Transforming Seismic Performance of Deficient Steel Concentrically Braced Frames through Implementation of Rocking Cores

Abstract

The use of steel concentrically braced frames (CBFs) has substantially increased recently. However, investigations and observations from past earthquakes suggest that some existing CBFs, particularly the older ones that are still in service but were designed without ductile detailing and compliance with state-of-the-art seismic provisions, may exhibit unfavorable performance during strong earthquake events. This research numerically examines the adequacy of a seismic rehabilitation technology for deficient multistory CBFs. The technology consists of one or multiple rocking cores (RCs) added to an existing CBF to redistribute the seismic forces applied to the frame and reduce the system seismic response. For demonstration purposes, one three-story and one six-story CBF buildings are selected and rehabilitated using the RC technology. Finite-element (FE) models of the considered systems, which explicitly take into account the effect of gusset plates, member yielding, brace buckling, brace rupture, and the