As civil infrastructures become highly complex and interconnected, accidental events such as fire, explosion, dropped objects and collision tend to occur more frequently, and are causing critical structural damage and socio-economic costs. Therefore, accidental loads should be considered appropriately during the structural design. To achieve this goal, the paper presents a reliability-based structural design framework against accidental loads. The proposed framework employs a scenario-based simulation in which the occurrence of an accidental load event and the resulting structural loads are modelled probabilistically. The probabilistic distribution of accidental loads is then determined based on the occurrence probabilities of identified scenarios and the conditional probability of structural loads given each accident scenario. In order to estimate the structural responses under accidental loads, an appropriate type of structural analysis is carried out for the given limit states of the structural resistance at the critical sections. The proposed framework is illustrated by an example of a cable-stayed bridge whose piers are under ship collision risk. To consider the dynamic amplification of bridge response caused by ship–bridge collision, time history analysis is performed for the equivalent static ship collision loads. The paper also identifies research needs and challenges in applying the proposed framework to other accidental loads.