Abstract: The dynamic response and damage assessment of reinforced concrete (RC) piers under lateral impact loads are investigated in this paper. High-fidelity finite element models of RC piers under lateral impact are developed established using the explicit dynamic analysis software LS-DYNA. The finite element models are calibrated by using the test data from lateral impact tests of RC piers. The influence of impact velocity, impact mass, impact location, and axial compression ratio on the dynamic response and damage evolution of RC piers are investigated. Based on the residual load-carrying capacity and residual displacement, the indicators of relative residual deformation and relative residual load-carrying capacity are proposed. The corresponding values of relative residual load-carrying capacity for slight damage, moderate damage, severe damage, and collapse are determined. Moreover, a mapping relationship between relative residual deformation and relative residual load-carrying capacity of RC piers with various axial compression ratios and impacted at different impact locations is established. A new damage assessment method for RC piers under impact load is proposed based on the mapping relationship. The research results indicate that RC piers subjected to impact at the mid-column position primarily exhibit flexural-shear failure, where as local shear failure predominantly occurs when the impact is at the column base. As the impact velocity and mass increase, the residual displacement increases significantly, while the residual bearing capacity decreases. The axial compression ratio within the range of 0.2 to 0.4 has a limited effect on the peak impact force and peak displacement but significantly affects the residual displacement when the impact occurs at the mid-column. When the mid-column region and the column base region are subjected to lateral impact, there exists an approximate linear relationship between relative residual deformation and relative residual load-carrying capacity, where the greater the relative residual deformation, the smaller the relative residual load-carrying capacity. Under equal conditions of relative residual deformation, the relative residual load-carrying capacity of column base impact is lower than that of mid-column impact, with a greater decrease in residual load-bearing performance. When the mid-column position and the column base position are subjected to lateral impact, there exists an approximate linear relationship between relative residual deformation and relative residual load-carrying capacity, such that the greater the relative residual deformation, the smaller the relative residual load-carrying capacity. Under conditions of equal relative residual deformation, the relative residual load-carrying capacity of the base-column impact is lower than that of the mid-column impact, with a more significant decrease in load-carrying capacity. The research findings could provide theoretical support for the impact resistance design and damage assessment of RC piers in practical engineering applications.