CFRP-Based Strengthening Technique to Increase the Flexural and Energy Dissipation Capacities of RC Columns
Publication: Journal of Composites for Construction
Volume 13, Issue 5
Abstract
A strengthening technique, combining carbon fiber-reinforced polymer (CFRP) laminates and strips of wet layup CFRP sheet, is used to increase both the flexural and the energy dissipation capacities of reinforced concrete (RC) columns of square cross section of low to moderate concrete strength class, subjected to constant axial compressive load and increasing lateral cyclic loading. The laminates were applied according to the near surface mounted technique to increase the flexural resistance of the columns, while the strips of CFRP sheet were installed according to the externally bonded reinforcement technique to enhance the concrete confinement, particularly in the plastic hinge zone where they also offer resistance to the buckling and debonding of the laminates and longitudinal steel bars. The performance of this strengthening technique is assessed in undamaged RC columns and in columns that were subjected to intense damage. The influence of the concrete strength and percentage of longitudinal steel bars on the strengthening effectiveness is assessed. In the groups of RC columns of 8 MPa concrete compressive strength, this technique provided an increase of about 67% and 46% in terms of column’s load carrying capacity, when applied to undamaged and damaged columns, respectively. In terms of energy dissipation capacity, the increase ranged from 40%–87% in the undamaged columns, while a significant increase of about 39% was only observed in one of the damaged columns. In the column of moderate concrete compressive strength (29 MPa), the technique was even much more effective, since, when compared to the maximum load and energy dissipation capacity of the corresponding strengthened column of 8 MPa of average compressive strength, it provided an increase of 39% and 109%, respectively, showing its appropriateness for RC columns of buildings requiring upgrading against seismic events.
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Acknowledgments
The writers wish to acknowledge the support provided by the “Empreiteiros Casais,” S&P, Secil (Unibetão, Braga). The study reported in this paper forms a part of the research program “Smart Reinforcement–Carbon fiber laminates for the strengthening and monitoring of reinforced concrete structures” supported by ADI-IDEIA, Grant No. UNSPECIFIED13–05-04-FDR-00031. The writers also wish to acknowledge the Erasmus Mobility Program between the University of Minho (Portugal) and University of Ferrara (Italy) which allowed the real possibility of this international cooperation.
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Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 13 • Issue 5 • October 2009
Pages: 372 - 383
Copyright
© 2009 ASCE.
History
Received: Sep 29, 2008
Accepted: Feb 12, 2009
Published online: Mar 6, 2009
Published in print: Oct 2009
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