利旧东海海上导管架油气生产平台作为CO₂海上封存注入平台研究是东海CCS（碳捕集与封存）项目的实施重要研究内容。因此，针对已建导管架平台准确的疲劳分析计算将尤为重要。基于结构系统和波浪加载机制线性假设的频谱疲劳分析方法，在计算海上导管架结构上的波浪荷载和随后的结构响应时，可以有效地描述环境海浪条件的随机性，常常被用于海上导管架平台设计，也适用于旧导管架结构的重新评估。尽管这种方法非常适合应用于波高和波浪力非线性不太严重的深水场景海上平台设计和疲劳分析，但该方法仍然在没有仔细考虑由于波高和波浪力之间的严重非线性因素而可能导致计算误差的情况下，被广泛用于浅水导管架平台的设计和评估。产生这种误差的主要原因是在生成随机波浪谱和结构应力相应谱之间的传递函数时，因上述波高和波浪力之间存在的严重非线性导致难以为一系列波周期选择适当正确的对应波高。该研究的重点是聚焦于浅水平台频谱疲劳分析方法可能存在的计算误差，介绍了减少频谱疲劳分析方法误差研究的优化计算结果，并提出了1种新的技术方法，即如何通过使用波高和周期联合概率密度函数，在海况波谱和结构应力相应谱之间获得更准确的传递函数，减少浅水平台频谱疲劳分析中的误差，从而合理地利用单个局部海况数据。因此，频谱疲劳分析法可以更精确地计算海上导管架结构管结点的疲劳损伤和寿命。这种改进的频谱疲劳分析法已被应用于东海导管架平台的设计评估。研究将疲劳分析结果与常规频谱疲劳分析方法的结果进行了对比和讨论。此外，由于现有设计软件中用于计算疲劳损伤的波高概率密度函数仅对窄带频谱有效，对宽带频谱造成额外误差。该研究对改进宽带频谱疲劳损伤计算也进行了讨论。这种改进的频谱疲劳分析法将可运用于海上CO₂注入利旧导管架平台的结构疲劳寿命分析计算。

The research on utilizing offshore jacket platforms in the East China Sea as offshore CO₂ sequestration and injection platforms is a critical component for the implementation of the East China Sea CCS project. Therefore, it is particularly important to perform accurate fatigue analysis and calculation for the existing jacket platforms. The spectral fatigue analysis method, based on the assumption of linearity of both structural system and wave loading mechanism, can effectively capture the randomness of environmental wave conditions when calculating wave loads and the subsequent structural responses on offshore jacket structures. This method is commonly utilized for the design of offshore jacket platforms and is also suitable for the reassessment of existing jacket structures. Although this method is highly suitable to be applied in offshore platform design and fatigue analysis for deepwater scenarios where nonlinearities between wave height and wave force are not very severe, it has still been widely utilized for the design and assessment of shallow water jacket platforms without carefully considering the possible calculation errors due to strong nonlinear factors between wave heights and wave forces. These errors primarily result from difficulties in choosing appropriate wave heights for a series of wave periods required for producing transfer functions between random wave spectra and structural stress response spectra, due to the significant nonlinearity between wave heights and wave forces mentioned above. This study focused on the potential calculation errors in the spectral fatigue analysis method for shallow water platforms. It presented optimized calculation results from research aimed at reducing the errors in the spectral fatigue analysis method and proposed a new technical approach. This approach could produce more accurate transfer functions between sea state spectra and structural stress response spectra by using the joint probability density function of wave height and period, thereby reducing errors in the spectral fatigue analysis of shallow water platforms and enabling rational utilization of individual local sea state data. Therefore, fatigue damage and service life at the tubular joints of offshore jacket structures could be calculated more accurately. The improved spectral fatigue analysis was applied to the design assessment of jacket platforms in the East China Sea. The results of the fatigue analysis were compared and discussed with those obtained by conventional spectral fatigue analysis methods. In addition, the wave probability density function used for computing fatigue damage in the existing design software was only effective for the narrow-band spectra, and it caused additional errors for the broad-band spectra. This study also discussed improvements in the calculation of fatigue damage for the broad-band spectra. This improved spectral fatigue analysis method can be applied to the structural fatigue life analysis and calculation of the offshore CO₂ injection retrofitted jacket platforms.