Behavior of post-tensioned connections with stiffened angles under cyclic loading

Post-tensioned (PT) connections are used in steel moment resisting frames to eliminate structural damage and minimize residual drifts under seismic loads. A steel post-tensioned connection with top and seat angles has recently been developed. The angles act as energy dissipation devices in PT connections. In this research, stiffeners are added to the top and seat angles to improve the energy dissipation capacity of post-tensioned connections. Numerical analysis is performed and some relations are proposed to predict the behavior of post-tensioned connections with stiffened angles. The analysis results show that adding stiffeners to the connection angles increases the connection resistance at high inter-story drift angles. Moreover, stiffeners help concentrating the more residual deformation in the top and seat angles and increase the energy dissipation capacity of the connection. According to the results, we obtain modification factors as a function of angle and stiffener geometry in derived relations to predict the total connection moments under applied loading.