Progressive collapse investigation of buildings with concentric and eccentric braced frames using nonlinear procedure

These days a lot of dangers threaten the construction structures. Many abnormal loads are not considered in the design of structures. The column sudden removal can occur due to the errors during construction, explosion, shock or any other abnormal causes in the structure. If the structural response leads to a rebalance during the sudden column removal, this causes the structure to remain safe, and if the force balance is not created in the structure, it can cause Progressive Collapse (PC) in the structures. Structures are not designed toward PC scenarios, such as the sudden column removal. The assessment of structures behavior in PC scenario lead to a correct understanding about the resistance of structures in these scenarios. This research investigated the behavior and response of braced steel structures to the sudden column removal using the alternate load path method and nonlinear static and dynamic analysis. For this purpose, the 10 and 20-story structures were modeled nonlinearly by OpenSees software after the initial design and they are subjected under sudden column removal. Static and dynamic pushdown curves of the structures are considered as a criterion to assess the behavior of structures. The results showed that not only the type of braces is effective on the behavior and response of the structures during the PC scenario, but also the geometry of bracing in this scenario is.