Abstract A method for evaluating the mechanical integrity of open-top cylindrical storage tanks subjected to a differential settlement is given. The settlement profile underneath the bottom circumference of the tank shell can be transformed into different harmonic components using the Fourier transformation. The existing method in American Petroleum Institute’s standard API 653, which is currently used by the industry in North America, does not differentiate the effect of different harmonic components. Nevertheless, the proposed method evaluates a cumulative damage factor by considering the effects of first five harmonic components individually. The paper further discusses other limitations of the existing method in API 653 document. Numerous finite element analysis (FEA) simulations are conducted to formulate and validate the proposed method by employing geometric nonlinear algorithm with nonlinear plastic material properties (GMNA) in ABAQUS finite element software. The trend for limiting settlement values with respect to different harmonic components under consideration and different tank geometries are discussed. The proposed method is validated by performing FEA using four actual settlement data profiles on different tank geometries. Lastly, the comparison is drawn between the FEA results, the existing API 653 method and the proposed method. The results of the allowable settlement indicate that the existing method is not consistent with the FEA findings. For some of the actual settlement data, the existing method results in overly conservative values and for others it gives non-conservative values. Thus, the existing method may not capture the true behavior of tanks under settlement and needs modifications. The results of allowable settlement from the proposed method are found to be consistent with the FEA results for all different settlement data and tank geometries. Therefore, it is recommended that the new method is used instead of the existing method.

中文翻译：

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受差异沉降影响的开顶储罐的适用性

摘要 给出了一种评价不同沉降作用下开顶圆柱形储罐机械完整性的方法。罐壳底部圆周下方的沉降剖面可以使用傅立叶变换转换为不同的谐波分量。美国石油协会标准API 653中现有的方法，目前北美行业使用的，没有区分不同谐波分量的影响。然而，所提出的方法通过单独考虑前五个谐波分量的影响来评估累积损伤因子。该论文进一步讨论了 API 653 文档中现有方法的其他限制。通过在 ABAQUS 有限元软件中采用具有非线性塑性材料特性 (GMNA) 的几何非线性算法，进行了大量有限元分析 (FEA) 模拟以制定和验证所提出的方法。讨论了在考虑的不同谐波分量和不同储罐几何形状方面限制沉降值的趋势。通过使用不同储罐几何形状的四个实际沉降数据剖面执行 FEA 来验证所提出的方法。最后，在有限元分析结果、现有 API 653 方法和建议方法之间进行比较。允许沉降的结果表明现有方法与 FEA 结果不一致。对于部分实际结算数据，现有方法导致过于保守的值，而对于其他方法，它给出了非保守的值。因此，现有方法可能无法捕捉沉降下储罐的真实行为，需要进行修改。发现所提出方法的允许沉降结果与所有不同沉降数据和储罐几何形状的 FEA 结果一致。因此，建议使用新方法而不是现有方法。