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CN117910120B - Buffeting response prediction method for wind-bridge system based on lightweight Transformer - Google Patents

Buffeting response prediction method for wind-bridge system based on lightweight Transformer Download PDF

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CN117910120B
CN117910120B CN202410321437.9A CN202410321437A CN117910120B CN 117910120 B CN117910120 B CN 117910120B CN 202410321437 A CN202410321437 A CN 202410321437A CN 117910120 B CN117910120 B CN 117910120B
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朱思宇
徐昕宇
向天宇
唐永康
杨轩昌
杨梦雪
张�杰
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Xihua University
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Abstract

The invention relates to the technical field of wind-resistant design of bridges, and discloses a buffeting response prediction method of a wind-bridge system based on a lightweight converter. Selecting a proper fluctuating wind speed model according to the set average wind speed, generating a fluctuating wind speed time sequence generated by superimposing the average wind speed after fluctuating wind speed, and converting the fluctuating wind speed time sequence into buffeting force time interval data after aerodynamic theory and Fourier transform calculation; then, establishing a finite element model of the suspension bridge, inputting the generated buffeting force time course data into the suspension bridge model, and integrating the generated data with the fluctuating wind speed time course data to obtain buffeting response samples of the suspension bridge; and constructing a seven-layer convolutional neural network model of a transducer structure for processing sequence data, and capturing the inherent characteristics and dynamic behaviors of the fluctuating wind speed and the buffeting response. The invention can efficiently predict buffeting response, provide information reference for construction and maintenance of bridge engineering, prolong the service life of the structural connecting piece of the bridge and save maintenance cost.

Description

Buffeting response prediction method for wind-bridge system based on lightweight transducer
Technical Field
The invention relates to the technical field of wind-resistant design of bridges, in particular to a buffeting response prediction method of a wind-bridge system based on a lightweight converter.
Background
In the past few decades, the construction of highway bridges in China has progressed rapidly. Due to its significantly high efficiency, convenience and large capacity for transportation efficiency, highways have become one of the main options for freight and passenger traffic. With the advancement of time, the length ratio of the large-span bridge is continuously increased, so that the large-span bridge is connected with various areas, and the development of regional economy is promoted. Therefore, the highway network must face unavoidable threat of buffeting response in construction and operation, and because buffeting response occurs frequently, when buffeting response occurs, probability of a vehicle passing through a bridge is remarkably increased, and riding comfort is reduced. In the last two decades, several bridge structural damage accidents caused by wind loads have occurred, and therefore it has become critical to ensure the safety of the running of vehicles on bridges under wind load excitation.
Particularly, the large-span bridge is widely used in areas with large wind load influence such as large-span scenes such as rivers, straits and the like. However, with the increasing span of the bridge, the structure has the characteristics of large flexibility, light weight, low damping and the like, so that the structure becomes very sensitive to wind load, and the wind resistance problem of the bridge also becomes more complex and severe. Among limited vibrations caused by wind load, buffeting is forced vibration under the action of a pulsating wind speed, is limited-amplitude vibration with forced vibration characteristics, and has smaller vibration amplitude and insufficient vibration amplitude to cause direct damage to a bridge compared with vortex vibration and wind-rain excitation. However, because the wind speed of the buffeting response is low and the efficiency is high, the buffeting frequency is very high, and bridges in the natural environment are difficult to avoid; and long-time buffeting can cause fatigue damage to the connecting members of the bridge, and meanwhile driving experience can be influenced. In general, in the study of buffeting response, the investigation of bridge system safety under wind load is relatively limited.
Currently, many studies focus on the prediction of buffeting response of train-bridge systems under wind loading. In these conventional research methods, there are limitations in that the computational complexity is high, and a large-scale structure requires a large amount of computational resources when faced with complex, highly nonlinear, and large-scale data sets. Deep learning is used as an emerging learning model, and the deep learning model automatically learns the characteristics and the representation of data without relying on complicated characteristic engineering. The multi-level, highly nonlinear structure enables it to better capture complex patterns in data and exhibit good performance over large data sets. The deep learning also has the capability of end-to-end learning, and the learning is directly performed from the original input to the output, so that the flow of model design is simplified. These advantages make deep learning excellent in handling complex, large-scale, high-dimensional data in time series problems, becoming a popular choice for intelligent prediction methods of buffeting responses.
At present, a plurality of researches fully prove that the deep learning has good prediction accuracy and subsequent research value on wind-bridge system prediction. The success of LSTM (Long Short-Term Memory) in time series prediction is widely applied to the fields with strong relevance such as price prediction, stock trend, bridge wind vibration displacement prediction and the like, but because of the structural problem of the model, when the model is used for processing Long time series, the calculation bottleneck may exist due to the characteristic of serial calculation. And the number of the super parameters is small, so that the training requirements of a large-scale data set are difficult to adapt well. In contrast, a transducer has greater expressive power and adaptability in processing long sequences, global dependencies, and large-scale datasets, becoming a powerful tool in processing sequence data.
Disclosure of Invention
Aiming at the problems, the invention aims to provide a buffeting response prediction method of a wind-bridge system based on a lightweight transducer, which utilizes a deep learning network technology to establish a relation model of the pulsating wind speed and the vertical bridge deformation of a bridge, and samples a novel transducer model. And the buffeting response prediction is efficiently carried out, information reference is provided for the construction and maintenance of bridge engineering, the service life of the structural connecting piece of the bridge is prolonged, and the maintenance cost is saved. The technical proposal is as follows:
A buffeting response prediction method of a wind-bridge system based on a lightweight transducer comprises the following steps:
step 1: selecting a fluctuating wind speed model according to the average wind speed, and determining parameters related to the fluctuating wind speed model; simulating the fluctuating wind speed by adopting a harmonic superposition method;
step 2: generating a pulsating wind speed time series data superimposed with the average wind speed as a pulsating wind speed sample by using the selected pulsating wind speed model and parameters;
step 3: converting the pulse wind speed time series data generated in the step 2 into buffeting force time series data serving as a bridge buffeting response sample;
Step 4: establishing a bridge motion model through commercial finite element software, inputting buffeting force time sequence data, and extracting vertical bridge deformation of the bridge;
Step 5: taking the pulsating wind speed time series data generated in the step 2 as an input set, taking the vertical bridge deformation of the bridge obtained in the step 4 as an output set, forming a plurality of data sets with different time series lengths, and dividing the data sets into a training set and a testing set;
Step 6: constructing a transducer deep learning network, verifying the prediction correctness of the network, and performing super-parameter setting on the network before training;
Step 7: inputting the training set into a transducer deep learning network for predictive training to obtain a predictive model of the vertical deformation of the bridge structure, and then storing the trained model;
And (3) carrying out data remodeling and normalization on the buffeting response sample and the fluctuating wind speed sample by adopting a transducer deep learning model: the transducer deep learning model comprises an input layer, a plurality of TransformerBlock layers and an output layer; utilizing the input layer part to adjust the format of the data into a proper transducer model; the transducer model consists of a plurality of TransformerBlock layers, and the output layer comprises a plurality of layers and is used for mapping learned potential distribution to output and predicting to obtain a prediction model of the vertical deformation of the bridge structure;
step 8: different time sequence lengths and different sample orders of magnitude buffeting response prediction samples are obtained through a transducer model, and the average value and standard deviation of the transducer model are calculated according to the buffeting response prediction samples.
