PhD Oral Exam - Hussein Atia, Civil Engineering

When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.

Abstract

Steel elements are widely used in buildings, bridges, and other critical infrastructure. In Canada, more than 25% of roadway bridges use steel girders as their primary load-bearing components. Increasing traffic demands, limited rehabilitation resources, and climate-related extreme events have accelerated bridge deterioration. Understanding the behavior of deteriorated steel elements is therefore essential for serviceability and failure assessment, life-cycle evaluation, and timely maintenance. However, even closely monitored bridges have failed because of inadequate methods and predictive tools for capacity assessment.

While advanced Finite Element Analysis (FEA) tools exist, their integration into bridge management remains limited because of the high modeling effort required. Full-bridge models typically combine multiple finite element types, producing complex systems that require specialist expertise to interpret. Although highly detailed, these models are often impractical for routine inspections and rapid condition assessments, creating a gap between research capabilities and the practical needs of bridge owners and operators. This research addresses that gap by advancing finite element modeling for thin-walled I-beams through the development of a beam-type finite element formulation, which we refer to as Distortion Beam Formulation 13 (DBF13). Unlike conventional formulations, DBF13 extends predictive capabilities beyond lateral–torsional buckling by accurately capturing local distortions, web bending, and some of the in-plane deformation modes of the cross-sections, which are traditionally modeled using shell elements. Validation against shell-element benchmarks demonstrated accuracy while maintaining computational efficiency. Case studies involving dominant web bending and distortion modes further confirmed its reliability, showing strong agreement with shell-model predictions.