Low-cycle fatigue of fiber-reinforced concrete under high strains

This study investigates the experimental response of cylindrical specimens made of plain concrete and concrete reinforced with PVA fibers that were subjected to low-cycle fatigue tests under compression. Two types of PVA fiber were used in the experiments, with lengths of 12 and 15 mm, and three volume levels were considered: 0%, 1%, and 2%. The experimental program included tests where the fatigue load was applied during the pre-crushing stage of the sample (pre-peak), as well as after the onset of strength degradation (post-peak). In the pre-peak compression fatigue tests, which are more common in the literature, a maximum stress level of 95% of the specimen strength was applied. The post-peak compression fatigue tests, which are not available in the literature and could help understand the durability of concrete with fibers under cyclic response, were conducted at two levels of strength degradation, measured with respect to the monotonic compressive strength: 2% and 10%. In addition, three levels of maximum compressive stress for the cycles were used: 85%, 90%, and 95%. Based on the results obtained, fatigue models (Wöhler) and models of secondary strain rate versus fatigue life were developed. Furthermore, the envelope of maximum strains at low cycle fatigue failure was analyzed for both pre-peak and post-peak tests.