PROBABILITY OF FATIGUE FAILURE OF STEEL FIBROUS CONCRETE CONTAINING MIXED FIBRES

The paper presents a study on the fatigue strength of Steel Fibre Reinforced Concrete (SFRC) containing fibres of mixed aspect ratio. To obtain the fatigue lives of SFRC at various stress levels, beam specimens of size 500 mm × 100 mm × 100 mm were tested under four-point flexural fatigue loading. Static flexural tests were also carried out to determine the static flexural strength of SFRC prior to fatigue testing. The specimens incorporated 1.0% volume fraction of corrugated mixed steel fibres of size 0.6 × 2.0 × 25 mm and 0.6 × 2.0 × 50 mm in different proportions. All the fatigue tests were conducted on MTS servo-controlled test system where as all the static tests were conducted on a similar INSTRON machine. Fatigue life data obtained has been analysed in an attempt to determine the relationship among stress level S, number of cycles to failure N and probability of failure Pf for SFRC. It was found that this relationship can be represented reasonably well graphically by a family of S-N-Pf curves. The experimental coefficients of the fatigue equation have been obtained from the fatigue test data to represent the S-N-Pf relationships analytically.