A total life-cycle cost-resilience optimization framework for infrastructures management using different retrofit strategies

Each of the total Life-Cycle Cost (LCC) and resilience index are valuable indicators of infrastructure management against hazard events during its service lifetime. In this study, the proposed multi-objective framework provides a systematic methodology for decision-makers to select the optimal retrofit strategies that minimize the LCC while satisfying a given level of resilience, for which various retrofit strategies are chosen. For each case, the fragility curves are established through IDA for calculating the resilience and LCC, which incorporates the effects of complete or incomplete repair actions of damage conditions induced by multiple occurrences of previous hazard events. This study employs a well-known 'NSGA II' to identify the optimal set of solutions. The various aspects of the optimal retrofit strategies are thoroughly investigated and discussed for an actual structure in the refinery sites as a case study infrastructure.