Further, the step 2 specifically includes:
Step 2.1: generating fluctuating wind speed fluctuation at different positions based on specified parameters by adopting a harmonic superposition method, wherein a wind field is decomposed into harmonic components; loading node coordinate information and setting basic parameters including wind speed, ground roughness and frequency resolution; a basic formula for pulsating wind speed is employed, wherein the vertical distribution of wind speed is represented by an exponential function:
(1);
in the formula, u z (i) is the average wind speed; v 10 is the base wind speed; z i is the vertical position of the node; alpha is an exponential parameter;
step 2.2: the friction wind speed at each node is calculated as follows:
(2);
In the formula, u z0 (i) is friction wind speed, and K is a constant; z 0 is the ground roughness;
Step 2.3: introducing a direct decomposition frequency; through the decomposition, the fluctuating wind speed signal is converted from a time domain to a frequency domain, and the distance between adjacent nodes is calculated, so that a foundation is provided for the establishment of a subsequent cross spectrum density matrix; in the process of the pulsating wind speed signal, when the Fourier decomposition is adopted for frequency analysis, the numerical method is adopted for calculating the Fourier transformation; the numerical method approximately calculates the frequency components of the signals, namely a Fourier decomposition numerical solution; decomposing the cross spectral density matrix by using a frequency component of a Fourier decomposition numerical solution through a cholesky decomposition method; wherein, the elements of the cross spectral density matrix are calculated by the correlation of the space distance and the frequency;
Step 2.4: the interpolation point calculation and interpolation method is used, wind speed components of different nodes are obtained through interpolation of the frequency domain representation, so that gaps among discrete frequency points are filled, and the smoothness of frequency domain components is ensured;
Step 2.5: converting the frequency domain representation into a time domain pulsating wind speed signal by adopting inverse fast Fourier transform; and (3) superposing the time domain representation of each frequency component by circularly traversing each node and frequency to obtain the final fluctuating wind speed time course of the node position, wherein the formula is expressed as follows:
(3);
(4);
In the formula, X is a fluctuating wind speed frequency domain sequence; n is the length of the sequence of fluctuating wind speeds; x n is the signal in the pulsatile wind speed time domain; x k is an element in the pulsatile wind speed frequency domain sequence, subscript k=0, 1,..; changes in frequency components over time and frequency index are described; k is an index of the frequency domain; n is the index of the time domain.
Further, the specific process in the step 3 is as follows:
Step 3.1: loading average wind speed U mean, transverse wind speed U 0, vertical wind speed w 0 and girder node position x pos from the simulated wind field data; the spatial variation of the transverse wind speed and the vertical wind speed is calculated by a finite difference method;
Step 3.2: obtaining the length L of the beam section and the distance between adjacent nodes through differential calculation; in the static wind load calculation stage, components at all nodes on the main beam section are calculated by adopting a formula based on aerodynamic theory, wherein the formula is as follows:
(5);
(6);
(7);
in the formula, F D、FL and M M are respectively a drag component, a lift component and a moment component; Is air density, U mean is average wind speed, H is influence height in wind speed vertical direction, B is bridge width, L is length of main girder section, C D、CL and C M are resistance coefficient, lift coefficient and moment coefficient respectively;
step 3.3: the dynamic wind load time course in the time domain is obtained by processing the transverse wind speed u 0 and the vertical wind speed w 0; converting the fluctuating wind speed of the frequency domain into a buffeting force time course of the time domain by adopting a Fourier transform method; the dynamic wind load time course formula is expressed as follows:
(8);
(9);
(10);
In the formula, F D(t)、FL (t) and M M (t) are respectively a drag component time interval, a lift component time interval and a moment component time interval; u (t) is the lateral wind speed in the time domain, w (t) is the vertical wind speed in the time domain, and t represents time.
Further, in the step 4, the bridge motion model is as follows:
(11);
(12);
In the formula, M xx and M yy are respectively the quality matrixes of the bridge in the transverse direction and the bridge in the vertical direction, AndThe transverse and vertical accelerations of the bridge are respectively, C xx and C yy are respectively the damping matrices of the bridge in the transverse and vertical directions,AndThe transverse and vertical speeds of the bridge are respectively, K xx and K yy are respectively stiffness matrixes of the bridge in the transverse and vertical directions, u and v are respectively transverse and vertical displacements of the bridge, and F gx (t) and F gy (t) are respectively transverse and vertical wind loads caused by buffeting force.
Further, the step 6 specifically includes:
Pre-training based on buffeting response of a simulated suspension bridge, and constructing a seven-layer convolutional neural network model of a transducer structure for processing sequence data, wherein the model comprises a plurality of TransformerBlock layers, and each layer comprises a self-attention mechanism, a feedforward network and layer normalization; the system is used for capturing the intrinsic characteristics and dynamic behaviors of the pulsating wind speed and buffeting response; taking the pulsating wind speed sample generated in the step (2) simulation as input data, and taking the bridge buffeting response sample generated in the step (3) simulation as output data; the input data is subjected to feature extraction through three TransformerBlock, then feature integration is performed through two full-connection layers, and finally a pre-trained transducer model is output.
Further, the step 7 specifically includes:
step 7.1: the input layer of the transducer deep learning model is a layers layer, and the input layer is used as the input of the model during training; defining the shape of a buffeting force time sequence and a fluctuating wind speed time sequence of a neural network model, allowing a transducer model to receive input with a set structure, and receiving training data for forward propagation of the model so as to ensure that the transducer model can read the data normally;
Step 7.2: the TransformerBlock layers contain self-attention mechanism, feedforward network and layer normalization; wherein the self-attention mechanism selects a multi-headed sub self-attention for learning feature associations in the input sequence in each TransformerBlock; in each layer, the model further learns buffeting response characteristic relation through a feedforward network on the basis of self-attention; calculating correlations of the buffeting response time sequence TransformerBlock with all keys, and using the correlations to perform weighted average on the values for layer normalization; parameter calculations are normalized in matrix form and layer as:
(13);
(14);
In the formula, Q, K and V respectively represent three parameter matrixes, X input is an input matrix, and W Q、K、V is a weight matrix corresponding to the three parameter matrixes; z is an output matrix; d k is the scaling factor; softmax is the activation function used to calculate the attention weight; t is a transposed symbol; attention is self-Attention mechanism operation;
The feedforward network comprises two full-connection layers, wherein the activation function of the first layer is Relu, the second layer does not use the activation function, and the structure of the feedforward network introduces nonlinear characteristics through the activation function; generating a coded information matrix C after the calculation of the multiple layers TransformerBlock, wherein the coded information matrix C is applied to a subsequent output layer;
Step 7.3: the output layer of the transducer deep learning model comprises a full-connection layer and a remodelling layer; the method has the effects that the modeled characteristics are mapped to an output space, and then the shape of the output is adjusted to be matched with the shape of the target output through a remodelling operation; during training, the output of the transform deep learning model is used to calculate the loss function for back propagation and weight updating.
