Performance of GFRP-Reinforced Concrete Circular Short Columns under Concentric, Eccentric, and Flexural Loads
Publication: Journal of Composites for Construction
Volume 24, Issue 5
Abstract
This paper presents test results of seven large-scale circular concrete columns reinforced with either steel or glass fiber-reinforced polymer (GFRP) reinforcement. The columns measured 355 mm in diameter and 1,750 mm in length and were tested to failure under concentric, eccentric, or four-point bending configuration. Test parameters included the reinforcement type (GFRP and steel), the GFRP spiral pitch (50 and 85 mm), and varying ratios of eccentricity-to-column diameter (e/D = 0, 0.085, 0.17, and 0.34). The obtained axial capacity of the GFRP-reinforced concrete (RC) column was approximately 17% less than that of the steel-RC counterpart. However, for e/D = 0.085, the GFRP-RC column with a lesser spiral pitch exhibited approximately 10% more axial capacity than the column with a larger pitch. As the e/D ratio increases from 0 to 0.34 the axial capacity reduced by 32%, 39%, and 70% from the axial capacity of the concentric column. A “knee”-shaped interaction diagram for circular GFRP-RC columns was developed and compared with the predictions of available codes and guidelines for GFRP-RC structures.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors would like to express their special thanks and gratitude to the Natural Science and Engineering Research Council of Canada (NSERC) and Manitoba Graduate Scholarship (MGS) for financial support. The authors would also like to thank the technical staff of W.R. McQuade Heavy Structures Laboratory at the University of Manitoba for their assistance while conducting the experimental work.
Notation
The following symbols are used in this paper:
- Af
- total area of GFRP longitudinal rebar (mm2);
- Ag
- gross area of circular column's cross section (mm2);
- a
- depth of equivalent rectangular stress block (mm);
- Cc
- compression force of concrete (kN);
- Cf1
- compression force of first layer GFRP longitudinal rebar (kN);
- Cf2
- compression force of second layer GFRP longitudinal rebar (kN);
- c
- distance from extreme compression fiber to the neutral axis (mm);
- D
- diameter of column (mm);
- df1
- distance from extreme compression fiber to the center of first layer GFRP longitudinal rebar (mm);
- df2
- distance from extreme compression fiber to the center of second layer GFRP longitudinal rebar (mm);
- df3
- distance from extreme compression fiber to the center of third layer GFRP longitudinal rebar (mm);
- df4
- distance from extreme compression fiber to the center of fourth layer GFRP longitudinal rebar (mm);
- Ef
- modulus of elasticity of GFRP longitudinal rebar (GPa);
- e
- eccentricity of axial load (mm);
- average cylindrical concrete compressive strength (MPa);
- Kn
- normalized axial force;
- k
- effective length factor;
- lu
- unsupported length (mm);
- Mn
- total nominal moment (kN · m);
- Mn1
- primary moment or nominal bending moment due to initial eccentricity (kN · m);
- Mn2
- secondary moment or nominal bending moment due to mid-height lateral displacement (kN · m);
- Pn
- nominal axial force or peak load (kN);
- Po
- nominal unconfined axial load capacity of column (kN);
- R
- radius of column (mm);
- Rn
- normalized bending moment;
- r
- radius of gyration (mm);
- Tf3
- tension force of third layer GFRP longitudinal rebar (kN);
- Tf4
- tension force of fourth layer GFRP longitudinal rebar (kN);
- yc
- distance of the centroid of concrete area under compression from the center of column's cross section (mm);
- y1
- distance of the compression force of first layer GFRP longitudinal rebar from center of column's cross section (mm);
- y2
- distance of the compression force of second layer GFRP longitudinal rebar from center of column's cross section (mm);
- y3
- distance of the tension force of third layer GFRP longitudinal rebar from center of column's cross section (mm);
- y4
- distance of the tension force of fourth layer GFRP longitudinal rebar from center of column's cross section (mm);
- α1
- ratio of average stress in rectangular compression block to the specified concrete strength;
- β1
- ratio of depth of rectangular compression block to depth of the neutral axis;
- Δn
- total axial displacement at peak load (mm);
- δn
- mid-height lateral displacement at peak load (mm);
- ɛcu
- ultimate strain in concrete;
- ɛf
- strain in longitudinal GFRP rebar;
- ɛf1
- strain in first layer GFRP longitudinal rebar;
- ɛf2
- strain in second layer GFRP longitudinal rebar;
- ɛf3
- strain in third layer GFRP longitudinal rebar;
- ɛf4
- strain in fourth layer GFRP longitudinal rebar;
- ρf
- Percentage of longitudinal reinforcement; and
- ρfs
- Percentage of transverse reinforcement.
References
ACI (American Concrete Institute). 2005. Building code requirements for structural concrete (ACI 318-05) and commentary (318R-05). Farmington Hills, MI: ACI.
ACI (American Concrete Institute). 2015. Guide for the design and construction of structural concrete reinforced with FRP bars. ACI 440.1R-15. Farmington Hills, MI: ACI.
