Title:
Fiber-Reinforced Polymer Reinforcing Bar-Reinforced Ultra-High-Performance Concrete Flexural Members with Compression-Controlled Design
Author(s):
Shih-Ho Chao and Venkatesh Babu Kaka
Publication:
Structural Journal
Volume:
122
Issue:
4
Appears on pages(s):
67-83
Keywords:
compression-controlled; compressive ductility; durability; fiber-reinforced polymer (FRP); resilience; restoring force; stiffness; ultra-high-performance concrete (UHPC); ultra-high-performance fiberreinforced concrete (UHP-FRC)
DOI:
10.14359/51745468
Date:
7/1/2025
Abstract:
Noncorrosive fiber-reinforced polymer (FRP) reinforcement presents an attractive alternative to conventional steel reinforcement, which is prone to corrosion, especially in harsh environments exposed to deicing salt or seawater. However, FRP reinforcing bars’ lower axial stiffness leads to greater crack widths when FRP reinforcing bars elongate, resulting in significantly lower flexural stiffness for FRP bar-reinforced concrete members. The deeper cracks and larger crack widths also reduce the depth of the compression zone. Consequently, both the aggregate interlock and the compression zone for shear resistance are significantly reduced. Additionally, due to their limited tensile ductility, FRP reinforcing bars can rupture before the concrete crushes, potentially resulting in sudden and catastrophic member failure. Therefore, ACI Committee
440 states that through a compression-controlled design, FRP reinforced concrete members can be intentionally designed to fail
by allowing the concrete to crush before the FRP reinforcing bars
rupture. However, this design approach does not yield an equivalent
ductile behavior when compared to steel-reinforced concrete
members, resulting in a lower strength reduction, ϕ, value of 0.65.
In this regard, using FRP-reinforced ultra-high-performance
concrete (UHPC) members offer a novel solution, providing high
strength, stiffness, ductility, and corrosion-resistant characteristics.
UHPC has a very low water-cementitious materials ratio (0.18
to 0.25), which results in dense particle packing. This very dense
microstructure and low water ratio not only improves compressive
strength but delays liquid ingress. UHPC can be tailored to achieve
exceptional compressive ductility, with a maximum usable compressive strain greater than 0.015. Unlike conventional designs where ductility is provided by steel reinforcing bars, UHPC can be used to achieve the required ductility for a flexural member, allowing FRP reinforcing bars to be designed to stay elastic. The high member
ductility also justifies the use of a higher strength reduction factor,
ϕ, of 0.9. This research, validated through large-scale experiments,
explores this design concept by leveraging UHPC’s high compressive
ductility, cracking resistance, and shear strength, along with a
high quantity of noncorrosive FRP reinforcing bars. The increased
amount of longitudinal reinforcement helps maintain the flexural
stiffness (controlling deflection under service loads), bond strength,
and shear strength of the members. Furthermore, the damage resistant capability of UHPC and the elasticity of FRP reinforcing
bars provide a structural member with a restoring force, leading to
reduced residual deflection and enhanced resilience.
Related References:
AASHTO, 2024, LRFD Bridge Design Specifications, 10th edition, American Association of State Highway and Transportation Officials, Washington, DC.
ACI Committee 318, 2025, “Building Code Requirements for Structural Concrete (ACI 318-25) and Commentary (ACI 318R-25),” American Concrete Institute, Farmington Hills, MI, 700 pp.
ACI Committee 440, 2015, “Guide for the Design and Construction of Structural Concrete Reinforced with Fiber Reinforced Polymer (FRP) Bars (ACI 440.1R-15),” American Concrete Institute, Farmington Hills, MI, 88 pp.
ACI Committee 440, 2022, “Building Code Requirements for Structural Concrete Reinforced with Glass Fiber-Reinforced Polymer (GFRP) Bars-Code and Commentary (ACI CODE-440.11-22),” American Concrete Institute, Farmington Hills, MI, 260 pp.
