Fatigue Strength of Hybrid Steel-Polypropylene Fibrous Concrete Beams in Flexure

Abstract

The paper presents results of an investigation on the flexural fatigue strength of Hybrid Fibre Reinforced Concrete (HyFRC) containing different proportions of steel and polypropylene fibres. An experimental programme was conducted to obtain the fatigue lives of HyFRC specimens at different stress levels in which approximately 115 flexural fatigue tests were conducted. Approximately 58 complimentary static flexural tests were also conducted to facilitate the fatigue tests. The specimen incorporated different proportions of steel and polypropylene fibres i.e. 25–75%, 50–50% and 75–25% by volume at a total fibre content of 0.5%. The fatigue test data has been used to determine a relationship between fatigue stress level S, fatigue life N and probability of failure Pf and to generate family of S-N-Pf curves for HyFRC. The experimental coefficients of the fatigue equation have also been obtained from the fatigue test data to represent the S-N-Pf curves analytically.