No abstract

No abstract

The construction industry consumes over 32% of the annually excavated natural resources worldwide. Additionally, it is responsible for 25% of the annually generated solid waste. To become a more sustainable industry, a circular economy is necessary: resources are kept in use as long as possible, aiming to reduce and recirculate natural resources. In this paper, the investigation focuses on pedestrian truss bridges of the types Warren and Howe. Many pedestrian bridges currently find themselves in their end-of-life phase and most commonly these bridges are demolished and rebuilt, thus needing a lot of new materials and energy. The aim is thus first and foremost to reduce the amount of necessary new materials. For this reason, a design tool will be created, using the software ‘Matlab’, in which truss bridges can be evaluated and compared in the conceptual design stage. The tool is based on the theory of morphological indicators: the volume indicator, displacement indicator, buckling indicator and first natural frequency indicator. These allow a designer to determine the most material efficient Warren or Howe truss bridge design with user-defined constraints concerning deflection, load frequency, buckling and overall dimension. Subsequently, the tool was tested and compared to calculations made in the finite element modelling software Diamonds. In total, 72 steel bridge structures were tested. From these it could be concluded that the manual calculations in Diamonds in general confirmed the results obtained with the automated design tool based on morphological indicators. As such, it allows a designer to converge more quickly towards the best performing structure, thus saving time, materials, and corresponding costs and energy.

The construction industry is responsible for approximately 40% of the worldwide material consumption. Therefore, the transition to a circular construction industry is of primary importance. In a circular economy, the maximum usage and preservation of materials and energy is suggested. The reuse of components is considered a circular economy best practice. This paper investigates the reuse of steel construction elements in Belgium and identifies the existing barriers. Therefore, a series of semi-structured interviews is conducted with a wide range of stakeholders representing the whole Belgian construction sector. The identified critical barriers to steel reuse are: cost, demand and time. Subsequently, these barriers were tested and quantified in practice in cooperation with a demolition contractor. A comparison is made between demolition and deconstruction of steel porticos considering cost, time and demand. It was found that, in practice, demand is the most pressing obstacle. Overcoming this obstacle will require a coordinated approach throughout the Belgian construction chain: improved deconstruction procedures on-site, a platform to match supply and demand, standardization of reusable steel elements, governmental policies and design strategies.

The construction industry is responsible for half of the currently excavated amount of raw materials. In addition, a quarter of all waste in the European Union is construction waste. This construction waste comprises numerous materials that can still be reused or recycled. Thus, a shift to a circular construction sector is necessary. To make this shift, it is vital to enable the measurement of and the progress toward circularity. Therefore, this paper investigates the currently available circularity indicators with regard to the 4 Rs—Reduce, Reuse, Recycle, Recover. Subsequently, a comprehensive Circular Construction Indicator framework is introduced that evaluates a construction project according to the three typical construction phases: design, construction, and end-of-life. In this, new partial indicators to assess material scarcity, structural efficiency, and service life prediction should help designers consider these aspects already in the conceptual design stage. Lastly, suggestions for further research are defined to develop further said new partial indicators.