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在一定应力水平的疲劳荷载作用下,混凝土强度会衰减,混凝土结构发生疲劳破坏.为了能反映出混凝土疲劳荷载作用的先后性(或时间性),论文提出了混凝土疲劳荷载权函数的概念,以剩余强度定义了累积损伤的变量,建立了累积损伤变量与疲劳荷载作用次数的曲线方程.继而分别推导了以混凝土剩余强度所定义的单级和多级荷载疲劳荷载权函数的数学表达式;通过建立的疲劳荷载权函数,推得单级和多级荷载作用下混凝土疲劳累积损伤的计算式,并分别推导和论证了混凝土疲劳破坏时的累积损伤值大于1,不同应力水平的疲劳荷载和不同的荷载作用次序所得到的混凝土疲劳累积损伤值不等同,相同荷载、不同作用顺序对结构疲劳累积损伤贡献不等等重要结论.
Under certain stress level, the strength of concrete will be attenuated and fatigue damage will occur to concrete structure.In order to reflect the orderliness (or temporality) of concrete fatigue loading, the paper proposes the concept of concrete fatigue load weight function The residual strength defines the variables of cumulative damage, and establishes the curve equations of cumulative damage variables and the number of fatigue loads, and then derives the mathematical expressions of the weight functions of single-stage and multi-stage loads as defined by the residual strength of concrete respectively. The fatigue load weighting function was established to calculate the cumulative fatigue damage of concrete under single-stage and multi-stage loads. The cumulative damage of concrete under fatigue failure was deduced and demonstrated respectively. The fatigue load and the different fatigue stresses at different stress levels The cumulative fatigue damage values of the concrete obtained by the order of loading are different, and the important conclusions are that the same load and different order of action contribute to the cumulative fatigue damage of the structure.