Embodied Energy Optimization of Steel-Concrete Composite Beams using a Genetic Algorithm

The optimisation of structural performance is acknowledged as a means of obtaining sustainable structural designs. The minimisation of embodied energy of construction materials is a key component in the delivery of sustainable future designs. This study attempts to understand the relationship between embodied energy and structural forms of composite floor plates repetitively used in multi-storey buildings, and highly optimise the form to minimise embodied energy. As a search method based upon the principles of genetics and natural selection, Genetic Algorithms (GA) have previously been used to optimise composite beams and composite frames for cost and weight objective functions. Parametric design models have also been presented in the literature as an optimisation tool to optimise steel floor plates for both cost and embodied carbon. In this paper, a Matlab algorithm incorporating MathWorks global optimisation toolbox GA and in accordance with Eurocode 4 design processes is employed to optimise a composite beam for five separate objective functions: maximise span length, minimise beam cross section, minimise slab depth, minimise weight, and minimise deflected shape. For each of these objective functions, candidate designs are assessed for embodied energy to determine individual relationships. It is concluded that correlation can be derived, and collective relationships between design and state variables as well as embodied energy can be determined.