Further, before the step 8, the method further includes: the model is evaluated by using a separate validation dataset, in particular:
step a: simulating the fluctuating wind speeds of N 0 suspension bridges under the average wind speed, and generating a fluctuating wind speed sample after superposition of the average wind speeds;
Step b: simulating to obtain bridge deformation under the given parameter condition according to the finite element model; the method comprises the steps of extracting a verification sample of a training sample set from a sample by using a random sampling method;
Step c: taking a pulsating wind speed sample as input, and taking the corresponding vertical deformation of the bridge as output;
step d: after each training period is finished, evaluating the performance of the model by using a verification set, and selecting a mean square error, an average absolute error, a decision coefficient and variance thereof as model evaluation indexes to evaluate the prediction performance and generalization capability of the transducer model;
Step e: if the model prediction effect is not ideal, optimizing the transducer model, including adjusting the architecture of the transducer model, the setting of an optimizer, the learning rate and the super parameters, and obtaining and storing the model with optimal performance in the training process.
Compared with the prior art, the invention has the beneficial effects that:
1) The invention provides an effective bridge buffeting response prediction method, which realizes data support for real-time and accurate judgment of a bridge by predicting the bridge buffeting response based on a lightweight transducer model and provides powerful support for timely finding and processing potential problems for operation management staff.
2) The invention provides a time sequence processing method for the influence of pulsating wind on a structure, which has excellent processing on long-range dependency relationship because a transducer model has the advantage of parallel computation, and can better capture the space-time dynamics of structural vibration caused by the pulsating wind.
3) The invention is based on a transducer model, because the self-attention mechanism allows the network to automatically focus on information at different positions in the input sequence, making it more adaptive. This provides insight into the subsequent study of process model migration, etc.
4) The invention is based on a transducer model, the self-attention mechanism of which makes it to a certain extent interpretable. Engineers can understand the specific input features of the model's interest in the predictions by analyzing the model's attention weights to better understand the influencing factors of the structural vibrations.
Drawings
FIG. 1 is a buffeting response prediction system analysis process.
FIG. 2 is a schematic diagram of a sample of fluctuating wind speeds.
Fig. 3 is a diagram of a suspension bridge arrangement.
Fig. 4 is a schematic diagram of a vertical bridge vibration sample.
Fig. 5 is a construction diagram of a transducer deep learning model.
Fig. 6 (a) shows the loss values for the training phase for two models of different sequence lengths (200).
Fig. 6 (b) shows the loss values for the training phase for two models of different sequence lengths (500).
Fig. 6 (c) shows the loss values for the training phase for two models of different sequence lengths (800).
Fig. 6 (d) shows the loss values for the training phase for two models of different sequence lengths (1000).
Fig. 7 (a) shows the loss values for the training phase under two different training sample sets (200) of the model.
Fig. 7 (b) shows the loss values for the training phase for two models with different training sample sets (150).
Fig. 7 (c) shows the loss values for the training phase for two models with different training sample sets (100).
Fig. 7 (d) shows the loss values for the training phase for two models with different training sample sets (50).
Fig. 8 (a) shows the prediction effect of the prediction phase for two models of different sequence lengths (200).
Fig. 8 (b) shows the prediction effect of the training prediction phase for two models of different sequence lengths (500).
Fig. 8 (c) shows the prediction effect of the training prediction phase for two models of different sequence lengths (800).
Fig. 8 (d) shows the prediction effect of the training prediction phase for two models of different sequence lengths (1000).
Fig. 9 (a) shows the prediction effect of the prediction phase under two different training sample sets (200).
Fig. 9 (b) shows the prediction effect of the prediction phase under two different training sample sets (150).
Fig. 9 (c) shows the prediction effect of the prediction phase under two different training sample sets (100).
Fig. 9 (d) shows the prediction effect of the prediction phase under two different training sample sets (50).
Detailed Description
The invention is described in further detail below with reference to the drawings and the detailed description.
The invention relates to the technical field of wind-resistant design of bridges, in particular to a buffeting response prediction method of a wind-bridge system based on a lightweight converter. The method can be divided into two parts, namely a simulation of a buffeting response sample and a transducer deep learning model. Firstly, selecting a proper fluctuating wind speed model according to a specific average wind speed, generating a fluctuating wind speed, overlapping the fluctuating wind speed, and converting a fluctuating wind speed time sequence generated after the average wind speed is superimposed into buffeting force time-course data after calculation of an aerodynamic theory and a Fourier transform mathematical tool; and then, establishing a finite element model of the suspension bridge, inputting the generated buffeting force time course data into the suspension bridge model, and integrating the generated data with the fluctuating wind speed time course data to obtain buffeting response samples of the suspension bridge.
After data collection is completed, a seven-layer transform structure convolutional neural network model for processing sequence data is constructed, wherein the model comprises a plurality of TransformerBlock layers, and the aim is to capture the intrinsic characteristics and dynamic behaviors of the pulsating wind speed and buffeting response; and taking the time series data of the pulsating wind speed as input data and taking the buffeting response of the bridge as output data.
Finally, after the model is trained and optimized, training data and test data are input into the constructed network model in batches in the training process of the transducer model, and in order to be capable of fully knowing the advantages of the model on processing long sequences, six model evaluation indexes of MSE, MAE, R 2 and variances thereof are introduced to evaluate the prediction performance and generalization capability of the transducer model. The flow is shown in figure 1, and the specific technical scheme is as follows:
step 1: based on the average wind speed, an appropriate pulsatile wind speed model is selected, and parameters associated with the pulsatile wind speed model, such as the number of frequency segments, cut-off frequency, etc., are determined. The invention adopts a harmonic superposition method to simulate the fluctuating wind speed.
A model is generated by adopting the fluctuating wind speed based on Fourier decomposition, the model has spectrum controllability, and the frequency components of the generated fluctuating wind speed signal can be flexibly adjusted by virtue of the Fourier decomposition, so that the characteristics of an actual scene can be better matched. Meanwhile, the Fourier decomposition can capture the contribution of various frequency components to pulsation; this helps to generate a more realistic and complex pulsating wind speed signal. Therefore, the Fourier decomposition-based pulsating wind speed generation model is more suitable for the pulsating wind speed research of the large-span bridge.
Step 2: programming a program ComputeWind in programming software Matlab; the program generates a time series of fluctuating wind speeds superimposed with the average wind speed as a sample of fluctuating wind speeds using the selected model of fluctuating wind speeds and parameters.
Code ComputeWind generates the fluctuating wind speed fluctuations at different locations based on specified parameters, and the code adopts a harmonic superposition method in which the wind field is decomposed into individual harmonic components. First, node coordinate information is loaded and basic parameters including wind speed, ground roughness, frequency resolution, etc. are set. The code uses a basic formula for fluctuating wind speeds, where the vertical distribution of wind speeds is represented by an exponential function:
(1);
In the formula, v 10 is the basic wind speed; z i is the vertical position of the node; alpha is an exponential parameter.
The friction wind speed at each node is calculated after the average wind speed u z (i) is obtained, by the following formula:
(2);
In the formula, K is a constant; z 0 is the roughness of the ground.
After the calculation is completed, the direct decomposition frequency is imported. Through the decomposition, the pulsating wind speed signal can be converted from a time domain to a frequency domain, so that the frequency characteristic of the signal can be better understood, the contributions of different frequency components can be identified, or operations such as filtering and the like can be performed; meanwhile, the distance between adjacent nodes is calculated, and a foundation is provided for the establishment of a subsequent cross spectrum density matrix; in the case of performing frequency analysis by fourier decomposition in the pulsating wind speed signal processing, since the signal is discrete, the fourier transform is calculated by a numerical method, and the frequency component in the analysis form is not obtained by the analysis method. Such numerical methods may be Discrete Fourier Transforms (DFT) or Fast Fourier Transforms (FFT) that calculate approximately the frequency content of the signal by means of computer algorithms, i.e. fourier decomposition numerical solutions. Decomposing the cross spectral density matrix by a Cholesky decomposition method by adopting frequency components of a Fourier decomposition numerical solution; wherein, the elements of the cross spectral density matrix are calculated by the correlation of the space distance and the frequency; the Matlab program is designed to cycle through each node and each frequency to obtain a frequency domain representation of the pulsating wind field.
