半潜平台结构疲劳寿命评估方法比较

摘要

为了研究各种疲劳评估方法对海洋结构物疲劳寿命评估结果的影响,利用S-N曲线方法和断裂力学方法分别计算了半潜式海洋平台的疲劳寿命,分析比较了二者计算结果的差别.同时比较了疲劳载荷预报中谱分析方法和设计波法的计算结果,分析研究半潜式海洋平台结构关键节点疲劳应力计算中设计波和载荷参数的确定方法,为半潜式海洋平台的疲劳寿命评估提供依据.经过比较分析,认为S-N曲线方法和断裂力学方法应用于评估海洋结构物疲劳寿命均是可行的,使用设计波法来计算半潜式海洋平台横撑与立柱交点处结构疲劳寿命时应该以60°浪向的横向扭矩为特征设计波浪载荷来决定设计波参数比较合理.%Fatigue lives of semi-submersible structures are estimated with S-N curve and fracture mechanics method to investigate the influence of different fatigue damage models on fatigue life of marine structures. Moreover, the fatigue stress ranges at specific structural joint are predicted with spectrum anfi design wave method and their effects on the fatigue lives are compared to investigate key load parameters/in fatigue damage process of structures. It is concluded that the S-N curve method and fracture mechanics method produce similar results in fatigue life predictions of the semi-submersible structures. And, the transversal torsional moment in 60° wave direction is the key load condition in design wave method for estimating structural fatigue life at intersection between cross-brace and column of the platform.