Comparison of Damage Predictions for Concrete Dams, Finite Elements with Smeared Crack vs. Discrete Element Models

Abstract

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.