侵蚀环境耦合作用下双重损伤预应力板梁碳纤维加固耐久性及疲劳特性研究

Environmental erosion is one of the main causes of the deterioration of the durability of the bridge structure and the decrease of the fatigue life. However, the deterioration mechanisms of the reinforcement durability and attenuation law of fatigue life of damaged bridge are far from elucidated. The purpose of this research is to fabricate large-size prestressed plate beam based on the similarity principle, to simulate the life cycle time axis destruction -reinforcement -destruction of plate beam, the durability experiments freeze-thaw cycle, chloride ion erosion and the coupling of freeze-thaw cycle and chloride ion erosion for plate beam are performed firstly, then the fatigue damage test of the beam members with durability deterioration is also carried out. As a result, the durability damage and fatigue damage of the plate and beam members are realized，and the mechanism of durability degradation of plate beam under different erosion environment and its Influence on structural fatigue are studied. On the basis of this, the damaged members are reinforced by pasting carbon fiber. Then the durability experiments and fatigue damage experiments are performed successively, and durability degradation and fatigue properties attenuation of the reinforcement palate beam are analyzed. Based on the data analysis and theory method, the degradation mechanism of the durability and the attenuation law of structure fatigue characteristic index of reinforced components are revealed, and the durability evaluation theory and the fatigue life prediction method which based on “damaged-reinforced-damaged” whole life cycle durability index of bridge structure are proposed. The research results have important theoretical value for improving the reinforced durability of bridge structure and prolonging its service life.

环境侵蚀是导致结构耐久性劣化及疲劳寿命衰减的主要诱因之一，然而侵蚀环境耦合作用下损伤桥梁加固耐久性劣化机理及疲劳寿命衰减规律远未阐明。课题拟基于相似比原理制作预应力板梁，模拟板梁“破坏-加固-破坏”全寿命周期耐久性轨迹，首先在对预应力板梁进行冻融循环、氯离子侵蚀及两者耦合作用耐久性试验的基础上，再对其开展疲劳损伤试验，研究不同侵蚀环境作用下板梁疲劳损伤机理。然后对环境—疲劳双重损伤预应力板梁进行碳纤维加固，再依次对其开展单一侵蚀环境及耦合环境作用下的耐久性试验及疲劳破坏试验，剖析侵蚀环境作用下损伤板梁加固耐久性劣化机理及其疲劳衰减规律。基于数据分析，辅以理论方法，揭示侵蚀环境耦合作用下环境—疲劳双重损伤预应力板梁碳纤维加固耐久性劣化机理及疲劳损伤演变规律，构建基于全寿命周期耐久性指标的预应力板梁加固评价理论及疲劳寿命预估模型。研究成果对提高结构加固耐久性及延长其服役寿命具有重要的理论价值。

侵蚀环境作是导致桥梁结构耐久性劣化及疲劳寿命衰减的重要诱因之一，然后侵蚀环境作用下损伤桥梁加固耐久性劣化机理及疲劳寿命衰减规律远未阐明。课题拟基于相似比原理制作预应力板梁，模拟板梁“破坏-加固-破坏”全寿命周期耐久性轨迹，首先在对预应力板梁进行冻融循环、氯离子侵蚀及两者耦合作用耐久性试验的基础上，再对其开展疲劳损伤试验，研究不同侵蚀环境作用下板梁疲劳损伤机理。然后对环境—疲劳双重损伤预应力板梁进行碳纤维加固，再依次对其开展单一侵蚀环境及耦合环境作用下的久性试验及疲劳破坏试验，剖析侵蚀环境作用下损伤板梁加固耐久性劣化机理及其疲劳衰减规律。基于数据分析，辅以理论方法，揭示侵蚀环境耦合作用下环境—疲劳双重损伤预应力板梁碳纤维加固耐久性劣化机理及疲劳损伤演变规律，构建基于全寿命周期耐久性指标的预应力板梁加固评价理论及疲劳寿命预估模型。研究成果对提高结构加固耐久性及延长其服役寿命具有重要的理论价值