Resistance of eccentric braced steel frames against progressive collapse and overload factor

Due to the possibility of sudden removal of the main structural members, which are the results of various reasons such as fire and explosion, it is required to reduce the damage as much as possible via a comprehensive understanding of the structural behavior affected by members' failure. The degree of damage directly depends on the type of lateral and gravity load resisting system. The present study intends to explore progressive failure in nine six-story five-bay steel frames with three types of eccentric braced frames. These braced frames were performed by nonlinear time history analysis. The structural behavior and failure progress against the omission scenario of column and braces with different arrangements were analyzed. Then, since the preliminary analysis cannot predict the residual strength of frames against progressive failure, vertical incremental dynamic analysis is utilized to determine the overload factor. The results of the analysis showed that the removal of the middle columns set the stage for more critical situation compared to the corner columns. Also, if the removal scenario occurs in the higher stories, the probability of starting failure from the braces will be more than that of columns.