Enhancement of seismic sustainability of critical facilities through system analysis

Proper functioning of critical facilities such as acute care hospitals and fire stations are essential in the aftermath of a severe earthquake. For these facilities to remain operational, not only their building structures must remain safe for continued occupancy, but also their nonstructural components/systems must remain functional. Motivated by a previous study by the second author, this paper demonstrates a probabilistic system analysis for enhancing the sustainability of deficient critical facilities. The analysis, in principle, utilizes event and fault tree procedures to evaluate the system fragility defined by the probability that the system will not perform its intended purpose. Enhancement of sustainability is demonstrated by using a representative numerical model of an existing facility. The study shows that by selecting the most vulnerable components, utilizing the concept of annual sensitivity index, the annual probability of failure can be reduced significantly in a cost-effective way.