Slender RC Columns Strengthened with a Novel Hybrid Strengthening System of External Longitudinal and Transverse FRPs
Publication: Journal of Structural Engineering
Volume 147, Issue 10
Abstract
In this study, the performance of slender circular concrete columns strengthened with a novel hybrid system of longitudinally bonded prefabricated fiber-reinforced polymer (FRP) laminates and transverse FRP wrapping is investigated. The novelty of the hybrid system is to improve the load-carrying capacity of slender steel-reinforced concrete (RC) columns under eccentric axial compression by providing high modulus longitudinal carbon FRP (CFRP) laminates through enhancing the flexural stiffness of the slender column and to laterally support the longitudinal laminates by FRP wraps to prevent debonding and local buckling. A total of 6 large-scale circular slender RC columns with a diameter of 260 mm and a length of 3,048 mm were tested under combined axial and flexural loads. The results showed that, for the strengthening of the slender columns, the hybrid system is a more effective strengthening system than wrapping controlling second-order deformations due to the slenderness effect and enhancing the load-bearing capacity. Also, the performance of the system was further investigated using an analytical-numerical model considering the second-order deformations of the slender columns. The model considered nonlinearity in material and confinement effects plus the geometrical nonlinearity via an iterative second-order analysis. The model was verified against experimental data from the current study (hybrid system) and an independent study (wrapping system) and showed a good agreement with the test results. Then, a comprehensive parametric study was conducted to study the effect of various parameters including slenderness ratio, load eccentricity, longitudinal and transverse FRP reinforcement ratios, concrete strength, and column diameter on the performance of slender RC columns strengthened with the hybrid system. It was found that the hybrid strengthening system was more effective for RC columns with high slenderness ratios, high load eccentricities, and low concrete strength.
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Data Availability Statement
Some or all data, models, or code generated or used during the study are available from the corresponding author by request (including test data).
Acknowledgments
The authors would like to thank Jordan Maerz and Brian Kennedy for their assistance in the lab. Also, the author would thank Raghad Kassab and Aidan McCracken for performing material tests for CFRP- and GFRP-wrapped coupons. The authors would also like to acknowledge and thank NSERC and Dalhousie University for their financial support.
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Published In
Journal of Structural Engineering
Volume 147 • Issue 10 • October 2021
Copyright
© 2021 American Society of Civil Engineers.
History
Received: Aug 21, 2020
Accepted: Jun 2, 2021
Published online: Jul 31, 2021
Published in print: Oct 1, 2021
Discussion open until: Dec 31, 2021
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