The weirs in the river Meuse reach their theoretical lifespan. The weirs were built in the early 1930s and now one is faced with a replacement task. Various studies have been carried out in recent years on the future of the weirs in the river Meuse. This concerns research into the entire weir system, different types of weirs and the way in which the current weirs should be replaced. This study does not focus on one specific task, but focuses on various aspects that are important for the replacement task, both “soft” and “hard” technical aspects. The first aspect is to find a suitable assessment framework that a new weir must meet. This assessment framework has been developed by means of literature research and interviews with specialists from Rijkswaterstaat, resulting in a risk and opportunity plan especially for weir structures. The assessment framework thus forms the basis for finding both a suitable weir type and a suitable solution for construction. A variant study has been carried out into different weir types. The considered weir types are delineated into a conventional variant, the flap weir, and three innovative variants, namely variants with inflatable technology. The steel-rubber gate, also known as the Obermeyer weir, scores best. This weir type consists of air-filled bellows that inflates and deflates the flaps. It is distinctive in terms of discharge capacity, nuisance and ease of maintenance.
The next phase is to make a conceptual design. A new weir regime has been developed on the basis of several considered weir configurations. A weir configuration with two weir spans of 50 m weir, each with 5 separate flap-bellow components has been designed. Furthermore, the weir sill has been designed with a length of 34 m. Based on the design loads on the bottom, a soil protection has been designed. A block mattress with a geotextile as a filter proves to be a suitable soil protection. The downstream length of the bottom protection is designed as a total of 50 m. Thereafter the forces in the membrane are determined, after which a suitable type of membrane is designed.
The last phase of this research focuses on finding a suitable solution for construction for the new weir in Linne. Three different construction methods have been developed, in-situ, side channel and prefab. For each method, the (global) weir dimensions are verified for the governing load situations. Ultimately, a suitable construction method is selected on the basis of an overall cost indication and assessment criteria, derived from the assessment framework that has been compiled in the first phase. Construction variant C, the prefab solution, scores best. It is an innovative solution in which the entire weir, including flap and bellow elements, is built in a construction dock upstream of the current weir and then transported using pontoons with winches. The major challenges of this construction method are the floating transport where the enormous weir construction must not be damaged, the coupling of the air supply pipes to the compressors in the abutment underwater by divers and the guarantee of a good transfer of forces from the weir sill to the bottom. On the other hand, there is considered to be a great advantage over the other variants in terms of, among other things, costs and construction time. The solution is therefore proposed as the implementation solution for the Obermeyer weir to replace the current weir in Linne.
In addition to this study, a strategy has been developed to deal with uncertainty in design as a depth study. The case of the bottom protection for the new weir has been used to apply this strategy. Different stability relations have been compared that come to the required nominal stone diameter. Based on a consideration of the impact in costs, impact on failure and risk mitigation measures included in this strategy, a broadly-based choice can be made for the design of the soil protection.

There is a growing demand for renewable sources of energy of which wave energy conversion is one. The Ocean Falls is an oscillating water column (OWC) system invented by BAM Infraconsult b.v. This system differs from conventional OWC systems since it includes a connection tube and an adjustable back wall. The OWC system is a resonance system for which maximum efficiency is obtained once the natural frequency matches the incoming wave frequency. This thesis focusses on the modelling of the OWC system with ANSYS AQWA and ANSYS Fluent. A parametric model and a CFD model are developed to assess the performance of the OWC system. An optimum is sought for in terms of system performance, constructability and cost effectiveness. Eventually a conceptual design of the Ocean Falls OWC system is made to assess the technical- and economic feasibility.

In the Netherlands, a lot of traffic congestion occurs on motorways. This problem is most severe nearby larger cities. Utrecht is one of these cities. To improve traffic flow in this area, a huge masterplan is designed by Rijkswaterstaat called “A27/A12 Ring Utrecht”. One part of this masterplan consists of the motorway A27 at Amelisweerd. Here, the A27 is situated in a U-shaped concrete structure and must be expanded at both sides. Across the motorway a deck structure is going to be constructed with on top a public garden. This structure spans the total width of the A27 for 249 meters and is called The Green Connection.
According to the original design of Rijkswaterstaat, this deck structure should be realized with an intermediate support. It will be advantageous to omit this structure, since it has a complex execution method. Therefore, it’s investigated if The Green Connection can be realized without the use of an intermediate support.
