of change of modal curvature. The formula for calculating the average rate of change of modal curvature is as follows: ， in This represents the average rate of change of the modal curvature of the m-th mode; The average rate of change of modal curvature is normalized to obtain the modal evaluation index. .

4. The method for arranging scour dynamic identification sensors for beam bridges based on a set of scour-sensitive modes according to claim 3, characterized in that: The formula for calculating the composite scouring sensitivity index is as follows: ， in This refers to the composite scouring sensitivity index of the m-th mode, and The range of values ​​is ; The weight of frequency evaluation indicators. The weights of the vibration mode evaluation index; The method for obtaining the set of scour sensitive states is as follows: sort the composite scour sensitivity indices from largest to smallest, and set a composite sensitivity threshold. Maximum number of candidate modes Before choosing The sensitivity index of composite scouring in the first mode is greater than or equal to The modes are considered as scour-sensitive modes, and all scour-sensitive modes constitute the scour-sensitive state set. .

5. The method for arranging scour dynamic identification sensors for beam bridges based on a set of scour-sensitive modes according to claim 1, characterized in that: The method for selecting target measurement points is as follows: if the amplitude of a certain measurement point is less than a preset value in all scour-sensitive modes, the measurement point is recorded as a common mode shape measurement point; all common mode shape measurement points are removed from the N measurement points, and the remaining measurement points are the target measurement points. The mode shape vector of the scour-sensitive mode after removing all common mode shape measurement points is recorded as the target mode shape vector. ,and ,in This refers to the number of target measurement points.

6. The method for arranging scour dynamic identification sensors for beam bridges based on a set of scour-sensitive modes according to claim 1, characterized in that: The single scour-sensitive mode monitoring scheme is as follows: when the scour-sensitive mode is the first-order mode, only one sensor is deployed at the target measurement point with the largest amplitude; when the scour-sensitive mode is the second-order mode, one target measurement point with the largest amplitude is selected in both the positive and negative directions of the mode shape curve, and sensors are deployed at these two target measurement points; when the mode order of the scour-sensitive mode is greater than 2, the number of sensors is consistent with the half-wave number of the mode shape of the scour-sensitive mode, and the target measurement point with the largest amplitude is selected and deployed within each half-wave segment of the mode shape.

7. The method for arranging scour dynamic identification sensors for beam bridges based on a set of scour-sensitive modes according to claim 4, characterized in that: The optimal deployment scheme for the corresponding default number of sensors is obtained as follows: For a specified number of sensors I, use The vector is encoded into the sensor deployment scheme L to obtain the feasible deployment vector of sensor deployment scheme L. ,in This refers to the number of target measurement points and the feasible deployment vector. The vector expression is as follows: , ,in Indicates at the target measurement point Sensors are deployed at the location. 0 indicates the target measurement point No sensors are deployed at this location; With any default number of sensors, for any scour-sensitive mode in the scour-sensitive state set, calculate its mode signal-to-noise ratio (SNR) under sensor deployment scheme L, and the formula for calculating the SNR is as follows: ， in, This represents the signal-to-noise ratio of the nth scour-sensitive mode under sensor deployment scheme L, where S refers to the excitation power spectral density under the excitation conditions. The spectral density represents the noise of the sensor channel. This represents the damping ratio of the nth scour-sensitive mode; Set the upper limit of the modal signal-to-noise ratio. The modal signal-to-noise ratio (SNR) of each scour-sensitive mode under all sensor deployment schemes is truncated to obtain the final SNR of each scour-sensitive mode under each sensor deployment scheme L. ,and ; Based on the final signal-to-noise ratio of sensor deployment scheme L, the weight of the scour-sensitive mode in the scour-sensitive state set, frequency evaluation index, and mode shape evaluation index, a comprehensive signal-to-noise ratio index is constructed, and the calculation formula of the comprehensive signal-to-noise ratio index is as follows: ， ； With the goal of maximizing the overall signal-to-noise ratio, the Grey Wolf optimization algorithm is used to iteratively optimize the sensor deployment scheme L, obtaining the optimal deployment scheme after iterative optimization for each default number of sensors. .

