Topologically Optimised Facade Brackets
Project Year: 2021
Project Team: Kostas Grigoriadis, Michael Herrmann
The metal components connecting different parts of a building’s structure and cladding are standard sized, materially homogeneous elements. Building loads, deflections, and thermal expansion rates, however, are non-uniform and act in a heterogeneous manner. Using material evenly in effect is inefficient and increases embodied energy and componentry manufacturing, transportation, and installation costs. The origins of this redundant material use go back to times when mass fabrication was the norm, environmental issues were not a main consideration, and design and fabrication techniques were different to today’s practices.
In response, we initially generated an inventory of the main types of metal components in a case study mid-rise office building in central London. We then selected the metal brackets connecting the building’s curtain wall panelling to its concrete floor slabs and redesigned them using topology optimisation. This CAD method is based on simulating support and loading conditions and calculating the corresponding optimal material distribution, effectively minimising the amount of material in the components. The resulting brackets were 3D printed in stainless steel and steel / bronze (420SS/BR) and milled in steel S275. Vertical and horizontal load testing of the optimised and original fabricated bracketry was done at the structural load testing facility at Lübeck University to compare their structural performance. The total material, weight, cost, embodied energy, and pollutant emissions of the conventional and optimised components were also calculated to derive the exact savings in material and the corresponding embodied carbon reductions.