The ability to predict the fatigue of flood gates due to dynamic wave loading is becoming increasingly important as coasts and waterways worldwide are being reinforced to suit a changing climate. There are few comprehensive ways to do so however, which often leads to conservative estimates. This thesis presents an integral framework with which the fatigue of flood gates due to dynamic waveloading can be described in much more detail, while also being efficient and adaptable to different circumstances. First, the fatigue experienced by a single load event is evaluated based on readily available data. This was done by creating a phase-amplitude model from a wave spectrum based on the site properties and environmental conditions. These wave loads can then be transformed to pressure spectra with linear wave theory and pressure impulse theory, which will dynamically excite the fluid-structure system. The gate is then parametrically modelled in a FEM software package in order to export the in-vacuo response modes. These are combined with a fluid-structure interaction model to derive the response of the system to external pressures. The fatigue was evaluated with the standard Eurocode method to find a fatigue damage factor. Next, the load events imposed on the gate over its lifetime were probabilistically defined. This was done by fitting two independent probability distributions to historical wind- and water level data, the latter of which was also adjusted for climate change. These probability distributions are then split into segments which are integrated to obtain discrete load cases with representative values for the average wind velocity, water level, and probability of occurrence. Two filters were also applied to remove the load cases which cause a negligible amount of fatigue. Computing the fatigue damage caused by the average values of each of these load case bins then gives a set of fatigue damage factors with an associated probability of occurrence, which can be used to perform a Monte Carlo analysis. A case study for a hypothetical parametrically defined gate with an overhang located in the Afsluitdijk was performed, where the response for different gate configurations and environmental conditions was evaluated. The fatigue response was evaluated for fatigue across the gate, at the critical coordinate, and per mode. A ULS check was also done for the chosen design. Results following from the model were also compared to those of methods commonly used in practice.The method gives insight into the relative importance of different modes and load events, can compute fatigue for the entire gate or just a critical coordinate, and does so in a much more time-efficient manner than current numerical models. It gives a more comprehensive view of the fatigue over the lifetime of the gate by modelling its entire lifespan rather than a set of design load events. The modular structure of the integral framework allows for easy adaptation to other use cases in hydraulic engineering where fatigue due to hydrodynamic loading is of interest.

Offshore wind turbines are being placed all over the world. The increased popularity of these structures comes with a boost to the development of wind turbines in general, resulting in larger and higher constructions. To ensure the support structures of the turbines are able to withstand the extreme loads and environmental conditions, it is subjected to a series of tests and checks, prescribed by codes and standards. This thesis focuses on buckling checks, with global buckling in particular. Several codes and standards define buckling checks, differing in approach. For example, the global buckling check is based on global buckling (compromised stability due to an axial force), but also takes eccentricities into account. How these parameters and safety factors are incorporated is analyzed for the Eurocode and the DNVGL, which are considered the most relevant design standards regarding offshore wind turbines around the Netherlands. Difference between both global buckling checks are analyzed using a monopile based reference wind turbine. Looking to the more mechanical termof global buckling (also called Euler buckling), one finds an expression for the buckling load, based on the flexural stiffness and the buckling length of the structure. However, both parameters vary over the height of the support structure: the monopile has one relevant buckling value, where the flexural stiffness varies with its geometry. Therefore the buckling length cannot be constant for the structure. To tell something about this buckling length, the support structure is modeled with Euler beams as visualized in the figure. Subsequently the buckling force is analyzed, a constant value for the flexural stiffness is derived and the buckling length is calculated. Finally, the influence of the soil conditions on the buckling length of the structure is analyzed. To determine whether a second order analysis is required to calculate the buckling force of the support structure, a comparison ismade. Two Euler-Bernoulli beam models are introduced, one with a second order term, one without. The influence of the term on the bending, rotation, moment and shear force is analyzed, as well as the influence of the Euler buckling force. Subsequently an incremental load factor is introduced to incorporate the second order effect in themore simplified beam model. Finally, the relevance of global buckling is considered. How relevant is the global buckling check for the currently installed wind turbines, and how relevant will it be for the larger support structures that are to be expected? To answer these questions, comparisons are made between the buckling checks and how far from failing the checks are. Subsequently, the local buckling is introduced to compare the global buckling check to the local buckling check regarding relevance.

This study develops a decision method for the implementation and assessment of standardisation in order to improve the Replacement & Renovation process of hydraulic structures. Possible improvements in the Replacement & Renovation process and the implementation of standardisation were identified by conducting semi-structured interviews. A general decision method results from combining the identified improvement points and the basic design principle. This general decision method is further developed by describing the required steps, decisions, input, and generated output. This decision method is a starting point for asset management organisations that want to start with implementing standardisation into the Replacement & Renovation process. A potential benefit of using the decision method is increased efficiency of the design process, as a learning curve is expected, saving time and money. Furthermore, the results can be used for an in-depth discussion about the feasibility of standardisation in the considered management area.