Investigation of the occurrence of progressive collapse in high-rise steel buildings with different braced configurations

The progressive collapse phenomenon refers to a chain of damages in a structure where all or a large part of the structure is destroyed by an initial local collapse in it, which can lead to very disastrous results. Therefore, the prevention of progressive collapse has become a necessary action in the design and analysis of buildings and it is vital to investigate this topic more accurately. This study aims to present a proposed pattern in the configuration of braces at the height of a high-rise steel building for reducing the probability of progressive collapse. In this regard, the vertical displacement of 18-story structure with four scenarios of column removal and five concentric bracing patterns including V, Inverted V, X, discontinuous X-bracing at height, and a combination of X-bracing in the side spans and discontinuous X-bracing at height in the middle spans are investigated and compared. In this study, the Alternative Path Method (APM) is used based on the GSA guideline for the analysis of progressive collapse. The results of this research showed that the use of X-bracing in the side spans and discontinuous X-bracing in the middle spans in nonlinear static and dynamic analyses performed better in reducing the probability of progressive collapse than other bracing configurations. Finally, it is recommended to use discontinuous X-bracing at the height that would place the bracings in one direction and providing alternative paths for force transferring in the structure.