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研究混凝土疲劳问题的主要困难之一 ,就是混凝土疲劳损伤的累积速度与不同强度循环荷载的作用次序有关 ,且是非线性的。但通常的一些非线性损伤模型却不能反映荷载作用次序的影响。为了解决此问题和混凝土结构在长期不稳定循环荷载作用下的疲劳问题 ,我们在Miner线性累积损伤模型的基础上提出了一个新的非线性累积损伤模型。通过两个疲劳损伤实例的计算证明了该模型不仅能够反映出不同强度应力水平先后作用次序对疲劳损伤演变情况的影响 ,而且保留了Miner模型概念明确、使用方便的优点。当通过试验得到一组有关曲线之后 ,不稳定循环荷载作用下的混凝土疲劳累积损伤计算将变得异常简单 ,极便于在工程设计中采用。
One of the major difficulties in studying concrete fatigue problems is that the cumulative fatigue damage rate of concrete is related to the order of action of cyclic loads with different intensities and is nonlinear. However, some non-linear damage models usually do not reflect the influence of load order. In order to solve this problem and the fatigue of concrete structures under long-term unsteady cyclic loading, we propose a new nonlinear cumulative damage model based on Miner’s linear cumulative damage model. The results of two fatigue damage cases show that the model can not only reflect the effect of order of different stress levels on the evolution of fatigue damage, but also retain the advantages of clear and easy-to-use Miner model. After a set of relevant curves are obtained through experiments, the calculation of cumulative fatigue damage of concrete under unstable cyclic loading will become extremely simple and easy to adopt in engineering design.