Aghdasi, P.; Heid, A. E.; and Chao, S.-H., 2016, “Developing Ultra-High-Performance Fiber-Reinforced Concrete for Large-Scale Structural Applications,” ACI Materials Journal, V. 113, No. 5, Sept.-Oct., pp. 559-570. doi: 10.14359/51689103
Ahlborn, T. M.; Harris, D. K.; Misson, D. L.; and Peuse, E. J., 2011, “Characterization of Strength and Durability of Ultra-High-Performance Concrete under Variable Curing Conditions,” Transportation Research Record: Journal of the Transportation Research Board, V. 2251, No. 1, pp. 68-75. doi: 10.3141/2251-07
Al-Sunna, R.; Pilakoutas, K.; Hajirasouliha, I.; and Guadagnini, M., 2012, “Deflection Behaviour of FRP Reinforced Concrete Beams and Slabs: An Experimental Investigation,” Composites Part B: Engineering, V. 43, No. 5, pp. 2125-2134. doi: 10.1016/j.compositesb.2012.03.007
Alkaysi, M.; El-Tawil, S.; Liu, Z.; and Hansen, W., 2016, “Effects of Silica Powder and Cement Type on Durability of Ultra High Performance Concrete (UHPC),” Cement and Concrete Composites, V. 66, pp. 47-56. doi: 10.1016/j.cemconcomp.2015.11.005
Alsayed, S. H., 1998, “Flexural Behaviour of Concrete Beams Reinforced with GFRP Bars,” Cement and Concrete Composites, V. 20, No. 1, pp. 1-11. doi: 10.1016/S0958-9465(97)00061-9
ASTM C109/C109M-20a, 2020, “Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50-mm] Cube Specimens),” ASTM International, West Conshohocken, PA, 11 pp.
Chao, S.-H.; Kaka, V.; and Shamshiri, M., 2023, “Structural Implications of the Synergistic Interactions between Steel Reinforcement and UHPC,” Third International Interactive Symposium on UHPC, June 4-7, Wilmington, DE.
FHWA, 2011, “Ultra-High Performance Concrete,” TechNote, FHWA-HRT-11-038, Federal Highway Administration, Washington, DC.
Jones, S.; Martys, N.; Lu, Y.; and Bentz, D., 2015, “Simulation Studies of Methods to Delay Corrosion and Increase Service Life for Cracked Concrete Exposed to Chlorides,” Cement and Concrete Composites, V. 58, pp. 59-69. doi: 10.1016/j.cemconcomp.2014.12.014
Kaka, V., and Chao, S.-H., 2018, “Investigation of Eliminating Prestress in Bridge Girders with the Use of Non-Prestressed Ultra-High-Performance Fiber-Reinforced Concrete Girders,” ASCE Structures Congress, Apr. 19-21, Fort Worth, TX.
Khaja, M. N., and Sherwood, E. G., 2013, “Does the Shear Strength of Reinforced Concrete Beams and Slabs Depend upon the Flexural Reinforcement Ratio or the Reinforcement Strain?” Canadian Journal of Civil Engineering, V. 40, No. 11, pp. 1068-1081. doi: 10.1139/cjce-2012-0459
Mehta, P. K., and Monteiro, P. J. M., 2014, Concrete—Microstructure, Properties, and Materials, fourth edition, McGraw-Hill, New York.
Nanni, A., 1993, “Flexural Behavior and Design of RC Members Using FRP Reinforcement,” Journal of Structural Engineering, ASCE, V. 119, No. 11, pp. 3344-3359. doi: 10.1061/(ASCE)0733-9445(1993)119:11(3344)
Nanni, A.; De Luca, A.; and Zadeh, H. J., 2014, Reinforced Concrete with FRP Bars: Mechanics and Design, CRC Press, Boca Raton, FL.
NCHRP, 2017, “Use of Fiber-Reinforced Polymers in Highway Infrastructure,” NCHRP Synthesis 512, National Cooperative Highway Research Program, Washington, DC.
Ovitigala, T.; Ibrahim, M. A.; and Issa, M. A., 2016, “Serviceability and Ultimate Load Behavior of Concrete Beams Reinforced with Basalt Fiber-Reinforced Polymer Bars,” ACI Structural Journal, V. 113, No. 4, July-Aug., pp. 757-768. doi: 10.14359/51688752
Scrivener, K. L.; Vanderley, M. J.; and Gartner, E. M., 2018, “Eco-
Efficient Cements: Potential Economically Viable Solutions for a Low-CO2 Cement-Based Materials Industry,” Cement and Concrete Research, V. 114, pp. 2-26. doi: 10.1016/j.cemconres.2018.03.015
Shah, S. P., 1992, “Do Fibers Increase the Tensile Strength of Cement-Based Matrix?” ACI Materials Journal, V. 88, No. 6, Nov.-Dec., pp. 595-602.
Stratford, T., and Burgoyne, C., 2003, “Shear Analysis of Concrete with Brittle Reinforcement,” Journal of Composites for Construction, ASCE, V. 7, No. 4, pp. 323-330. doi: 10.1061/(ASCE)1090-0268(2003)7:4(323)
Wang, H., and Belarbi, A., 2005, “Flexural Behavior of Fiber-
Reinforced-Concrete Beams Reinforced with FRP Rebars,” 7th International Symposium on Fiber-Reinforced Polymer (FRP) Reinforcement for Concrete Structures, SP-230, American Concrete Institute, Farmington Hills, MI, pp. 895-914.
Wight, J. K., 2022, Reinforced Concrete—Mechanics and Design, eighth edition, Pearson Education, Hoboken, NJ, 1144 pp.