Finite element procedures for fluid-structure interactions and application to liquid storage tanks

Most of the failures of large tanks after severe earthquakes are suspected to have resulted from the dynamic buckling caused by overturning moments of seismically induced liquid inertia and surface slosh waves. In this paper, a nonlinear finite element method is presented which can treated the structural behavior of the tanks in conjunction with fluid, including the dynamics and buckling. Both the formulation and computer implementation aspects are presented. The areas upon which attention is focused are: the mixed Lagrangian-Eulerian kinematical description for modeling fluid subdomains in fluid-structure interaction problems, the finite rotation effects in numerical integration of rate constitutive equations arising in large-deformation analysis and the implicit-explicit finite element techniques for transient analysis. All these nonlinear methodologies have been integrated into a finite element computer code [47]. A number of physically important buckling and dynamic analyses of tanks are being investigated. Various other fluid structure phenomena such as the stability of off-shore structures can be analyzed with this computer program. The proposed nonlinear finite-element procedures can serve as a basis for future developments of various other fluid-structure phenomena such as the transient motion of submerged or partially submerged structures.