HYBRID LIGHTWEIGHT STRUCTURAL SYSTEMS FOR LOW-COST HOUSING (HYLIGHTS)

The legally binding UK government target to reach net zero carbon emissions by 2050 cannot be achieved without minimizing the carbon footprint of the construction sector. Over one-quarter of the world`s annual steel production is used in the construction of buildings but a study based on steel-framed designs for schools, offices and residential buildings, sourced from leading UK design consultancies, reveals the average material utilisation ratio for typical steel buildings is below 50% of their capacity. This suggests steel content in buildings could be significantly reduced by designing for minimum material, which would annually avert 214 million tonnes of carbon dioxide emissions worldwide. To reduce steel consumption in construction, the development of novel, materially efficient and sustainable lightweight structures is essential. There's a global need for housing as populations grow which creates tension with our need to cause less emissions by building less or more efficiently.

Light steel frame (LSF) structures made of cold-formed steel (CFS) stud-walls and joisted floors are gaining growing popularity in modern construction practice worldwide, both in new developments and as a cost-effective and low-carbon solution for vertical extensions to existing buildings. The ease of offsite manufacturing utilising LSF structures offers many benefits compared to traditional methods, including: (a) improved quality and productivity, reduced material use, less wastage and savings of 30-50% in total construction time and associated costs; (b) flexibility for more tailored design solutions complying with the Design for Manufacture and Assembly approach; and (c) scalability for the technologies around automated construction. LSF systems can, therefore, directly contribute towards meeting the UK Government's ambitious house building commitments and reducing the initial cost of construction and whole life cost of assets, and CO2 emissions by 33% and 50%, respectively. However, the current use of LSF structural systems is limited due to critical drawbacks such as low local buckling resistance of thin-walled CFS elements, low lateral stiffness and robustness of typical LSF systems and limitations of current design and optimisation approaches to exploit their full capacity. These challenges should be addressed before LSF systems can be widely used both in the UK and overseas.