EXPERIMENTAL INVESTIGATIONS ON HIGH PERFORMANCE FIBER REINFORCED CONCRETE UNDER VARIOUS LOADING

Abstract

   This study experimentally evaluated the shear performance of reinforced concrete (RC) beams strengthened with U-shaped High-Performance Fibre-Reinforced Concrete (HPFRC) under static and fatigue loading. The key parameters were HPFRC jacket thickness and the shear span-to-depth (a/d) ratio of the beams. Under static loading, five beams were tested to assess ultimate shear strength, followed by fatigue testing on identical beams at 30–70% of their ultimate shear strengths at a frequency of 4 Hz. The results showed that HPFRC jacketing effectively enhanced the shear strength of RC beams by 95% to 130% without altering their failure mode. Instead, the strengthened beams displayed pseudo-ductile behavior. However, the shear enhancement decreased with a higher a/d ratio. In fatigue loading tests, all HPFRC systems significantly improved the fatigue life of the beams. Beams with an a/d ratio of 2.0 saw an increase in fatigue life from 75 cycles to a maximum of 951 cycles, while those with an a/d ratio of 3.5 showed an increase from 12,525 cycles to 48,786 cycles. Additionally, a predictive model was developed to estimate the fatigue life of HPFRC/UHPFRC shear-strengthened beams based on maximum fatigue load and ultimate shear strength under static loading conditions.