Performance of Concrete Beams Reinforced with Various Ratios of Hybrid GFRP/Steel Bars

Phan Duy Nguyen, Vu Hiep Dang, Ngoc Anh Vu


This paper aims to study the flexural behavior of concrete beams reinforced with hybrid combinations of GFRP/steel bars. To this purpose an experimental program was carried out on four concrete beams reinforced with Glass Fiber Reinforced Polymer (GFRP) and twelve hybrid GFRP/steel Reinforced Concrete (RC) beams. Flexural behavior of the tested beams such as stages of response, failure modes, crack patterns, stiffness, toughness and ductility were analyzed. The experimental results showed that depending on GFRP/steel reinforcement configurations, the behavior of hybrid GFRP/steel RC beams undergoes three or four stages, namely: pre-cracking stage; after concrete cracking and before steel yielding; post-yield stage of the steel bar until peak load and failure stage. Totally six failure modes of hybrid RC beams are reported depending on reinforcement rations and configuration. The effect of reinforcement configuration and ratio of GFRP to steel (ρg) on the crack patterns, stiffness, ductility and toughness of hybrid RC beams are significant. Based on the non-linear deformation model, an analytical model has been developed and validated to determine the steel yielding moment and ultimate moment of hybrid GFRP/steel RC beams. It could be seen that the experimental values were in good agreement with the predicted values.


Concrete Beam; Hybrid Reinforcement; Flexural Strength; Failure Mode; Fiber Reinforced Polymers.


Leung, H.Y., and R.V. Balendran. “Flexural Behaviour of Concrete Beams Internally Reinforced with GFRP Rods and Steel Rebars.” Structural Survey 21, no. 4 (October 2003): 146–157. doi:10.1108/02630800310507159.

Qu, Wenjun, Xiaoliang Zhang, and Haiqun Huang. “Flexural Behavior of Concrete Beams Reinforced with Hybrid (GFRP and Steel) Bars.” Journal of Composites for Construction 13, no. 5 (October 2009): 350–359. doi:10.1061/(asce)cc.1943-5614.0000035.

Lau, Denvid, and Hoat Joen Pam. “Experimental Study of Hybrid FRP Reinforced Concrete Beams.” Engineering Structures 32, no. 12 (December 2010): 3857–3865. doi:10.1016/j.engstruct.2010.08.028.

Mustafa, Suzan A.A., and Hilal A. Hassan. “Behavior of Concrete Beams Reinforced with Hybrid Steel and FRP Composites.” HBRC Journal 14, no. 3 (December 2018): 300–308. doi:10.1016/j.hbrcj.2017.01.001.

Pang, Lei, Wenjun Qu, Peng Zhu, and Jiajing Xu. “Design Propositions for Hybrid FRP-Steel Reinforced Concrete Beams.” Journal of Composites for Construction 20, no. 4 (August 2016): 04015086. doi:10.1061/(asce)cc.1943-5614.0000654.

Xingyu, Gu, Dai Yiqing, and Jiang Jiwang. “Flexural Behavior Investigation of Steel-GFRP Hybrid-Reinforced Concrete Beams Based on Experimental and Numerical Methods.” Engineering Structures 206 (March 2020): 110117. doi:10.1016/j.engstruct.2019.110117.

Bui, Linh Van Hong, Boonchai Stitmannaithum, and Tamon Ueda. “Ductility of Concrete Beams Reinforced with Both Fiber-Reinforced Polymer and Steel Tension Bars.” Journal of Advanced Concrete Technology 16, no. 11 (November 14, 2018): 531–548. doi:10.3151/jact.16.531.

Maranan, G.B., A.C. Manalo, B. Benmokrane, W. Karunasena, P. Mendis, and T.Q. Nguyen. “Flexural Behavior of Geopolymer-Concrete Beams Longitudinally Reinforced with GFRP and Steel Hybrid Reinforcements.” Engineering Structures 182 (March 2019): 141–152. doi:10.1016/j.engstruct.2018.12.073.

