Long-term Deflections of Hybrid GFRP/Steel Reinforced Concrete Beams under Sustained Loads

Phan Duy Nguyen, Vu Hiep Dang, Ngoc Anh Vu, Polikutin Aleksei Eduardovich


One of the solutions to improve the flexural behavior of Glass fiber reinforced polymer (GFRP) reinforced concrete (RC) beams is the addition of tensile longitudinal steel reinforcement. The numerous studies to date on hybrid GFRP/steel RC elements have mainly focused on the static and short-term responses, very little work has been done regarding the long-term performance. This paper presents experimental results of time-dependent deflections of cracked GFRP and hybrid GFRP/steel RC beams during a 330-day-period in natural climate conditions. Three hybrid GFRP/steel and one GFRP RC beams with dimensions 100×200×2000 mm were tested in four-point bending. Different steel reinforcement ratios were used to evaluate the effect of the steel reinforcement on the long-term behavior of the beams. Experimental results show that the immediate deflections are inversely proportional to the additional steel reinforcement. With the same initial instantaneous deflection, the total deflection increases when increasing the steel reinforcement ratio. Also, temperature (T) and relative humidity (RH) significantly affect the long-term deflection of the tested beams. The measured long-term deflections were found to be in good agreement with the theoretical values calculated from the proposed method. However, there was an overestimation when using ACI 440.1R-15 or CSA-S806-12 procedures.


GFRP; Hybrid; Concrete Beam; Long-term; Time-dependent; Sustained Load; Deflection.


Toutanji, Houssam, and Yong Deng. “Deflection and Crack-Width Prediction of Concrete Beams Reinforced with Glass FRP Rods.” Construction and Building Materials 17, no. 1 (February 2003): 69–74. doi:10.1016/s0950-0618(02)00094-6.

Cheung, Moe M.S., and Terry K.C. Tsang. “Behaviour of Concrete Beams Reinforced with Hybrid FRP Composite Rebar.” Advances in Structural Engineering 13, no. 1 (February 2010): 81–93. doi:10.1260/1369-4332.13.1.81.

Soric, Zorislav, Tomislav Kisicek, and Josip Galic. “Deflections of Concrete Beams Reinforced with FRP Bars.” Materials and Structures 43, no. S1 (April 14, 2010): 73–90. doi:10.1617/s11527-010-9600-1.

Al-Sunna, Raed, Kypros Pilakoutas, Iman Hajirasouliha, and Maurizio Guadagnini. “Deflection Behaviour of FRP Reinforced Concrete Beams and Slabs: An Experimental Investigation.” Composites Part B: Engineering 43, no. 5 (July 2012): 2125–2134. doi:10.1016/j.compositesb.2012.03.007.

NIIZHB. “Concrete structures reinforced with fibre-reinforced polymer bars. Design rules (SP 295.1325800.2017)”. 2018: Moscow. p. 55.

ACI. “Guide for the design and construction of structural concrete reinforced with FRP bars (ACI 440.1R-15)”. 2015, American Concrete Institute.

Gross, Shawn P., Joseph Robert Yost, and George J. Kevgas. “Time-Dependent Behavior of Normal and High Strength Concrete Beams Reinforced with GFRP Bars Under Sustained Loads.” High Performance Materials in Bridges (September 5, 2003). doi:10.1061/40691(2003)40.

Miàs, C., Ll. Torres, A. Turon, M. Baena, and C. Barris. “A Simplified Method to Obtain Time-Dependent Curvatures and Deflections of Concrete Members Reinforced with FRP Bars.” Composite Structures 92, no. 8 (July 2010): 1833–1838. doi:10.1016/j.compstruct.2010.01.016.

Miàs, C., Ll. Torres, A. Turon, M. Baena, I. Vilanova, and M. Llorens. “Experimental Study of Time-Dependent Behaviour of Concrete Members Reinforced with GFRP Bars.” Advances in FRP Composites in Civil Engineering (2011): 352–355. doi:10.1007/978-3-642-17487-2_76.

Walkup, Stephanie L., Eric S. Musselman, and Shawn P. Gross. “Effect of Sustained Load Level on Long-Term Deflections in GFRP and Steel-Reinforced Concrete Beams.” International Congress on Polymers in Concrete (ICPIC 2018) (2018): 609–615. doi:10.1007/978-3-319-78175-4_78.

Miàs, C., Ll Torres, A. Turon, and I.A. Sharaky. “Effect of Material Properties on Long-Term Deflections of GFRP Reinforced Concrete Beams.” Construction and Building Materials 41 (April 2013): 99–108. doi:10.1016/j.conbuildmat.2012.10.1.055.

Bazant Z.P. “Prediction of Concrete Creep Effects Using Age-Adjusted Effective Modulus Method.” ACI Journal Proceedings 69, no. 4 (1972). doi:10.14359/11265.

