Discrete element based analyses of structure-reservoir problem for gravity dams

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2021-1-25
Soysal Albostan, Berat Feyza
The prediction of the nonlinear behavior of gravity dams under seismic actions is challenging. Firstly, a clear damage indicator to quantify the performance limits of such structures is limited. Besides, a proper numerical model producing reliable results both in the linear and nonlinear ranges for the dam body has to be established, coupled with its surrounding reservoir. This study is focused on damage assessment of gravity dams with the goal of determining seismic and post-seismic behavior considering crack propagation, crack openings, and leakage estimations through these cracks. A robust discrete element-based methodology, the modified applied element method (MAEM), was first developed, accurately simulating the behavior of plain concrete structures, representing a variety of Poisson’s ratio. Having validated this methodology under various loading conditions, the successful coupling of MAEM with the implemented fluid finite elements was shown. Incremental dynamic analyses (IDA) were then conducted on concrete and roller-compacted concrete (RCC) gravity dam-reservoir systems to assess the damage. The damage on the dam body was evaluated first by utilizing fragility curves considering crack propagation. Then, crack widths on the upstream faces were computed as a new damage indicator, and the leakage through these cracks was estimated for the post-seismic state. A relationship between ground motion intensity measures and maximum crack widths were sought. The results show that although cracking was more pronounced in the RCC dam due to weak lift joints, the crack opening and leakage were more critical for the concrete dam.

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Citation Formats
B. F. Soysal Albostan, “Discrete element based analyses of structure-reservoir problem for gravity dams,” Ph.D. - Doctoral Program, Middle East Technical University, 2021.