Reliability analysis of circular reinforced concrete columns subject to sequential vehicular impact and blast loading

This study investigates the first-order second-moment structural reliability of circular reinforced concrete (RC) bridge columns subjected to vehicular impact, explosive blast, and sequential vehicular impact and explosive blast loading. The analysis is performed for five vehicle types of increasing size, mass, and explosive charge capacity. The structural reliability under vehicular impact is shown to be highly sensitive to column diameter, reinforcement ratio, and vehicle velocity. The structural reliability under explosive blast loading is shown to be highly sensitive to column diameter, reinforcement ratio, and blast standoff distance. In general, the structural reliability is lower under explosive blast loading. The structural reliability under sequential loading is evaluated by the newly proposed resistance reduction method and by fault tree analysis. A resistance reduction factor for the second event is defined as a function of the probability of failure under the first event. The resistance reduction method is shown to be more conservative than fault tree analysis and has the added benefit of allowing for the derivation of the density function for performance under sequential loading.