Shell based finite element modeling of Herøysund Bridge

Abstract

This master's thesis thoroughly examines the application of the Finite Element Method (FEM) to the numerical modal analysis of the Herøysund Bridge, focusing on the theoretical backdrop, construction process, FEM techniques, and Eurocode recommendations for concrete structures. This study aims to demonstrate the utility of FEM in bridge analysis by utilizing ANSYS 2023 R1 to conduct a full numerical investigation of the bridge's technical specifications and design features. The thesis discusses the theoretical background, including the context of applying FEM for bridge design and main bridge construction techniques. It then examines the specific FEM approaches applied and their advantages and disadvantages. The Herøysund Bridge analysis employs a two-pronged strategy consisting of a 3D-Solid Model and a Shell Model. To forecast the physical behavior of a structure, assumptions, modeling methodologies, and the incorporation of specific components such as pillars are applied to both approaches. The document describes the complexity of bridge design from the selection of units and materials through the development of connections and meshes. The full report also emphasizes the importance of boundary conditions, examining the structural effects of standard earth gravity, post-tensioned load, and railing and asphalt load. The results section thoroughly explores the mode shapes and frequencies for the 3D-Solid and Shell models. The Modal Assurance Criteria analysis compares modal frequencies across several modes, including flexural, transverse bending, and twist modes. The conclusion of the thesis includes findings obtained from the study, implications for the Herøysund Bridge, detailed resonant frequencies of the structure, and a comparison of both modeling strategies. It also incorporates ideas for future research. It also guides employing FEM 3D-Solid and Shell methods to design and construct more efficient, resilient, and durable bridge structures.