One-Way Shear Strength of FRP–Reinforced Concrete Members Without Stirrups: Design Provision Review
Publication: Journal of Composites for Construction
Volume 25, Issue 3
Abstract
The American Concrete Institute recently updated their one-way shear provisions for steel–reinforced concrete (RC), and it is time to consider updating provisions for one-way shear in fiber-reinforced polymer (FRP)-reinforced concrete (FRP–RC). The shear strength of FRP–RC is lower than steel–RC mainly because FRP, particularly glass–FRP, has a much lower modulus of elasticity than steel. This study evaluates the performance of current design provisions at predicting the one-way shear strength of RC members without stirrups that are internally reinforced with longitudinal FRP bars, based on 147 tests available in the literature. Further, shear parameter effects (concrete strength, size effect, span to effective depth ratio, modulus of elasticity, and longitudinal reinforcement ratio) were also investigated. One-way ANOVA analysis was used to classify each provision, and results show that the codes, standards, and guidelines are identified as more consistent groups compared with the proposed models. The method proposed in the CSA S806-12 standard is the most consistent of the studied approaches at predicting the shear strength of the tested members with a mean predicted-to-experimental strength closest to one and the minimum average absolute error.
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Acknowledgments
The authors gratefully acknowledge the Hadhramout Foundation, which supplied the first author during his PhD program.
Notation
The following symbols are used in this paper:
- Af
- area of FRP flexural tension reinforcement (mm2);
- a
- shear span (mm);
- ag
- nominal maximum size of coarse aggregate (mm);
- bw
- member effective shear width (mm);
- c
- neutral-axis depth for a cracked transformed section (mm);
- d
- effective depth to the centroid of tensile reinforcement (mm);
- dv
- effective shear depth (mm);
- Ec
- modulus of elasticity of concrete (MPa);
- Ef
- modulus of elasticity of FRP reinforcement (MPa);
- Es
- modulus of elasticity of steel reinforcement (MPa);
- cylinder compressive strength of concrete (MPa);
- fcr
- concrete cracking strength (MPa);
- cube compressive strength of concrete (MPa);
- h
- overall member thickness (mm);
- k
- ratio between the depth of the neutral axis of the cracked transformed section and the tensile reinforcement effective depth, d;
- km
- moment–shear interaction factor;
- kr
- reinforcement stiffness factor;
- ks
- size effect factor;
- Mu
- factored moment (Nmm);
- nf
- ratio of modulus of elasticity of FRP bars to modulus of elasticity of concrete;
- sze
- effective crack spacing for members without stirrups (mm);
- Vc
- one-way shear resistance provided by concrete and FRP flexural reinforcement (kN);
- Vu
- factored shear (N);
- Vexp.
- experimental shear strength (kN);
- Vpredicted
- predicted shear strength (kN);
- β
- factor used to account for shear resistance of cracked concrete;
- βd
- size effect factor;
- βp
- axial stiffness factor;
- γb
- member safety factor;
- γd
- size effect factor;
- ɛx
- longitudinal strain at mid-depth of the cross section;
- ρf
- longitudinal FRP reinforcement ratio;
- τRd
- design shear stress (MPa);
- λ
- concrete density factor;
- ϕc
- material reduction factor for concrete;
- compression zone stress (MPa);
- θc
- inclined crack angle in the compression zone; and
- ξ
- combined size and slenderness factor.
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Published In
Journal of Composites for Construction
Volume 25 • Issue 3 • June 2021
Copyright
© 2021 American Society of Civil Engineers.
History
Received: May 8, 2020
Accepted: Feb 19, 2021
Published online: Mar 25, 2021
Published in print: Jun 1, 2021
Discussion open until: Aug 25, 2021
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