Numerical Investigation of Axial Force–Bending Moment Interaction for FRP-Confined Reinforced Concrete Columns with Internal Steel Transverse Reinforcement
Publication: Journal of Composites for Construction
Volume 27, Issue 2
Abstract
Externally bonded fiber-reinforced polymer (FRP) laminates are widely used in the retrofitting and rehabilitation of reinforced concrete (RC) columns because they can increase the axial and bending moment capacities of these columns through a confinement mechanism. The confinement produced by FRP laminates acts in addition to that exerted by the internal transverse steel, although the latter is often neglected in current design standards and guidelines. In this study, a recently developed FRP-and-steel-confined concrete constitutive model was employed to numerically investigate the axial force–bending moment interaction for FRP-confined RC columns modeled using finite-element (FE) analysis. The proposed model was first validated against experimental data available in the literature and then used to quantify, through an extensive parametric study, the effects of transverse steel confinement, FRP strength, FRP stiffness, FRP reinforcement ratio, column diameter, concrete compressive strength, and load eccentricity ratio on the strength of FRP-confined RC columns subject to combined axial compression and bending moment. It was found that the internal steel confinement can substantially enhance the strength of these columns, especially for low concrete compressive strengths, large cross sections, and small eccentricities. When design code provisions limiting concrete and FRP deformations were considered for eccentrically loaded columns, the contribution of the steel confinement increased for increasing FRP reinforcement ratio. Based on the parametric study results, this investigation proposed an extension to eccentric axial compression of two relative confinement coefficients, which were previously developed to describe the contribution of transverse steel confinement to the peak strength of FRP-confined RC columns subject to pure compression.
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Acknowledgments
The authors gratefully acknowledge partial support to this research by the Brazilian National Council for Scientific and Technological Development (CNPq—Brazil). Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the writers and do not necessarily reflect the views of the sponsors.
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© 2023 American Society of Civil Engineers.
History
Received: May 20, 2022
Accepted: Nov 18, 2022
Published online: Jan 24, 2023
Published in print: Apr 1, 2023
Discussion open until: Jun 24, 2023
ASCE Technical Topics:
- Columns
- Compressive strength
- Concrete
- Concrete columns
- Engineering materials (by type)
- Fiber reinforced concrete
- Fiber reinforced polymer
- Material mechanics
- Material properties
- Materials engineering
- Polymer
- Reinforced concrete
- Steel columns
- Strength of materials
- Structural behavior
- Structural engineering
- Structural members
- Structural strength
- Structural systems
- Synthetic materials
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