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.
Highlights
A way to limit the excavation is by changing from a linear economy model, where the idea is based on a ‘take, make and dispose’ model, to a circular economy (CE) model [2]
The R of Recover is covered in the bioeconomy
Truss bridges are drawn with the same input parameters as the ones used in the design tool based on morphological indicators
Summary
In the current linear economy, the excavation rate of non-renewable materials is alarming. If this trend continues, the annual extraction of non-renewable resources will reach 170–184 billion tonnes by 2050, which will quickly result in their depletion [1]. The first step is always to ‘Reduce’ the amount of required material This can be done by designing with material-efficiency in mind. When the materials cannot be recycled, the embedded energy in the material should be ‘Recovered’ in heat and power plants. The latter is mostly reserved for the bioeconomy
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