STUDIES IN FLEXURAL BEHAVIOUR OF FIBRE REINFORCED RC BEAMS

Abstract

Although considerable research has been conducted on the flexural strength of Fibre Based Concrete, the debate as to the effect of major variables on the cracking and ultimate flexural strength has yet to be unequivocally established. Although the increase in compressive strength of concrete was found marginal through the addition of fibres, yet the increase in Modulus of rupture (Flexural tensile strength) was found to be significantly large (nearly 50% for fibre addition of 1 %). The load deformation response (stress-strain profile) drawn up for fibre based concrete, clearly indicate that sufficient amount of ductility in induced in brittle concrete through the addition of fibres rendering the material tough from seismic point of view. The results of good number of wide beam elements which were tested to investigate the influence of steel fibres on the flexure and deformation characteristics of Fibre Based Reinforced Beam Elements have been presented. Variables studied include, fibre content, aspect ratio and tensile reinforcement ratio. It was found that increased cracking and ultimate flexural strength, flexural toughness and improved ductility largely depend on the volume fraction of fibres. The beam elements with reinforcement ratio of I% and above which failed in shear; exhibited pure moment failure at a fibre content of 1 %. Nonetheless, the Fibre based beams which failed in Flexure and Flexure-Shear mode, did exhibit sufficient ductility.