عنوان مقاله [English]
In this paper, performance of steel moment frame connections is investigated under different cyclic loadings. Three moment frame connections representing light, medium, and heavy connections are modeled in a finite element program. Light, medium, and heavy connections are adopted from existing structural designs of seven, twelve, and twenty story buildings, respectively. The models are loaded with different cyclic loading protocols, and their behavior and capacity parameters are examined and compared. These connections are analyzed under SAC basic, SAC near-field, FEMA, and ATC loading protocols, in addition to a monotonic loading. Deformation capacities are assessed at two strength loss levels of 80% and 50%, for different loading protocols. In addition to strength capacity, the failure mode and equivalent plastic strain of each connection are investigated at the target rotation point (0.04 radian) and during failure.Connections that are subjected to SAC loading protocols experience demands that are in good agreement with target values of the loading protocol, and these connections show the ability to bear larger rotations. Furthermore, these connections have greater strength capacities in comparison with connections loaded by other protocols. ATC and FEMA loading protocols impose larger demands on the connections, and result in lower capacity parameters in comparison with other protocols. Due to the direct influence of loading time history on the imposed equivalent plastic strain, the connections undergo different levels of equivalent plastic strain. Moreover, the connections that are studied under near-field loading history show a strength capacity close to connections that are subjected to monotonic loading.Finally, a novel loading protocol is developed, according to the target values of loading time history, and considering the fact that in an earthquake, cycle numbers with small deformation ranges are more than cycles with large deformation ranges. Connections subjected to the proposed loading show an increase in deformation capacity and strength capacity parameters.