This paper deals with the lateral buckling behavior of an axially compressed beam interacting with the ground on which it is resting. Such a simple model is supposed to reproduce the same trends as observed during the lateral buckling of offshore pipelines on the seabed. In such practical analyses, the pipe-soil interaction relates the ground to the neutral axis of the pipeline. It is shown that, although such a constraint significantly affects the buckling behavior of the pipeline, it cannot reflect the torsional component of the buckling modes. However, this component is encountered in practice and may further modify the critical loads. Therefore, in this present preliminary study, the interaction between the beam in hand and the surrounding ground is modeled by a connection (a continuous distribution of lateral springs) related to the bottom line of the beam. In this way, the real contact between the soil and the bottom line of a pipe is mimicked, allowing for both flexural and torsional deformations in the buckling response. The problem is investigated analytically using an Euler–Bernoulli beam model with an isotropic linear elastic constitutive law and also an elastic interaction law. Original analytical solutions are derived and compared to numerical results obtained through finite element computations. In comparison with classical solutions (with the connection related to the neutral axis), new types of buckling modes may appear when considering torsional effects, depending on the boundary conditions, with generally much lower critical loads. These first results are certainly representative of some features of the global/localized lateral buckling of offshore pipelines, indicating that torsional effects should also be taken into account in such more comprehensive analyses.

中文翻译：

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轴压下地面管状梁横向屈曲的扭转效应研究

本文讨论了轴向压缩梁与其所支撑的地面相互作用的横向屈曲行为。这样一个简单的模型应该重现与海底管道横向屈曲过程中观察到的相同趋势。在这样的实际分析中，管土相互作用将地面与管道的中性轴联系起来。结果表明，尽管这种约束对管道的屈曲行为有显着影响，但它不能反映屈曲模式的扭转分量。然而，这个组件在实践中会遇到并且可能会进一步修改临界负载。因此，在本次初步研究中，手上的梁与周围地面之间的相互作用是通过与梁底线相关的连接（横向弹簧的连续分布）来模拟的。通过这种方式，模拟了土壤和管道底线之间的真实接触，允许屈曲响应中的弯曲和扭转变形。使用具有各向同性线弹性本构定律和弹性相互作用定律的 Euler-Bernoulli 梁模型对该问题进行分析研究。推导出原始解析解，并与通过有限元计算获得的数值结果进行比较。与经典解决方案（与中性轴相关的连接）相比，在考虑扭转效应时可能会出现新类型的屈曲模式，具体取决于边界条件，通常具有低得多的临界载荷。这些初步结果肯定代表了海上管道整体/局部横向屈曲的一些特征，表明在这种更全面的分析中也应考虑扭转效应。