Influence of Geometrical Dimensions of Reservoir on the Fluid- Structure Coupled Dominant Modes in Concrete Gravity Dams

Resumo

Properly determining the dynamic structural response of a dam is complex as it involves aspects related
to fluid-structure interaction (FSI). The coupled response depends on numerous variables, and among them is the
fluid domain, which has a significant influence on the coupled dominant modes. In the design phase, such a
reservoir is idealized as an acoustic cavity that must have dimensions and boundary conditions appropriate to the
problem. However, depending on these geometric parameters considered for the reservoir, the natural frequency
ranges and the order of the fluid vibration modes are different, directly influencing the coupled fluid-structure
vibrations, this is because the coupled response depends on the decoupled frequency range of the structure and
fluid domain in isolation. Thus, in this paper the uncoupled and coupled fluid-structure free vibrations of the Koyna
gravity dam located in India are studied. The natural frequencies, vibration modes of the structure and
hydrodynamic pressures are investigated and compared under different numerical modeling (reservoir dimensions)
using the finite element method (FEM) by means of ANSYS®. For validation of the numerical approaches
presented here the results obtained are compared with values available in the literature.