This study investigated deformation behavior of structural steel subjected to large strain. When structures experience powerful earthquakes, strain amplitudes at the fracture locations can be quite large, and the material fractures after few loading cycles. The Manson-Coffin relationship is commonly used to predict failure of metals subjected to cyclic loadings. However, the traditional Manson–Coffin relationship does not necessarily hold for some materials under extremely large strain amplitude. There are few relevant experiments, largely because it is difficult to reproduce structural steel behavior under large amplitude cyclic stains in the laboratory due to buckling. In this study, 71 steel plate specimens of structural steel were loaded until fracture under diverse cyclic axial strain loadings and monotonic tension. The relationship between cumulative strain and its skeleton portion was obtained based on the analysis of the hysteresis loops. Due to the limitation of test setup, the largest compression strain amplitude is 6%, which is still not sufficient to study the material behavior of structural steel under severe earthquakes. Therefore, numerical simulations of single steel elements subjected to cyclic strain were conducted to complement the material behavior under extremely large constant strain amplitudes. The cumulative deformation capacity of structural steel subjected to extremely large strain amplitudes was evaluated through a strain-life curve with the experimental and analytical results. In the final part of this study, experimental results from former research were introduced to validate the proposed strain-life curve.

这项研究调查了结构钢在大应变下的变形行为。当结构遭受强烈地震时，断裂位置的应变幅度可能会很大，并且在几次加载循环后材料就会断裂。曼森-科芬关系通常用于预测承受循环载荷的金属的失效。但是，传统的曼森-棺材关系不一定适用于某些在极大应变幅度下的材料。相关实验很少，主要是因为在实验室中由于屈曲很难在大振幅循环污点下重现结构钢的行为。在这项研究中，加载了71块结构钢钢板标本，直到在不同的循环轴向应变载荷和单调张力下断裂。通过对磁滞回线的分析，获得了累积应变与其骨架部分之间的关​​系。由于试验装置的局限性，最大压缩应变幅值为6％，这仍然不足以研究大地震下结构钢的材料性能。因此，进行了单钢元件承受循环应变的数值模拟，以补充在极大的恒定应变幅度下的材料行为。通过应变-寿命曲线，通过实验和分析结果评估了结构钢承受极大应变幅度时的累积变形能力。在本研究的最后部分，介绍了先前研究的实验结果，以验证所提出的应变寿命曲线。