The ductile crack initiation observed in structural steels subjected to ultra-low cycle fatigue (ULCF) loading often leads to the catastrophic failure in steel structures. In the existing ULCF damage models, there is always a contradiction between the cost of model parameters calibration and prediction accuracy. In order to solve the contradiction, a one-parameter model for ULCF damage evaluation of structural steels was proposed based on the concept that ULCF damage consists of ductile damage in tensile loading and cyclic damage under cyclic plastic stain loading, and a simple and practical parameter calibration method only using tensile results of coupon specimens is developed. Tests and finite element analysis were carried out on circular notched specimens to verify the prediction accuracy of proposed model. The results show that predicted results are in good agreement with test results, indicating a good performance of the proposed model for ULCF damage evaluation of structural steels.

在承受超低周疲劳（ULCF）载荷的结构钢中观察到的延性裂纹萌生通常会导致钢结构的灾难性破坏。在现有的ULCF损伤模型中，模型参数校准的成本与预测精度之间始终存在矛盾。为了解决这一矛盾，基于ULCF损伤包括拉伸载荷下的延性损伤和循环塑性污渍载荷下的循环损伤，以及简单实用的参数，提出了一种结构钢的ULCF损伤评估的单参数模型。开发了仅使用试样试样拉伸结果的标定方法。对圆形缺口试样进行了测试和有限元分析，以验证所提出模型的预测准确性。