Abstract: In response to the reality of fine grading of stress levels, large number of specimens, long test cycles, and high costs in fatigue testing, as well as the lack of fatigue system test data for flexible fiber reinforced concrete (FFRC), static flexural tests and flexural fatigue tests on FFRC with a volume fraction of 0.15% and on plain concrete was respectively conducted, and fatigue equations were obtained through regression analysis. The experimental results show that at stress levels of 0.75 and 0.65, the relative fatigue life of FFRC reaches 7.53 and 29.6 times that of plain concrete, respectively, and the improvement in fatigue life is particularly significant at the 0.65 stress level. The fatigue equations show that if the failure probabilities are 0.1, 0.3 and 0.5 respectively, and the fatigue lives are 2 million times, 1.5 million times and 1 million times respectively, the stress levels corresponding to the fatigue strength of FFRC are 0.564, 0.569 and 0.575, 0.557, 0.564 and 0.574, as well as 0.556, 0.566 and 0.580, respectively. While the stress levels corresponding to the fatigue strength of ordinary concrete are 0.539, 0.544 and 0.550, 0.555and 0.563, as well as 0.537, 0.544 and 0.554, respectively. Therefore, the fatigue strength of FFRC is significantly improved. The research results can provide a basis for the theoretical design and engineering application of FFRC.

Key words: road engineering; flexible fiber; fiber-reinforced concrete; fatigue life; fatigue equation

摘要： 针对疲劳试验应力水平分级细、试样数量多、试验周期长、花费高的现实和柔性纤维混凝土（FFRC）疲劳系统试验数据欠缺的现状，针对体积掺量为0.15%的FFRC和普通混凝土分别开展了静力弯拉试验和弯拉疲劳试验，并采用回归分析得到了疲劳方程。试验结果表明：在0.75与0.65应力水平下，FFRC相对疲劳寿命分别达到普通混凝土的7.53倍和29.60倍，在0.65应力水平下，疲劳寿命的提高程度尤为显著；疲劳方程显示，若失效概率分别为0.1、0.3和0.5，疲劳寿命分别为200万次、150万次、100万次时，FFRC疲劳强度对应应力水平分别为0.564、0.569、0.575，0.557、0.564、0.574和0.556、0.566、0.580，而普通混凝土疲劳强度对应应力水平分别为0.539、0.544、0.550，0.550、0.555、0.563和0.537、0.544、0.554，FFRC的疲劳强度显著提高。研究结果可为FFRC的理论设计与工程应用提供依据。

关键词: 道路工程；柔性纤维；纤维混凝土；疲劳寿命；疲劳方程