The aim of this thesis is to present a design for a bicycle and pedestrian bridge which meets the requirements of Circular Economy; by incorporating strategies such as design for disassembly and modularity a structure is created which improves upon the long-term value of existing bridges. Circular Economy has in recent years begun to replace the sustainability paradigm as it provides more tangible strategies to achieve the same goals. Civil engineering is a large contributor to environmental impact and waste production therefore reducing this represented the main goal for this thesis; by designing a structure which uses alternative materials and connections to traditional methods the impact was reduced. The design of the structure consisted of the following main aspects; girders, connections, and detailing, these were verified using European norms to demonstrate the feasibility of the proposed design. Analyses were performed for the key structural aspects of strength, stability, and dynamic response; together with detailing of the components it was demonstrated that implementation of such a bridge is possible in practice. Once the final design was determined it was compared to a set of bridges designed with a traditional civil engineering approach to demonstrate the benefits of circular design in terms of environmental impact. It is concluded that a post-tensioned aluminium girder bridge represents a sufficiently strong and stiff solution for an 18m span and 3m width; the modular design allows for disassembly and modification on site meaning elements can be conveniently reused or replaced. In terms of environmental impact the result is dependent on the LCA method chosen; the Dutch method which allows bonus from reuse and recycling provides an even result while without this detraction the traditional structure is favoured significantly.

This thesis concerns research into the parametric modelling and optimization of steel-concrete bridge typologies typically found in the Netherlands, in order to further the automation of preliminary bridge designs. The research question posed is: "How can a parametric bridge design model be composed to fit into the
overall road design process in order to get a comparative overview of structurally sound bridge designs of different typologies?". Within the literature review some background information is provided about the design of steel-concrete bridges, parametric design, finite element modelling and evolutionary solvers for optimization. With this information seven different bridges are designed according to boundary conditions and requirements posed in a fictitious case. These bridge designs cover the beam-, truss-, arch- and cable stayed
bridge typologies. The designs are then parametrically modelled and converted to a finite element model in a single parametric design environment, after which they are structurally analysed and optimized for minimum costs. The result is that, for the fictitious case considered, the Warren truss without verticals is the
solution with the lowest costs. This bridge design is able to carry the loads, according to load model 1 from the Euro Codes,with a lower amount of structural steel compared to the girder beam bridges, and the absence of expensive cables in the structure makes it less expensive than the arch and cable stayed bridges. Due to the scope defined at the start of the research, there are some limitations. The costs calculated for the bridges are purely based on the bridge structure itself, foundations and approach structures are not considered and this has to be kept in mind when comparing the bridges. Finally, the research into how to implement this design and optimization tool into the overall design process has not been performed, however, the model is composed in such a way that it will be compatible with minor changes to the start and end of the process.

This research paper is a TU Delft Master’s thesis for graduation track in the field of Building Technology. Its main theme, digital manufacturing of reinforced concrete structures, has already been studied/researched by many other enthusiasts; but they adopted approaches mainly based on the digital production of formworks or 3D printing of concrete. None or very few re-searchers have tried tackling this topic by only investigating the reinforcement production methods. Reinforcement is an essen-tial part of any concrete structure and neglecting its role in de-veloping techniques of digital manufacturing concrete structure makes the technique unreliable. Therefore this report ap-proached this topic according to the suitable production tech-niques for reinforcement structures of freeform concrete struc-tures. Various techniques and concepts in production of rein-forcement structures have been designed and one chosen. This chosen concept got developed into its last minute details as well as its assemblage process got demonstrated on a freeform wall structure.
All the stages are also fully explained providing a source of in-spiration for anyone interested in the topic to employ the pre-sented research in creation of other possible systems.
Those research related to production technique which is done by the researcher of this report, can also be employed in other fields such as lattice mesh structure production or 3D printing of carbon fibers.