Integrated approach and analysis of reliability, robustness, resilience and infrastructure applications

A rising number of man-made and natural disasters have occurred since the beginning of the 21st century in the United States. Improving the quality of civil infrastructure in an increasingly hazardous environment has become a top priority. One of the predominant reasons that hurricanes and earthquakes become community disasters is the failure of civil infrastructure systems, also known as "lifelines", on which communities rely. An integrated approach is presented here to model the reliability, robustness, and resilience through the use of system-based models of performance. The models are based on empirical evidence of the ability of the underlying structural systems to provide essential infrastructure services to the community. The reliability and robustness are modeled through fragility functions, which are used to represent the probability of failure of a structure or lifeline system conditional upon a hazard or set of hazards. Traditional analyses of infrastructure performance have relied upon evaluating the effect of one hazard or demand variable such as wind speed or peak storm surge on the loss of structural capacity. This investigation suggests that multivariate distributions of the demand variables of wind speed, storm surge, and rainfall are important for the analysis of infrastructure performance. The resilience of a structure or lifeline system is characterized in part by an inoperability function that is modeled as the mechanical analog of the single-degree-of-freedom (SDOF) system. Interdependency is assessed first through previously derived input-output models of recovery to storm hazards and then significantly expanded. The combined fragility and resilience model framework derived here allows for the implementation of numerical simulations to predict system performance for various demand levels.