Sandwich pipes (SPs) composed of two concentrically steel tubes with a strain hardening cementitious composite (SHCC) filling core is a new concept designed for oil and gas transportation in deep waters. In this concept, the SHCC core is the most critical component that should withstand the combined loading of high hydrostatic pressure and bending moment. This paper proposes a particular concrete damage plasticity (CDP) model for the SHCC core based both on experimental data and on the continuum damage mechanics theory. The basic fundamentals of the CDP model can be divided into three major issues, namely, damage evolution, yield criterion, and plastic flow rule. For the damage evolution, two models of damage variables, under tension and compression, respectively, were built based on uniaxial experimental data available and the fracture energy theory. For the yield criterion, the parameters for the Lubliner model were fitted according to available experimental data from uniaxial and biaxial compressive tests. For the plastic flow rule, the dilation angle was deduced from the results of triaxial compressive tests combined with the Drucker-Prager type plastic flow rule. Finally, four-point bending tests were carried out on SHCC specimens and collapse tests were conducted on SP models to allow a correlation study between experimental data and results obtained from numerical simulations incorporating the proposed CDP model. The correlation between numerical and experimental results showed good agreement, demonstrating that the proposed CDP model can accurately reproduce the mechanical behavior and damage distribution experienced by an SHCC material.

中文翻译：

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基于实验的参数应用于夹层管中应变硬化水泥基复合材料的混凝土损伤塑性模型

夹心管（SPs）由两根同心钢管组成，并带有应变硬化水泥基复合材料（SHCC）填充芯，是一种专为深水油气输送而设计的新概念。在这个概念中，SHCC 核心是最关键的部件，它应该承受高静水压力和弯矩的组合载荷。本文基于实验数据和连续介质损伤力学理论，为 SHCC 岩心提出了一种特殊的混凝土损伤塑性 (CDP) 模型。CDP模型的基本原理可以分为三大问题，即损伤演化、屈服准则和塑性流动规则。对于损伤演化，两种损伤变量模型，分别在拉伸和压缩下，是基于可用的单轴实验数据和断裂能理论建立的。对于屈服准则，Lubliner 模型的参数根据来自单轴和双轴压缩试验的可用实验数据进行拟合。对于塑性流动法则，膨胀角由三轴压缩试验的结果结合 Drucker-Prager 型塑性流动法则推导出来。最后，对 SHCC 试样进行了四点弯曲试验，并对 SP 模型进行了坍塌试验，以允许对实验数据与结合所提出的 CDP 模型的数值模拟获得的结果进行相关性研究。数值和实验结果之间的相关性显示出良好的一致性，