The growing number of terrorist attacks in the past decade has focused the public’s attention on the severity of such a man–made hazard. The rising threat of improvised explosive devices — one of the most successful attack strategies — has significantly increased the number of threats on the ground, in the form of suicide–bombs, vehicle–bombs, etc., thereby requiring the development of more effective blast risk mitigation measures. However, the modern proliferation of such measures poses the problem of evaluating their cost–effectiveness, which prompts the need for a comprehensive optimization methodology — capable of maximizing the resilience of the built environment. The aim of this paper is to lay out the foundations of a resilience–based framework for quantifying the performance of different infrastructure elements incurring blast threats, by means of functionality and resilience indicators. The proposed framework can quantify the consequences of multiple outdoor explosions typified by the emblematic car–bomb scenario. The level of localized damage is evaluated via pressure–impulse diagrams; local failures are then aggregated into the definition of resilience and functionality indicators, designed to provide the analyst with a comprehensive picture of global damage, residual functionality, and downtime of the structural system.