Assistant Professor, Department of Civil Engineering Nehru Institute of Technology
Detection of damage in concrete gravity dams (CGDs) is one of the challenges that need to be overcome since dam failure may lead to irreversible consequences. This research aims to detect structural damage within CGDs by wavelet analysis. From a structural point of view, stiffness is an important factor in the dynamic behaviour of concrete gravity dam systems. Any sudden change in the stiffness leads to alteration in the dynamic response of the structures. The proposed analysis of such a condition will help to investigate the responses before and after the occurrence of any structural damage. The main contributions of this paper are to detect the existence of any damage in the dam structure and determine the damage location along the height of the dam. In order to achieve these purposes, three finite element models of the Pine Flat, Bluestone, and Folsom dams are chosen as case studies. These dams have been modelled for both intact and damaged states, and their geometrical, physical, and mechanical characteristics are defined by SAP2000 software. A series of modal analyses was performed to determine the frequencies and shapes of the structural motions. After reduction of the elasticity modulus by 20% and 50%, the Discrete Wavelet Transform (DWT) was applied to the difference between the intact and damaged observations. Then, the DWT outputs were analysed to get information about the existence of damage as well as its location in the dam structure. Overall, from the obtained results, the main finding of this study states that the location and severity of the structural damages have been efficiently detected according to the significant amplitude variations in DWT diagrams.