Probabilistic Fatigue Life Prediction and Risk Assessment of Aging Bridges in Cold Regions

该奖项的研究目标是为寒冷地区的老化桥梁开发一种创新的寿命预测和风险评估方法。详细的疲劳机理建模、除冰盐对腐蚀环境的影响以及先进的概率方法将被系统地整合到一个总体框架中。该方案将考虑一般多轴随机荷载作用下的疲劳损伤累积行为，以反映桥梁的实际使用条件。采用腐蚀损伤扩展与疲劳裂纹扩展耦合分析方法，研究寒冷地区钢桥的损伤交互作用。将使用随机过程理论和贝叶斯方法进行严格的不确定性量化和传播分析。在考虑力学损伤和腐蚀损伤累积的情况下，采用有效的概率方法来解决桥梁的时变可靠性问题。如果研究成功，将对寒冷地区老化桥梁的多物理损伤耦合有一个详细的认识。该方法具有较强的通用性，不仅有利于桥梁结构的分析，而且对汽车、飞机等结构的长期耐久性评估也具有一定的参考价值。提出了系统的多层次教育计划，以改善本科教育、研究生研究和学生课外活动。研究方法、工具和结果将被记录下来，并用于加强本科生和研究生的课程。预计该研究的成功将极大地促进寒冷地区钢桥的设计、分析和评估。接受过该项目培训的学生将在老化桥梁的风险管理中发挥重要作用，因为他们中的许多人毕业后将成为寒冷地区的土木工程师和政府雇员。

The research objective of this award is to develop an innovative life prediction and risk assessment methodology for aging bridges in cold regions. The detailed fatigue mechanism modeling, corrosive environmental effects due to deicing salts, and advanced probabilistic methods will be systematically integrated into a general framework. Fatigue damage accumulation behavior under general multiaxial random loading will be considered in this project to represent the realistic service conditions of bridges. Coupled corrosion damage growth and fatigue crack growth analysis will be used to investigate the damage interaction of steel bridges in cold regions. A rigorous uncertainty quantification and propagation analysis will be performed using random process theory and Bayesian methodology. Efficient probabilistic methods will be employed to solve the time-dependent reliability problem of bridges considering mechanical and corrosive damage accumulation. If successful, this research will result in a detailed understanding of multi-physics damage coupling of aging bridges in cold regions. The developed methodology is general enough and will not only benefit the bridge analysis, but also benefit other types of structures, such as automobiles, aircrafts, etc. for their long term durability evaluation. A systematic multi-level educational plan is proposed to improve the undergraduate education, graduate research, and student extracurricular activities. The research methodology, tools, and results will be documented and used to enhance both undergraduate and graduate curriculum. It is expected that the success of the proposed study will significantly enhance the design, analysis and evaluation of steel bridges in cold regions. Students trained in the proposed project will play important roles in the risk management of aging bridges as many of them will be civil engineers and government employees in cold regions after their graduation.