基于三参数Weibull模型的玄武岩再生混凝土疲劳寿命分析

Fatigue life analysis of basalt recycled concrete based on three-parameter Weibull model

为了研究玄武岩纤维再生混凝土(basalt fiber recycled aggregate concrete,BFRAC)的疲劳寿命,采用MTS Landmark系统进行了抗压疲劳试验。结果表明:在不同纤维体积掺量和长径比下,BFRAC的单轴抗压疲劳寿命(N)均有一定的提升;纤维体积掺量为0.3%、长度为12 mm时,BFRAC的单轴抗压疲劳寿命达到最高,其值为再生混凝土的2倍;但随着应力水平由0.75提升至0.85,疲劳损伤加快,疲劳寿命降低至原来的1/20~1/200。利用三参数Weibull分布构建双对数疲劳方程,分析在不同应力水平(S=0.75、0.80、0.85)和不同存活率(P=0.9、0.7、0.5)下的P-S-N曲线及疲劳强度理论损伤,结果表明:存活率为0.5、纤维体积掺量为0.3%、长度为12 mm时,疲劳极限强度达到最高(0.8648);当玄武岩纤维长度为6~12 mm时,疲劳极限强度总体上随着纤维长度的增加而增强,且在12 mm时,增强效果最佳。

To study the fatigue life of basalt fiber recycled aggregate concrete(BFRAC),the MTS Landmark system was used to conduct a compressive fatigue test.The test results show that the uniaxial compressive fatigue life(N)of BFRAC has a certain increase under different fiber volume contents and length-to-diameter ratios.When the fiber volume content is 0.3%and the length is 12 mm,the highest uniaxial compressive fatigue life of BFRAC is reached,and its value is twice that of recycled concrete.However,as the stress level is raised from 0.75 to 0.85,fatigue damage is accelerated,and the fatigue life is reduced to 1/20-1/200 of the original.The three-parameter Weibull distribution was used to construct a double logarithmic fatigue equation to analyze the P-S-N curve and fatigue strength theoretical damage at different stress levels(S=0.75,0.80,0.85)and different survival rates(P=0.9,0.7,0.5).The results show that when the survival rate is 0.5,with the fiber volume content 0.3%and the fiber length 12 mm,the maximum fatigue ultimate strength(0.8648)is reached.The fatigue ultimate strength increases with the increase of the basalt fiber length from 6 mm to 12 mm,and the increase effect is the best at 12 mm.