Abstract: Six normal and high-strength reinforced concrete slabs were subjected to simulated blast loading using a Blast Loading Simulator at the U.S. Army Corps of Engineers, Engineering Research and Design Center. A blind prediction contest was sponsored to evaluate the effectiveness of various modelling approaches to predict the blast response of the normal and high-strength concrete slabs. This paper describes a contest submission in the single-degree-of-freedom (SDOF) category generated using software program RCBlast. RCBlast was developed to perform inelastic analysis of structural members subjected to blast-induced shock waves. The program uses a lumped inelasticity approach to generate resistance functions for SDOF analysis. Incorporated into the development of the resistance functions were: material models and dynamic increase factors (DIF) appropriate for normal and high-strength concrete and steel reinforcement; member modelling capable of describing the gradual formation and progression of plastic behavior, and; hysteric modelling to account degradation in stiffness and energy dissipation.