Effects of earthquake characteristics on seismic progressive collapse potential of steel moment-resisting frames equipped with gate bracing

The progressive collapse in building frames refers to the spread of an initial localized chain collapse in all or some parts of the structure. This phenomenon occurs following the removal of one or more load-bearing elements and eventually leads to the total or partial collapse of the structure. In previous studies, the progressive collapse has been analyzed mainly using the method proposed in building codes under gravitational loading with a defined load combination. This study aims to investigate the progressive collapse of steel moment-resisting frames equipped with gate (hat) bracing under seismic loading. For this purpose, the effect of the seismic properties of the acceleration records such as peak ground acceleration (PGA), Arias intensity, frequency content, and a vertical component are examined, following the introduction of several acceleration groups. Next, progressive collapse analysis with side and middle column removal is simulated under various scenarios during an earthquake. The results showed a high effect of about 66% PGA and predominant period on frame responses and, at the same time, a slight effect of the vertical component application on frame responses.