Comparative investigation on effect of fibers in the flexural response of post tensioned beam

Abstract

Post tensioning has been proved to be economical and efficient for long span bridges and flyovers. Further it has been established that in addition to prestressing, introduction of fibers arrests cracks and enhances ductility characteristics of concrete. From the literature, it is evident that research on the effect of fibers in post tensioned beams is limited. This paper presents a comparative investigation on the flexural behavior of post tensioned beams reinforced with optimum volume fractions of basalt and polypropylene fibers. The test parameter was the optimum volume fraction of basalt and polypropylene fibers. Peak load carrying capacity, Peak deflection, energy absorption and ductility factor were the structural aspects to be studied during the flexural behavior of fiber reinforced post tensioned beams. For both the fibers, a range of low volume fractions of concrete viz 0.25%, 0.5% and 0.75% were chosen and mechanical properties were studied. By comparative analysis, it was found that there was considerable improvement when polypropylene and basalt fibers were used in 0.25% volume fraction which had to be considered as optimum volume fraction. Post tensioned beams containing optimum volume fraction of fibers were cast and tested for flexural behavior. Beams reinforced with basalt fibers (BFRC) exhibited higher load carrying capacity then polypropylene fiber reinforced beams. Furthermore, all the fibred beams demonstrated enhancement in ductility and energy absorption, with highest values for the BFRC beams. By and large it can be concluded that basalt fibers proved to have higher structural efficiency than polypropylene fibers when used in the tested specimen.