Predicting Flexural Behavior of Fiber Reinforced High Performance Concrete Beams

High-performance concrete (HPC) is concrete that has been designed to be more durable and stronger than conventional concrete. HPC mixtures are composed of essentially the same materials as conventional concrete mixtures, but the proportions are designed, or engineered, to provide the strength and durability needed for the structural and environmental requirements of the structures. Fibre Reinforced High Performance Concrete (FRHPC) is developing quickly to a modern structural material with a high potential. The behavior of tensile strain-hardening of FRHPC beams is presented. Though there are many publications proposing stress block models for FRHPC beams, a universally accepted stress block model is yet to be developed. In most design standards, the conventional rectangular stress block developed for Normal Strength Concrete is still being used for design of FRHPC beams. As per IS: 456-2000 for concrete of grades higher than M55, design parameters given in the code of practice may not be applicable and values may be obtained from specialized literatures and experimental results. Whilst there are many publications proposing stress block models for HPC beams, stress block model for FRHPC is yet to be developed. In most design standards, the conventional rectangular stress block developed for Normal Strength Concrete is still being used for design of FRHPC beams. For the preparation of acceptable design recommendations for FRHPC a number of principles should be respected. The code should be consistent with existing deign recommendations for structural concrete. The aim of this study was to study the flexural behavior of FRHPC beams. In this paper, model proposed in European design standard EC: 02-2004 and current Indian Standard IS: 456-2000 have been analysed to compare the experimental and theoretical moment capacities considering actual Fck and Fy values obtained from tests done. Twelve numbers Reinforced Concrete Beams of size 200 x 200 x 2400 mm using concrete mix with three different w/c ratios (0.45, 0.35 and 0.25) were cast for flexural strength test. For flexural strength assessment, the beam was placed in simply supported condition over two fixed steel pedestals to get a clear span of 2000 mm (Figure-1). Keeping in view the specimen size to be tested and failure load, the loading was decided to be applied at the rate of 0.2 mm/minute in displacement control. Two mechanical dial gauges were placed at L/3 distance from both the supports for measurement of deflection. Apart from this one linear variable differential transformer (LVDT) was placed in centre of beam to measure mid-point deflection.