中文摘要：

在施工和运营过程中，钢结构构件上出现的裂纹缺陷可能会扩展而导致其发生断裂破坏，因此对含裂纹缺陷钢结构构件的安全性进行评估具有重要意义。首先，引入断裂力学KIC断裂判据和失效评定图（FAD）概念，并介绍了结构整体性评估程序（SINTAP）的原理；给出了裂纹缺陷评定所需材料参数的确定方法，以及含裂纹缺陷构件的断裂力学参数和塑性屈服荷载的计算方法；然后，提出了基于SINTAP-FAD的含裂纹缺陷钢结构构件的安全性评估流程。最后，以华南和华东两个电厂锅炉钢结构大板梁的焊接缺陷为例，进行了基于KIC断裂判据和SINTAP-FAD的裂纹缺陷安全性评定研究。结果表明，基于SINTAP-FAD的方法为含裂纹缺陷工作的钢结构构件的安全性评估提供了一种行之有效的方法，考虑多裂纹耦合作用的安全性评定方法有待进一步研究。

英文摘要：

During the construction and operation period, the induced crack defects in the structural components of steel structures may propagate and eventually result in the fracture failure of the structural components. Therefore, it is of great significance to assess the safety of structural components containing crack defects. Firstly, the principle of failure assessment diagram （FAD） and Kic fracture criterion were introduced, which are based on fracture mechanics, and on the assessment method of SINTAP. Then, the experimental methods for obtaining material parameters required by SINTAP-FAD assessment procedure, and the calculation methods of fracture mechanics parameters and plastic collapse loads of the flawed components, were presented. Finally, the safety assessment of crack defects within the butt welds on large-size plate girders of boiler steel structures from two power stations were conducted, using KIC fracture criterion and SINTAP-FAD method. The results show that the proposed method based on SINTAP-FAD provides an effective and practical approach for the safety assessment of structural components with cracks or crack-like defects in steel structures. Further research should be dedicated to the assessment method considering the multiple-crack coupling effect.