SEISMIC TIME HISTORY ANALYSIS OF A CONCRETE GRAVITY DAM USING 2-D FINITE ELEMENT METHOD

Abstract

A Gravity dam is a large dam that stores huge quantity of water for various water utility purposes. An earthquake is a significant risk for such dams, most of which have been built in seismically prone locations due to their intended purpose. Earthquakes are one of the most dangerous natural hazards, yet it is also well-recognized that earthquakes cannot be avoided. The analysis of the impact of seismicity on Concrete dams is very important as its failure will result in massive losses as a result of uncontrolled discharge of water. Because an earthquake is a sudden event, its consequences are severe. When a dam is subjected to seismic activity, it experiences dynamic forces that can significantly affect its structural integrity. A proper seismic safety evaluation study is essential for these large dams to evaluate the seismic vulnerability. The goal of this study is to examine the seismic response parameters of a Concrete gravity dam, such as stresses, displacement, frequency, mode shape, and tensile damage pattern. These parameters can be obtained by conducting linear and nonlinear structural analysis of the dam by considering seismic force as the dynamic load. The finite element method is widely recognized as the supreme method of analysis to any other methods, for determining stresses and deformations developed in a structure under induced loading. In this study, the two-dimensional finite element analysis considering plane stress conditions, for the dam section, is done using the ABAQUS-CAE program. The static and dynamic loading comprising dead load, hydrostatic pressure, uplift pressure, and earthquake acceleration are included in the analysis. An actual earthquake acceleration data was scaled down to a different PGA to truly represent the actual properties of the dam, which was meant for a particular location. The linear and nonlinear time-dependent analysis of the dam is conducted, taking into account, “the dam is fixed at a stiff base” and “the dam is fixed on a non-rigid foundation". The response variables (Stress, displacement) obtained after the analysis process are presented and compared with the permissible values. The initiation and propagation of tensile cracks have been simulated. The importance of considering the depth of the reservoir and flexibility of the foundation in the evaluation of the seismic behavior of a dam is also covered in this study. The parametric studies show an increasing trend of response values with an increase in the depth of the reservoir and the same trend follows with an increase in the flexibility of the foundation. The impact of surface interaction can be seen in the results for different systems which consist of a dam, reservoir, and foundation.