Monolith of a concrete gravity dam inclusive of foundation are normally idealized as 2D structures for analysis. However, for dams situated on a V-shaped valley or a canyon with stepped or tapered monolith, the 2D idealization may not always be justified. The variation of stiffness along the length of the monolith results in a differential displacement resulting in greater stress on the stiffer side of the monolith. A 3D model of such a gravity dam monolith is compared with the corresponding 2D model using ANSYS. Further, a modal analysis indicates the presence of out of plane modes in the case of 3D model, which the 2D model could not represent. As a consequence, the 3D model shows higher stress than the 2D for response spectrum analysis. it is recommended that, in such cases a judicious approach be adopted and a parametric study be conducted to address the shortcomings.
Finite element method, Gravity dam, Foundation-structure interaction, 3D analysis
