Life-cycle performance of structures subject to multiple deterioration mechanisms

This paper studies structural deterioration as a result of the combined action of progressive degradation (e.g., corrosion, fatigue) and sudden events (e.g., earthquakes). The structural condition at a given time is measured in terms of the system’s remaining life, which is defined in practice by an appropriate structural performance indicator (e.g., inter-story drift). Structural reliability is evaluated against prescribed design and operation thresholds that can be used to establish limit states or intervention policies. It is assumed that sudden events conform to a compound point process with shock sizes and interarrival times that are independent and identically distributed random variables. Progressive deterioration is initially modeled as a deterministic function. Randomness is later included also as a shock process with times between random deterioration jumps described by a suitable deterministic function. Structural performance with time is modeled as a regenerative process and an expression for the limiting average performance is obtained. The model is illustrated with some examples and compared with similar models showing the importance of including the damage history when studying the life-cycle performance of infrastructure systems.