Then, by interpolating the frequency domain representation, wind speed components of different nodes are obtained. The step uses interpolation point calculation and interpolation methods to fill the gap between discrete frequency points and ensure the smoothness of frequency domain components.
Finally, an Inverse Fast Fourier Transform (IFFT) is used to convert the frequency domain representation into a time domain pulsating wind speed signal. And (3) superposing the time domain representation of each frequency component by circularly traversing each node and frequency to obtain the final fluctuating wind speed time course of the node position, wherein the formula is expressed as follows:
(3);
(4);
In the formula, X is a fluctuating wind speed frequency domain sequence; n is the length of the sequence of fluctuating wind speeds; x n is the signal in the pulsatile wind speed time domain; x k is an element in the pulsatile wind speed frequency domain sequence, subscript k=0, 1,..; changes in frequency components over time and frequency index are described; k is an index of the frequency domain; n is the index of the time domain.
FIG. 2 is a sample of the generated pulsatile wind speed.
Step 3: programming a program ComputeForceBridge in programming software Matlab; the program converts the pulse wind speed time series data generated in the step 2 into buffeting force time series data, and the buffeting force time series data is a buffeting response sample.
The ComputeForceBridge code is based on wind field simulation data, and through the application of aerodynamic theory and a Fourier transform mathematical tool, accurate modeling of static and dynamic wind load time courses on the bridge structure is realized, and buffeting force on a target structure is calculated. According to the basic principle that the elastic structure is subjected to wind load, the values of parameters such as air density, reference area of the structure, resistance coefficient and the like are determined, and the wind speed is converted into buffeting force. The procedure is described below:
First, the average wind speed U mean, the transverse wind speed U 0, the vertical wind speed w 0, and the girder-node position x pos are loaded from the simulated wind field data. The spatial variation of the transverse wind speed and the vertical wind speed is calculated by a finite difference method. Next, the length L of the beam section and the distance between adjacent nodes are obtained by differential calculation. In the static wind load calculation stage, components at all nodes on the main beam section are calculated by adopting a formula based on aerodynamic theory, wherein the formula is as follows:
(5);
(6);
(7);
In the formula (i), Is the air density, U mean is the average wind speed, H is the height of influence in the vertical direction of the wind speed, B is the bridge width, L is the length of the main girder section, and C D、CL and C M are the drag coefficient, lift coefficient and moment coefficient, respectively.
The dynamic wind load time course in the time domain is obtained by processing the transverse wind speed u 0 and the vertical wind speed w 0. And converting the fluctuating wind speed of the frequency domain into a buffeting force time course of the time domain by adopting a Fourier transform method. The dynamic wind load time course formula is expressed as follows:
(8);
(9);
(10);
In the formula, F D(t)、FL (t) and M M (t) are respectively a drag component time interval, a lift component time interval and a moment component time interval; u (t) is the lateral wind speed in the time domain, w (t) is the vertical wind speed in the time domain, and t represents time.
And outputting time course data to corresponding files after the static and dynamic wind load calculation is completed, so as to be used for subsequent transducer and other model training.
Step 4: and establishing a bridge motion model through commercial finite element software Ansys, inputting buffeting force time course data, and extracting vertical bridge deformation of the bridge.
The Ansys establishes a finite element model of the bridge, and firstly, geometric information of a main structural part of the bridge needs to be determined; then, determining material characteristics of the bridge, such as elastic modulus, poisson ratio, density and the like, based on the actual performance parameters of the bridge material; and finally, creating a finite element model of the bridge in ANSYS.
In the finite element model design process, complex environmental factors possibly existing in the bridge under the actual working condition, such as wind load, temperature change, earthquake and the like, need to be considered. These environmental factors can be modeled by setting corresponding loads and boundary conditions in the finite element model. The method comprises the steps of setting fluid-structure interaction conditions, including establishing a geometric model, dividing grids, setting a structure and a fluid model, and realizing coupling of fluid and the structure through an FSI module, so as to finally solve and analyze the influence of interaction on the structure. Fig. 3 is a diagram of a suspension bridge.
Importing the buffeting force time series data obtained in the step 3 and the created finite element model of the suspension bridge in the operation stage into ANSYS software; then, a simulation function of ANSYS software is operated, the buffeting force is simulated to generate wind-induced vibration to the suspension bridge within a certain time, and a buffeting force-bridge model solution is obtained, so that buffeting response data of the bridge are obtained.
And the motion equation of the bridge under the effect of buffeting force:
(11);
(12);
In the formula, M xx and M yy are respectively the quality matrixes of the bridge in the transverse direction and the bridge in the vertical direction, AndThe transverse and vertical accelerations of the bridge are respectively, C xx and C yy are respectively the damping matrices of the bridge in the transverse and vertical directions,AndThe transverse and vertical speeds of the bridge are respectively, K xx and K yy are respectively stiffness matrixes of the bridge in the transverse and vertical directions, u and v are respectively transverse and vertical displacements of the bridge, and F gx (t) and F gy (t) are respectively transverse and vertical wind loads caused by buffeting force.
After the result is calculated by the motion equation of the bridge under the effect of the buffeting force, the deformation of the bridge is stored, the result with larger deformation is tidied, and the data is stored for subsequent use. Fig. 4 is a schematic diagram of a vibration sample generated by the Ansys finite element software.
Step 5: taking the pulsating wind data generated in the step 2 as an input set and taking the bridge deformation calculated by the Ansys finite element model in the step 4 as an output set to form a data set; wherein the first 80% is used as training set and the last 20% is used as test set
And (3) sorting and summarizing the transverse bridge deformation data and the vertical bridge deformation data generated by the Ansys finite element model in the step (4), comparing the transverse bridge deformation data and the vertical bridge deformation data, and extracting the vertical bridge deformation as an output set of training data.
In the training process, training data and test data are input into a constructed network model in batches, and in order to be able to more fully understand the advantages of the model on processing long sequences, in this embodiment, time sequence data with a sequence length of 200-500-800-1000 are used as training data sets 1-4 respectively; transformer has stronger expressive power and adaptability in processing long sequences, global dependencies, and large-scale datasets; therefore, as the length of the sequence expands, the prediction accuracy of the bridge buffeting response slowly decreases.
When the same time sequence length is the same, the smaller the order of magnitude is, the influence of the transducer model on the learning degree of the internal connection of the data is generated, so that the prediction accuracy of the model is influenced, and therefore, the time sequence data with the sample order of magnitude of 50-100-150 and the general length of 200 under the condition of the sequence length of 1000 are respectively used as training data sets in the embodiment.
