Fluid-structure interaction of Brezina arch dam: 3D modal analysis

In this paper, modal responses of the Brezina concrete arch dam, Algeria, are determined using the finite elements commercial packages ANSYS. The dam-water-foundation soil system is investigated based on the added mass and Lagrangian approaches. The former approach is simpler and less costly but cannot provide the sloshing frequencies. Furthermore, as reported by other researchers, the added mass approach gives higher coupled frequencies as compared to the actual ones, which are better approximated by those obtained from the Lagrangian approach. The natural frequencies of the dam-water-massless foundation model are well below those of the dam-massless foundation model (without water). But, unexpectedly, the frequencies of the dam-water-foundation model are higher than those of the dam-foundation model. This contrasts with the results of other arch dams, including the Morrow Point dam. The results found herein are likely due to the geometric characteristics of the Brezina dam, which are not typically those of an arch dam. Lastly, considering the coupled mode that yields the largest effective mass, its frequency moderately decreases with the increase of the water level, except for the 10 m water height at which the natural frequency is the highest.