During a large earthquake, traditional seismic lateral resisting systems can experience significant damage distributed throughout the structural system, and residual drifts that make it difficult, if not financially unreasonable, to repair. A controlled rocking system has been devised which virtually eliminates residual drifts and concentrates the majority of structural damage in replaceable fuse elements. The controlled rocking system consists of three major components: 1) a stiff steel braced frame that remains virtually elastic, but is not tied down to the foundation and thus allowed to rock, 2) vertical post-tensioning strands that anchor the top of the frame down to the foundation, which brings the frame back to center, and 3) replaceable structural fuses that absorb seismic energy as the frames rock. This paper describes preliminary results from a half-scale test conducted at the University of Illinois at Urbana-Champaign. The experimental hysteretic response is compared to predictions made with a two-dimensional analytical model. The controlled rocking system exhibited excellent self-centering properties, and effectively concentrated the energy dissipation and structural damage in the replaceable fuse elements.
M.R. Eatherton J.F. Hajjar G.G. Deierlein H. Krawinkler S. Billington X. Ma
Ph.D. Candidate, Dept. of Civil and Env. Engrg.,University of Illinois at Urbana-Champaign, Illinois Professor, Dept. of Civil and Env. Engrg., University of Illinois at Urbana-Champaign, Illinois, U.S Professor, Dept. of Civil and Env. Engrg., Stanford University, California, U.S.A. Associate Professor, Dept. of Civil and Env. Engrg., Stanford University, California, U.S.A.. Ph.D. Candidate, Dept. of Civil and Env. Engrg., Stanford University, California, U.S.A.