弯曲荷载下玄武岩纤维混凝土疲劳寿命与韧性分析

Analysis on fatigue life and toughness of basalt fiber reinforced concrete under bending load

为研究弯曲荷载下的玄武岩纤维混凝土(basalt fiber reinforced concrete, BFRC)的疲劳寿命方程和疲劳韧性,以不同玄武岩纤维体积百分比掺量(0,0.1%,0.2%,0.3%,0.4%)设计5组棱柱体混凝土小梁,对该批混凝土小梁试件进行不同应力水平下(0.6,0.7和0.8)的三点弯曲加载疲劳试验。结果表明,不同掺量的玄武岩纤维混凝土弯曲疲劳寿命均服从两参数威布尔分布。同一应力水平下,玄武岩纤维混凝土的弯曲疲劳寿命远高于素混凝土的,其弯曲疲劳寿命随玄武岩纤维掺量增加逐渐提高。通过威布尔分布的参数分析,得到不同可靠性概率要求的玄武岩纤维混凝土双对数弯曲疲劳寿命方程。随着混凝土试件可靠性概率要求的提高,其相应的疲劳寿命方程曲线逐渐向左侧偏移,表示其疲劳寿命在减小。从荷载做功的原理对玄武岩纤维混凝土的疲劳韧性进行分析,结果表明,玄武岩纤维提高了混凝土的疲劳韧性,纤维掺量越高,其相对疲劳韧性越大。

In order to study the fatigue life equation and fatigue toughness of basalt fiber reinforced concrete(BFRC)under bending load, five groups of prismatic concrete beams were designed with five different basalt fiber volume percentages(0,0.1%,0.2%,0.3% and 0.4%),and three-point bending fatigue tests were carried out under different stress level(0.6,0.7 and 0.8).The experimental results showed that the flexural fatigue life of basalt fiber reinforced concrete with different content conformsed to the Weibull distribution of two parameters.Under the same stress level, the flexural fatigue life of basalt fiber reinforced concrete was much higher than that of plain concrete, and the flexural fatigue life of basalt fiber reinforced concrete increased with the increase of basalt fiber content.Through the parameter analysis of Weibull distribution, the double logarithmic bending fatigue life equation of basalt fiber reinforced concrete with different reliability probability requirements was obtained.With the increase of reliability probability of concrete, the corresponding fatigue life equation curve shifted to the left, which indicated that the fatigue life was decreasing.The fatigue toughness of basalt fiber reinforced concrete was analyzed on the principle of work done by load.The results showed that basalt fiber improved the fatigue toughness of concrete.The higher the fiber content was, the greater the relative fatigue toughness was.