ABSTRACT

A new type of seismic steel moment resisting frame (MRF) making use of post-tensioning has recently been proposed as an alternative to welded MRFs. Results from previous studies on the hysteretic characteristics of these connections, and of frame systems incorporating these connections are briefly presented. The seismic responses of idealized single degree-of-freedom oscillators exhibiting the flag-shaped and elastoplastic hysteresis are also presented. The study is then extended to multi-degree-of-freedom frame systems by comparing the response of traditional welded MRFs designed according to current building code requirements to that of MRFs incorporating PTED connections under design level earthquakes. Results show the improved response of the PTED frames, which undergo similar maximum deformations as the welded MRFs while limiting residual deformations only to the base of the first story columns. The traditional MRFs suffered significant inelastic and permanent deformations throughout the height of the buildings.