Effect of Macrosynthetic and Hybrid Fibers on the Behavior of Square Concrete Columns Reinforced with GFRP Rebars under Axial Compression

Abstract The durability of steel-reinforced concrete (RC) members reduces significantly under aggressive environmental conditions due to the corrosion of steel rebars. The use of fiber-reinforced polymer (FRP) rebars is an attractive alternative for steel rebars in RC members. However, the brittle failure of FRP RC members is a significant concern. The addition of discrete fibers in FRP RC members can improve their postcracking behavior and provide pseudoductility. The objective of this study is to understand the effects of macrosynthetic polyolefin (PO) and a hybrid combination of steel and macrosynthetic PO fibers on the compression behavior of glass FRP (GFRP) RC columns. Fourteen square GFRP-RC columns were cast with various fiber dosages. The test matrix included (1) GFRP RC control specimen with no fibers; and (2) GFRP RC columns with six different fiber dosages which include: (a) 0.35% of PO; (b) hybrid dosage of 0.175% of steel and 0.175% of PO; (c) 0.70% of PO; (d) hybrid dosage of 0.35% of steel and 0.35% of PO; (e) 1.0% of PO; and (f) hybrid dosage of 0.50% of PO and 0.50% of steel fibers. Test results revealed that the fiber addition improved peak load, postpeak behavior, and pseudoductility under pure compression. Specimens with hybrid fibers had higher energy absorption and pseudoductility than those with macrosynthetic fibers.