The out-of-plane impact performances of reinforced concrete(RC)floor slabs strengthened with externally bonded steel plates were investigated in this paper,by means of explicit finite element method.In the numerical analysis,impact load was idealized as a triangular pulse,the rate effects of concrete and steel materials were taken into account by using dynamic increase factors,and no slips between concrete and reinforcement/steel-plates were considered for the sake of simplifying calculation.Failure modes and dynamic responses were simulated.Performances of the strengthened RC slabs were assessed,including impact stiffness and resistance.The parameters considered in the study consisted of the amount of steel plates,strengthening scheme,and location of steel-plate bonding.Meanwhile,different height of explosion was also taken into account.The results indicate that the bonded steel plates can enhance the impact stiffness and resistance of RC slabs,these aforementioned factors have significant influences on the impact performances of RC slabs strengthened with externally steel plates.