Between the 1950’s and 1970s, a large increase in bridge construction was realized accompanying a large increase in infrastructure. The increase in traffic intensity and weight results in that many of these bridges are now in need of reevaluation, possibly resulting in renovation or renewal. Meanwhile human-caused adverse environmental effects are increasingly impacting the world, of which the infrastructure sector is a large contributor.
This thesis provides a study into more sustainable renewal projects. The objective of this study is to provide a design which will increase the sustainability of renewing bascule bridges. The approach for this study is to:
• Literature review to set a scientific basis for this thesis project.
• Design study to explore the possibilities for bridge leaf design.
• Summary, conclusions, and recommendations to conclude the research project.
To design a more sustainable alternative the “Design for sustainable infrastructure” is followed. The ambitions identified following the “Ambition web” methodology highlights a great influence of a structural engineer in environmental sustainability. Key opportunities to increase environmental sustainability include reusing structural elements, maintaining or reducing the mass of the bridge leaf and designing the structure to fit inside the footprint of the current bridge.
The design process starts by applying “Circular design principles” to design a variant which reuses most of the available elements. Following variants increasingly differ from the current structure by removing elements, changing the materials from of the elements, or using free forming opportunities of FRP to come to new designs.
The sustainability performance is strongly dependent on the current state of the structure. Reusing the main structure and renewing only the deck can reduce the environmental impact of the bridge leaf by up to 53%, while not increasing the mass or requiring more space. Redesigning the entire structure with a full FRP structure can reduce the environmental impact by up to 48% and could reduce the mass of the bridge leaf by up to 33%. For both scenarios, the use of FRP, with a balsa core and partly recycled resins, was thus beneficial for the sustainability of a bascule bridge renewal project.

The use of Glass Fibre-Reinforced Polymer as a building material in structures or structural components is on the rise. Standards such as CUR96, DNV and JRC provide a basis of design with the material. However, there is a lack of confidence in the design phase with structures made of Glass Fibre-Reinforced Polymer, resulting in the use of large safety factors causing the components to be bloated in size. At the time of writing this report, the technical committee, CEN/TC 250 (responsible for developing structural Eurocodes), establishes a technical design specification for Fibre-Reinforced Polymer (FRP) structures. This technical specification describes a simplified and linear criterion to determine the capacity of a GFPR Laminate, in addition to being open for the use of Progressive Failure Analysis (PFA). However, the simplified and linear criterion is overly conservative, whereas there is a lack of faith in the use of the PFA considering the failure theories and degradation models that are currently in use. This report discusses the PFA, a non-linear, 5-step, advanced 2D analysis model, that can predict the static strength of in-plane stress dominated Glass Fibre-Reinforced Polymer laminate, with an arbitrary lay-up composition, based on existing knowledge and experiments, including the damage development under multi-axial stress states and stress redistribution. The research is limited to in-plane behavior, under tensile and compressive stresses. The static material response is characterized on a unidirectional ply level based on principal directions and based on experimental results obtained from the OptiDat program. The response predicted by the PFA for both tension and compression was in reasonable agreement with the experimental results. However, depending on the failure theory and degradation model used, there is potential for optimistic predictions of the laminate stress capacity. For future work, it is recommended to continue the research on a larger variety of laminate lay-ups and include more failure theories and degradation models.

With the rising demand for renewable energy, floating offshore wind turbines have gained importance, particularly in regions where deep waters prevent the use of traditional monopile structures. These floating turbines rely on mooring lines for stability against environmental conditions, particularly when facing strong winds and high waves. Ensuring a satisfactory lifetime and health of mooring lines is critical. Moreover, degradation can compromise the turbine’s functionality or even lead to catastrophic failures. While direct monitoring is ideal, it is often hampered by high costs and extensive maintenance. This Master’s thesis introduces a novel method to assess mooring line degradation. The proposed approach simulates the impact of environmental conditions on the mooring lines, considering various forces and weather scenarios. The research presents modeling of fatigue and corrosion effects along the mooring line. A unique corrosion model calculates variations based on seawater’s oxygen and temperature profiles. Concurrently, mooring line stresses are deduced from real-world environmental conditions. Integrating these, a finite element model is constructed to analyze different load scenarios and the onset of corrosion on line degradation. The model considers the joint impact of corrosion and fatigue on mooring lines, including the influence of hydro static pressure and out-of-plane bending. Validation of this methodology draws upon existing research and experimental results on mooring lines.