Seismic Behavior of GFRP-Reinforced Concrete Beams and Moment Frames

The use of fiber reinforced polymer (FRP) bars as internal reinforcement for concrete structures has grown in frequency within the past thirty years, owing mainly to the material’s resistance to corrosion. This development is prevalent in coastal regions where the chemical attack from seawater can weaken steel reinforcement, the traditional reinforcing material in concrete. However, a large obstacle remains in replacing all steel reinforcement with FRP reinforcement in these areas: coastal regions are some of the most seismically active areas in the world. Research on FRP bars shows they behave linear-elastically and exhibit brittle, as opposed to ductile, failure. This is impractical for acceptable seismic design, where the ductile performance of the structure is advantageous to absorb the earthquake loads. Due to this, the outlook for FRP reinforced concrete in seismic zones is seemingly limited. But recent research, although from a small sample size, has shown promising results. This research aims to build upon these findings and expand the knowledge of FRP reinforced concrete performance under seismic loads, especially for beams and moment frames. An analytical study was performed to examine (i) the cross-section of a hybrid glass (G)FRP-steel-reinforced beam through moment-curvature analysis and (ii) two concrete moment frames with GFRP-reinforced beams and steel-reinforced columns subjected to simulated seismic loading through pushover analysis. The performance of the primarily GFRP reinforced concrete design was evaluated by parameters such as curvature ductility (9.0), structural ductility (2.1 and 5.0), and lateral drift. The results showed significant potential for the use of GFRP in seismically active regions.