Seismic Rehabilitation of Concentrically Braced Frames Using Stiff Rocking Cores
Publication: Journal of Structural Engineering
Volume 143, Issue 9
Abstract
Existing steel concentrically braced frame (CBF) buildings subjected to seismic hazards can exhibit an undesirable soft-story response, in which drift and damage are concentrated in a single story, whereas other stories remain relatively undamaged. This paper investigates the fundamental behavior and proposes a rehabilitative design procedure that uses a stiff rocking core (SRC) to redistribute lateral demands, thereby preventing soft-story response. The technique is relatively nonintrusive compared to traditional rehabilitative measures and can satisfy a maximum specified story drift for a given hazard level. Representative low-rise and midrise prototype CBFs are used to illustrate the fundamental mechanical and dynamic behavior of the SRC in support of the proposed rehabilitation design procedure. Results from nonlinear transient seismic analysis of both existing and SRC-rehabilitated CBFs are used to evaluate the SRC’s ability to improve the seismic performance of existing CBF structures. These results indicate that the SRC can be designed to prevent soft-story formation and, at the same time, achieve a target maximum interstory drift for a given seismic hazard.
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Acknowledgments
The research reported in this paper was supported by the U.S. National Science Foundation under Award Number CMMI-1134953. Any opinions, findings, conclusions, and recommendations presented herein are those of the authors and do not necessarily reflect the views of the sponsor.
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Information
Published In
Journal of Structural Engineering
Volume 143 • Issue 9 • September 2017
Copyright
©2017 American Society of Civil Engineers.
History
Received: Mar 17, 2016
Accepted: Feb 3, 2017
Published online: Apr 20, 2017
Published in print: Sep 1, 2017
Discussion open until: Sep 20, 2017
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