Afifi, M. Z., H. M. Mohamed, and B. Benmokrane. 2014. “Axial capacity of circular concrete columns reinforced with GFRP bars and spirals.” J. Compos. Constr. 18 (1): 04013017. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000438.
Benmokrane, B., E. El-Salakawy, A. El-Ragaby, and S. El-Gamal. 2007. “Performance evaluation of innovative concrete bridge deck slabs reinforced with fiber-reinforced polymer bars.” Can. J. Civ. Eng. 34 (3): 298–310. https://doi.org/10.1139/l06-173.
Choo, C. C., E. I. Harik, and H. Gesund. 2006. “Strength of rectangular concrete columns reinforced with fiber-reinforced polymer bars.” ACI Struct. J. 103 (3): 452–459.
CSA (Canadian Standards Association). 2009. Carbon steel bars for concrete reinforcement. G30.18-09. Toronto, ON: CSA.
CSA (Canadian Standards Association). 2017. Design and construction of building structures with fiber-reinforced polymers. CSA/S806-12 (R2017). Toronto, ON: CSA.
CSA (Canadian Standards Association). 2019a. Specification for fibre-reinforced polymers. CSA/S807-19. Toronto, ON: CSA.
CSA (Canadian Standards Association). 2019b. Design of concrete structures. CSA/A23.1-19. Toronto, ON: CSA.
CSA (Canadian Standards Association). 2019c. Design of concrete structures. CSA/A23.3-14. Toronto, ON: CSA.
CSA (Canadian Standards Association). 2019d. Canadian highway bridge design code. CSA/S6-19. Toronto, ON: CSA.
El-Gendy, M. G., and E. F. El-Salakawy. 2018. “Lateral displacement deformability of GFRP-RC slab-column edge connections.” ACI Spec. Publ. 327: 52.1–52.20.
Ghomi, S. K., and E. F. El-Salakawy. 2016. “Seismic performance of GFRP-RC exterior beam-column joints with lateral beams.” J. Compos. Constr. 20 (1): 04015019. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000582.
Hadhood, A., H. M. Mohamed, and B. Benmokrane. 2017a. “Experimental study of circular high-strength concrete columns reinforced with GFRP bars and spirals under concentric and eccentric loading.” J. Compos. Constr. 21 (2): 04016078. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000734.
Hadhood, A., H. M. Mohamed, and B. Benmokrane. 2017b. “Failure envelope of circular concrete columns reinforced with GFRP bars and spirals.” ACI Struct. J. 114 (6): 1417–1428. https://doi.org/10.14359/51689498.
Hadi, M. S. N., H. Karim, and M. N. Sheikh. 2016. “Experimental investigations on circular concrete columns reinforced with GFRP bars and helices under different loading conditions.” J. Compos. Constr. 20 (4): 04016009. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000670.
Mahmoud, K., and E. El-Salakawy. 2016. “Size effect on shear strength of GFRP-RC continuous beams without shear reinforcement.” ACI Struct. J. 113 (1): 125–134. https://doi.org/10.14359/51688065.
Mirmiran, A., W. Yuan, and X. Chen. 2001. “Design for slenderness in concrete columns internally reinforced with fiber-reinforced polymer bars.” ACI Struct. J. 98 (1): 116–125.
Mohamed, H., M. Afifi, and B. Benmokrane. 2014. “Performance evaluation of concrete columns reinforced longitudinally with FRP bars and confined with FRP hoops and spirals under axial load.” J. Bridge Eng. 19 (7): 04014020. https://doi.org/10.1061/(ASCE)BE.1943-5592.0000590.
Mousa, S., H. M. Mohamed, and B. Benmokrane. 2018. “Flexural strength and design analysis of circular reinforced concrete members with glass fiber-reinforced polymer bars and spirals.” ACI Struct. J. 115 (5): 1353–1364. https://doi.org/10.14359/51702282.
Pultrall Inc. 2019. Private Communications. Thetford Mines, QC, Canada: ADS Comp. Group.
Rizkalla, S., T. Hassan, and N. Hassan. 2003. “Design recommendations for the use of FRP for reinforcement and strengthening of concrete structures.” Prog. Struct. Mater. Eng. 5 (1): 16–28. https://doi.org/10.1002/pse.139.
Tobbi, H., A. S. Farghaly, and B. Benmokrane. 2012. “Concrete columns reinforced longitudinally and transversally with glass fiber-reinforced polymer bars.” ACI Struct. J. 109 (4): 551–558.
Zadeh, H. J., and A. Nanni. 2013. “Design of RC columns using glass FRP reinforcement.” J. Compos. Constr. 17 (3): 294–304. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000354.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 24 • Issue 5 • October 2020
Copyright
© 2020 American Society of Civil Engineers.
History
Received: Feb 17, 2020
Accepted: May 5, 2020
Published online: Jul 9, 2020
Published in print: Oct 1, 2020
Discussion open until: Dec 9, 2020
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.