The differences in the responses of square steel plates subjected to blast loads of cubic and spherical charge explosions were investigated in the study. A finite element model (FEM) was developed by LS-DYNA, and the FEM was validated by experiment and UFC 3-340-02. Based on the validated numerical model, the incident and reflect loads of cubic and spherical detonations were compared. In the x-z plane, the incident pressures of cubic explosives are observed to be concentrated in the x and z directions while that of spherical charges are uniform in all directions. Furthermore, cubic explosives have substantially higher normal reflect pressures than spherical charges. For square steel plates, the results indicate that cubic explosives can produce more significant deformations and plastic damage than spherical explosives. Moreover, quantification metrics was proposed to assess the differences in responses of steel plates subjected to blast loads of cubic and spherical explosives. The ratios of average maximum displacement (D-am) under cubic and spherical charge detonation were analyzed, as well as the ratio of average residual displacement (D-ar). Equivalent coefficient (zeta) was defined to equate a cubic explosive to a spherical explosive. Finally, a damage number for steel plates subjected to blast loads was presented. The relationships between damage number and displacements were created. The damage number and displacements have linear correlations. Moreover, the displacement ratios of steel plates under blast loads of cubic and spherical explosives can be approximated by using the damage number. The damage number can also be used to approximately derive the equivalent coefficients.