Kara, Ilker Fatih, Ashraf F. Ashour, and Mehmet Alpaslan Köroğlu. “Flexural Behavior of Hybrid FRP/steel Reinforced Concrete Beams.” Composite Structures 129 (October 2015): 111–121. doi:10.1016/j.compstruct.2015.03.073.

Kim, Seongeun, and Seunghun Kim. “Flexural Behavior of Concrete Beams with Steel Bar and FRP Reinforcement.” Journal of Asian Architecture and Building Engineering 18, no. 2 (March 4, 2019): 89–97. doi:10.1080/13467581.2019.1596814.

Ruan, Xiangjie, Chunhua Lu, Ke Xu, Guangyu Xuan, and Mingzhi Ni. “Flexural Behavior and Serviceability of Concrete Beams Hybrid-Reinforced with GFRP Bars and Steel Bars.” Composite Structures 235 (March 2020): 111772. doi:10.1016/j.compstruct.2019.111772.

Sun, Zeyang, Linchen Fu, De-Cheng Feng, Apete R. Vatuloka, Yang Wei, and Gang Wu. “Experimental Study on the Flexural Behavior of Concrete Beams Reinforced with Bundled Hybrid steel/FRP Bars.” Engineering Structures 197 (October 2019): 109443. doi:10.1016/j.engstruct.2019.109443.

ACI Committee. "Guide for the Design and Construction of Structural Concrete Reinforced with Fiber-Reinforced Polymer (FRP) Bars (ACI 440. 1R-15)." Farmington Hills, Michigan: American Concrete Institute (2015).

Lucier, G. "Tension Tests of GFRP Bars (Prepared for: Fiber reinfor polymer Viet Nam)." North Carolina State University (2016): p. 7.

Baikov, V.N. and E.E. Sigalov. “Reinforced concrete structures. General Course. Textbook for Higher Institutes of Learning, 5th Edition” (1991).

Jia, B., S. Liu, X. Liu, and R. Wang. “Flexural Capacity Calculation of Hybrid Bar Reinforced Concrete Beams.” Materials Research Innovations 18, no. sup2 (May 2014): S2–836–S2–840. doi:10.1179/1432891714z.000000000498.

Ge, Wenjie et al. "Flexural behavior of concrete beam with hybrid reinforcement of FRP bars and steel bars." Journal of Southeast University. Natural Science Edition 42.1 (2012): 114-119.

Ge, Wenjie, Jiwen Zhang, Dafu Cao, and Yongming Tu. “Flexural Behaviors of Hybrid Concrete Beams Reinforced with BFRP Bars and Steel Bars.” Construction and Building Materials 87 (July 2015): 28–37. doi:10.1016/j.conbuildmat.2015.03.113.

Aiello, Maria Antonietta, and Luciano Ombres. “Structural Performances of Concrete Beams with Hybrid (Fiber-Reinforced Polymer-Steel) Reinforcements.” Journal of Composites for Construction 6, no. 2 (May 2002): 133–140. doi:10.1061/(asce)1090-0268(2002)6:2(133).

Grace, N. F., A. K. Soliman, G. Abdel-Sayed, and K. R. Saleh. “Behavior and Ductility of Simple and Continuous FRP Reinforced Beams.” Journal of Composites for Construction 2, no. 4 (November 1998): 186–194. doi:10.1061/(asce)1090-0268(1998)2:4(186).

Naaman, A. and S. Jeong. “Structural ductility of concrete beams prestressed with FRP tendons.” Non-Metallic (FRP) Reinforcement for Concrete Structures: Proceedings of the Second International RILEM Symposium, Vol. 29 (23-25, August 1995).

Polakowski, Natalis Horace, and Edward Joseph Ripling. "Strength and structure of engineering materials." (1966).

NIIZHB named after A. A. Gvozdev. “Concrete and reinforced concrete structures. General provisions (SP 63.13330:2018).” Federal Registry of National Building Codes & Standards (2019).

Full Text: PDF

DOI: 10.28991/cej-2020-03091572


  • There are currently no refbacks.

Copyright (c) 2020 Duy Nguyen Phan, Hiep Vu Dang, Anh Vu Ngoc

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.