Experiments on Large Structures - Dynamic Behavior of Concrete and Seismic Engineering - page 227

Resonance modes are obtained from amplitudes and phase delays for the
different measuring positions on the crown. They make it possible to detect the
appearance of a new mode due to interaction between the dam and the ice covering.
This has a symmetric shape, as is the case with the first mode observed in summer.
Figure 6.21. Finite element model for the dam, the reservoir and the foundation
These results have been used to calibrate a finite element model developed for
the dam-reservoir-foundation set. This model is illustrated in Figure 6.21, which
shows the mesh for the three structures. In this study, EACD-3D software [FOK 86],
designed for three-dimensional seismic analysis of concrete dams, was used to carry
out a parametric analysis. Effects due to dam and foundation stiffness, water
compressibility (energy dissipation through upstream wave propagation) and dam-
reservoir interactions were studied. The frequency responses on the crown, inside
galleries and in the reservoir were compared and proved each sub-structure made its
own contribution to the dynamic response of the construction works [PRO 97].
The results of the study were also used to develop a two-dimensional model of
the ice covering [BOU 02], which was added to EAGD software used for the
seismic analysis of gravity dams [FEN 84]. A parametric study confirmed the
appearance of a new mode, together with the stiffness and damping modifications
previously observed during the tests.