Coupled arch dam-reservoir-massed foundation problem under different earthquake input mechanisms

Abstract

The aim of the present study is to investigate a coupled arch dam-reservoir-massed foundation problem under two earthquake input mechanisms. The problem nonlinearity originates from opening/slipping of the vertical contraction joints of the dam body. The reservoir-structure interaction is taken into account assuming compressible reservoir. Also, the meshing approach (structured mesh vs. unstructured one) in the foundation medium is investigated. The Karoun-I double curvature arch dam is selected as a case study. Three components of the 1994 Northridge earthquake are selected as the free-field ground motion. A deconvolution analysis in 3D space is conducted to adjust the amplitude and frequency contents of the earthquake ground motion applied to the bottom of the massed foundation to determine the desired acceleration response at various points on the dam-foundation interface taking into account the coupling between the foundation and the structure. It is found that in the deconvolved earthquake input models, the maximum tensile and the compressive stresses increase by 19% and 12%, respectively in comparison with those of the free-field input models. In addition, modeling foundation using the unstructured mesh decreases the maximum compressive stresses within the dam body by about 20% in comparison with that obtained using the structured mesh model. In the same way, the maximum crest displacements in the horizontal direction decreases by about 30%.