Bicycle and pedestrian bridge for the circular economy

Abstract

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.