Abstract: In order to investigate the effects of strain rate and inertia on the behaviour of slender RC columns subjected to dynamic concentric compressive loadings, experimental study and finite element analysis on slender RC columns under concentric rapid loading were carried out. A total of 6 specimens with slenderness ratios of 12 and 22 were tested dynamically with a strain rate at the order of . The experimental results indicate the axial compressive load-carrying capacity and the corresponding axial deformation increase obviously under axial rapid loading compared with the case under quasi-static loading, and the dynamic increasing factor increases with the increase of the slenderness ratio. By introducing the uniaxial stress-strain relation considering strain rate effect of concrete in CEB-FIP Model Code to the concrete damaged plastic model, an explicit dynamic finite element analysis model was established in ABAQUS to predict the behaviour of slender RC columns subjected to dynamic axial loadings and validated by comparing the simulated results with the experimental results. Finally, the mechanism for dynamic increase in strength of slender RC columns under axial rapid loading was investigated by using the validated numerical model. Results indicate that for RC columns with small slenderness ratio, the inertial effect can be neglected and the increase in strength can be described mainly by the strain rate effect. With the increase of slenderness ratio, the inertial effect becomes more dominant and may play key roles in strength increasing, and the strain rate effect is still non-negligible.