Step 6: constructing a transducer deep learning network, verifying the prediction correctness of the network, and performing super-parameter setting on the network before training;
Pre-training based on buffeting response of a simulated suspension bridge, and constructing a seven-layer convolutional neural network model of a transducer structure for processing sequence data, wherein the model comprises a plurality of TransformerBlock layers, and each layer comprises a self-attention mechanism, a feedforward network and layer normalization; the method aims at capturing the inherent characteristics and dynamic behaviors of the fluctuating wind speed and buffeting response; taking the pulsating wind speed sample generated in the step (2) simulation as input data, and taking the bridge buffeting response sample generated in the step (3) simulation as output data; the input data is subjected to feature extraction through three TransformerBlock, then feature integration is performed through two full-connection layers, and finally a pre-trained transducer model is output. The architecture of the transducer deep learning model is shown in FIG. 5.
Step 7: inputting the training set into a transducer deep learning network for predictive training to obtain a predictive model of the vertical deformation of the bridge structure, and then storing the trained model.
And (3) carrying out data remodeling and normalization on the buffeting response sample and the fluctuating wind speed sample by adopting a transducer deep learning model: the transducer deep learning model comprises an input layer, a plurality of TransformerBlock layers and an output layer; utilizing the input layer part to adjust the format of the data into a proper transducer model; the transducer model consists of a plurality of TransformerBlock, and is a key part for learning characteristic connection in a buffeting response sequence; the output layer comprises a plurality of layers, and the aim of the layers is to map the learned potential distribution to the output and predict to obtain a prediction model of the vertical deformation of the bridge structure.
The input layer of the transducer deep learning model is a layers layer, and during training, the input layer is used as the input of the model, the process defines the shape of pulsating wind data of the transducer, the transducer model is allowed to receive the input with a specific structure, training data is accepted for forward propagation of the model, and the process ensures that the transducer model can read the data normally.
The TransformerBlock layers contain a self-attention mechanism, a feed forward network, and layer normalization, where the self-attention mechanism selects multi-headed sub self-attention, which is used to learn the feature connections in the input sequence in each TransformerBlock. In each layer, the model further learns the characteristic relation between the time sequence of the fluctuating wind speed and the buffeting response through a neural network layer on the basis of self-attention; among them, self-Attention (Self-Attention) is the main object of study and is the focus of the transducer model. For the pulsatile wind speed time series TransformerBlock, the correlations with all keys are calculated, and then the values are weighted averaged using these correlations, layer normalization is performed, and the time correlation characteristics of the wind speed time course are deeply mined. The transducer model may better focus on the portions of the buffeting response time series data that are relevant to the current query. Parameter calculations are normalized in matrix form and layer as:
(13);
(14);
In the formula, Q, K and V respectively represent three parameter matrixes, X input is an input matrix, and W Q、K、V is a weight matrix corresponding to the three parameter matrixes; z is the output matrix of the self-attention layer; d k is a scaling factor to ensure that dot product does not cause problems of gradient explosion or gradient disappearance when the dimension is large; softmax is an activation function used to calculate the attention weights, ensuring that the sum of the attention weights of the model at different positions is 1, so that the model can focus on information at different positions in the input sequence; attention is a self-Attention mechanism operation.
The Feed Forward network (Feed Forward) is a two-layer fully connected layer composition, the first layer has an activation function Relu, the second layer does not use an activation function, and its structure introduces nonlinear characteristics through the activation function, allowing the model to learn more complex features and representations. The combination of linear transformation and nonlinear activation functions enables the model to better adapt to complex data distributions. The coding information matrix C is generated after the calculation of the layers TransformerBlock, and the coding information matrix C is applied to the subsequent output layer.
Step 8: and obtaining a buffeting response prediction result through a transducer model by adopting a training set sample, and calculating the mean value and standard deviation of the transducer model prediction result.
The performance of the model is evaluated using a validation set, and six model evaluation indices, mean square error (Mean Squared Error), mean absolute error (Mean Absolute Error), decision coefficient (R2), and variance thereof, are selected to evaluate the transform model predictive performance and generalization ability.
In summary, the method provides an effective bridge buffeting response prediction method, and the method realizes data support for real-time and accurate judgment of the bridge by predicting the bridge buffeting response based on a lightweight transducer model, and provides powerful support for timely finding and processing potential problems for operation management staff. The invention provides a time sequence processing method for the influence of pulsating wind on a structure, which has excellent processing on long-range dependency relationship because a transducer model has the advantage of parallel computation, and can better capture the space-time dynamics of structural vibration caused by the pulsating wind. Second, the method is based on a transducer model, because the self-attention mechanism allows the network to automatically focus on information at different locations in the input sequence, making it more adaptive. This provides insight into the subsequent study of process model migration, etc. Finally, because the method is based on a transducer model, its self-attention mechanism makes it somewhat interpretable. Engineers can understand the specific input features of the model's interest in the predictions by analyzing the model's attention weights to better understand the influencing factors of the structural vibrations. Fig. 5 is a diagram showing a construction of a transducer deep learning model.
Example verification:
And selecting a certain extra-large-span suspension bridge, and comparing the processing capacity and training effect of different models on the long sequence. The bridge has a total length of 2470.58 meters and a main span of (320+1196+320) meters. The longer the span of the bridge is, the more sensitive the bridge is to wind load, so that the research object is a midspan section, and the research wind speed is the average wind speed at the position 10.0 meters away from the bridge deck. The overall arrangement of the main bridge is shown in fig. 3. The bridge deck width is 33.44 meters, the design is two-way four lanes, and the road design grade is road grade I. The numerical model of the bridge was developed with ANSYS, all girders, piers and main towers were modeled by 3D girder elements with 6 degrees of freedom per node, while the tension ropes were modeled by 3D rod elements with 3 degrees of freedom per node. The cross-sectional area of the sling was 0.001283 x 4m 2, and the elastic modulus of the elastic material of the sling was 1.1e 11.
Setting the actual roughness as B-class z 0 =0.05, and the ground roughness angle or slope alfa=0.016 according to the technical specification of the actual project; c D、CL and C M are respectively a drag coefficient, a lift coefficient and a moment coefficient, and the values in the embodiment are respectively 1.4557, -0.0853 and 0.0419; the influence height h=3 in the wind speed vertical direction; setting the wind speed gradient to be 0.25s; k is 0.4.
Calculating: verifying buffeting response prediction accuracy of each model under action of pulsating wind of certain bridge
The present example considers the wind load to buffeting force as a deterministic process regardless of the influence of the uncertainty parameters. And the calculation example compares the results of the LSTM model and the transducer model to show the difference in accuracy of the two models in terms of calculation results.
Through analysis of the pulsating wind speed at a certain bridge, 200 groups of prepared pulsating wind speed data are calculated and converted into buffeting force, so that time-course data output after static and dynamic wind load calculation are obtained. The calculated step size of the pulse wind schedule data is 0.25s. Because the data length of the selected comparison is 200-500-800-1000, interpolation operation is used to ensure that the interpolation pulsation wind speed time sequence of the main span is the uniform length of 50s-125s-200s-250s and is arranged into a data set 1-4; meanwhile, in order to compare the prediction precision of two models under different sample number sets, the data sets with the sample number sets of 50-100-150-200 under the condition of the data length of 1000 are adopted in the calculation example, and are arranged into data sets of 4-7. In order to compare the processing capacity and convergence speed of the transducer model with that of the LSTM model over a long time sequence, the epoch super-parameter values of the model in this example are uniformly 150. Fig. 6 (a) -6 (d) and fig. 7 (a) -7 (d) show loss values of training phases of two models under different sequence lengths and different training sample sets, and fig. 8 (a) -8 (d) and fig. 9 (a) -9 (d) show prediction effects of two models under different sequence lengths and different training sample sets. It is noted that, overall, the LSTM model converges more rapidly, but the convergence effect is far less than the contemporary fransformer model; furthermore, when the sequence length is smaller, the training effect of the transducer model is equivalent to that of the LSTM model, and as the sequence length is increased, the LSTM model is slower in convergence of the loss value of the training stage of the long-time sequence, so that the inherent relation of the model can not be well learned, and the situation of memory forgetting occurs in the prediction of the actual value. In contrast, the transducer model has a faster convergence rate and a better prediction result when processing a long-term sequence.
