Fatigue performance of ordinary concrete under discontinuous cyclic loading

Concrete structures often serves under discontinuous fatigue loading. In this work, discontinuous fatigue tests were designed for the first time to investigate the fatigue performance of ordinary concrete under discontinuous cyclic loading. During discontinuous fatigue tests, repeated stress cycles were interrupted by no-load time intervals with different durations. Results showed that time interval could promote the development of plastic deformation produced by cyclic loading. The residual strain in a spaced cycle (S cycle), which follows one time interval, was significantly larger than that in a normal cycle (N cycle), which is not preceded by any interval. The fatigue life, which was estimated by an energy dissipative model, of the specimen used in discontinuous fatigue tests was smaller than that from conventional fatigue tests. However, the dilatancy angle stayed constant in both S and N cycles. The threshold of the time interval was identified at 120 s, with the maximum catalytic rate of 117% for the tested concrete.