Effect of glass-fiber rods on the ductile behaviour of reinforced concrete beams

Abstract

Ductility can be defined as the “ability of material to undergo large deformations without rupture before failure”. The use of Glass-fiber reinforced polymer (GFRP) bars instead of steel in reinforcing concrete structures is currently encouraged by many structural engineers, especially for their lightness and non-corrosive properties. The study compared the ductile behaviour of beams reinforced with glass-fiber to beams reinforced with steel reinforcement. A total of eighteen beams divided into six groups, each group consists of three identical beams were experimentally tested to investigate their ductile behaviour. Another objective for this study is to evaluate the existing methods utilized to estimate ductility of glass-fiber reinforced beams.Diana finite element program was used before the experimental work to investigate the theoretical behaviour of the beams such as the moment-curvature relationship and distribution of stress and strain along the beam cross-section. The study concluded that, the conventional definitions of ductility are inappropriate for evaluation of the ductility of glass-fiber reinforced (GFR) concrete beams because the GFR have no yield point. Thus, there is a need for both quantitative and qualitative evaluations of ductility when using GFR in reinforced concrete members. The deformability factor and the performance factor for steel reinforced beams have the same trend as conventional ductility, especially the deformability factor. Thus, the deformability factor may be used as a comparison index for both steel reinforced beams and GFR beams. The deformability factor showed that, the ductile behaviour of GFR beams enhanced by increasing the GFR ratio. This may be referring to the increasing in the deformation capacity before failure for the beams that reinforced with high GFR ratio. Keywords: Ductility, Bond behaviour, Deformability, Glass-fiber reinforcement bars, RC beams