A plasticity-based approach has been proposed for reinforced concrete (RC) subjected to impact and blast loading. The proposed approach includes a new failure surface together with modified descriptions related to equation of state, strain rate effect and damage taken from literature. These selective descriptions in numerical analysis have been found to give better results than the existing models. A user-defined UMAT subroutine for the commercial software LS-DYNA has been developed for the proposed model. Dynamic analysis for both blast and impact type of loading on RC slabs are performed. The results are compared with an in-built material model in commercial software LS-DYNA, namely the Winfrith concrete model (WCM) and with experimental results taken from literature. A parametric study is carried out by analyzing the mechanical and damage response by varying parameters such as concrete strength, slab thickness and reinforcement ratio. The proposed approach is found to be effective in predicting the behavior under both impact and blast analysis. © 2020 World Scientific Publishing Company.