超大型浮体目标可靠度及极限强度可靠性研究

Target reliability and ultimate strength reliability analysis for very large floating structure

目标可靠度是超大型浮体结构极限强度可靠性的重要衡量指标,超大型浮体作为一种新颖海洋结构物,其结构可靠性设计衡准未有直接经验可借鉴。本文基于风险分析理论和原则,通过对结构失效概率和失效后果的考量,提出适用于超大型浮体的目标可靠度合理可行区域;应用简化逐步破坏分析方法确定了典型剖面的极限承载能力;基于三维线性势流理论对处于我国南海海洋环境下的浮体垂向极限波浪弯矩进行预报;根据选定的目标可靠度对浮体极限强度可靠性进行校核。研究结果表明,风险分析方法可用于建立合理的目标可靠度范围;超大型浮体总纵强度结构设计存在不足,在工程设计时应予以加强。

Target reliability is a key indicator for measuring ultimate strength reliability of Very Large Floating Structures (VLFS).Reliability design criteria for VLFS as novel marine structures,is not available at present.The paper calculates the reasonable scope of target reliability for VLFS based on risk analysis theory and principle,taking into account structure failure probability and consequence.The simplified method is used to determine the ultimate bearing capacities of the typical sections.Based on the three dimensional potential flow theory,the paper predicts the vertical extreme wave bending moment of VLFS in the context of South China Sea condition and the uncertainties of wave loads are also analyzed.At last, the paper analyzes the ultimate reliability of VLFS on account of the selected target reliabilities.It is found that,risk analysis method is applicable to determining reasonable and practicable scope of target reliability.The longitudinal strength design of VLFS is insufficient and should be strengthened in engineering practice.