冰区海洋平台的时变疲劳可靠性分析

冰区海洋平台在交变冰力作用下的管节点疲劳是影响平台安全的主要因素。本文结合现有的冰疲劳环境荷载及冰力谱函数,提出了相对于冰速、冰厚随机冰载的管节点应力幅显式近似计算公式;将海洋平台管节点的全寿命划分为裂纹萌生和扩展两个阶段,分别采用S-N曲线法和Paris公式来计算相应的寿命;并考虑了管节点抗力随时间的衰减,得到了时变疲劳可靠性计算公式;最后对渤海JZ20-2 MSW平台进行时变疲劳可靠性分析。结果表明,本文提出的疲劳应力幅近似计算方法和时变可靠性分析方法是合理有效的。

Time-dependent fatigue reliability analysis of offshore platforms in ice zone

In ice zone,the fatigue of the tubular joints of offshore platforms induced by the dynamic ice load is the key factor of the structural safety.According to the fatigue environment in the ice zone and the ice-force spectrum function,this paper establishes the approximate explicit formula of nodes stress with respect to the ice velocity and thickness.The fatigue life includes two stages,crack growth and propagation,whose time-dependent reliabilities are analyzed based on the S-N formula and Paris formula,considering the resistance degradation of tubular joints.Finally,the time-dependent fatigue reliability of MSW platforms of JZ20-2 in Bohai bay is evaluated,and the results demonstrate the method proposed in the present paper is rational and efficient.