Browsing by Author "Soysal, B.F."

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Comparison of Damage Predictions for Concrete Dams, Finite Elements with Smeared Crack vs. Discrete Element Models
(International Association for Earthquake Engineering, 2024) Soysal, B.F.; Arici, Y.
The seismic assessment of gravity dam monoliths has been treated within the framework of performance based earthquake engineering (PBEE) in the last decade. The necessary inclusion of the soil-structure-reservoir interaction in combination with predicting the damage on these structures for use in PBEE is a significant challenge. Within this context, smeared crack models with general purpose finite element codes became to be used generally as the assessment tool for these systems. Perhaps the most practical limitation in this approach is the difficulty with providing discrete cracks and the corresponding impediment to the rating of the damage on these systems leading to possibly subjective conclusions. On the other hand, discrete element techniques offer a proficient simulation alternative to the FE, enabling the interpretation of results from the main aspect of the damage on these system, i.e. cracking. A novel discrete element framework, incorporating dam-reservoir interaction, has been developed to this end as part of the doctoral studies of the first author. The model incorporates individual elements connected by multiple springs, successfully modelling initial continuum with the accurate prediction of discrete cracks at the latter stages of loading. The predicted damage and damage rating of a generic monolith is compared to the FE counterparts in this work. A comprehensive comparison with different ground motions at several levels focusing on crack widths is shown. The results showed the cracking on the system is very different in severe shaking compared to similar predictions in lower earthquake excitations. The FE simulations, commonly adopted for the investigation of these systems with smeared crack modelling, yielded less cracking as well as smaller propagation in severe shaking conditions. © 2024, International Association for Earthquake Engineering. All rights reserved.
A Discrete Element Method for Evaluating the Seismic Performance of Concrete Gravity Dam-Reservoir Systems Under Main Shock-Aftershock Events
(Tulpar Academic Publishing, 2025) Soysal, B.F.
Dams are crucial for water supply, flood prevention, and hydroelectric power generation. Often located in seismically active regions, they are vulnerable to main shock-aftershock (MS-AS) sequences, which can compromise structural integrity and hydraulic safety. Critical aspects of dam response to MS–AS events remain unclear, particularly the required rest time between successive events and threshold AS-to-MS intensity measure ratios that could serve as predictors of additional damage. This study addresses these gaps by analyzing concrete gravity dam–reservoir systems of three heights (50 m, 100 m, and 150 m) using the developed discrete element–based approach coupled with displacement/pressure-based mixed finite elements for the reservoir. Empirical rest time equations were derived from 124 as-recorded ground motions, while seismic performance under varying intensity levels was evaluated using 14 as-recorded MS–AS sequences. Damage was quantified using discrete indices of base crack length, maximum base crack width, and maximum total upstream crack width. Results indicate that AS primarily propagate existing cracks at lower intensities, whereas higher intensities generate new cracks along the upstream face, increasing crack widths by 25–30% on average. The 50 m high dam remained within the mild damage category, while taller dams occasionally reached moderate levels, posing potential seepage risks. Threshold AS-to-MS ratios for four different intensity measures were identified. These findings provide mechanistic insight into crack propagation under MS-AS events, providing practical guidance for post-earthquake dam safety assessment, inspection prioritization, and incorporating sequential seismic effects into design and emergency planning. © 2025 by the Author.