عنوان مقاله [English]
The phenomenon of progressive collapse is very important in the management of structures as well as the discussions related to passive defense. Due to the increasing terrorist threats in recent decades and the prevalence of such issues, this phenomenon has become more pronounced. The soil-structure interaction is also a new science in civil engineering. The structure behavior changes due to interactions with the soil and the literature review reveals various methods that have been presented for modelling this phenomenon in recent years. The main problem of the present study is to determine the critical column in the phenomenon of progressive collapse in steel flexural frame by considering the effect of soil-structure interactions with both the direct and indirect methods. The phenomenon of progressive collapse in the present study has been done with the help of column deletion scenario. In addition, the effect of soil-structure interactions has been modeled using the two direct and indirect methods in both Sap and Plaxis software. The two-dimensional steel frames are made for 5, 10, 15 and 20 story structures and are analyzed by the nonlinear static analysis and examined by the corner and middle column removal scenario. Various parameters such as the coefficient of behavior, base shear, displacement of the operating point and top of the node displacement are removed and the expansion of plastic joints are proposed as evaluation indicators. The results of the present study shows that the corner columns are in a more critical condition and the effect of soil-structure interactions in the direct method is much more significant.