EUROPEAN COMMITTEE, et al. “Design of Concrete Structures—Part 1-1: General Ruels and Rules for Buildings (EN 1992-1-1 Eurocode 2)”. European Committee: Brussels, Belgium, 2005.

Hall, Tara, and Amin Ghali. “Long-Term Deflection Prediction of Concrete Members Reinforced with Glass Fibre Reinforced Polymer Bars.” Canadian Journal of Civil Engineering 27, no. 5 (October 1, 2000): 890–898. doi:10.1139/l00-009.

Plevris, Nikolaos, and Thanasis C. Triantafillou. “Time‐Dependent Behavior of RC Members Strengthened with FRP Laminates.” Journal of Structural Engineering 120, no. 3 (March 1994): 1016–1042. doi:10.1061/(asce)0733-9445(1994)120:3(1016).

Al Chami, G., M. Thériault, and K.W. Neale. “Creep Behaviour of CFRP-Strengthened Reinforced Concrete Beams.” Construction and Building Materials 23, no. 4 (April 2009): 1640–1652. doi:10.1016/j.conbuildmat.2007.09.006.

El-Sayed, Ahmed K., Rajeh A. Al-Zaid, Abdulaziz I. Al-Negheimish, Ahmed B. Shuraim, and Abdulrahman M. Alhozaimy. “Long-Term Behavior of Wide Shallow RC Beams Strengthened with Externally Bonded CFRP Plates.” Construction and Building Materials 51 (January 2014): 473–483. doi:10.1016/j.conbuildmat.2013.10.055.

Hong, Sungnam, and Sun-Kyu Park. “Long-Term Behavior of Fiber-Reinforced-Polymer-Plated Concrete Beams Under Sustained Loading: Analytical and Experimental Study.” Composite Structures 152 (September 2016): 140–157. doi:10.1016/j.compstruct.2016.05.031.

Ahmed, Ehsan, and Habibur Rahman Sobuz. “Immediate and Long-Term Deflection of Carbon Fiber Reinforced Polymer (CFRP) Concrete Beams.” Key Engineering Materials 471–472 (February 2011): 73–78. doi:10.4028/www.scientific.net/kem.471-472.73.

ACI, Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures (ACI 440.2R-17). (2017). American Concrete Institute.

ACI. “Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures (ACI 440.2R-17)” (May 2017). doi:10.14359/51700867.

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

R., Balamuralikrishnan, and Saravanan J. “Finite Element Analysis of Beam–Column Joints Reinforced with GFRP Reinforcements.” Civil Engineering Journal 5, no. 12 (December 1, 2019): 2708–2726. doi:10.28991/cej-2019-03091443.

Nguyen, Phan Duy, Vu Hiep Dang, and Ngoc Anh Vu. “Performance of Concrete Beams Reinforced with Various Ratios of Hybrid GFRP/Steel Bars.” Civil Engineering Journal 6, no. 9 (September 1, 2020): 1652–1669. doi:10.28991/cej-2020-03091572.

ACI. “Building Code Requirements for Structural Concrete (ACI 318-19): An ACI Standard: Commentary on Building Code Requirements for Structural Concrete (ACI 318R-19)”. (2019). American Concrete Institute.

Baikov V.N. and Sigalov E.E. “Reinforced concrete structures, General Course: book for higher schools, 5th edition”. (1991), Stroyizdat, Moscow.

Shariq, M., H. Abbas, and J. Prasad. “Effect of Magnitude of Sustained Loading on the Long-Term Deflection of RC Beams.” Archives of Civil and Mechanical Engineering 19, no. 3 (May 2019): 779–791. doi:10.1016/j.acme.2019.03.004.

Tan, Kiang Hwee, and Mithun Kumar Saha. "Long-term deflections of reinforced concrete beams externally bonded with FRP system." Journal of Composites for Construction 10, no. 6 (2006): 474-482. doi:10.1061/(ASCE)1090-0268(2006)10:6(474).

Li, Pengfei, and Shiqin He. “Effects of Variable Humidity on the Creep Behavior of Concrete and the Long-Term Deflection of RC Beams.” Advances in Civil Engineering 2018 (October 29, 2018): 1–12. doi:10.1155/2018/8301971.

CSA. “Design and construction of building components with fiber-reinforced polymers (CSA-S806-12 (R2017))”. (2017). Mississauga, Ontario, Canada.

Torres, Ll., C. Miàs, A. Turon, and M. Baena. “A Rational Method to Predict Long-Term Deflections of FRP Reinforced Concrete Members.” Engineering Structures 40 (July 2012): 230–239. doi:10.1016/j.engstruct.2012.02.021.

ACI. “Guide for modeling and calculating shrinkage and creep in hardened concrete (ACI 209.2R-08)”. (2008): 48p. American Concrete Institute.

Full Text: PDF

DOI: 10.28991/cej-2020-SP(EMCE)-01


  • There are currently no refbacks.

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

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