【作者】 张小辉；

【导师】 何天淳；

【作者基本信息】 昆明理工大学 ， 工程力学， 2001， 硕士

【摘要】 本文对钢纤维混凝土在各应力水平下的等幅弯曲疲劳性能进行了实验研究，测得了钢纤维混凝土疲劳寿命、变形和弹性模量衰减量。在实验基础上，用疲劳统计学理论研究了钢纤维混凝土弯曲疲劳寿命的概率分布规律，得出钢纤维混凝土的疲劳寿命方程，并根据实测数据回归出了钢纤维混凝土疲劳变形和抗折弹性模量衰减规律的经验公式。疲劳破坏过程实际上是微损伤累积过程，本文根据损伤力学理论并结合实验数据得出钢纤维混凝土弯曲疲劳损伤演变方程。 钢纤维混凝土可以看作为由混凝土基体和钢纤维组成的二项复合材料，本文运用复合材料细观力学中的剪滞法推导了材料受力时轴向和斜向钢纤维的应力分布以及纤维和混凝土基体粘结界面中剪应力分布。根据短纤维在基体中取向的几何模型，建立了钢纤维在基体中分布的概率函数。在此基础上，推出了钢纤维单向分布和随机分布两种情况下钢纤维混凝土的拉伸强度，并根据已有的界面粘结理论，推导出了钢纤维混凝土拉伸初裂强度和极限强度。 本文研究结果可归纳得出：钢纤维混凝土静压抗折强度比素混凝土有较大提高，抗疲劳性能有明显改善，钢纤维混凝土弯曲疲劳寿命分布服从两参数威布耳分布，文中得出的疲劳寿命方程、疲劳变形经验公式和疲劳损伤演变方程能正确描述钢纤维混凝土弯曲疲劳特性。理论研究结果表明，用复合材料细观力学可以建立细观参数与宏观力学性能关系，对了解钢纤维混凝土增强机理、指导钢纤维混凝土的细观设计等具有重要意义。更多还原

【Abstract】 Theoretic and experimental research on the bending fatigue and its damage properties of Steel Fiber Reinforced Concrete (SFRC) under several stress levels constant amplitude loading is carried out in this paper, and the experimental data of fatigue life, strain and degradation of bending modulus are obtained. Based on the experimental results, fatigue life distribution of SFRC is studied using fatigue life statistics theory, the fatigue life equation is established, and some experimental formulas for evaluating strain and degradation of bending modulus are gained. The fracture procedure of material under fatigue loading is a micro-damage cumulative procedure. According to the fatigue cumulative damage theory, a cumulative damage model for bending fatigue of SFRC is derived. SFRC can be simply looked as a kind of composite material composed of steel fiber and concrete, so tensile stress distribution in steel fiber and shear stress distribution in interface when tensile loading is applied on SFRC are derived by using shear-lagging method. The probability density functions of fibers?distribution in concrete are established according to the geometric models of fibers?distribution in concrete. Based on these results, the tensile strengths of aligned fiber reinforced concrete and random fiber reinforced concrete are derived, furthermore, the first-crack strength and the limited strength of random fiber reinforced concrete are also obtained from interfacial debonding theory. The study results in the paper can be concluded that the bending strength of SFRC is much higher than that of plain concrete and bending fatigue properties of SFRC are better than that of plain concrete, that bending fatigue life of SFRC can be described by two parameter Weibull distribution, and that the fatigue life eql~ation, experimental formulas and the cumulative damage model can describe correctly the bending fatigue behaviors of SFRC. Theoretic study results indicate that using composite material micro-mechanics can establish the relationship between micro-structure parameters and macro-mechanic properties of SFRC, which is significant to understand the reinforce mechanism and to conduct micro-design of SFRC.更多还原