半潜式平台立柱与浮筒连接节点疲劳可靠性分析

Fatigue Analysis of Connection Between Column and Pontoon of Semi-Submersible Units

半潜式平台结构和受力条件复杂。能否准确把握关键节点结构在复杂受力条件下的疲劳性能,直接影响到平台整体结构的疲劳可靠性。针对目前频繁出现的平台立柱与浮筒连接节点疲劳失效,首先总结工程中主流的四种立柱与浮筒连接节点形式;然后,利用设计波法计算总体载荷,子模型法获得热点应力,以及简化疲劳方法评估节点疲劳寿命;再次,采用古特曼模型以及Gerber模型讨论平均应力对节点结构寿命的影响,计算结果表明,四种不同方案的节点形式热点应力水平和疲劳寿命差异很大。据此,从半潜式平台总体结构响应入手,通过对比分析各个方案结构形式和计算结果,阐述导致节点计算疲劳寿命差异的主要原因。最后根据挪威船级社(DNV)规范提供的数据简要分析该节点的疲劳寿命对整个平台可靠度的影响。

Fatigue strength of connections between column and pontoon directly influences the reliability of the whole semi-submersible structure. Due to the frequently occurring fatigue failure of existing semi-submersible units, we carry out fatigue analysis based on simplified method for four type connections which have been used in present design. The connections fatigue life is modified by considering the mean stress accounted for the Goodman curve and Gerber curve. Then we compare the results to find out the optimized connection type. At last, the influence of the fatigue life on the reliability of the whole semi-submersible units is analyzed based on the data obtained from the Det Norske Veritas （DNV） rules.