Experimental and numerical study on the behavior of circular RC columns under impact loading

Columns of overpasses are highly exposed to the potential hazard of vehicular collisions. This type of collisions occurred in the past, sometimes with catastrophic consequences. Previous research reported in the literature has explored the dynamic response of RC column under impact loading using both numerical and experimental methods. The majority of the available tests were performed on horizontal elements featuring beam characteristics. In this context, a new facility for the testing of vertical elements featuring the real characteristics of RC columns was realized in the Collision Laboratory of Nanjing Tech University. Four impact tests on cantilever circular RC column were conducted using this facility. The diameter of the column is 330 mm and the height is 1700 mm. The column is a one-third scaled model of a 5.2 m tall RC bridge pier. All the columns have the same configuration of the longitudinal reinforcement bars and two different hoop spacings both representing the case of a low shear reinforced structural element. Impact force, lateral displacements and accelerations were measured. A high-speed camera was adopted to record the evolution of the damage of the RC column during the impact. A brittle shear-type damage was observed characterized by one main diagonal crack located from the rear base of the column to the base of the impact point. Finally, a numerical study was also conducted using LS-DYNA showing a good agreement with the experimental results, especially in the low-velocity impacts. Results highlighted the vulnerability of these structural elements under impact loading.