Seismic energy demands on steel framed structures with rigid and, alternatively, with post-tensioned semi-rigid connections

Normally, the aim of the semi-rigid posttensioned connections in steel frames is to dissipate energy and to avoid the damage in the main structure (i.e., avoid the damage in beams and columns). This type of structural system has been proposed recently as an alternative for controlling the structural damage and to improve the behavior of steel structures in seismic areas (Ricles et al., 2001, 2002, Christopoulos et al., 2002a, 2002b, Garlock et al., 2005, 2007, 2008). The frames with post-tensioned connections (FPC) are designed to prevent brittle fractures in the nodes areas of steel frames, which may cause reduction in the ductility capacity of the frame (as happened in many cases during the 1994 Northridge earthquake). The FPC frames are designed to provide capacity of self-centering of the frame, and at the same time to provide energy dissipation.