低次数疲劳加载下短切钢纤维对碳纤维织物增强混凝土力学性能的影响

Influence of short steel fiber on mechanical properties of carbon textile reinforced concrete under low-cycle fatigue loading

  • 摘要: 为了研究低次数疲劳加载下短切钢纤维对碳纤维织物增强混凝土(C-TRC)力学性能的影响,通过万能试验机对不同短切钢纤维掺量(0vol%、0.5vol%、1.0vol%)的试件进行低次数疲劳加载实验和疲劳加载前后的准静态拉伸试验,并结合数字图像相关分析得到拉伸状态下裂纹与应变分布。结果表明:添加短切钢纤维能够增大C-TRC的拉伸强度、杨氏模量和韧性,降低试件的能量耗散及剩余累积应变,增加裂纹条数和裂纹宽度。疲劳荷载能够降低C-TRC的刚度、极限强度、峰值应变及韧性,加快C-TRC的破坏。添加短切纤维能够降低疲劳加载造成的性能损耗,且0.5vol%掺量的增强效果最佳。基于现有的剩余强度-剩余刚度关联模型和实验数据,改进了强度退化模型,对实验数据进行拟合并与现有模型进行对比,其结果与实验数据吻合更好。该成果对于织物增强混凝土(TRC)疲劳性能的评价具有指导意义。

     

    Abstract: In order to study the influence of the short steel fiber on the mechanical properties of carbon textile reinforced concrete (C-TRC) under low-cycle fatigue loading, low-cycle fatigue loading test and quasi-static tensile tests before and after fatigue loading were conducted on specimens with various contents of short steel fiber (0vol%, 0.5vol% and 1.0vol%) by a universal testing machine, and distributions of crack and strain were obtained by digital image correlation (DIC) method. The results show that the addition of short steel fiber can increase the tensile strength, the Young’s modulus and toughness of C-TRC, reduce the energy dissipation and residual accumulated strain and increase the crack number and crack width. Fatigue load can reduce the rigidity, tensile strength, peak strain, and toughness, and accelerate the destruction of C-TRC. The addition of short steel fiber can reduce the property degradation caused by fatigue loading, and the 0.5vol% addition has the best enhancement effect. The strength degradation model was modified based on the existing residual strength-residual stiffness coupled model and experimental data, The modified model is used to fit the experimental data and be compared with the existing model. The results show that the modified model is more consistent with the experimental data. These findings will be available for the fatigue performance evaluation of textile reinforced concrete (TRC).

     

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