An experimental research into the use of basalt as reinforcement in concrete to reduce the ECI value of a concrete quay wall apron. In this research experiments with basalt minibars and basalt reinforced polymer rebars are performed to compare directly to steel fibres and steel rebars. With the test results 4 designs are produced resulting in material requirements per type of reinforcement. By using these amounts of material an ECI value is determined showing that in this research basalt is an option to reduce the environmental impact. The ECI value presented in this research are in euros/year lifespan, meaning that for a different lifespan the material shows different values. Here the pros of basalt come out as the material is resistant to corrosion as it is a stone like material. Therefore in this research with a product that is placed in water, the lifespan of a steel reinforced apron could only reach 50 years where the apron with basalt reinforcement reached 100 years.

The main motivation within this thesis is to explore the possibility of increasing the service life of box-beam bridge girders to aid the ambition of the Dutch government to become a circular economy. The construction industry still follows a more or less linear economy system. Many bridges in the Netherlands are approaching the end of their service lives, and efforts are being made to extend the lives of these bridges. This is but a temporary solution, and these bridges will require replacement within 20-30 years. This provides an opportunity to incorporate circularity within new and upcoming structures from the design phase onward rather than only as an end-of-life practice. Therefore this thesis explores the possibilities of incorporating the strategy of lifespan extension, in the form of a cover increase against chloride-induced corrosion. The exact increase was calculated through the use of a relevant service life design model (DuraCrete) and compared with the Eurocodes. The reliability of the model was checked using a Monte Carlo simulation. Subsequently, the circular aspects of future adaptability were also investigated considering a fictitious scenario of increased traffic load. Hence, it was concluded that a marginal increase in concrete volume and prestressing steel per beam would allow for a more durable and adaptable beam for the future.

Nowadays, most of the historical bridges (Amsterdam, 2019) of Amsterdam do not meet the load-bearing criteria of the current design code (Eurocode: 2012). This has several reasons. It comes partly because of the overdue of the maintenance (Amsterdam, 2019) but also because the traffic load for which the bridge has been designed, is lower than the present traffic load (Amsterdam, 2019). The current Eurocode 4 does not guarantee the safety of this type of bridge decks. To guarantee the safety and the remaining service life of the historical bridges in Amsterdam, the municipality has started an investigation on historical steel-concrete-composite-bridge-decks. The focus in this thesis is on historical steel-concrete-composite-bridge-decks (a.k.a. Verbundträger brücken in German) because this type of bridges does not contain shear connectors in their configuration. This leads to the fact that the capacity of the bridge deck is almost not determined in the longitudinal and completely not determined in the transversal direction. The bridge deck in the longitudinal direction satisfies the unity check based on the protocol of the municipality of Amsterdam to check this type of bridges on safety, where they only consider the steel profile to define the capacity of the bridge in this direction. This is very conservative because the concrete is not taken into account during the calculation of the cross-section. In the transverse direction, the bridge deck does not fulfil the necessary unit check limit, because the municipality takes only the shrinkage reinforcement into consideration during their calculations. In addition to this, the state of the bridge decks and relevant research about how the bridge deck is build-up, is investigated. The main conclusion that can be taken from the cross-section of these type of bridge decks is that there is a lot of variation in all the components of the bridge decks.

Furthermore, during the investigation of the bridge decks it is decided to choose three typical bridge decks (A, B, C), which will be simulated to gain more insights about the cross-section of these historical bridge decks. The current Eurocode 4, which is implemented to guarantee the safety of the type of cross-section containing steel and concrete, does not provide an answer to calculate the load-bearing capacity of historical steel-concrete-composite-bridge-decks, because of a significant difference between the designed current Eurocode 4 model and the designed cross section of the historical model.

The behaviour of the bridge is studied in two directions based on the available literature. In the longitudinal direction, the focus is on the interaction between steel and concrete and how this interaction can be described. In the transverse direction, the aim is to find the relevant failure mechanism and corresponding modelling approach to define the behaviour of the bridge deck in the transverse direction of these bridge decks. The failure mechanisms that were evaluated are: Punching shear failure, compressive membrane action, and failure of concrete strut.

The assessment of the aforementioned failure mechanisms is carried out and the most logical model which can be used to validate during the FEA-simulation is the failure of concrete strut which can be modelled by strut and tie model. This model will also be carried out on the other two chosen bridges, next to bridge A on which the in-situ-load-test is done, to validate this model on more than one bridge deck. There was made use of an analytical model based on Eurocode 2, which has been compared the values of the numerical simulations…

The main motivation for this research originated from two ambitions, which involve many challenges for which circular solutions have to be developed. First, the ambition of the Dutch government to achieve a circular economy, which also includes a circular construction industry, in the Netherlands by 2050 at the latest. Secondly, in line with the first, the ambition of Rijkswaterstaat to work climate-neutral and circular in 2030. At this moment, the main focus in the Dutch construction industry is on developing circular solutions which can be implemented and applied during the enormous replacement and renovation task of many of the almost 40.000 bridges and (mostly) viaducts in the Netherlands. Therefore, the main focus of this research has been on developing circular solutions for concrete viaducts for (governmental) roads. This has resulted in the development of a concept demountable footing to foundation (F2F) dowel connection which has been based on, and is suitable for application in, the proposed design of a standard (circular concrete) viaduct. Besides, attention has been paid to desired monitoring aspects regarding such a circular viaduct, and to the life-cycle costs of a circular viaduct compared to those of the same viaduct, constructed in a traditional way, characterized by a linear life-cycle model.

