基于小波有限元的移动荷载激励下桥梁结构自适应损伤识别研究

A finite element model (FEM) in which the refinement extent adaptively keeps in compatible with time-varying moving load conditions and damage scenarios can improve the efficiency and accuracy of model updating based damage detection of bridge structures subjected to moving load. Such dynamic matching depends on a flexible and adaptive FEM. However, the current traditional FEM has a difficulty to fulfill this objective. In this project, the wavelet FEM (WFEM) with favorable multi-resolution and localization properties will be introduced into the field of damage detection of bridge structures under moving load excitation. Considering the need of adaptive dynamic analysis of bridge structures subjected to moving load and simulation of local damages, appropriate wavelet function will be constructed, and then the corresponding wavelet finite element formulation and adaptive lifting algorithm will be derived. Subsequently, adaptive dynamic analysis and progressive damage detection methods will be proposed for bridge structures. This project aims to solve the key problem on adaptive matching between structural FEM, time-varying moving load conditions and gradually identified damage scenarios through theoretical analysis, numerical simulation and experimental study. Thus the number of degrees-of-freedom (DOFs) in the model and updating parameters in model updating process can be reduced and the detection efficiency and accuracy can be enhanced.

建立各区域的精细化程度随着时变的移动荷载和结构损伤状况自适应调整的有限元模型，可有效提高基于模型修正的移动荷载激励下桥梁结构损伤识别的效率和精度。这种动态匹配依赖于灵活的自适应有限元模型，而传统的有限元方法在实现自适应匹配时有其本质的不足。项目将具有局部性和多分辨率的小波有限元模型引入移动荷载激励下的桥梁结构损伤识别领域；综合考虑时变移动荷载激励下桥梁结构动力分析和结构局部损伤模拟的需要，构造合适的小波函数，推导相应的小波单元列式及其自适应提升算法；提出移动荷载激励下，桥梁结构动力响应的自适应分析方法和多尺度渐近式损伤识别方法。本项目采用理论分析、数值模拟与试验相结合的研究方法，解决结构模型同时与时变的移动荷载位置和逐步识别的结构损伤状况相匹配的难题，大幅度缩减有限元模型的自由度和模型修正过程中的待修正参数的数量，提高识别的效率和精度，研究具有较大的理论意义和工程实用价值。

基于模型修正的移动荷载激励下桥梁结构损伤识别通常需要一个各区域精细化程度能随着时变的移动荷载和结构损伤状况动态匹配的有限元模型。这种动态匹配依赖于灵活的自适应有限元模型，而传统的有限元方法在实现自适应匹配时有其本质的不足。本项目将具有局部性和多分辨率的小波有限元模型引入移动荷载激励下的桥梁结构损伤识别领域，提高损伤识别的效率和精度。项目取得的主要成果包括：（1）提出了基于小波有限元的移动荷载激励下桥梁结构自适应动力分析方法，模型中小波单元的尺度随着移动荷载—桥梁接触位置的变化而动态调整，以少量的结构模型自由度数获得足够的动力分析精度；（2）提出了基于小波有限元的移动荷载激励下桥梁结构多尺度渐进式损伤识别方法。模型中各区域的精细化程度随着与时变的移动荷载位置和逐步识别的结构损伤状况自适应改变，有效提高识别效率和精度；（3）基于模态摄动法和模态叠加法，推导了移动荷载作用下损伤梁的动力响应闭合解，引入离散小波变换分离“驱动频率成份”响应和“自振频率成份”响应，提出了利用“驱动频率成份”响应定位损伤的方法；（4）提出了基于小波有限元的移动荷载激励下两阶段损伤识别方法。首先通过离散小波变换得到桥梁位移动力响应的“驱动频率成份”来定位损伤；随后通过自适应小波有限元模型修正逐步定量损伤程度；（5）项目在国内外期刊发表论文10篇，其中SCI收录9篇。项目成果为桥梁健康监测和状态评估提供依据，具有较大的理论意义和工程实用价值。