Beyond the Factor of Safety: Developing Fragility Curves to Characterize System Reliability

The U.S. Army Engineer Research and Development Center announces the publication of a new document on its Web site.

ERDC SR-10-1

Beyond the Factor of Safety: Developing Fragility Curves to Characterize System Reliability by Martin T. Schultz, Ben P. Gouldby, Jonathan D. Simm, and Johannes L. Wibowo

Abstract: Fragility curves are becoming increasingly common components of flood risk assessments. This report introduces the concept of the fragility curve and shows how fragility curves are related to more familiar reliability concepts, such as the deterministic factor of safety and the relative reliability index. Examples of fragility curves are identified in the literature on structures and risk assessment to identify what methods have been used to develop fragility curves in practice. Four basic approaches are identified: judgmental, empirical, hybrid, and analytical. Analytical approaches are, by far, the most common method encountered in the literature. This group of methods is further decomposed based on whether the limit state equation is an explicit function or an implicit function and on whether the probability of failure is obtained using analytical solution methods or numerical solution methods. Advantages and disadvantages of the various approaches are considered.

If you wish to access/download the document (60 pages/625 kb) in pdf format, the address is: http://libweb.wes.army.mil/uhtbin/hyperion/ERDC-SR-10-1.pdf