The annual accident probabilities of building structures due to external explosions are assessed using a tree model approach. This study focuses on the effect of accidental explosions within hazardous facilities on the surrounding environment. Branch probabilities in the event trees are heuristically determined. The major factors influencing branch events are identified by fault trees. Domestic accident databases are utilized to calculate the annual occurrence probabilities of accidental explosions. Furthermore, past explosions are reevaluated using the present approach, considering their annual accident probabilities.
