针对已发现结构裂纹的海洋油气导管架平台，基于工程临界评定（ECA）技术，形成适用的结构完整性评价及维修周期策略制定方法，并对某导管架平台进行了案例分析。使用莫里森方程（Morison equation）对目标平台进行了水动力学分析，估算了平台关键节点的极限载荷。通过有限元分析方法及热点应力线性外推法对关键节点进行了热点应力评估。通过帕里斯公式（Paris'law）对关键节点处裂纹扩展行为进行了相关模拟，求解目标裂纹尖端应力强度因子。通过失效评定图（FAD）对相关裂纹进行了ECA评估，给出了临界裂纹范围。结合临界裂纹深度和裂纹扩展关系，给出参考维修周期。结果表明：管架水平杆与立管相连节点为易于受疲劳损伤杆件。通过失效评定，该结构裂纹深度方向失效以塌陷失效为主，裂纹长度方向存在塌陷失效和裂纹失效可能。针对案例分析中平台，建议考虑临界裂纹深度5.3 mm，临界裂纹半宽长度9.8 mm。如发现0.5~2.0 mm的裂纹，建议在13.2~5.2 h内完成维修。该方法可推广应用于周边海域相似海洋油气平台已发现裂纹评定。

For offshore oil and gas jacket platforms with detected structural cracks, a methodology for structural integrity evaluation and maintenance cycle strategy formulation was developed based on engineering critical assessment (ECA) techniques. A case study was conducted on a specific jacket platform. The Morison equation was used for hydrodynamic analysis of the target platform to estimate the ultimate load of joints prone to failure. Hotspot stress assessment was performed on these joints using the finite element analysis method and linear extrapolation. Crack propagation behavior at critical joints was simulated using Paris' law, and the stress intensity factor at the crack tip was determined. Cracks were assessed using failure assessment diagrams (FAD), and the critical crack sizes were provided. Based on the relationship between critical crack depth and crack propagation, a reference maintenance cycle was proposed. The results showed that the joints connecting horizontal braces and risers of the jacket structure were prone to fatigue damage. Failure assessment indicated that failure in the crack depth direction was primarily dominated by collapse, while failure in the crack length direction may involve both collapse and fracture. For the analyzed platform, it was recommended to consider a critical crack depth of 5.3 mm and a critical crack half-width of 9.8 mm. If cracks ranging from 0.5 to 2.0 mm were detected, maintenance was recommended within 13.2 to 5.2 h. This methodology can be extended to similar offshore oil and gas platforms with detected cracks in adjacent sea areas.