Dynamic time-based vulnerability assessment in pursuit of critical infrastructure resilience

One of the main principles of critical infrastructure resilience (CIR) is risk assessment for severe shocks caused by natural or man-made disasters. Vulnerability assessment plays an important role in calculating risk. One type of vulnerability assessment is the sequential-function vulnerability assessment, which is based on the network characteristics and interdependencies of different assets. A further significant area of vulnerability among resilient infrastructures relates to time. Time can change interdependencies, it can modify the inherent properties of individual assets, and it can superpose impacts through pathways between receptors and sources during each shock. This study aims to develop a new technique for assessing dynamic time-based vulnerability as a main factor in risk analysis for achieving resilience. In this study, a new analytical equation is developed based on the effect of the source and the interdependencies between the receptors as nodes in the infrastructure network. Direct and indirect impacts on each infrastructure receptor are simulated by impulse functions and Heaviside functions superposed in the total function. The equation for time-based vulnerability assessment for interdependent assets in critical infrastructures is obtained by employing a Laplace transformation. Finally, the developed equation is tested on a hypothetical case study to assess vulnerability.