Abstract: The numerical analysis model that considers the boundary condition of substructure was used, the deformation and damage of steel beam under blast loading were introduced into the anticollapse analysis of substructures, and the pressure- impulse curve plot and expression were established to evaluate the anti- collapse performance of steel frame beam- column substructures subjected to explosion. The parametric analysis was conducted out to investigate the effect of restraint stiffness and spandepth ratio. The results show that the arch action occurs at the first stage, then the flexural action works and the catenary action plays a key role finally. The reduction degree of anti-collapse performance of substructures may exhibit non- monotonic behavior as the intensity of the explosion increases. Except for the hinge joint, horizontalrestraint stiffness has a less effect on the development of the vertical resistance. The overpressure and impulse corresponded to the same index increases with the decrease of the span- depth ratio, but the substructure will trend to the shear deformation mode when the span depth ratio decreases to a low level, leading to the decrease of the ultimate deformation and maximum vertical resistance at the stage of catenary action stage.

Key words: blast, beam-column substructure, damage, anti-collapse performance, parametric analysis