Flexural Behavior of Confined Hybrid Fibre in the Plastic Hinging Region of the High Strength Concrete Beams

Abstract

Objectives: The prime objective of this research is to incorporate the Steel and Polypropylene fibre with varying volume fractions only at the critical sections along with stirrup confinement to improve the flexural behavior and ductility of a high strength concrete beam. Methods: 13 beams of sized 120mm×200mm×2100mm were designed as an overreinforced section by providing higher percentage of steel more than balanced state. Out of 13 beams one beam was kept as a reference beam without fibre reinforcement, four beams were designed with steel fibre and the remaining with hybrid fibres. Except for reference beam all the other beams were placed with fibers at the plastic hinging region. Findings: As per ASTM C 78 all the beams are tested under third point loading and deflections were measured at the respective places using dial gauges. Based on the outcomes from the experimental work, the moment and curvature readings were calculated finally it was concluded that beam improves the Flexural behavior, Load carrying capacity of the beam and behaves as a ductile manner though the beam is an over-reinforced section. Applications: Most of the design codes demand only the ductile failure of the beams which is the major drawback of the over-reinforced concrete. Probably these beams are utilized in the modern construction practices having slender structures with adequate stiffness. Moreover, it’s a proven fact that, a confined concrete definitely increases the strength and ductile behavior of RC beams.