Adopt the concept of demountable and rebuildable brides to an existing idea of an integral bridge. An understanding of the different forces and moments that the bridge will have to take up and how the critical connections (deck-abutment) can be realized. Applying the understanding of how integral and demountable bridges behave and try to integrate the characteristics of both to achieve rebuildable/demountable construction. In this additional thesis, the first steps to make an integral bridge demountable is looked at in detail. The concepts of vertical prestressing with unbonded bars are explored to achieve the demountable abutment, and abutment- deck connection. The different forces that arise due to this method of prestressing have been accounted for to ensure the basic safety of this design is met.

3D concrete printing (3DCP) is a new, innovative construction method in which concrete structures are produced layer-by-layer using a 3D printer. A printed concrete structure, can be self-supporting, which means no formwork is required anymore, increasing the freedom of form, while decreasing construction cost and material use. However, the engineer designing 3DCP structures is challenged, because the construction process is completely different than from designing conventional concrete structures. The fresh concrete structure must be stiff and stable enough to resist the increasing self-weight of the subsequent layers and the material properties can become anisotropic due to a limited bond-strength between two layers. The objective of this research is to integrate the manufacturing process into the structural design of a simply supported 3DCP cyclist bridge, to provide guidelines for designers and for future research. Using a parametric research model, the performance and feasibility of the design can be assessed as a function of 22 parameters describing the bridge geometry, material properties (fresh and hardened) and printing process parameters. The model is built in Grasshopper and Python by using analytical formulations only. The use of FE software is omitted to make the model as fast as possible. Like this, a global sensitivity analysis based on thousands of parameter combinations could be conducted, revealing the most important parameters for determining the design's performance and feasibility, as well as the absolute effect of specific parameters. These results were used in an optimisation run, seeking the most cost-efficient and sustainable design. The research shows that integrating the manufacturing process into the structural design of 3DCP objects yields more optimal designs and the analytical model that has been developed has proven to be a useful tool for research and design.

The World Heritage Site Kinderdijk consists of a landscape of preserved 18th-century windmills and is a popular touristic location. The number of visitors is continuously growing for the World Heritage Site at Kinderdijk. Visitors arriving via the water network have to cross a busy road to reach the heritage site. This is an unsafe and unfavourable situation. A new water entrance at Kinderdijk is the solution to this problem. The plan is to add the function of a pedestrian passage to the existing discharge sluice at Kinderdijk named the Elshoutsluice. The discharge sluice is part of a flood defence and must keep its original function. The objective of this thesis is to provide a conceptual structural design for the multi-functional use of the discharge sluice at Kinderdijk including the functions for water discharge, flood defence, passage for (motorised) vehicles and pedestrians, which fulfils standards for flood safety and buildings in the Netherlands. This thesis shows how to approach a design case for adjustments of an existing hydraulic structure as a part of a flood defence. A conceptual design was made for the adaptation of the Elshoutsluice. For this study a design method according to Roozenburg and Eekels (1995) and Voorendt (2020) was used. The Elshoutsluice was divided into different subsystems and elements. The concepts for the location of the new pedestrian tunnel, the floor configuration, the roof and gates were developed. After the functional verification and evaluation, a selection was made from the best remaining alternatives for the elements and subsystems. The selected alternative is a pedestrian tunnel above culvert number 2. As a result, the existing gates of culvert 2 will be replaced with new gates to provide flood protection in case of high water. A flap gate and a vertical unfolding gate are selected. The existing technical area expands above culvert number 3. A multi-functional space is included above culvert number 3. Culverts 1 and 4 remain unchanged. Additional soil will be placed on top of the structure to provide a slope for the connection of the heightened road on top of the sluice to the road at the adjacent levee. The conceptual design and construction phase was checked for the flood safety based on the WBI 2017 and OI 2014 and fulfils the requirements. Stability checks were performed for governing load situations of the Elshoutsluice for the construction phase and use phase. The difference in loading on the structure for the initial design and the new situation was analysed. Additional checks are needed for the lateral walls in all the culverts and the top slab of culvert 1 and 4 due to the increase in shear force and bending moments. The conclusion is the resulting conceptual design.