Numerical Study of Damage Modes and Assessment of Circular RC Pier under Noncontact Explosions

Since the September 11, 2001, attack in New York, the number and intensity of terrorist activities around the world have attracted our attention toward infrastructure systems. Also, unintentional explosions resulting from fuel oil (gas) and fireworks in transit can lead to the interruption of the highway system. In addition, crucial bridges in a local war are main targets for hostile forces because they convey military supplies. Bridge piers are main axial bearing components and readily suffer damage under blast loading, so damage modes of bridges in different cases and explosive damage assessments should be studied to provide design advice for protection against explosion. In this paper, numerical models of reinforced concrete (RC) piers are built and verified by the explosion experimental acceleration data and the theoretical ultimate bearing capacity. Based on the verified model, different damage modes of RC piers in three noncontact explosive cases are investigated, in which the locations of explosive centers are at the bottom, the midheight, and the top of the pier. RC piers always experience flexural failure in these cases. The residual bearing capacities of piers before collapse are also studied, and the relations between trinitrotoluene (TNT) mass and residual bearing capacity are fitted by a cubic polynomial, resulting in a downward trend. From damage index and polynomial, the damage extent after blasting can be evaluated.