AbstractA common approach of blast-resistant design for external detonation is to design the envelope of a structure to absorb most of the applied blast load impulse, by exploiting the mechanisms of plastic energy absorption and inertial resistance, thus minimizing damage on the supporting structure. The influences of these two mechanisms on the response of the supporting structure are investigated in the present study through a dimensionless, two-degree-of-freedom (2DOF) model representing the cladding (first DOF) and the supporting structure (second DOF). The 2DOF model is validated with nonlinear dynamic finite element analyses of a specific cladding-to-framing system and by comparing 2DOF results with experimental and analytical results found in the literature. Using the validated 2DOF model, the effects of the cladding’s mass, stiffness, ultimate resistance, and ductility are explored with parametric studies for a wide range of parameters. The differentiating factors between the corresponding spectrum regimes (impulsive, dynamic, and quasistatic), where the two mechanisms are activated, are thoroughly examined, and their limits are highlighted. It is shown that the plastic energy absorption mechanism is activated in specific spectrum regimes, through low yield strength and high ductility in the cladding, whereas the inertial resistance mechanism can be activated over the entire spectrum, by applying increased mass and/or low stiffness to the cladding.