极地船舶结构设计思考

Structural design considerations for ships operating in arctic regions

  • 摘要: 冰脊和冰山与极地船体发生碰撞将影响船体结构安全,并决定船体结构设计载荷。船体结构设计应遵循基于风险的设计原则,通常涉及以下极限状态设计准则:1)服务极限状态 (SLS);2)最终极限状态(ULS);3)疲劳极限状态(FLS);4)事故极限状态(ALS)。最终极限状态和事故极限状态对应于发生概率极低的船与冰脊作用以及冰山撞击事件,旨在确保船体结构不会完全损毁。然而,对于较低概率水平的冰载荷分析,需进行较大数据量的工况分析,计算耗时无法承受。为此,引入环境等值轮廓方法,来大幅减少冰载荷分析所需工况数量,并给出设计工况最有可能的冰体参数组合方式。结合最终极限状态和事故极限状态,举例说明这一方法的运用方式。环境等值轮廓方法可为现有极地船舶船体结构设计方法提供有效补充。

     

    Abstract: The safety of Arctic ships will be influenced by the interactions with ice ridges and icebergs. Generally, the structural design loads will be governed by these ice features. In order to design ship structures, the principles of risk-based design should be considered and followed. The following limit state design criteria are usually applied in structural design: 1) Serviceability Limit States (SLS); 2) Ultimate Limit States (ULS); 3) Fatigue Limit States (FLS); 4) Abnormal/Accidental Limit States (ALS). The ULS and ALS correspond to impact events with a very low probability to occur, and its intention is to ensure that a ship hull structure does not suffer from a complete loss of integrity. However, for analysis of the ice loads with low probability levels, the number of relevant load cases is significant and the computation amount is huge. In this work, the so-called environmental contour method is introduced in order to reduce the required number for ice loads analysis as well as to identify the most likely combinations of the relevant design parameters. Utilization of this approach is illustrated in connection with the ULS and ALS in the present paper. Application of the proposed method could be a valuable supplementary for structural design of Arctic ships.

     

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