公路钢筋混凝土梁桥地震下整体易损性分析与全寿命风险评估

Currently, the existing highway reinforced concrete (RC) bridges, especially the latest ones, can not generally meet the requirements of the updated seismic design specifications. Additional, the economic losses, fatalities, social and environmental impacts due to structural failure have not been systematically incorporated within seismic design and assessment process of bridges. Thus, once earthquake happens, it will bring disastrous consequences to the society and economy. Under the framework of life-cycle design, this project introduces the theory of bridge system-level reliability into the seismic vulnerability analysis of RC bridges. The numerical simulation and experimental study will be conducted to reveal the correlation between the vulnerable components. The effects of the randomness of earthquakes and uncertainties of variables on the system-level vulnerability of the bridges will also be investigated by both numerical and experimental studies. By comprehensively analyzing various risk losses caused by the bridge failure, a quantitative estimation method of life-cycle risk will be proposed. The evolution law of earthquake risk in a life cycle context will developed and the probabilistic analysis method will be used to establish the life-cycle risk. Furthermore, the adaptability and reliability of the proposed theoretical system will be verified by engineering examples and historical data. A novel and practical system of bridge disaster prevention and mitigation framework based on life-cycle quantitative risk will be developed to improve the performance and resilience of highway RC bridges. Overall, the proposed approach will not only impact the state-of-the-art and the state-of-practice for hazard assessment and mitigation of the RC bridges in China, but also can have important theoretical value and engineering significance for the development and improvement of the theoretical system of the life-cycle reliability and performance of bridges under the earthquakes.

我国在役公路钢筋混凝土桥梁特别是最新抗震细则颁布之前修建的往往无法满足现行抗震细则要求，且未能考虑全寿命周期内桥梁整体失效对于社会、经济及环境等的影响，因此地震灾害势必对桥梁安全和社会经济造成极大危害。本项目在全寿命设计框架下，将桥梁系统可靠度理论引入到公路钢筋混凝土梁桥的地震易损性分析中；通过数值模拟和试验研究，揭示易损构件的相关性、地震的随机性以及变量的不确定性等对桥梁易损性的影响规律；综合分析桥梁失效所造成的各类风险损失，提出基于概率的全寿命地震风险定量估计方法；进而揭示全寿命周期内地震风险的演化规律，利用概率解析的方法建立全寿命内风险评估以及预测的理论模型，同时结合工程实例和历史数据验证此理论体系的适应性与可靠性，最终形成基于全寿命定量风险的桥梁防灾减灾新体系。本项目的研究结果对于发展和完善地震灾害作用下桥梁的全寿命可靠性理论体系，具有重要的理论价值与工程意义。

桥梁在我国社会经济发展中发挥了重要作用。地震灾害导致桥梁破坏，对我国人民群众的生命财产安全造成威胁。传统的桥梁抗震设计和决策大多以满足安全性为目标。在多个地震事件中发现，尽管桥梁按照传统目标进行设计和维养，地震可导致桥梁损坏，进而对经济、社会、环境造成严重的后果。同时，在桥梁的使用寿命内，可能发生多次地震灾害，从而对桥梁结构产生多次破坏，造成累积后果。本项目在全寿命的理论框架下，通过数值模拟和试验研究，揭示桥梁构件和系统在地震下的破坏模式，提出了考虑多个地震需求相关性的系统易损性计算方法，揭示了各类不确定性对桥梁易损性的影响规律；提出了地震下桥梁损坏造成经济、社会、环境后果的指标和量化方法，考虑不确定性，提出基于概率的地震风险定量评估方法；考虑地震发生时间、数量、强度的不确定性，从全寿命维度研究地震下桥梁的损失和风险，进而揭示了全寿命周期内地震风险的演化规律，推导了全寿命内后果预测的解析模型。本研究最终形成了地震下桥梁全寿命风险评估的理论和框架。从全寿命、可靠度、风险角度，为我国防灾减灾事业发展提供一定技术支撑。