Fatigue Life Analysis of Basalt Fiber–Reinforced Concrete under Axial Constant-Amplitude Cyclic Tension

The aim is to research the fatigue life of basalt fiber–reinforced concrete (BFRC) under axial constant-amplitude cyclic tension. The two factors, stress level and basalt fiber volume fraction, were considered. Twelve sets of concrete specimens were designed and fabricated to carry out axial tensile fatigue test studies by means of a self-developed concrete axial tensile test device. The whole process of BFRC axial tensile fatigue was analyzed and the effects of fiber content and stress level on the tensile fatigue life of concrete specimens were investigated. The research results show that the tensile fatigue deformation of BFRC can be divided into three stages: rapid growth stage, stable development stage, and fatigue damage stage. Compared with normal concrete, basalt fibers enhance toughness and resistance to cracking, the ultimate fatigue strain of BFRC is relatively large, and the tensile fatigue damage shows certain plastic damage characteristics. The addition of basalt fibers improves the tensile fatigue strength of concrete by about 5%–8%. With the increase of the volume fraction of basalt fiber, the fatigue life of BFRC showed the change rule of increasing first and then decreasing. When the volume fraction of basalt fibers was 0.3%, the fatigue life increased the most. The probability distribution of the BFRC fatigue life conforms to the two-parameter Weibull distribution, and its correlation coefficient is greater than 0.92. Based on the fatigue test data, the tensile fatigue equation containing fiber characteristic parameters under different failure probabilities was established, which can effectively predict the fatigue life of BFRC. The research results can provide a reference for the fatigue-resistant design of BFRC structures.