Structural and Fire Resistance of a Reusable Steel/Concrete Composite Floor System

One sixth of the world's CO2 emissions from energy and industrial process are released from the production of steel and cement, most of which is used in construction. Although reducing embodied energy in structures is increasingly being considered by structural engineers, it is very difficult to achieve meaningful results with today's construction methods because the different existing mainstream structural systems, whether steel, concrete or composite construction, use similar amounts of virgin materials and have similar embodied energy values. We propose a radically different approach to reduce the environmental impact of construction: by making structural components reusable at the end of life of the structure. This can potentially reduce the use of new materials of a structure by 50%. The concept of reusable structural components has been talked about, but no feasible solution is available. Without making structural components reusable, at the end of life of a building, although all the steel and concrete materials in the building structure remain serviceable, the building is demolished destructively, larger steel elements are recycled by energy-intensive melting, and the rest of the material is landfilled. This approach to construction is clearly wasteful - of energy, emissions and potentially cost.

This project aims to develop a reusable composite floor system to be used in steel/concrete composite structures. It is important that this method of construction is developed as a mainstream structural engineering solution, rather than limited to very special conditions, so as to maximize the benefits of design and construction of reusable structural components at the end of life. Steel/concrete composite structures are chosen because this building type is the most commonly used in the UK.

The proposed reusable floor system is a totally different form of construction, with new modes of structural behaviour that have not been investigated before. A complete rethink of composite floor structural and fire engineering design is necessary to ensure safety of the proposed floor system. Extensive new physical tests at ambient and elevated temperatures and in fire for the different components of the proposed floor system have been planned to identify the different modes of behaviour and failure of the system. Supplemented by extensive numerical simulations, this project will develop thorough understanding of the structural and fire performance of the new structural system to develop practical design methods. This project will be carried out in collaboration between the Universities of Bradford and Manchester, which have international leading experiences in composite structural behaviour and design at ambient temperature and in fire, and have dedicated and experienced research teams and experimental facilities.

A steering group, consisting of high level representatives from key construction companies, will advise the research teams to ensure practical relevance of the research and to help promote the outcomes of the research. Various impact pathways have been planned, including a dedicated website for the project and APPs for designers, promotion of the research outcome to relevant Eurocode 4 (Eurocode for composite structures) committees (where the two applicants, Professors Lam and Wang, represent the UK for structural safety (Eurocode 4 Part 1.1, or EN 1994-1-1) and fire safety (Eurocode 4 Part 1.2, or EN 1994-1-2)), and a one-day colloquium at the end of the project.

Building construction consumes a vast quantity of energy and natural resources. The different current mainstream structural systems, whether using steel, concrete or composite construction, use similar amounts of raw materials and have similar amounts of embodied energy. So the scope of improvement is small. By making steel framed building structural components reusable at the end of life, which is the aim of this project, has the potential to achieve 50% reduction in raw material use and embodied energy of future steel/concrete composite structures. Therefore, this project has the potential to revolutionize the design and construction of steel/concrete composite structures, the most common type of multi-storey construction in the UK, by substantially reducing the cost of construction, the use of raw materials and the environmental impact of structures.