In this study, the behavior of two buildings designed with steel structures Buckling Restrained Braced (BRB) and conventional bending frame was studied to analyze their strengths against progressive collapse. The structures were designed and analyzed in accordance with Iranian regulation No. 2800 for the design of buildings. Using nonlinear static pushover analysis, the performance of the structure after removal of the center and the corner columns were investigated and it was demonstrated that removing the corner column provides more critical conditions for the investigated buildings. Furthermore, the use of BRB elements provides better performance for the analyzed buildings due to the ability of BRB in absorbing and dissipating more energy induced from the external loading sources like the earthquake.