Analytical Development of A Plastic Hinge Detail for Steel SMFs

Abstract

A modular plastic hinge seismic special detail has been developed for use in steel special moment frames (SMFs). The aim of the special detail design is to dissipate seismic energy through stable yielding of a beam "link" in plastic hinge region. Reliable and repeatable energy dissipation at high ductility is assured through the elimination of weld failure modes, and the mitigation of local buckling and high multi-axis restraint. A casting process is used to configure the modular detail directly to meet these performance objectives. The primary features of the link region are an isolated flange with an integrally cast stiffener and a reduced section isolated web. Two forms of the detail exist: a plastic hinge modular node (PH-MN) and a bolted alternative, the bolted plastic hinge connector (BPHC). The PH-MN, a "node" occupying the entire beam-to-column joint, was used to develop the concept. The PH-MN configuration removes the field weld from the critical cross-section, reduces triaxiality and eliminates through-thickness failure modes at the beam/column interface. The BPHC preserves the primary features of the PH-MN and provides performance at nearly the same efficiency, but, as a replaceable field-bolted component, is significantly more economical, improves modularity, and has certain practical advantages. A design procedure was developed to create a family of modular designs.