Influence of earthquake excitations on concrete gravity dams founded on homogeneous and layered foundation

The present paper investigates the response of dams with homogeneous and layered foundation systems under different earthquake excitations. For this purpose, the finite element analyses are conducted for three cases: Case 1-Effect of horizontal (H) component on a dam-homogenous foundation system, Case 2-Effect of combination of horizontal and vertical (H + V) component on a dam-homogenous foundation system and Case 3-Effect of combination of horizontal and vertical (H + V) component on the dam-layered foundation system. Tensile crack failure in the dam is captured by providing the nonlinear behavior using the concrete damaged plasticity model. Nonlinear material behavior is given to the underlying foundation using the Mohr-Coulomb failure model. The one-way plane strain infinite elements are used for the earthquake wave propagation through the vertical and bottom faces of the foundation domain. Eleven seismic ground motions that correspond with the Conditional Mean Spectrum are adopted for earthquake analyses. Results show that the (H + V) component when compared to the (H) component of seismic ground motions, has considerable influence on the dissipation energy and crest acceleration response; however, it has a marginal impact on the displacement and stress response of the dam. As compared to a homogeneous foundation, a layered foundation greatly affects the overall earthquake response of the dam since a substantial amplification of earthquake waves is seen through it. It is observed that the tensile crack failure in the dam is significantly increased due to the (H + V) component of seismic ground motions and is barely affected by the layered foundation.