Finite Element Analysis for Cyclic Behavior of Localized Bottom Bulge in Aboveground Oil Storage Tanks under Liquid Pressure

摘要

The bottom plate of aboveground oil storage tanks usually bulges, separating from the foundation due to welding deformation. when such bulge is subjected to liquid pressure, it deforms continuously to make contact with the foundation from the edge, and the remaining area of the bulge decreases with increasing liquid pressure. As a result, the deformation is extremely localized and plastic strain occurs at the bulge. In evaluation of the suitability for continued service, permissible bulge is given by API Standard 653. However, there are few studies concerning this bulge. This paper presents plane strain finite element analysis for the localized bottom bulge in aboveground oil storage tanks. Load-incremental, elastic-plastic large deformation analysis is carried out considering contact with the foundation. The relationship of the plastic strain at the bulged bottom plate to the liquid pressure are discussed together with the bulged deformation. After the center of the bulge makes contact with the foundation, the stress and strain do not increase with increasing liquid pressure. In addition, the permissible bulged profile specified by API Standard 653 elastically deforms to make contact with the foundation under low liquid pressure.