The performance of corroded carbon steel pipelines over the course of their design life is generally assessed by probabilistic variables with explicit limit state functions, rather than the realistic representation with stochastic spatial variability and implicit failure considerations. This could be due to the complexities associated with the uncertainty quantification and performance estimation approaches. The consideration of random process representation of corrosion defect propagation and material properties, along with computationally effective implicit formulation is expected to lead to accurate reliability outcomes. This paper proposes a stochastic-based reliability framework considering suitable failure modes represented with surrogate models, that lead to time-variant reliability estimation. The approach combines surrogate computational model with scalar random variables and random field discretisation of underlying characteristics to generate experimental designs and corresponding surrogate models over a time period, which are used to derive reliability estimates. The outcomes of this approach are compared with the results of explicit time-dependent functions. It was observed that reliability estimates of the corroded pipeline change rapidly after the fifth year, providing a much lesser probability of failure (of at 30th-year) compared to the existing models (of at 30th-year), thereby providing an effective pathway for risk-based maintenance and management.

中文翻译：

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具有相互作用的腐蚀簇的腐蚀管道的基于随机有限元的可靠性

腐蚀碳钢管道在其设计寿命期间的性能通常通过具有明确极限状态函数的概率变量来评估，而不是通过具有随机空间变化和隐式失效考虑的实际表示来评估。这可能是由于与不确定性量化和性能估计方法相关的复杂性造成的。考虑腐蚀缺陷传播和材料特性的随机过程表示，以及计算上有效的隐式公式，预计将产生准确的可靠性结果。本文提出了一种基于随机的可靠性框架，考虑了用代理模型表示的合适故障模式，从而实现了时变可靠性估计。该方法将替代计算模型与标量随机变量和基本特征的随机场离散相结合，以生成一段时间内的实验设计和相应的替代模型，用于导出可靠性估计。该方法的结果与显式时间相关函数的结果进行了比较。据观察，腐蚀管道的可靠性估计在第五年后迅速变化，与现有模型（第 30 年）相比，故障概率（第 30 年）要小得多，从而为基于风险的维护和管理。