Effects of fibre wrapping degree and ratio on the tensile properties of carbon FRP-steel hybrid reinforcements

Abstract

The aim of this study is to develop carbon fibre reinforced polymer (CFRP)-steel hybrid reinforcements that are more cost effective than CFRP reinforcements, resistant to external influences, have low creep, high modulus of elasticity, high tensile strength and high ductility. In this context, hybrid reinforcements were produced by winding epoxy impregnated carbon fibre on ribbed steel reinforcements with diameters of 8, 10 and 12 mm at 3 different angles (15, 30 and 45 degrees) and 3 different layer thicknesses (from 1 layer to 3 layers) by filament winding method. In the study, the effect of reinforcement diameter, fibre ratio in the reinforcement (I) and fibre wrapping angle on hybrid reinforcement, yield and tensile stress, modulus of elasticity, energy dissipation capacity and ductility were investigated by tensile tests.As a result of the study, the tensile properties of the reinforcements hybridised by filament winding method improved more than the reinforcements hybridised by other methods (pultrusion, braidtrusion). Modulus of elasticity of the reinforcements developed by this method was 6%-38% higher than the other hybrid reinforcements and the energy dissipation capacity under maximum force was 5%-114% higher. In addition, the fibre ratio between 9% and 32% in specimens with 15 degrees fibre winding angle improved the maximum tensile stress of the steel reinforcement by 3%-35% on average, while the specimens with 30 and 45 degrees FRP winding angle had almost no contribution. It was observed that for the hybrid reinforcement to exhibit very linear behaviour, the fibre ratio (I) should be minimum 0.13 & LE; I and 0.29 & LE; I for the reinforcements with 15 and 30 degrees wrap angle, respectively. The study also includes a theoretical stress-strain model to be in good agreement with the experimental results.