基于改进同步挤压小波变换的时变结构参数识别与损伤识别研究

Bridges often suffer damages when they are subjected to working loads，extreme loads and environmental factors. As a result, Bridges in service belong to time-varying and nonlinear structural systems and their response signals are non-stationary. This research starts with response signal processing of time-varying structures by considering the characters of bridges and their ambient environment. Then the improved synchrosqueezing wavelet transform is employed to process non-stationary signals for the purpose of identifying the instantaneous character parameters and furthering research on theory, algorithm and computer implement by the way of theoretical innovation, numerical simulation as well as test verification. The focus of this study is the selecting of wavelet parent functions and wavelet parameters, wavelet ridge extraction, signal reconstruction, the presentation of time-varying damage index and so on. As a result，a new instantaneous characteristic parameter identification method is proposed, which reflects the time-varying property and nonlinearity. Furthermore, new time-varying damage indexes are presented to track the evolution of structural damage based on parameter identification results. Actually, this research seeks to make some progress in the field of time-varying parameter identification and damage detection. Meanwhile, it can provides the basis for the study of bridge disaster mechanism, health monitoring and safety evaluation. Therefore, it is of great importance in theory and engineering to further study parameter identification and damage detection of time-varying structures.

服役期内的桥梁结构在工作荷载、极端荷载和外部环境等因素作用下将不可避免地出现损伤，本质上属于时变和非线性结构系统，结构响应呈现非平稳特性。本项目紧密结合桥梁结构和所服役环境的特点，以时变结构的工作振动响应处理为出发点，采用具有处理非平稳信号功能的改进同步挤压小波变换算法，以识别时变结构的瞬时特征参数为突破口，从理论、数值模拟和试验验证三个方面，对时变结构参数识别与损伤识别理论、算法和计算机实现进行深入研究。重点解决瞬时特征参数识别技术中小波基函数及小波参数选取、脊线提取、分量信号重构以及时变损伤指数构建等相关问题；提出能够反映结构时变特性的瞬时特征参数识别技术。同时在参数识别的基础上，提出新的时变损伤指数来追踪结构的损伤演化趋势。本项目旨在桥梁结构时变参数识别与损伤识别方法上取得进展，为更好的研究重大桥梁灾变机理、健康监测和安全评估提供基础和依据，具有较大的理论意义和工程实用价值。

服役期内的桥梁结构在工作荷载、极端荷载和外部环境等因素作用下将不可避免地出现损伤，本质上属于时变和非线性结构系统，结构响应呈现非平稳特性。本项目紧密结合桥梁结构和所服役环境的特点，以时变结构的工作振动响应处理为出发点，采用具有处理非平稳信号功能的改进同步挤压小波变换算法，以识别时变结构的瞬时特征参数为突破口，从理论、数值模拟和试验验证三个方面，对时变结构参数识别与损伤识别理论、算法和计算机实现进行深入研究。重点解决瞬时特征参数识别技术中小波基函数及小波参数选取、脊线提取、分量信号重构以及时变损伤指数构建等相关问题；提出能够反映结构时变特性的瞬时特征参数识别技术。同时在参数识别的基础上，提出新的时变损伤指数来追踪结构的损伤演化趋势。本项目旨在桥梁结构时变参数识别与损伤识别方法上取得进展，为更好的研究重大桥梁灾变机理、健康监测和安全评估提供基础和依据，具有较大的理论意义和工程实用价值。