Shear-fatigue behavior of high-strength reinforced concrete beams under repeated loading

The purpose of this experimental study is to investigate the damage mechanism due to shear-fatiguebehavior of high-strength reinforced concrete beams under repeated loading. The relationship betweenthe number of cycles and the deflection or strain, the crack growths and modes of failure with the increaseof number of cycles, fatigue strength, and S-N curve were observed through a fatigue test. Based on thefatigue test results, high-strength reinforced concrete beams failed at 57-66 percent of static ultimate strengthfor 2 million cycles. The fatigue strength at 2 million cycles from S-N curves was shown as about 60percent of static ultimate strength. Compared to normal-strength reinforced concrete beams, fatigue capacityof high-strength reinforced concrete beams was similar to or lower than fatigue capacity of normal-strengthreinforced concrete beams. Fatigue capacity of normal-strength reinforced concrete beams improved by over60 percent.