Finite element models and cyclic behavior of self-centering steel post-tensioned connections with web hourglass pins

A new self-centering steel post-tensioned connection has been proposed by the authors. The connection uses high-strength steel post-tensioned bars to provide self-centering behavior and steel energy dissipation elements that consist of cylindrical pins with hourglass shape to provide enhanced deformation capacity. Large-scale experimental tests showed that the connection has robust self-centering behavior by eliminating residual drifts and beam damage for drifts lower or equal to 6%. This paper presents finite element models which can be used to reliably assess the design and behavior of the connection. A simplified connection model was first developed using simple mechanics. This model can predict the connection stiffness and strength with reasonable accuracy, and enables the preliminary design of self-centering steel moment-resisting frames using the proposed connection. A detailed nonlinear finite element model was also developed. This model was calibrated against experimental results and found capable to trace the nonlinear cyclic behavior of the connection and capture all possible local failure modes. The calibrated finite element model was used to conduct a series of simulations to study the effect of different parameters on the connection behavior. The parameters studied include the adopted design procedure, beam reinforcing detailing, and the beam and column section sizes.