The occurrence of unanticipated extreme events in modern societies typically induces significant damage and losses to the built heritage and people, but also concern and fear in the population. The capacity of structures to resist to extreme events has been deserving the attention of researchers during the last decades. The occurrence of explosion-based terrorist attacks in the last two decades has caused a great concern among decision makers and had led to important investments towards the characterization of the structural response of buildings subjected to blast loads. The work presented in this paper was performed in collaboration with one of the largest Public Transportation Operators in Portugal and addresses the problem of risk assessment due to terrorist actions in the case of external explosions, and structural safety evaluation of buildings when subjected to different explosion scenarios.This work was supported by FCT (Portuguese Foundation for Science and Technology) under Project CHSECURE (PTDC/EMC/120118/2010), and within ISISE, project UID/ECI/04029/2013. The first author also acknowledges the support from his PhD FCT grant with the reference SFRH/BD/45436/2008