Table 1 shows the mean and variance of MAE, mean Square Error (MSE) and decision coefficient (R 2) between all predicted data and corresponding real data for data sets 1-4 in the dataset. At a sequence length of 200, the error between the two models is not significant. When the sequence length is 500 or more, for the LSTM model, the average value of R 2 has negative number, generally, the value range of the R 2 determination coefficient is [0,1], and when R2 is 1, the model perfectly predicts the data; when R 2 is 0, the representation model cannot interpret the data variance. In this example, the R 2 decision coefficient is used to compare the performance of two different models, the closer the value is to 1, the more the variance of the data representing model interpretation, the better the performance; the reason for the occurrence of the negative number is that the prediction error of the obtained fitting function is larger than the prediction error of the function, namely the prediction error of the average value of all sample points, namely the prediction model is invalid, and the inherent relation of the data cannot be learned. Meanwhile, for the MAE variance and MSE variance transducer model, the values are more than ten times smaller than that of the LSTM model, and the transducer model is more stable.
TABLE 1 loss values at different sequence lengths
Table 2 shows the mean and variance of MAE, mean Square Error (MSE) and decision coefficient (R 2) between all predicted data and corresponding real data for different number set sizes of data sets 4-7 in the data set. From the table, it can be seen that the transducer model can still predict long-time sequences well under the condition of different quantity sets, and the prediction effect is also better and better.
Table 2 loss values at different number set sizes
In summary, the method performs pre-training based on buffeting response of the simulated suspension bridge, and constructs a seven-layer convolutional neural network model of a transducer structure for processing sequence data, wherein the model comprises a plurality of TransformerBlock layers, and each layer comprises a self-attention mechanism, a feedforward network and layer normalization; the method aims at capturing the inherent characteristics and dynamic behaviors of the fluctuating wind speed and buffeting response; taking the time series data of the pulsating wind speed as input data and taking the buffeting response of the bridge as output data; the input data is subjected to feature extraction through three TransformerBlock, then feature integration is performed through two full-connection layers, and finally a pre-trained transducer model is output. According to practical calculation examples, under the conditions of different time sequence lengths and the same sample number set, the prediction capability of the transducer model is gradually stronger than that of the LSTM model along with the continuous increase of the time sequence lengths, and all indexes of the transducer model have obvious advantages. Under the condition of the same time sequence length and different sample number sets, as the sample number sets are continuously increased, the prediction capability of the transducer model is stronger than the prediction effect of LSTM. In addition, compared with the LSTM model, the transducer model has faster convergence speed and finds the internal relation between data, which shows that the transducer model has higher efficiency under the condition of adapting and accurately predicting the variable condition.

Claims (5)

1.基于轻量化Transformer的风-桥系统抖振响应预测方法,其特征在于,包括以下步骤:1. A method for predicting buffeting response of a wind-bridge system based on a lightweight Transformer, characterized by comprising the following steps: 步骤1:根据平均风速,选择脉动风速模型,确定与脉动风速模型相关的参数;采用谐波叠加法对脉动风速进行模拟;Step 1: According to the average wind speed, select the pulsating wind speed model and determine the parameters related to the pulsating wind speed model; use the harmonic superposition method to simulate the pulsating wind speed; 步骤2:利用所选的脉动风速模型和参数,生成与平均风速叠加的脉动风速时间序列数据,作为脉动风速样本;Step 2: Using the selected fluctuating wind speed model and parameters, generate fluctuating wind speed time series data superimposed on the average wind speed as fluctuating wind speed samples; 步骤3:将步骤2生成的脉动风速时间序列数据转化为抖振力时间序列数据,作为桥梁抖振响应样本;Step 3: Convert the fluctuating wind speed time series data generated in step 2 into buffeting force time series data as the bridge buffeting response sample; 步骤4:通过商业有限元软件建立桥梁运动模型,输入抖振力时间序列数据,提取桥梁的竖桥向变形;Step 4: Use commercial finite element software to establish a bridge motion model, input the buffeting force time series data, and extract the vertical deformation of the bridge; 步骤5:将步骤2生成的脉动风速时间序列数据作为输入集,将步骤4中得到的桥梁的竖桥向变形作为输出集,组成多个不同时间序列长度数据集,并分为训练集和测试集;Step 5: Use the fluctuating wind speed time series data generated in step 2 as the input set, and use the vertical deformation of the bridge obtained in step 4 as the output set to form multiple data sets with different time series lengths, and divide them into training sets and test sets; 步骤6:构建Transformer深度学习网络,验证其预测正确性,在训练之前对其进行超参数设置;Step 6: Build the Transformer deep learning network, verify its prediction accuracy, and set its hyperparameters before training; 所述步骤6具体为:The step 6 is specifically as follows: 基于模拟悬索桥的抖振响应进行预训练,构建一个七层处理序列数据的Transformer结构卷积神经网络模型,其中包含多个TransformerBlock层,每层包含自注意力机制、前馈网络和层归一化;用于捕捉脉动风速与抖振响应的内在特性和动态行为;将步骤2模拟生成的脉动风速样本作为输入数据,将步骤3模拟生成的桥梁抖振响应样本作为输出数据;输入数据经过三个TransformerBlock进行特征提取,接着通过两个全连接层进行特征整合,最终输出预训练的Transformer模型;Based on the pre-training of the buffeting response of the simulated suspension bridge, a seven-layer Transformer structure convolutional neural network model for processing sequence data is constructed, which includes multiple TransformerBlock layers, each of which contains a self-attention mechanism, a feedforward network and layer normalization; it is used to capture the intrinsic characteristics and dynamic behaviors of the fluctuating wind speed and buffeting response; the fluctuating wind speed samples simulated and generated in step 2 are used as input data, and the bridge buffeting response samples simulated and generated in step 3 are used as output data; the input data is subjected to feature extraction through three TransformerBlocks, and then feature integration is performed through two fully connected layers, and finally the pre-trained Transformer model is output; 步骤7:将训练集输入到Transformer深度学习网络中进行预测训练,得到桥梁结构竖向变形的预测模型,然后将训练好的模型保存;Step 7: Input the training set into the Transformer deep learning network for prediction training to obtain a prediction model for the vertical deformation of the bridge structure, and then save the trained model; 所述步骤7具体为:The step 7 is specifically as follows: 步骤7.1:Transformer深度学习模型的输入层为layers层,在训练时,输入层将作为模型的输入;定义神经网络模型的抖振力时间序列与脉动风速时间序列的形状,允许Transformer模型接收具有设定结构的输入,接受训练数据用于模型的前向传播,以确保Transformer模型能够正常读取数据;Step 7.1: The input layer of the Transformer deep learning model is the layers layer. During training, the input layer will be used as the input of the model. Define the shape of the buffeting force time series and the pulsating wind speed time series of the neural network model, allow the Transformer model to receive input with a set structure, and accept training data for the forward propagation of the model to ensure that the Transformer model can read the data normally. 