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The purpose of this paper is to determine the failure progression resistance of the steel moment-resisting frames subjected to various beam-removal scenarios after application of the design earthquake pertinent to the structure by investigating a generic eight-story building.

The structure is first pushed to arrive at a target roof displacement corresponding to life safety level of performance. To simulate the post-earthquake beam-removal scenario, one of the beam elements is suddenly removed from the structure at a number of different positions. The structural response is then evaluated by using nonlinear static and dynamic analyses.

The results show that while no failure is observed in all of the scenarios, the vulnerability of the upper stories is much greater than that of the lower stories. In the next step, the structural resistance to such scenarios is determined. The results confirm that for the case study structure, at most, the resistance to failure progression in upper stories is 58 percent more than that of lower stories.

Failure and fracture of beam-to-column connections resulting in removal of beam elements may lead to a chain of subsequent failures in other structural members and eventually lead to progressive collapse in some cases. Deficiency in design or construction process of structures when combined by application of seismic loads may lead to such an event.

Post-earthquake fire (PEF) can lead to a rapid collapse of structures partially damaged by earthquake. As there is almost no established PEF provisions by codes and standards, PEF investigations are therefore needed for those buildings. The paper aims to discuss these issues.

A non-linear PEF analysis comprises three steps, which are the application of gravity loads, earthquake loads and then fire loads. As a fire generally initiates on one floor and then spreads to other floors, applying a sequential fire is more realistic than applying a concurrent fire on several floors. Hence, in this study, the fire is applied sequentially to the floors with a time delay.

The results indicate a substantial reduction in the resistance of the damaged frame when subjected to PEF. In addition, the results of applying the PEF sequentially is more realistic than the concurrent fire.

It was better to perform an experimental test to have a better understanding of the issue.

PEF can potentially result in a catastrophe in areas located in seismic regions. Thus, investigating the effect of PEF on previously damaged structures is of importance.