Then, the execution aspects of the original design will be discussed more thoroughly. The first challenge is constructing the extended parts which is explicated according to 11 main tasks. These tasks seem to be relatively straightforward to execute. After realizing the extended parts, an intermediate support must be constructed. It is found that the existing foundation lacks bearing capacity by far. A new strengthened strip foundation with extra foundation piles must be realised in the middle of the motorway. Due to the boundary conditions (such as the water pressure beneath the structure and permanent drainage is prohibited), the only possibility left is to construct small building pits, compartments, within the existing structure. Such a compartment has a rough length of about 20 meters, will be about 6.5 meters wide and must be constructed 13 times.
Thereafter, the deck structure should be assembled. Three alternatives in methods of assembly are outlined and discussed with the help of the same key-words. All three methods could be realized. But, it’s important to indicate that with some extra investments, the remaining space for traffic could be maximized during assembly.
After discussing the execution aspects of the original design, the technical feasibility of the single span deck structure was investigated more thoroughly. In the Preliminary Study was deduced that two structural designs seem to be a possible solution in constructing The Green Connection. It turned out that the box beam design seems to be advantageous. Although this judgement is substantiated with preliminary calculations and an overall execution plan, it still required more research. Therefore, a reliable structural design is performed for a 75-meter span beam which can be used as a single span deck structure. It does exceed the boundary condition of 280 tons which was posed initially with 8%. However, no optimizations have been applied to this design. If the enumerated optimizations are performed, a beam can be designed according the boundary condition and possibly even less.
When the original design of Rijkswaterstaat is compared to the single span design, the differences are quite straightforward. In essence, the question arises whether the extra money of constructing a single span deck structure outweigh the money which can be saved by leaving out the intermediate support and constructing the extended parts 25% narrower.
Rijkswaterstaat has performed a design with an intermediate support. In this thesis, the feasibility of this design is investigated, and in particular this support. The only possible method of execution in realizing the support is upon condition that a temporary applied drainage system will be feasible and approved by the authority. When the authority states that draining ground water is prohibited, the original design isn’t feasible anymore. In that case, the single span design isn’t just an alternative to the original design, but is the only feasible solution.
Concludingly, providing the applied principles of this thesis, it is strongly recommended against constructing an intermediate support within the existing U-shaped concrete structure. Since the structural reliability of a 75-meter span beam is proven, an intermediate support wall is redundant. Therefore, the single span design is less risky, less time consuming and less expensive compared to the original design.

In this thesis, existing concrete municipal slab bridges are regarded. Many of these bridges were designed and built in the 1960s and 1970s. These bridges are still in service, and subjected to higher and more frequent loads than at the time of design. This leads to uncertainties in the safety of these bridges. Many municipalities become increasingly aware of these uncertainties and want to verify their bridges according to current standards. Especially the shear assessment is critical, since some former codes do not contain shear checks. Municipalities usually do not have sufficient financial resources to investigate and recalculate all of their bridges. A Quick Scan model is a cheap and fast tool to do structural checks, or to classify a number of bridges for structural safety. A literature study and Finite Element Modelling research was performed in order to make the Quick Scan more accurate. In general, existing municipal bridges are not exposed to the same heavy traffic as governmental highways. Nevertheless, municipal bridges were calculated with the same load models as governmental bridges. For the assessment of existing municipal bridges research was done to the possibility of reducing the design loads of Load Model 1 (LM1) from the Eurocode. This reduction can be done with the α- factor on variable loads. The possible reasons for this reduction is threefold. Firstly, municipal roads are significantly less exposed to heavy traffic compared to governmental highways. Therefore the chance of occurrence of the governing vehicle according to LM1 is decreasing. This assumption was supported by Weight-in-Motion measurements on a municipal road in Rotterdam. With the reliability index (β) for existing bridges in Consequence Class 2, this lead to a governing axle load of 225 kN, instead of the 300kN from LM1. The second reason for the reduction of the design load is the fact that municipal bridges usually have relatively small spans (5-20m). LM1 is designed to simulate a fully loaded bridge with a span of at least 20m. For small spans it can be useful to calculate with real occurring traffic, since axle distance is more important than axle loads only. A third (small) reduction is the fact that an existing bridge has a shorter reference period than a new bridge. This leads to smaller chances of the occurrence of the governing vehicle. New load models for small span municipal bridges were designed taking into account these reductions. The governing vehicle for small span bridges is a 5-axle vehicle with axle loads of 137,5-165 kN and axle distances of 140-175mm. Occurring shear forces due to these loads are higher than