步骤7.2:TransformerBlock层中包含自注意力机制、前馈网络和层归一化;其中,自注意力机制选择多头子自注意力,用于在每个TransformerBlock中学习输入序列中的特征联系;在每层中,模型在自注意力的基础上,通过前馈网络进一步学习抖振响应特征关系;针对抖振响应时间序列,TransformerBlock计算其与所有键的相关性,然后使用这些相关性来对值进行加权平均,进行层归一化;参数计算以矩阵形式和层归一化为:Step 7.2: The TransformerBlock layer contains a self-attention mechanism, a feedforward network, and layer normalization; the self-attention mechanism selects multi-head sub-self-attention to learn the feature connections in the input sequence in each TransformerBlock; in each layer, the model further learns the chatter response feature relationship through the feedforward network based on self-attention; for the chatter response time series, the TransformerBlock calculates its correlation with all keys, and then uses these correlations to weighted average the values and perform layer normalization; the parameter calculation is in matrix form and layer normalization as: Q、K、V=Xinput·WQ、K、V (13);Q, K, V = X input · W Q, K, V (13); 公式中,Q、K和V分别表示三个参数矩阵,Xinput为输入矩阵,WQ、K、V是三个参数矩阵对应的权重矩阵;Z为输出矩阵;dk为缩放因子;Softmax为被用于计算注意力权重的激活函数;T为转置符号;Attention为自注意力机制运算;In the formula, Q, K, and V represent three parameter matrices, X input is the input matrix, W Q, K, and V are the weight matrices corresponding to the three parameter matrices; Z is the output matrix; d k is the scaling factor; Softmax is the activation function used to calculate the attention weight; T is the transpose symbol; Attention is the self-attention mechanism operation; 前馈网络包括两层全连接层,第一层的激活函数为Relu,第二层不使用激活函数,其结构通过激活函数引入非线性特性;经过多层TransformerBlock的计算后生成编码信息矩阵C,编码信息矩阵C将应用到后续的输出层中;The feedforward network consists of two fully connected layers. The activation function of the first layer is Relu, and the second layer does not use an activation function. Its structure introduces nonlinear characteristics through the activation function. After calculations of multiple layers of TransformerBlock, the encoding information matrix C is generated, and the encoding information matrix C will be applied to the subsequent output layer. 步骤7.3:Transformer深度学习模型的输出层包括一层全连接层和重塑层;其作用是将模型学到的特征映射到输出空间,然后通过重塑操作将输出的形状调整为与目标输出相匹配的形状;在训练时,Transformer深度学习模型的输出被用于计算损失函数,进而进行反向传播和权重更新;Step 7.3: The output layer of the Transformer deep learning model includes a fully connected layer and a reshape layer; its function is to map the features learned by the model to the output space, and then adjust the shape of the output to match the target output through the reshape operation; during training, the output of the Transformer deep learning model is used to calculate the loss function, and then perform backpropagation and weight update; 采用Transformer深度学习模型对抖振响应样本和脉动风速样本进行数据重塑和归一化:Transformer深度学习模型包括输入层、多个TransformerBlock层和输出层;利用输入层部分将数据的格式调整为合适Transformer模型;Transformer模型由多个TransformerBlock层组成,输出层包含多个层,用于将学到的潜在分布映射到输出,并预测得到桥梁结构竖向变形的预测模型;The Transformer deep learning model is used to reshape and normalize the buffeting response samples and fluctuating wind speed samples: the Transformer deep learning model includes an input layer, multiple TransformerBlock layers, and an output layer; the input layer is used to adjust the format of the data to a suitable Transformer model; the Transformer model consists of multiple TransformerBlock layers, and the output layer contains multiple layers, which are used to map the learned potential distribution to the output and predict the vertical deformation of the bridge structure. 步骤8:通过Transformer模型得到不同的时间序列长度和不同样本数量级抖振响应预测样本,并以此计算Transformer模型的均值和标准差。Step 8: Obtain jitter response prediction samples of different time series lengths and different sample magnitudes through the Transformer model, and use them to calculate the mean and standard deviation of the Transformer model. 2.根据权利要求1所述的基于轻量化Transformer的风-桥系统抖振响应预测方法,其特征在于,所述步骤2具体包括:2. The method for predicting buffeting response of a wind-bridge system based on a lightweight Transformer according to claim 1, wherein step 2 specifically comprises: 步骤2.1:采用谐波叠加的方法,基于指定参数生成不同位置的脉动风速波动,其中风场被分解为各个谐波分量;加载节点坐标信息和设置基本参数,包括风速、地面粗糙度以及频率分辨率;采用脉动风速的基本公式,其中风速的垂直分布由指数函数表示:Step 2.1: Use the harmonic superposition method to generate fluctuating wind speed fluctuations at different locations based on the specified parameters, where the wind field is decomposed into various harmonic components; load the node coordinate information and set basic parameters, including wind speed, ground roughness, and frequency resolution; use the basic formula for fluctuating wind speed, where the vertical distribution of wind speed is represented by an exponential function: 公式中,uz(i)为平均风速;v10为基本风速;zi为节点的竖向位置;α为指数参数;In the formula, u z (i) is the average wind speed; v 10 is the basic wind speed; zi is the vertical position of the node; α is the exponential parameter; 步骤2.2:计算每个节点处的摩阻风速,公式如下:Step 2.2: Calculate the friction wind speed at each node using the following formula: 公式中,uz0(i)为摩阻风速,K为常数;z0为地面粗糙度;In the formula, u z0 (i) is the friction wind speed, K is a constant; z 0 is the ground roughness; 步骤2.3:导入直接分解频率;通过这种分解,将脉动风速信号从时域转换到频域,同时计算相邻节点之间的距离,为后续互谱密度矩阵的建立提供基础;在脉动风速信号处理中,采用傅立叶分解进行频率分析时,采用数值方法来计算傅立叶变换;所述数值方法近似地计算信号的频率成分,即为傅立叶分解数值解;通过乔里斯基分解法,采用傅立叶分解数值解的频率成分,对互谱密度矩阵进行分解;其中,互谱密度矩阵的元素通过空间距离和频率的相关性计算;Step 2.3: Import direct decomposition frequency; through this decomposition, the fluctuating wind speed signal is converted from the time domain to the frequency domain, and the distance between adjacent nodes is calculated at the same time, providing a basis for the subsequent establishment of the cross-spectral density matrix; in the processing of the fluctuating wind speed signal, when Fourier decomposition is used for frequency analysis, a numerical method is used to calculate the Fourier transform; the numerical method approximately calculates the frequency component of the signal, which is the Fourier decomposition numerical solution; through the Cholesky decomposition method, the frequency component of the Fourier decomposition numerical solution is used to decompose the cross-spectral density matrix; wherein, the elements of the cross-spectral