The assessment of civil engineering structures undergoing extreme loading events relies on advanced numerical models that must be capable of capturing the strong nonlinearities occurring during such events—strain localizations, cracking, or members detaching from the structure. Numerous models exist that allow for a highly detailed representation of those phenomena. The Discrete Element Methods (DEM) represent a structure as an assembly of distinct elements exchanging forces at their interfaces. The Finite Element Methods (FEM), on the other hand, represent the structure rather as a mesh of interconnected deformable elements. While the former are particularly well-suited for structures displaying strong discontinuities, they often come with an increased computational cost. The FEM performs well in cases of moderate inelasticity, but leads to complex meshes or formulations when discontinuities need to be accounted for. In this work, a novel method is proposed under the name Hybrid Discrete-Finite Element Method (HybriDFEM), which constitutes a hybridization between DEM and FEM: its formulation is inherently discrete, as it models interactions between rigid blocks, but it is developed in a framework that allows for the coupling with classical finite elements. This feature enables leveraging the strengths of both approaches, building a model in which regions of strong discontinuities are modeled with HybriDFEM, while the others are modeled using FEM. Throughout this work, the HybriDFEM method is developed for increasingly diverse and complex problems: starting with static analysis of linear elastic beams, it progressively incorporates effects of large displacements, and nonlinear material models. It is then extended to model various structural typologies, such as unreinforced masonry or reinforced concrete structures. It is followed by the extension to modal analyses of discrete or hybrid systems, and ultimately to nonlinear response-history analyses to model, among others, the dynamic response of masonry arches and frames subjected to seismic loading.
Membres du jury :
Prof. João Almeida (UCLouvain) (Promoteur)
Dr. Michele Godio (RISE) (Promoteur)
Prof. Nicolas Moës (UCLouvain) (Président)
Dr. Nicolas Docquier (UCLouvain) (Secrétaire)
Prof. Rui Pinho (University of Pavia)
Prof. Alberto Taliercio (Polictecnico di Milano)
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