Analysis of RC Hollow Columns Strengthened with GFRP
Publication: Journal of Composites for Construction
Volume 15, Issue 4
Abstract
Reinforced concrete (RC) hollow piers in bridges withstand high moment and shear demands ensured with reduced mass and lower stress on foundations compared with solid piers. Failure of hollow columns is typically affected by premature buckling of reinforcing bars and concrete cover spalling. At present, no guidelines are available for the design of their upgrade, and few research investigations can be found on hollow columns strengthened by using fiber-reinforced polymer (FRP) materials. This paper discusses an experimental program carried out on purely compressed RC hollow columns externally wrapped with glass-fiber-reinforced polymer (GFRP). Three specimens were tested: one specimen was unstrengthened and used as the benchmark; the other two specimens were GFRP-wrapped with different confining reinforcement ratios. Each specimen was designed according to dated codes (i.e., prior to 1970) accounting only for gravity loads. In particular, steel longitudinal bars cross section and steel tie-spacing were designed with the minimum amount of longitudinal reinforcement and minimum tie area at maximum spacing. Tests results highlight that the GFRP-jacket mainly provided ductility increases before low strength increments could be obtained. Refined and simplified numerical models for hollow square RC columns, previously proposed by the authors, herein extend to hollow rectangular members. Comparisons of experimental results and theoretical predictions on the basis of both refined and simplified confinement models were performed and showed good agreement. In the case of the simplified model, a value for the effective ultimate FRP strain was suggested.
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Acknowledgments
The writers gratefully acknowledge the support of the NSF Industry/University Cooperative Research Center for “Repair of Buildings and Bridges with Composites”NSF (RB2C) at the University of Miami, the support of the “REte dei Laboratori Universitari di Ingegneria Sismica” (RELUIS) at the University of Naples “Federico II,” and the support of Mapei S.p.A.
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© 2011 American Society of Civil Engineers.
History
Received: Jul 14, 2010
Accepted: Nov 15, 2010
Published online: Nov 17, 2010
Published in print: Aug 1, 2011
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