density matrix are calculated by the correlation between spatial distance and frequency; 步骤2.4:使用插值点计算和插值方法,通过对频域表示的插值,得到不同节点的风速分量,以填补离散频率点之间的差距,确保频域成分的光滑性;Step 2.4: Use interpolation point calculation and interpolation method to obtain wind speed components at different nodes by interpolating the frequency domain representation to fill the gap between discrete frequency points and ensure the smoothness of the frequency domain components; 步骤2.5:采用逆快速傅立叶变换,将频域表示转换为时域脉动风速信号;通过循环遍历每个节点和频率,将各频率分量的时域表示进行叠加,得到最终的节点位置的脉动风速时程,其公式表达为:Step 2.5: Use inverse fast Fourier transform to convert the frequency domain representation into the time domain fluctuating wind speed signal; by looping through each node and frequency, superimposing the time domain representation of each frequency component, the final fluctuating wind speed time history at the node position is obtained, which is expressed as follows: X=[X0,X1,...,XN-1] (3);X = [X 0 , X 1 , ..., X N-1 ] (3); 公式中,X为脉动风速频域序列;N是脉动风速序列的长度;xn为脉动风速时域中的信号;Xk为脉动风速频域序列中的元素,下标k=0,1,...,N-1;描述了频率成分随着时间和频率索引的变化;k为频率域的索引;n为时域的索引。In the formula, X is the frequency domain sequence of the pulsating wind speed; N is the length of the pulsating wind speed sequence; xn is the signal of the pulsating wind speed in the time domain; Xk is the element in the frequency domain sequence of the pulsating wind speed, and the subscript k = 0, 1, ..., N-1; Describes the change of frequency components over time and frequency index; k is the index in the frequency domain; n is the index in the time domain. 3.根据权利要求1所述的基于轻量化Transformer的风-桥系统抖振响应预测方法,其特征在于,所述步骤3中具体过程如下:3. The method for predicting buffeting response of a wind-bridge system based on a lightweight Transformer according to claim 1, wherein the specific process in step 3 is as follows: 步骤3.1:从模拟风场数据中加载平均风速Umean、横向风速u0、竖向风速w0以及主梁节点位置xpos;其中,横向风速和竖向风速的空间变化通过有限差分法计算得到;Step 3.1: Load the average wind speed U mean , lateral wind speed u 0 , vertical wind speed w 0 and main beam node position x pos from the simulated wind field data; wherein the spatial variation of lateral wind speed and vertical wind speed is calculated by finite difference method; 步骤3.2:通过差分计算得到梁段的长度L以及相邻节点间的距离;在静态风荷载计算阶段,采用基于气动力学理论的公式计算主梁段上各节点处的分量,其公式为:Step 3.2: The length L of the beam segment and the distance between adjacent nodes are obtained by differential calculation. In the static wind load calculation stage, the components at each node on the main beam segment are calculated using a formula based on aerodynamic theory. The formula is: 公式中,FD、FL和MM分别为阻力分量、升力分量和力矩分量;ρ是空气密度,Umean是平均风速,H是风速垂直方向上的影响高度,B是桥梁宽度,L是主梁段的长度,CD、CL和CM分别是阻力系数、升力系数和力矩系数;In the formula, F D , F L and M M are the drag component, lift component and moment component respectively; ρ is the air density, U mean is the average wind speed, H is the influence height in the vertical direction of the wind speed, B is the width of the bridge, L is the length of the main beam section, CD , CL and CM are the drag coefficient, lift coefficient and moment coefficient respectively; 步骤3.3:通过对横向风速u0和竖向风速w0进行处理,得到在时域上的动态风荷载时程;采用傅立叶变换的方法,将频域的脉动风速转化为时域的抖振力时程;其涉及动态风荷载时程公式如下表示:Step 3.3: By processing the lateral wind speed u 0 and the vertical wind speed w 0 , the dynamic wind load time history in the time domain is obtained; the pulsating wind speed in the frequency domain is converted into the buffeting force time history in the time domain by the Fourier transform method; the dynamic wind load time history formula is expressed as follows: 公式中,FD(t)、FL(t)和MM(t)分别为阻力分量时程、升力分量时程和力矩分量时程;u(t)是时域内的横向风速,w(t)是时域内的竖向风速,t表示时间。In the formula, FD (t), FL (t) and MM (t) are the time history of the drag component, the time history of the lift component and the time history of the moment component, respectively; u(t) is the lateral wind speed in the time domain, w(t) is the vertical wind speed in the time domain, and t represents time. 4.根据权利要求1所述的基于轻量化Transformer的风-桥系统抖振响应预测方法,其特征在于,所述步骤4中桥梁运动模型为:4. The method for predicting buffeting response of a wind-bridge system based on a lightweight Transformer according to claim 1, wherein the bridge motion model in step 4 is: 公式中,Mxx和Myy分别是桥梁在横向和竖向的质量矩阵,分别是桥梁的横向和竖向加速度,Cxx和Cyy分别是桥梁在横向和竖向的阻尼矩阵,分别是桥梁的横向和竖向速度,Kxx和Kyy分别是桥梁在横向和竖向的刚度矩阵,u和v分别是桥梁的横向和竖向位移,Fgx(t)和Fgy(t)分别是抖振力引起的横向和竖向风载荷。In the formula, M xx and M yy are the mass matrices of the bridge in the horizontal and vertical directions, respectively. and are the lateral and vertical accelerations of the bridge, C xx and Cyy are the lateral and vertical damping matrices of the bridge, and are the lateral and vertical velocities of the bridge, K xx and Kyy are the stiffness matrices of the bridge in the lateral and vertical directions, u and v are the lateral and vertical displacements of the bridge, F gx (t) and F gy (t) are the lateral and vertical wind loads caused by the buffeting force, respectively. 5.根据权利要求1所述的基于轻量化Transformer的风-桥系统抖振响应预测方法,其特征在于,所述步骤8之前还包括:通过使用独立的验证数据集对模型进行评估,具体为:5. The method for predicting buffeting response of a wind-bridge system based on a lightweight Transformer according to claim 1, characterized in that before step 8, it also includes: evaluating the model by using an independent validation data set, specifically: 步骤a:模拟N0个悬索桥在平均风速下的脉动风速,和平均风速叠加后生成脉动风速样本;Step a: simulate the fluctuating wind speed of N0 suspension bridges under the average wind speed, and generate fluctuating wind speed samples after superimposing them with the average wind speed; 步骤b:依据有限元模型,在既定的参数条件下模拟得到桥梁的变形;其中,应用随机抽样法,从样本中抽取出训练样本集的验证样本;Step b: According to the finite element model, the deformation of the bridge is simulated under the given parameter conditions; wherein, a random sampling method is applied to extract a verification sample of the training sample set from the sample; 步骤c:将脉动风速样本作为输入,而对应的桥梁竖向变形作为输出;Step c: taking the fluctuating wind speed sample as input and the corresponding vertical deformation of the bridge as output; 步骤d:在每个训练周期结束后,使用验证集评估模型的性能,选择均方误差、平均绝对误差、决定系数和其方差作为模型评估指标来评估Transformer模型预测性能和泛化能力;Step d: After each training cycle, the validation set is used to evaluate the performance of the model. The mean square error, mean absolute error, coefficient of determination and its variance are selected as model evaluation indicators to evaluate the prediction performance and generalization ability of the Transformer model. 步骤e:若模型预测效果不理想,则进行Transformer模型的调优,包括调整Transformer模型的架构、优化器的设置、学习率和超参数,在训练的过程中,获得并保存表现最优的模型。Step e: If the model prediction effect is not ideal, the Transformer model is tuned, including adjusting the Transformer model architecture, optimizer settings, learning rate and hyperparameters. During the training process, the best performing model is obtained and saved.
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