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-fatigue<br />behavior of high-strength reinforced concrete beams under repeated loading. The relationship between<br />the number of cycles and the deflection or strain, the crack growths and modes of failure with the increase<br />of number of cycles, fatigue strength, and S-N curve were observed through a fatigue test. Based on the<br />fatigue test results, high-strength reinforced concrete beams failed at 57-66 percent of static ultimate strength<br />for 2 million cycles. The fatigue strength at 2 million cycles from S-N curves was shown as about 60<br />percent of static ultimate strength. Compared to normal-strength reinforced concrete beams, fatigue capacity<br />of high-strength reinforced concrete beams was similar to or lower than fatigue capacity of normal-strength<br />reinforced concrete beams. Fatigue capacity of normal-strength reinforced concrete beams improved by over<br />60 percent.