Effect of Untreated Surface Disbonds on Performance of FRP-Retrofitted Concrete Beams
Publication: Journal of Composites for Construction
Volume 13, Issue 6
Abstract
Retrofitting concrete structures with externally bonded fiber-reinforced polymer (FRP) laminates has become an increasingly common practice. Disbonds at the concrete-FRP interface, if left untreated, may adversely affect the performance of the retrofitted system. Disbonds in the form of surface voids and cracks are the subject of this paper. Voids may occur due to poor compaction or defective formwork, or in the form of air entrapment between resin and FRP laminate during application. Cracks, on the other hand, generally result from loading. This study is comprised of a detailed experimental program and a nonlinear finite-element analysis. In the experiments, surface cracks were simulated by cutting slits in concrete, herein termed as surface cuts. The study shows that leaving surface disbonds untreated, within the considered range of disbond variables, does not have a significant impact on the overall structural performance. A threshold of 12.7 mm for void diameter was deemed conservative for structural performance. On the other hand, 38 mm spacing was considered an appropriate threshold for epoxy injection in crack widths between 0.25 and 0.8 mm. Hence, conservative thresholds in current practice may be revised accordingly, unless considered necessary to avoid environmental effects.
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Acknowledgments
This study was sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration, conducted as part of the National Cooperative Highway Research Program (NCHRP) Grant No. UNSPECIFIED10-59B, administered by the Transportation Research Board of the National Research Council, Senior Program Officers, Mr. David Beal, and Dr. Amir Hanna. The tests were carried out at the Structures and Construction Laboratory of the Florida International University. The contributions of the subconsultants, Dr. Mohsen Shahawy, Dr. Vistasp Karbhari, and Dr. Antonio Nanni is greatly acknowledged. The writers are also grateful to Sika Corp. and Hughes Brothers, Inc. for providing some of the materials for the tests. Findings and opinions expressed here, however, are those of the writers alone, and not necessarily the views of the sponsoring agencies.
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Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 13 • Issue 6 • December 2009
Pages: 476 - 485
Copyright
© 2009 ASCE.
History
Received: Aug 2, 2008
Accepted: Feb 24, 2009
Published online: Nov 13, 2009
Published in print: Dec 2009
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