A Simplified Method to Predict Damage of Axially-Loaded Circular RC Columns Under Lateral Impact Loading

Detailed finite element (FE) models are often employed to predict the impact responses of reinforced concrete (RC) columns. However, they always require substantial investments of time and effort in modeling and analysis so that they are not widely used in practice, particularly in preliminary designs. Moreover, although some simplified models have been established for beams and slabs under impact loading, few attempts have been made on modeling RC columns. For these reasons, this paper proposes a simplified modeling method to accurately capture the impact-induced response and damage of circular RC columns. In the proposed method, a two-degree-of-freedom (DOF) system was used to describe the interaction between the impactor and the impacted column. The formulas, and procedure to estimate the force-deformation relationship with strain-rate effects were presented according to the section-based analysis. The influence of the unloading stiffness on the residual deformation was addressed, and the method to determine the unloading stiffness of circular columns was proposed. Furthermore, a fiber-based beam-column element modeling method was developed to estimate the force-deformation relationship of the columns with strain-rate effects. The proposed simplified method was demonstrated by the drop-hammer impact tests to be capable of predicting the impact response of RC columns well. Its accuracy in the residual deformation is superior to that of the detailed FE simulation. Parametric studies were performed to investigate the damage characteristics of axially-loaded circular RC columns under various impact scenarios.