Accounting for Earthquake-Induced Dam-Reservoir Interaction Using Modified Accelerograms

Abstract

This paper proposes a new practical and efficient procedure to investigate the seismic response of gravity dams that (1) avoids the finite or boundary element discretization of the impounded reservoir; (2) can be applied using standard finite-element software not necessarily including fluid-structure interaction capabilities; and (3) accounts for dam and foundation flexibility, water compressibility, and reservoir bottom wave absorption. The proposed technique consists of modifying the original input ground acceleration to obtain a new accelerogram that directly accounts for the complex effects of fluid-structure interaction. This new accelerogram can then be applied to a dam or dam-foundation system without the impounded reservoir. The exact and simplified formulations of the proposed method are developed, and its efficiency is validated through examples of dam-reservoir systems with different geometries. Very satisfactory agreement is obtained when comparing the results to more advanced finite-element solutions including fluid-structure interaction capabilities. The new procedure enhances the efficiency of seismic assessment of gravity dams by reducing the modeling and computational burden associated with reservoir discretization while keeping the main advantages of conventional solid finite-element software in conducting dynamic analyses and providing the resulting stresses, strains, force distributions, and other dam response indicators.