Formulation of Time Period for Gravity Dam

Gravity dams are solid structures that maintain their stability against design loads from the geometric shape, mass and strength of the concrete. The catastrophic consequences on life and property resulting from failure of large dams have led engineers to design and built these structures to resist failure with no or only minor damages. In this aspect, stability analysis plays a major role and hence the stability of dam has to be analyzed properly. The study focuses mainly on the formulation of time period for gravity dams. Each time it is not possible to calculate the natural time periods through modal analysis. In order to simplify the problem, a relation between natural time period, height and base width is formulated. Inorder to get emperical formula for natural time period, a family of concrete gravity dam with varying height, base-width and side slope is analyzed using finite element software ANSYS. Dams are modeled with 2-D plane strain elements. A regression analysis is carried out on the modal properties obtained from the finite element analysis in order to develop empirical relation between time period, height and base width.