LONG-TERM DEFLECTIONS OF GFRP-REINFORCED CONCRETE BEAMS

Abstract

The results of an experimental study on the long-term behavior of glass fiber-reinforced plastic (GFRP) reinforced concrete beams are reported. Four beams, 4 inches (100 mm) wide by 6 inches (150 mm) high and reinforced with two #3 (9.5 mm) bars, were tested under sustained loading on a 6 foot (1.8 m) simple span. Two beams were cast with GFRP bars and two with steel reinforcement. The study was conducted at ambient temperature over an 8 month period. The GFRP-reinforced beams had initial deflections that were 3.76 times larger than did the steel-reinforced beams; however, creep deflections averaged only 1.80 times greater. It is shown that long-term deflections in GFRP-reinforced beams can be predicted using techniques developed for steel-reinforced concrete, provided the ultimate creep coefficient is modified to account for the different levels of initial deflection and compression-zone stress in FRP-reinforced sections.