基于结构健康监测系统的大跨钢桥多尺度疲劳损伤演化分析研究

The purpose of this project is to perform the multi-scale fatigue damage evaluation of long-span steel bridge on the basis of the structural health monitoring system at the aspects of theoretical analysis, experimental study, numerical simulation and engineering application. The strategy and implementation for multi-scale modeling of long-span steel bridge considering structural global responses and local damage simultaneously are firstly investigated. The fatigue damage test of critical component with typical local welding details is then carried out in laboratory. The proper fatigue failure code is further incorporated in damage constitutive model for fatigue damage evolving mechanism and failure path of local details subjected to vehicle loading as well as environmental factors. The physical nature and coupling effects of multi-scale fatigue damage, and the relationships between local failure and global lapse are also studied. The Tsing Ma Bridge and its structural health monitoring system are taken as engineering application case study in order to propose the general procedure and effective implementation methods for multi-scale fatigue damage analysis of long-span bridge structure. This investigation enhance the knowledge of fatigue nature in fatigue damage process of critical locations and better understandings of fatigue failure behaviors as well as failure path of large bridge structure. Finally this study may express the great engineering application significance for extending the developed strategies and methods to more accurate assessment of fatigue damage status for large complex bridge structures.

针对基于结构健康监测系统的大跨钢桥疲劳损伤状态评估研究中亟待解决的关键问题，从理论分析、实验研究、数值模拟和工程应用四个方面，提出了针对大跨桥梁结构特性进行整体结构响应与局部损伤同步计算的多尺度模拟分析方法，通过对含有典型焊连接细节的钢箱梁关键构件的疲劳损伤实验，建立了引入合适疲劳损伤本构模型和恰当疲劳失效准则的损伤实验模型，揭示了在车辆交通载荷和环境因素共同影响下所关注细节的疲劳损伤演化机理与失效路径，考虑了损伤破坏的多尺度物理机理及其耦合作用，深入研究了细节局部失效与整体结构破坏之间的关系。通过对工程实例香港青马大桥及其结构健康监测系统数据的研究，总结出适用于大跨钢桥的多尺度疲劳损伤模拟的通用步骤及高效实施策略，其研究成果加强了我们对桥梁关键部位疲劳损伤特性和疲劳失效行为本质的了解，对进一步推广应用于大跨复杂桥梁结构更准确的疲劳损伤状态评估，有极其重要的工程意义。

本项目针对大跨钢桥结构健康监测和状态评估的需要，研究同时考虑结构整体特性和局部细节特性的结构行为多尺度有限元模拟及其在工程目标桥梁上的应用。首先，从理论框架上探讨了复杂土木结构的多尺度模拟的方法和策略，以纵向桁架缩尺试样的实验研究为平台，具体研究了基于多点约束方程法的多尺度有限元模型的建立、修正和验证过程。其次将考虑细节特性的钢桥多尺度模拟方法应用于香港青马大桥，通过对实际桥梁以结构健康监测和损伤评估为目标进行的结构多尺度模拟过程的研究，提出了多尺度模型进行结构疲劳损伤分析的方法与策略，并通过基于参数敏感度以动力特性为目标的模型修正和以实测位移影响线的模型验证，验证了所构建的多尺度模型的有效性和准确性，在此基础上进一步研究了该大跨钢桥多尺度模型在日常交通载荷和诸如台风、地震极限情况下的所关注细节的疲劳损伤，进而利用有限元软件提供的用户开发界面引入合适的疲劳损伤本构模型，满足不同尺度下结构特性分析和局部损伤演化过程仿真计算的需要。最终提出了大跨钢桥的多尺度疲劳损伤演化计算的通用步骤及高效实施策略，实现了基于结构健康监测系统的大跨钢桥的物理非线性疲劳损伤计算和结构健康状态评估，加深了我们对桥梁关键部位疲劳损伤特性和疲劳失效行为本质的了解，同时也有助于将此研究成果推广到类似复杂构型的大跨桥梁结构更为准确的疲劳损伤状态评估过程中。