Keywords: Multihazard approaches. Performance-based designs. Natural hazards. Structural systems. Nonstructural systems. System performance. Lifetime losses. Fragility. Site hazard analyses. Probabilistic analyses. Models. Risk analyses. Life-cycle analyses.
Abstract: This study presents a new methodology for: (1) assessing performance of structural/nonstructural systems subjected to multiple hazards during their lifetime and (2) identifying a strategy from a collection of design alternatives that is optimal in some sense. System performance is measured by the total lifetime losses and the system fragility, that is, the probability that a system response exceeds a critical value subjected to a hazard event specified by its intensity and other parameters. Accordingly, fragility is a surface with support the defining parameters of a hazard. The methodology is based on site hazard analysis, system fragility analysis and capacity and cost estimation. Probabilistic models are developed for characterizing natural hazards occurring at a given site at single/multiple points. The authors present two methods for estimating system fragility, crossing theory of stochastic processes and Monte Carlo simulation. The proposed models are implemented in computer programs and the life-cycle risk analysis methodology is illustrated through numerical examples.