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以能量和残余应变作为损伤变量,将损伤过程划分为三个阶段。针对损伤发展的第二阶段,研究疲劳载荷与环境因素协同作用下混凝土耐久性的劣化情况。随着残余应变的增加,结构混凝土中氯离子扩散系数和空气渗透系数均变大,而且当残余应变超过60×10-6时,增加幅度变得明显。尤其当残余应变增加到120×10-6时,相应的系数提高了一个数量级。结论同样适合疲劳载荷与冻融循环的耦合作用。因此,可以把残余应变分别为30×10-6～60×10-6和120×10-6视为影响混凝土耐久性的起劣区间和陡劣点。
With energy and residual strain as damage variables, the damage process is divided into three stages. In the second stage of damage development, the deterioration of concrete durability under the synergistic effect of fatigue load and environmental factors was studied. As the residual strain increases, the chloride ion diffusion coefficient and air permeability coefficient of the structural concrete become larger, and when the residual strain exceeds 60 × 10-6, the increase range becomes obvious. Especially when the residual strain increases to 120 × 10-6, the corresponding coefficient increases by one order of magnitude. The conclusion is also suitable for the coupling of fatigue loading and freeze-thaw cycles. Therefore, the residual strain of 30 × 10-6 ~ 60 × 10-6 and 120 × 10-6 can be considered as the impact of concrete durability of the inferior and abrupt point.