due to a long vehicle with higher loads, mora axles and greater axle distances. The new governing vehicle was used to determine the reduction factor α. This was determined by a comparative research in the Finite Element Modelling program RFEM. The resulting shear stresses and flexural stresses from the different load models were compared. For spans up to 11m the loads from LM1 can be reduced by an α factor 0,8. This factor increases linearly to a factor 1,0 for a 20m span. Besides the differences in loads and dimensions, municipal bridges also differ from governmental bridges in lay-out. In general, the distance from the carriageway to the edge of the slab is larger for municipal bridges due to the presence of a footpath or bicycle lane separated by a kerb. Bridges in 10 different municipalities were examined on lay-out. Roughly 58% of the municipal bridges in the Netherlands have significant edge distance (>1,2m) This leads to a difference in the force transmission, since the high axle loads from LM1 cannot occur near the edge of the slab. The influence of this edge distance for different spans was investigated with RFEM. Also, the variable and permanent loads were investigated separately to give insight in the resulting shear stress due to different loads. Distinction was made between slabs in cracked and uncracked state. Cracking has significant influence on the transverse force transmission of the axle loads. The transverse force transmission is influenced by the ratio between longitudinal and transverse stiffness, which was conservatively chosen as 1/3. Also, distinction was made between in-situ casted slabs and prefab slabs. The self-weight of in-situ casted slabs leads to a constant shear force on the support. A prefab slab was treated like a theoretical slab, where the self-weight leads to peak forces near the edge due to torsional moments near the edge. The critical edge distance was determined for different spans. For a cracked in-situ casted slab with an edge distance >1,5m, the middle of the slab is always governing in shear. An edge distance <0,7 leads to the edge of the support being governing in shear. Research by Eva Lantsoght to shear force in reinforced slabs under concentrated loads close to the supports was used for rules and assumptions based on experiments. These rules were used to get a better understanding of the results in RFEM, and to develop the Quick Scan Model. The Quick Scan model uses findings from literature research combined with findings from finite element modelling. The output is a Unity Check which can function as real structural shear check if the concrete compressive strength and steel yield strength are known. When only dimensions are known, the Quick Scan model can function as classification for a series of bridges in a municipality. The Quick Scan model was tested by a series of case studies, which did not yet lead to the verification of the model. Results from the Quick Scan model were compared to results from the FEM research. Occurring shear stresses in the Quick Scan model are conservative with a maximum error of 11%. With the possibility of lowering the reliability index β to 2,5 (‘disapproval’ level) and taking into account the possible error due to several uncertainties, the upper boundary of the Unity Check was found as 1,4. Bridges with a Unity Check: 1 < UC < 1,4 according to the Quick Scan model need further assessment or material testing in order to fulfil the requirements. Extensive research was done to loads according to the Eurocode (LM1) on slab bridges and the force transmission of these loads. The capacity of existing concrete slabs was investigated relatively brief. More research to the capacity side of existing concrete bridges is expected to be beneficial.

To combat global warming a transition towards renewable energy sources (RES) is essential. Although RES have much lower life-cycle emissions, they do not offer a continuous and fully predictable output like their fossil-fuelled counterparts. Energy storage is paramount in order to include the growing share of these intermittent sources into the grid and provide a reliable supply of energy. In 2016 a long term vision which involves the creation of an artificial island on the Dogger Bank in the North Sea was presented. The island would act as the central spill in an interconnected future economy fuelled by RES. Currently there are no competitive energy storage technologies under consideration that could contribute to this ‘energy hub’. In Europe pumped hydropower storage (PHS) represents over 90% of the grid-connected storage capacity and continues to be identified as the most cost-efficient energy storage technology available today and in the future. Unfortunately, conventional PHS is restricted to mountainous areas and the remaining potential (2291GWh) does not suffice to future demand (estimated at 3596GWh). The plans of developing a large wind farm via the construction of an island made it an attractive base to test the contribution and feasibility of a substitute to conventional PHS: inverse offshore pumped hydropower storage (IOPHS). It relies on the same principles as conventional PHS, only the process is inverted. When the wind farm generates a surplus of energy, the excess power is used to drive hydraulic turbines which pump the water out of the artificially created lake into the surrounding sea. Then when there is a higher demand for energy than the wind farm generates at that time, the sea water is allowed to flow back into the interior lake driving the same turbines. Although the idea of inverse offshore pumped hydropower storage has been around for years, it has never been constructed. The objective of this research is to identify the possible design alternatives and determine how the costs of an offshore pumped hydropower storage facility scale with the power and storage capacity, using existing construction technologies. The construction of the storage plant consists of four main elements: the dam, dredging works, turbines and the turbine housing...