Development Length of GFRP Rebars in Reinforced Concrete Members under Flexure
Alvaro Ruiz Emparanza, Francisco De Caso, and Antonio Nanni
Appears on pages(s):
GFRP; bond; development length; composites; flexure; sustainability
In reinforced concrete (RC) structures, a proper bond between the reinforcement and the concrete is key for appropriate composite action. To date, limited studies exist that evaluate the bond of fiber-reinforced polymer (FRP) bars in concrete members under flexure and its effect on the development length required to ensure a full stress transfer. In this paper, the bond strength developed by glass FRP (GFRP) and steel rebars is evaluated and compared by testing 16 RC beams under three-point bending. The beams were 1.83 m long and had a section of 150 x 360 mm. Different embedment lengths were evaluated as a function of the bar diameter (db): 30 db, 40 db, and 50 db for GFRP reinforced specimens, and 20 db, and 30 db for steel reinforced beams. Two different GFRP rebar types (six beams for each) and conventional steel (four beams) were used as reinforcement; all the rebars had a nominal diameter of 12.7 mm. Based on the results presented herein, GFRP rebars have a lower bond capacity than steel rebars. Also, the development lengths as suggested by actual code provisions for GFRP rebars (ACI 440.1R-15) appear to be over-conservative: the theoretical development length values were around 110% - 188% higher than the experimental results for the tested GFRP rebars, while the predicted development length for steel rebars according to ACI 318 was about 83% higher than the experimental results.