The Damage Identification Method Of Cable-stayed Arch-truss Based On Vibration Test Data Fusion

The cable-stayed arch-truss is one of the structural forms commonly used in large-span public buildings.In the course of its service,due to the influence of the natural environment and random loads,the potential for damage is greater.Moreover,the damage is difficult to detect.If structural damage cannot be discovered and dealt with in time,it will seriously affect the normal use of the structure or even lead to structural damage.Therefore,the research on damage identification of the cablestayed arch-truss in the whole life cycle has great practical significance.At present,damage identification methods based on frequency-domain data and time domain-data lack relevant research on cable-stayed arch-truss.Besides,the problem of damage identification accuracy is not ideal.A complete theory system for damage identification of cable-stayed arch-truss has not been formed.The data fusion method can synthesize a variety of information and it has good fault tolerance and reliability.It provides a new research idea for structural damage identification.In this paper,the "vibration-test data" and the "data fusion theory" are effectively combined.From the two aspects of "damage location" and "damage degree",based on "frequency-domain data" and "time-domain data",the research on fusion damage identification of cable-stayed arch-truss is carried out.The main contents include:(1)Single damage identification indexes based on frequency-domain data suitable for cable-stayed arch-truss is selected.A simplified cable-stayed arch-truss model obtained by reducing the scale of an actual project is selected for finite element analysis to verify the identification effects of curvature mode difference,change rate of superposition curvature mode and modal flexiblity difference curvature.Cable-stayed arch-truss is susceptible to interference or even misjudgment when using single damage diagnosis method for damage identification.The recognition effect of change rate of superposition curvature mode and modal flexiblity difference curvature is superior to curvature mode difference,and they can be used as the benchmark index for fusion.(2)A damage location method based on frequency-domain data fusion for the cable-stayed arch-truss is established.This paper combines the data fusion method with damage identification index.D-S evidence matrix theory is used to fuse the identification results of change rate of superposition curvature mode and modal flexiblity difference curvature,and single fusion and two-stage fusion recognition methods for damage location of cable-stayed arch-truss are proposed.In this paper,single damage conditions and multiple damage conditions for different rods and different positions are designed.The finite element method is used to verify that the method can accurately identify the cable-stayed arch-truss damage.Besides,the influence of different levels of noise on the damage identification of cable-stayed arch-truss is considered.The results show that the damage location method based on frequency-domain data fusion can reduce the noise interference and has good robustness.In this paper,the effectiveness of the proposed method is verified by numerical simulation,which provides a simple and effective identification method for the actual cable-stayed arch-truss damage location.(3)A damage quantitative method based on frequency-domain data fusion is proposed.This paper introduces the idea of classification and comparison into the damage identification of cable-stayed arch-truss.Based on the theory of curvature and stiffness,this method puts forward the concept of equivalent damage degree of the cable-stayed arch-truss element.The relationship between the damage degree of the component and the equivalent damage degree of the element in the interval is established by finite element analysis.The method mainly includes: analysis preparation,finite element analysis to establish a sample database of the damage degree of the cable-stayed arch-truss,identification of the damage position of the structure based on the data fusion method,and judgment of the damage degree of the structure.Through a cable-stayed arch-truss model,the sample database of cable-stayed arch-truss damage identification and the establishment of classification index are introduced in detail.(4)A damage identification method based on time-domain data fusion for the cable-stayed arch-truss is established.Combined with the characteristics of cable-stayed arch-truss damage identification,a convolutional neural network is selected to identify structural damage.The method mainly includes: establishment of a time-domain data sample database by finite element analysis,data pre-processing and data augmentation,and selection of appropriate parameters to construct convolutional neural networks respectively according to the identification characteristics of the damage position and damage degree of the cable-stayed arch-truss,training and testing of convolutional neural networks.Taking a cable-stayed arch-truss as an example,the structural acceleration time-history data is selected as the network input,and the recognition effect of the method on noisy and noise-free data is analyzed.The results show that the convolutional neural network can effectively identify the damage degree and damage location of the cable-stayed arch-truss.It has good robustness.(5)The actual engineering damage identification of the cable-stayed arch-truss was carried out.This paper carried out a damage identification study of the cable-stayed arch-truss through numerical simulation and the damage test data of cablestayed arch-truss.The results show that the method is still ideal for identifying the actual cable-stayed arch-truss and the test structure.It also verifies that the method has good anti-noise capability.