Fatigue of Cracked Steel Fibre Reinforced Concrete Subjected to Bending

This paper presents an experimental investigation on the post-crack flexural fatigue behaviour of a steel macrofiber reinforced concrete (SFRC) and a high performance steel microfiber reinforced concrete (HPFRC), on notched beams considering the crack opening for serviceability condition. Different load levels were applied by means of three-point bending tests in order to verify the fatigue life. Performance of SFRC and HPFRC was compared under cyclic dynamic tests. Higher load levels seem to lead to failure through a continuous pull-out of the fibres, generating a more ductile response. Smaller load levels can be responsible for the progressive weakening of the fibre-matrix interface through micro-cracks. The conducted probabilistic approach has demonstrated to be suitable to predict the flexural fatigue life of pre-cracked SFRC and HPFRC for a desired probability of failure. From the experimental intrinsic scatter of the fatigue phenomenon, in particular for high levels of applied fatigue load, the amount of fibres in the cracked cross section seems to play an important role in withstanding the fatigue load.