Numerical Investigation on the Cyclic Behavior of Post-tensioned Steel Moment Connections with Bolted Angles

Post-tensioned (PT) steel frames have recently been introduced to resist lateral load and to provide self-centering capability. In these frames, high strength steel strands that run parallel to the beam web, have been used to provide moment resisting and restoring force. Also, the top and seat angles have been used to provide suitable energy dissipation capacity. In this paper, ten interior connections of these frames are designed such that we could numerically investigate the effects of angle and strand parameters on their stiffness, moment and energy dissipation capacity, as well as on their self-centering capability. Also, it is aimed to determine the effects of angle parameters on the amount and distribution of plastic deformation in the column and beams. To validate the numerical results, two of these specimens are considered to be the same as experimentally tested PT connections that are available in the literature. The results showed that our numerical results are in good agreement with the experimental ones. Also, PT connections will have appropriate strength and stiffness along with excellent energy dissipation capacity and ductility, if the number of strands and angle thickness be chosen properly. In story drifts corresponding to the design based earthquake, the column and beams are remain elastic and the PT connection returns to its plump position after unloading (self-centering capability). Upon applying a story drift corresponding to the maximum considerable earthquake, these connections are able to retain their special characteristics (such as self-centering capability and ductility). At this story drift, minor yielding occurs in the column panel zone and in the beams at the end of reinforcing plates.