Fault-tree-based integrated approach of assessing the risk of failure of deteriorated reinforced-concrete bridges

Life cycle cost analysis is becoming an important consideration for decision making in relation to bridge design, maintenance, and rehabilitation. An optimal solution should ensure reliability during service life while minimizing the life cycle cost. Risk of failure is an important component in whole life cycle cost for both new and existing structures. This paper presents a fault-tree-based integrated methodology to assess the systematic risk of failure. The methodology provides alternatives for the users for qualitative or quantitative assessment of the risk of failure, depending on the availability of detailed data. The qualitative model is capable of obtaining the relative severity of the likelihood and the risk of occurrence of a distress mechanism, ranking the overall risk of failure of serviceability among different components of a bridge or among a group of bridges. The quantitative methodology can lead to a quantitative risk of failure of major bridge subsystems and provides inputs for estimating the expected failure cost in life cycle cost analysis based on the availability of the quantitative probability of failure due to the initiation of a distress mechanism of a structural component.