The building and construction industry is one of the main polluting sectors contributing to climate change, and is responsible for around 37% of global CO2 emissions. A circular approach is needed to address the global demand for construction materials and resources in a sustainable way. Steel is a commonly used material in construction and fully recyclable. Recycled steel has to be melted in a furnace, which is a polluting process. For reuse of steel only disassembly and transport is necessary. The general shift from recycling to reusing steel can offer environmental benefits. A number of steel bridges in the Netherlands are being renovated or replaced by Rijkswaterstaat in the coming years. Rijkswaterstaat has been investigating the reuse of its bridges on object level, i.e. reusing the complete structure. This has proven to be difficult. Disassembling the bridge and reusing the structure on an element-level has not been thoroughly investigated. As reuse of construction elements in general is relatively novel practice, not much is known about how to determine the reuse potential of structural bridge elements. This thesis aim to identify current knowledge gaps and provide research results that encourages future reuse of steel bridges. As a case study the eastern Van Brienenoord bride is investigated. This bridge is scheduled to be replaced in 2026-2028 and there currently are no plans for reuse. The goal of this thesis is to examine the reuse potential of steel bridges on element-level, focusing on two critical factors: fatigue and corrosion. Fatigue and corrosion are two of the most deteriorating processes for steel bridges. The reuse potential can be evaluated using the remaining service life of the elements. The remaining service life based on both fatigue and corrosion can be determined by implementing the corrosion assessment in the fatigue calculation. Fatigue assessments are based on stress ranges in structural members. Corrosion leads to a reduction in the cross sectional area, increasing the stress and thus stress ranges occurring in the critical structural details. The design, decomposition, loading history and technical condition of the eastern Van Brienenoord are analysed. After critical review of the Van Brienenoord the structural elements of the bridge deck are selected to investigate further. Inspection reports by Rijkswaterstaat and Nebest are used to locate corrosion damage on the Van Brienenoord. The corrosion damage is determined using functions for uniform surface corrosion for steel. The critical structural details of the selected elements in the bridge deck are identified. Using the fatigue assessment procedure described in the Eurocode in combination with the reduced cross section the remaining service life of the structural elements is determined. According to the results of the proposed assessment method in this research, all structural elements of the eastern Van Brienenoord bridge deck have significant service life left and are therefore suitable for reuse after disassembly. However, certain specific details that have a higher calculated fatigue damage may need to be repaired or removed.

Waste generation is one of the main environmental problems and is a result of the current linear economy. Materials/elements are used whereafter they are wasted which is a problem considering the finite material supply on earth. Therefore, the current linear economy needs to move towards a circular one in which materials are reused and thus kept in the circle. However, reuse is still not a common practise. This is due to the fact that there are no insights in the structural feasibility, potential savings on environmental impact, and costs related to reuse. Besides the lacking knowledge about the different aspects there is no clear image where the potentials for reuse are located within the sector. The goal of this research is to give insights in the reuse potentials and to find opportunities within the sector. This research started with a material flow analysis to find promising material flows in the sector. In this material flow analysis it was found that the demolition of office buildings is responsible for a big portion of the outgoing material flow and the majority of the ingoing material flow is related to the new construction of serial houses. In the analysis it was found that the elements with the highest ECI and mass are floor elements. Next the available floor elements coming from office buildings and the floor elements needed for the construction of serial houses were examined to check possible matches. It was found that new plank- and hollow core slab floors used in serial houses can potentially be substituted for reused monolithic- and hollow core slab floors out of office buildings. Thereafter, two different tools were developed. One related to the reuse of monolithic floors and one related to the reuse of hollow core slab floors. These tools are means to give insights in the reuse potentials considering the structural feasibility, potential savings on environmental impact, and costs. Different cases were checked using the tools and the following results were found: -In all cases it was structurally feasible to use reused floors coming from office buildings in the new construction of serial houses. -When reused floor elements are used it is possible to save 40-90% on environmental impact. -Reused floor elements can be cheaper or more expensive as new floor elements. These results are promising and hopefully contribute to an acceleration of reuse in practise. The research states where the potentials for reuse are located in the sector and presents two tools which check the reuse potentials considering structural feasibility, environmental impact, and costs.

We are currently facing a transition of economy. Previous years were focused on a linear economy, consisting of the make-waste concept. The products that are made with raw materials are thrown away after its use. Unfortunately the Earth does not contain an unlimited source of materials and we need to focus on reusing materials. Concluding to create a circular economy in which waste does not exist at all. The goal is to start with reusing as of today, instead of in the future. In other words, using the current existing elements. However, to do so it must be known which elements are available. Therefore, a data analysis has been done on the current existing structures as well as the future perspective. These analyses combined concluded in a common scope, visualized as a Lego box. This Lego box does not only consist of all the current existing structures (within the determined scope), but also provides a future perspective on the demolishing plans in the near future. Based on a time-consuming manual research a variety of nearly 70 viaducts have been examined. This lead to the summarization of 5 different girder categories: Box girders, inverted T-girders, Infilled girders, T-girders and remaining. With the specific girders known, design applications can be created. The focus on these applications is to think outside the box and reusing a girder in a different function than the original purpose. The design applications are created with a brainstorm session. For this session multiple different broad-minded individuals had been invited for an open discussion which concluded in over 20 different design applications. Thereafter, these applications have been examined with the help of an MCDA, based on the three main criteria. This MCDA is executed with the help of multiple different experts with a background regarding one of the three main criteria. With these expert judgements the total amount of design applications have been demarcated to a top 5. Reusing a girder as: Bicycle bridges, (non-)residential buildings, retaining walls, sound barriers and culverts In conclusion, this thesis provides valuable outputs and the first impressions regarding reuse in another application seem at least interesting. With the different impact factors determined, the possibility looks very promising. It can be stated that reusing in general will be better for the environment, as well as for your own wallet. Reusing a girder as culvert can in theory be seen as a good reuse application, but not higher in a general value than reusing again as a girder. This is based due to the fact that using the girder as a culvert will take more research in practice, especially regarding structural aspects. However, from this thesis it the first impression conclude in the fact that the impact in costs as well as environmental impacts are bigger when reusing the girder in another function