Abstract The structural reliability of a pipe-in-pipe system operating in deep-waters under high internal pressure and high temperature is assessed. First, the major failure modes are identified and the respective limit state functions are formulated. In particular, the collapse of the outer and inner pipes, the local buckling of the inner and outer pipes under combined loading, the burst of the inner pipe and the buckle propagation are addressed. Additionally, a serviceability limit state function is formulated for the lateral buckling response due to excessive axial force on the outer pipe. Appropriate resistance and load models for the pipe-in-pipe configuration are included in the limit state functions. Uncertainties in the structure, operating and environmental conditions are incorporated in the limit state functions through probabilistic modelling. First-Order and Second-Order, reliability methods and Monte Carlo Simulation techniques are used to assess the structural reliability and the effect of limit state variables on the probability of the PiP failure modes. System reliability bounds for combined failure modes are estimated through a second-order series bounds approach. The importance of basic variables of the limit states is evaluated through sensitivity analysis. Several parametric studies are conducted to show the influence of the limit state variables on the reliability of each failure mode and on the bounds of the system reliability.

中文翻译：

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海底管中管系统主要故障模式的可靠性评估

摘要 评估了在高内压高温下在深水中运行的管中管系统的结构可靠性。首先，确定主要失效模式并制定相应的极限状态函数。特别是解决了外管和内管的坍塌、内管和外管在组合载荷下的局部屈曲、内管的爆裂和屈曲扩展等问题。此外，由于外管上过大的轴向力，为横向屈曲响应制定了使用极限状态函数。管中管配置的适当阻力和负载模型包含在极限状态函数中。结构的不确定性，通过概率建模将操作和环境条件纳入极限状态函数。一阶和二阶可靠性方法和蒙特卡罗模拟技术用于评估结构可靠性和极限状态变量对 PiP 故障模式概率的影响。组合故障模式的系统可靠性界限是通过二阶序列界限方法估计的。通过敏感性分析评估极限状态的基本变量的重要性。进行了多项参数研究，以显示极限状态变量对每种故障模式的可靠性和系统可靠性范围的影响。可靠性方法和蒙特卡罗模拟技术用于评估结构可靠性和极限状态变量对 PiP 故障模式概率的影响。组合故障模式的系统可靠性界限是通过二阶序列界限方法估计的。通过敏感性分析评估极限状态的基本变量的重要性。进行了多项参数研究，以显示极限状态变量对每种故障模式的可靠性和系统可靠性范围的影响。可靠性方法和蒙特卡罗模拟技术用于评估结构可靠性和极限状态变量对 PiP 故障模式概率的影响。组合故障模式的系统可靠性界限是通过二阶序列界限方法估计的。通过敏感性分析评估极限状态的基本变量的重要性。进行了多项参数研究，以显示极限状态变量对每种故障模式的可靠性和系统可靠性范围的影响。通过敏感性分析评估极限状态的基本变量的重要性。进行了多项参数研究，以显示极限状态变量对每种故障模式的可靠性和系统可靠性范围的影响。通过敏感性分析评估极限状态的基本变量的重要性。进行了多项参数研究，以显示极限状态变量对每种故障模式的可靠性和系统可靠性范围的影响。