Abstract
Throughout this paper, the progressive collapse of steel structure with dual system is studied by considering the removing column scenario. Due to this objective, two lateral load resisting systems are modeled in ABAQUS software with omitting various columns, and the performance of systems against progressive collapse are compared with each other. The results of performed finite element simulations represent that whenever a structure is experiencing an unusual external load such as collision of a vehicle, the most critical columns are those placed at the nearest external frame of the structure. Thus, these members should be considered as highly important members because they could play a significant role in progressive collapse potential reduction as key members.