CO2 reduction of resolved wall structures: A load-bearing capacity-based modularization and assembly approach

The demand for new housing is constantly growing and cannot be met by artisanal, in-situ construction methods. At the same time, CO2 emissions generated from the construction of new buildings need to be significantly reduced. Precast concrete elements offer the potential for an optimized design with minimal material consumption using high-performance materials. However, this only makes sense when the precast modules can be fabricated in a serial manner. Therefore, a modularization approach is developed that resolves structures into a small number of similar modules to enable an efficient and rapid mass production. Walls and wall-like beams are divided into hexagonal honeycomb structures mainly consisting of Y-modules and columns. The load-bearing capacity of these modules is described holistically for bending, shear and stability. By means of clustering, modules with low CO2 emissions with respect to their load-bearing capacity are grouped into construction kits. These kits are then used to assemble the final honeycomb structures. This combinatorial optimization problem is solved with two metaheuristics, Tabu Search and Simulated Annealing. Three case studies show that this modular approach reduces CO2 emissions by up to 80% compared to monolithic structures. The optimized positioning saves a further 23% with the same load-bearing capacity.