Accuracy and reliability: A computational tool to minimise steel mass and carbon emissions at early-stage structural design

Building structures often represent the element with the largest mass in a building project, with significant effects on the buildings life cycle environmental impacts. Amongst structural materials, steel is characterised by its suitability to a large number of structures as well as a highly pollutant supply chain. Therefore, even a small reduction of the amount of steel currently used in building structures, would undoubtedly be beneficial towards the mitigation of environmental impacts. This paper presents a computational tool that aims to help practitioners to design material-efficient structures for multi-storey buildings frames. The tool is based on an optimisation framework, which -given a small set of input parameters defining the overall frame geometry and the system of loadings- seeks for optimised cross-sections for each structural member, based on a finite set of commercially available section profiles. Results are fully compliant with British and European standards for structural design. The user can therefore quickly and reliably assess a wide range of alternative frame layouts in a nearly real-time frame. To avoid misleading the decision-maker with very definite numbers, both structural mass and embodied carbon coefficients are considered along with their uncertainty through Montecarlo simulation. The final output consists of a probability density function of the embodied carbon for the specific structural design under consideration. The mathematical model which underpins the tool has been extensively validated. Results of an application to a practical example show a carbon emissions reduction potential of 23%. To maximise the impact of the research findings, the described work has been implemented into a plug-in tool for a widely used CAD software. This will help practitioners to take into account embodied carbon consideration early on in the design process when the room for improvement is greatest and the economic repercussions of design changes are low. This tool represents a fundamental first step to translate research on embodied carbon reduction into a means that is useful to, and usable by, industry professionals to mitigate building-related carbon emissions and progress towards national and international carbon targets.