New Method of Strengthening Reinforced Concrete Square Columns by Circularizing and Wrapping with Fiber-Reinforced Polymer or Steel Straps
Publication: Journal of Composites for Construction
Volume 17, Issue 2
Abstract
This study investigates three methods of strengthening existing reinforced square concrete columns under different loading conditions. Four groups of sixteen reinforced concrete square columns were made from normal-strength concrete. Reinforcement was kept at minimum ratio, simulating columns that need retrofitting. Columns of the first group were reference columns (Group N), while the corners of the second group columns (Group RF) were rounded and wrapped with three layers of carbon-fiber-reinforced polymers (CFRPs). The sides of the columns of the third group (Group CF) were bonded with four pieces of concrete with a segmental circular shape, thus changing the cross section of the column from a square to a circle before each column was wrapped with three layers of CFRP. The columns of the last group (fourth) were modified as the third group to result in a circular cross section, but were confined with steel straps. Results from the study showed that all confinement methods increased the capacity and ductility of columns. In particular, segmental circular concrete covers dramatically reduced the stress concentration at the corners and increased confinement efficacy. The interaction (–) diagrams of experimental results and theoretical analysis all confirmed high performance of groups RF and CF.
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Acknowledgments
The authors would like to acknowledge Ph.D. Scholar Mr. Ida Bagus Rai Widiarsa, who designed the loading heads that were used in the experimental program, and Mr. Frank Crabtree, technical officer at the High Bay Laboratory, who constructed the loading heads. Furthermore, the contribution of Mr. Fernando Escribano, the main technical officer of this study, is appreciated. Finally, the second author would like to acknowledge the Vietnamese Government for the support of his full Ph.D. scholarship.
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© 2013 American Society of Civil Engineers.
History
Received: Feb 13, 2012
Accepted: Sep 21, 2012
Published online: Sep 23, 2012
Published in print: Apr 1, 2013
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