8. The method for arranging scour dynamic identification sensors for beam bridges based on a set of scour-sensitive modes according to claim 7, characterized in that: The range of engineering quantities for sensors is: The method for determining the minimum number of sensors is as follows: right Extract the number of sensors z within any interval. The optimal deployment scheme and its corresponding comprehensive signal-to-noise ratio index And calculate the modal signal-to-noise ratio of all scour-sensitive modes. ; If the modal signal-to-noise ratio of a certain scour-sensitive mode is less than If the quantity z is less than the preset lower limit of the project, then the quantity z is recorded as an infeasible quantity. If the number of sensors z is less than the half-wave number of the highest-order scour-sensitive mode in the scour-sensitive mode set, then the number of sensors z is recorded as an infeasible number. Eliminate For the infeasible number within the interval, sort all remaining sensor numbers in ascending order and calculate the improvement in the combined modal signal-to-noise ratio between two adjacent numbers; When the increase in the number of sensors z is less than the preset convergence value, and satisfies When z is the minimum number of sensors, then the quantity z is recorded as the minimum number of sensors.

9. A sensor arrangement system for identifying scour dynamics in beam bridges based on a set of scour-sensitive modes, characterized in that: include, The model simulation unit establishes a three-dimensional finite element dynamic model of the beam bridge to be monitored, and sets N discrete measuring points on the three-dimensional finite element dynamic model. The modal screening unit applies excitation conditions to a three-dimensional finite element structural dynamic model, extracts the modal frequencies and mode shapes of each mode under various scouring conditions, and constructs a composite scouring sensitivity index based on the modal frequencies and mode shapes. Based on this composite scouring sensitivity index, scouring-sensitive modes are screened from each mode to obtain a set of scouring-sensitive modes. The method for constructing the composite scouring sensitivity index is as follows: The influence of scouring conditions on modal frequencies is quantified to obtain frequency evaluation indicators. The modal components of each mode under different scouring conditions at each measuring point are extracted from the modal vibration modes, and the influence of scouring conditions on the modal vibration modes is quantified based on the modal components to obtain the modal evaluation index. Set the weights of frequency evaluation index and mode evaluation index, and construct a composite scour sensitivity index; The measurement point screening unit selects target measurement points from N measurement points based on the amplitude of the mode shape of the scour-sensitive mode at N measurement points; A single-mode monitoring unit, when there is only one scour-sensitive mode in the scour-sensitive mode set, sets a single scour-sensitive mode monitoring scheme based on the amplitude of the target measurement point of the scour-sensitive mode, and arranges sensors on the bridge to be monitored using the single scour-sensitive mode monitoring scheme; The multi-modal monitoring unit, when there are two or more scour-sensitive modes in the scour-sensitive mode set, sets up a multi-scour-sensitive mode monitoring scheme, and deploys sensors on the bridge to be monitored using the multi-scour-sensitive mode monitoring scheme; the method of setting up the multi-scour-sensitive mode monitoring scheme is as follows: Set a default number range for sensors, with a minimum value of 2 and a maximum value of the target measurement point. Selectively place any default number of sensors on the target measurement point to obtain a multi-sensor deployment scheme under the corresponding default number of sensors. With any default number of sensors, for any scour-sensitive mode in the scour-sensitive state set, calculate its mode signal-to-noise ratio under different sensor deployment schemes. Combine the mode signal-to-noise ratio, the weight of the scour-sensitive mode in the scour-sensitive state set, and the composite scour sensitivity index to select the optimal sensor deployment scheme for each default number of sensors from multiple sensor deployment schemes. Set the range of the number of sensors. The range of the number of sensors is a subset of the default range. Based on the range of the number of sensors, determine and compare the optimal layout scheme corresponding to each number of sensors. Select the minimum number of sensors from the range of the number of sensors. The optimal layout scheme corresponding to the minimum number of sensors is the multi-scour sensitive mode monitoring scheme.

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