Can Strengthening for Earthquake Improve Blast and Progressive Collapse Resistance?
Publication: Journal of Structural Engineering
Volume 131, Issue 8
Abstract
Some engineers suggest that current seismic design provisions, both for new buildings and for strengthened existing buildings, can improve resistance to blast loads and progressive collapse. However, there have been few attempts to quantify such improvement. To begin analyzing this possible relationship between seismic detailing and blast and progressive collapse resistance, the Federal Emergency Management Agency of the Department of Homeland Security sponsored a study at the U.S. Army Engineer Research and Development Center. The study was an analysis of the Alfred P. Murrah Federal Building, which was severely damaged in a 1995 terrorist attack. The building was first evaluated for seismic vulnerabilities as if it were located in a seismically active region. Three strengthening schemes were then designed for the vulnerabilities found during the evaluation: a pier-spandrel system and a new special concrete moment frame, both for the street face of the building, and a set of internal shear walls. In addition to these strengthening schemes, the original ordinary concrete moment frame on the street face of the building was redetailed to bring it into compliance with current building code provisions, without including a lateral load analysis. The three strengthening schemes and redetailed frame were then analyzed for their responses to the same explosion that occurred in 1995. Blast and corresponding progressive collapse analyses showed that the pier-spandrel and special moment frame schemes, as well as the redetailed original system, reduced the degree of direct blast-induced damage and subsequent progressive collapse, compared with the behavior of the original building. Internal shear walls, however, were not as effective in reducing the blast and progressive collapse damage. A key finding of the study was that strengthening the perimeter elements using current seismic detailing techniques improved the survivability of the building, while strengthening elements internal to the building envelope was not nearly as effective in reducing damage.
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Acknowledgments
The work presented in this paper is jointly sponsored by the Federal Emergency Management Agency (FEMA) of the Department of Homeland Security (DHS) and the U.S. Army Corps of Engineers (USACE), Engineer Research and Development Center (ERDC). However, this paper and its conclusions represent the writers’ views and do not necessarily represent the views of FEMA, the DHS, or the USACE. The writers gratefully acknowledge the guidance and feedback provided by the project sponsors at FEMA, Mr. Mike Mahoney and Dr. Robert Hanson. The writers also sincerely appreciate the impetus provided by Mr. Ugo Morelli of FEMA, who retired in early 2003, for initiating the project. The writers also appreciate the willing assistance provided by Mr. Bela Palfalvi of the General Services Administration, and Mr. Paul Kirkpatrick, the structural engineer of record for the original Murrah building, for providing as-built drawings of the Murrah Building for use in this study. The writers also acknowledge with appreciation the assistance provided by Mr. Chad Schrand, a graduate student assistant at the University of Illinois at Urbana-Champaign, and Mr. Larry Wong and Ms. Taryn Williams of Degenkolb Engineers.
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Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 131 • Issue 8 • August 2005
Pages: 1157 - 1177
Copyright
© 2005 ASCE.
History
Received: Feb 2, 2004
Accepted: Jun 10, 2004
Published online: Aug 1, 2005
Published in print: Aug 2005
Notes
Note. Associate Editor: Barry Thomas Rosson
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