【作者】 宫建国；

【导师】 金涛；

【作者基本信息】 浙江大学 ， 化工过程机械， 2014， 博士

【摘要】 立式圆柱形钢制储罐是石油和化工领域的重要储存装置。由于储罐多位于地基较松软地区,储罐底部通常存在一定程度的不均匀沉降。当不均匀沉降达到某一临界值时,易造成壳体的屈曲。本文将不均匀沉降考虑成谐波沉降的形式,采用理论分析和数值计算的研究方法,针对立式圆柱形钢制储罐在谐波沉降下的屈曲行为和缺陷敏感度问题进行研究,主要的工作如下：(1)基于弯矩理论以及相应的模型假设,提出了立式圆柱形钢制储罐仅在谐波沉降下静力解析解。同时,推导了立式圆柱形钢制储罐在谐波沉降和静油压力同时作用下的静力解析解。并通过类比圆柱壳体的轴压屈曲,得到了储罐在谐波沉降下的屈曲理论公式。(2)分析了储罐在谐波沉降下的屈曲行为,并对不同结构参数的储罐进行了参数化分析。研究了弹塑性材料模型、顶部加强梁等因素对储罐屈曲强度的影响。并将浮顶罐的屈曲行为与锥顶罐的屈曲行为进行对照,分析了两种储罐屈曲行为的差异。(3)研究了储罐在谐波沉降下对不同缺陷形式的敏感度,包括屈曲点处屈曲模态形式的缺陷、鼓胀屈曲模态形式的缺陷、焊接缺陷等；研究了影响储罐在谐波沉降下的最危险的缺陷形式；对比了实际环向焊缝与纵向焊缝对壳体屈曲强度影响以及差异；探讨了顶部加强梁、弹塑性材料模型等因素对储罐缺陷敏感度的影响。(4)研究了储罐在谐波沉降和静油压力作用下的屈曲行为,分析了静油压力对储罐屈曲强度的影响；分析了静油压力对储罐缺陷敏感度的影响；提出了采用临界液面高度法判断壳体是否屈曲的研究方法。(5)根据理论分析以及数值结果,初步建立了立式圆柱形钢制储罐在谐波沉降下的临界沉降控制法则。采用该公式得到的预测结果与数值计算较为一致,可以用来预测储罐在谐波沉降下的屈曲强度。这可为将来的储罐不均匀沉降设计,提供一定的参考。更多还原

【Abstract】 The vertical cylindrical steel tanks are widely adopted in petroleum and chemical fields, which are mainly used for the storage of oil and other chemical products. Considering that the steel tanks are usually located on the soft soils, large differential settlement can be monitored beneath the tank walls. When the differential settlement reaches a critical value, it is prone to cause the buckling of the tank. In this paper, the differential settlement is treated as the form of harmonic settlement. Based on this assumption, the theoretical analyses and numerical calculations are taken to investigate the buckling behavior and imperfection sensitivity of cylindrical steel tanks subjected to harmonic settlement. Main work conducted is as follows:(1) Based on the theory of shell bending with the given model hypotheses, the solutions for two cases are provided:one case is that the vertical cylindrical steel tanks subjected to harmonic settlement, and the other case is that the tank under harmonic settlement and the hydrostatic pressure. Moreover, the buckling formulas are proposed according to the assumption of axial buckling of cylindrical shells.(2) The buckling behavior of cylindrical shells subjected to harmonic settlement is reported. Then, parametric studies are conducted for tanks with various structure parameters, including the height-to-radius ratio and the radius-to-thickness ratio. Besides, the effects of the material models, as well as the top stiffening rings on the buckling behavior are given. Meanwhile, the buckling behavior of floating roof tanks is compared with that of conical roof tanks.(3) The imperfection sensitivity analyses are conducted for steel tanks subjected to harmonic settlement. Three kinds of imperfections are included, such as the imperfections as the form of the buckling mode corresponding to the limit point, dimple buckling mode and the weld depressions. Meanwhile, the worst imperfection for tanks subjected to harmonic settlement is stated. Then, the effects of the circumferential weld depressions on the buckling strength of the tanks are compared with that of vertical weld depressions. Also, the influences of the top stiffening rings and material models on the imperfection sensitivity of the tank are studied.(4) The buckling performance of cylindrical steel tanks subjected to harmonic settlement and hydrostatic pressure are reported. Simultaneously, the impact of the hydrostatic pressure on the settlement-loading capacity of the tank is analyzed. Meanwhile, the effect of the oil pressure inside the tank on the imperfection sensitivity of the tank is provided. Moreover, a method named critical liquid height method is established, which is employed for evaluating the state of the tank subjected to harmonic settlement and hydrostatic pressure.(5) According to the theoretical analyses and numerical results, the critical harmonic settlement rule for tanks subjected to harmonic settlement is preliminarily established. The results predicted by this formula are consistent with numerical results, presenting that this formula is accurate enough for predicting the critical harmonic settlement of the tank. This settlement prediction formula may give structural enginners some references in the future design of the tank.更多还原