Design and Detailing of Glass Fiber-Reinforced Polymer-Reinforced Concrete Beams According to ACI CODE-440.11-22

Abstract

This paper aims to analyze practical considerations in the design of glass fiber-reinforced polymer-reinforced concrete (GFRP-RC) beams based on the newly adopted ACI 440.11-22 Building Code, addressing strength, serviceability, and detailing criteria. A beam example was taken from ACI Reinforced Concrete Design Handbook, a companion to ACI 318-19, and re-designed using GFRP bars and stirrups to analyze the effect of changing reinforcement type. In the first phase, the beam was designed as an over-reinforced member with high-modulus (Ef = 60,000 MPa) and low-modulus (Ef = 44,815 MPa) GFRP bars. In the second phase, a parametric study was carried out to analyze the impact of changing key design parameters, namely: bond factor kb, concrete compressive strength f’c, and maximum deflection limit. GFRP-RC beams require more reinforcement area compared to conventional steel-RC which may result in bar congestion. Current Code provisions related to detailing, in particular, are based on conservative assumptions due to a lack of experimentation and greatly penalize the design of GFRP-RC beams. The current Code provisions for development length, bar spacing, skin reinforcement, and stress at service make GFRP-RC design challenging.