EFFECTS OF DAM-RESERVOIR-FOUNDATION INTERACTION ON MODAL BEHAVIOUR OF GRAVITY DAM
Keywords:
modal period, foundation flexibility, gravity dam, mode shapes, natural frequency, reservoirAbstract
Dams have played a vital role in regulating water flow to cater to the needs of irrigation, for human
consumption for harnessing hydroelectric power, as well as control of floods. Some of the important aspects that may
affect the response of gravity dams subjected to earthquakes have been recognized through the dam-reservoir-foundation
interaction. Modal characteristics such as natural frequencies and mode shapes undergoes modifications due to these
interaction. The influence of foundation flexibility on the dynamic response of gravity dam is also significant. Modal
analysis is a simple way to find the various periods at which structure will naturally resonate. These periods of vibration
are very important in earthquake engineering. The present study aims to determine the effects of dam-reservoir-foundation
interaction on modal behaviour of gravity dam. The effect of foundation flexibility on the modal period is also studied.
Relation between modal period, height and base width is also obtained. Modelling is done using ANSYS 16.2 computer
program. The analytical results obtained from 2D finite element modal analysis of concrete gravity dam show that modal
period of dam is functions of its overall height and also dam- reservoir-foundation interaction and foundation flexibility
has a significant influence on the modal periods and mode shapes. So, its consideration is essential while designing the
gravity dam for safety, reliability and quality
