MODELING ISSUES RELATED TO SEISMIC ANALYSIS OF CONCRETE GRAVITY DAM

Abstract

Darns are very important Civil Engineering structures. Dam is associated with the production of energy and irrigation purposes. Darn failure may cause catastrophe. So, safety of dam is of paramount i rnportance. 'there are various dam analysis techniques available. Depending on the purpose and available resources any technique can follow to analyze a dam section. The main objective of the study is to compare various aspects of dam analysis. An extensive study on different analysis techniques like Shear beam method, Lumped mass method, Simplified method, Finite Element method have been performed. An optimization methodology based on (lie sliding factor of safety and stress is presented in the dissertation. The objective of the optimization is to achieve a section which has minimum cost. A MATLAB coding "Opti-Dam" has been generated during the tenure of the thesis. Impounded reservoir water has a considerable effect on the seismic response of dam. Fluid-soil-structure interaction has been performed to analyze a dam section. Different modeling aspect of fluid domain is a part of the dissertation topic. Response of reservoir-dam considering the water to be incompressible in one case and compressible in another case has been compared. A novel methodology has been suggested for incompressible water model. The new model not only considers the inertial effect of impounded reservoir water but also the effect of energy transmission from the boundaries of the reservoir. Modeling of unbounded medium is very important from seismic analysis point of view. If the foundation is not properly behaving as energy sink then the solution becomes time dependent. A comparative study on the performance of various unbounded medium is present in the dissertation. The performance of all the boundaries is verified by wave propagation techniques. Nonlinear analysis has also been performed to assess the crack pattern. Concrete damage plasticity model has been used to simulate the non-linear effects of concrete. Non-linearity makes a significant difference between the responses. Simulation of seismic motion plays a vital role in seismic analysis. Response compatible time history has been generated using Seismo-Artif software from site specific response spectra. The artificial accelerogram has been dc-convoluted to the depth of the considered rock foundation. The dc-convoluted motion has been applied to the base of the foundation to compute the seismic response of dam. The linear, nonlinear seismic analysis considering fluid-soil-structure interaction has been performed in ABAQUS 6.11.