Relations between the explosive demolition design variables and progressive collapse resisting capacity of RC frame structures

Progressive collapse is the partial or entire collapse of structures caused by the local damage of structural members arising from an abnormal load such as impact or explosion. Explosive demolition is a method to induce progressive collapse of the whole structure by removing primary structural members through blasting. Unlike progressive collapse, the explosive demolition induces progressive collapse of the structure by controlling the local damage of structural members at appropriate delay time. In this study, the progressive collapse resisting capacity depending on the number of floors in the structure, height of column at the target floor for blasting, and changes in the span length among the explosive demolition design variables of RC frame structure was evaluated. The final collapse pattern of each analysis model with vertical and free fall displacements applied to the direct top elements of the removed columns were analyzed using the AEM (Applied Element Method) based ELS (Extreme Loading for Structures) software. Also, the vertical displacement applied to the direct top elements of the removed columns was compared with the vertical internal force applied to the adjacent columns. The normal stress of reinforcing bar acting on as per time between the girders, which are the removed columns and adjacent columns, and the adjacent column connections were compared, and the progressive collapse resisting capacity by the catenary action was analyzed.