预应力混凝土梁疲劳损伤演变规律及其疲劳失效机理研究

With the development of high-speed railway and heavy haul railway, the fatigue effect of high frequency and high axle load of train puts forward new requirements on the fatigue performance of prestressed concrete bridge structure. It needs to carry out research on the evolution process and the failure mechanism of prestressed concrete beams under the fatigue load to improve the related design theory and method. In view of the dynamic properties of the structure can reflect its actual service condition, and the change of dynamic response parameters such as acceleration, damping and mode shape of structure can reflect the whole process of damage evolution of the structure under fatigue load. This project aims to based on cumulative damage theory and structural dynamics principle, the key modal parameters of prestressed concrete beams under fatigue load are extracted and a complete modal set are constructed for fatigue damaged structure. A inversion analysis method of damage process for prestressed concrete beams under fatigue load is proposed based on the structural modal parameter matrix. Fatigue tests of prestressed concrete beams are conducted to reveal the fatigue damage evolution characteristic of prestressed concrete beams and its failure mechanism, and the mechanism of the fatigue damage evolution on the modal response of prestressed concrete structure are constructed, and fatigue constitutive relationships of prestressed concrete beam are established. Finally, a fatigue damage identification of prestressed concrete beam using inversion method and the mode of finite element model updating is proposed based on the dynamic parameters. The research results will provide technical support and theoretical basis for improve the fatigue strength and life-span design theory and method for prestressed concrete bridge structures.

高速铁路和重载铁路发展所带来的高频和大轴重列车荷载的疲劳作用，对预应力混凝土桥梁结构的疲劳性能提出了新的要求，亟需开展预应力混凝土梁的疲劳损伤演变过程及其失效机理的研究，以完善现行的有关设计理论和方法。鉴于结构的动力特性能够真实地反映结构状态，加速度、阻尼和振型等结构动力响应参数的变化与结构整个疲劳过程中的损伤演变相关，本项目拟基于结构动力学和累积损伤理论，提炼疲劳作用下预应力混凝土梁关键模态参数并构建疲劳伤损结构的完整模态集，提出基于结构模态参数矩阵反演的预应力混凝土梁疲劳损伤历程分析方法。开展预应力混凝土梁的疲劳损伤试验研究，揭示其疲劳损伤演化规律以及失效机理；研究疲劳损伤演化对预应力混凝土梁结构模态响应的影响机制，建立预应力混凝土梁疲劳本构关系，提出基于变化模态修正有限元模型的预应力混凝土梁的疲劳损伤反演识别方法，为完善预应力混凝土桥梁结构疲劳强度和寿命的设计理论及方法提供支撑。

高速铁路和重载铁路发展所带来的高频和大轴重列车荷载的疲劳作用，对预应力混凝土桥梁结构的疲劳性能提出了新的要求，亟需开展预应力混凝土梁的疲劳损伤演变过程及其失效机理的研究，以完善现行的有关设计理论和方法。鉴于结构的动力特性能够真实地反映结构状态，以结构固有频率和振型为主的结构模态响应参数的变化与结构疲劳历程中的损伤演变相关，本项目基于结构动力学和累积损伤理论，提炼了疲劳作用下预应力混凝土梁关键模态参数并构建了疲劳伤损结构的完整模态集，提出了基于结构模态参数反演的预应力混凝土梁疲劳损伤历程分析方法，建立了疲劳作用下模态参数的疲劳计算理论公式。开展了预应力混凝土梁的疲劳损伤试验研究，揭示了其疲劳损伤演化规律以及失效机理；研究了疲劳损伤演化对预应力混凝土梁结构模态响应的影响机制，建立了预应力混凝土梁经典材料的疲劳本构关系和疲劳表征模型，提出了基于变化模态修正有限元模型的预应力混凝土梁的疲劳损伤反演识别方法。本项目为完善预应力混凝土桥梁结构疲劳性能和寿命预测的理论及方法提供支撑。