Flexural Fatigue Behavior of PAN Fiber Reinforced Concrete under Cyclic Loading

摘要: The flexural fatigue performance of polyacrylonitrile (PAN) fiber reinforced concrete (PANFRC）was investigated by third-point loading tests. Based on the previous research work, optimum mixture proportions of PANFRC for highway overlays and bridge decks that satisfied both the minimum compressive and bending strengths, and showed excellent mechanical properties, were selected for fatigue testing. The experimental program included a total of 69 flexural specimens, 15 of which were plain concrete specimens, and the remaining 54 specimens were PANFRC specimens. Three mixes containing 0.0%, 0.1 %, and 0.15% of PAN fiber volume fractions were selected. For each mix, 4 different target load ranges were applied: 10–75%, 10–80%, 10–85%, and 10–90% of the ultimate flexural capacity, as obtained from the corresponding control static test. The bending fatigue life of PANFRC specimens under various stress ratios are proved to follow two-parameter Weibull distribution. Both a semi-logarithm and a double-logarithm P-S-N equations with various failure probabilities are derived from the experimental measurements. The denifition of the fatigue damage variable and damage evolution equation for PANFRC are furtherly proposed based on theory of continuum damage mechanics.