The equivalent viscous damping (EVD) ratio is a crucial parameter in the application of the displacement based method. Previous works have correlated the EVD ratio as a function of the displacement ductility level based on the hysteretic response of reinforced concrete members subjected to blast loads. Furthermore, the displacement response factor (DRF) for blast loads was proved as a function of the EVD ratio and the ratio of impulse duration to the natural period. The explosive charge weight and stand-off distance required to impose a given damage level were predicted by the DBD method based on these research results. In order to examine the feasibility of assessing the blast-resistant capacity of concrete (RC) slabs using the displacement based design (DBD) method. A RC slab was tested under real blast loads in the out-of-plane direction. Test results showed that the blast loads were effectively estimated and the damage levels observed from the field tests correlated well with the predicted levels.