Design, Structural Optimization and Fabrication of Concrete Shell Through Fiber-Reinforced 3D Printing (2024-08)¶

The construction industry, particularly the cement sector, significantly impacts the environment due to its extensive material consumption. To mitigate CO2 emissions, the European Climate Foundation’s report proposes three complementary strategies: reducing CO2 across the structural unit, concrete unit, and cement unit. This paper focuses on the structural scale to present a comprehensive study on the design, structural optimization, and fabrication methodologies for lightweight shell structures thanks to advanced techniques in reinforced 3D printed mortar. The paper presents an integrated design to production workflow taking account of 3D printing concrete constraint and structural engineering considerations to achieve optimal load-bearing capacity while minimizing material usage. A simple criterion based on the critical cantilever angle during printing is proposed. The necessity to perform sensitivity analysis (with various load cases and imperfections) and the need for integration within a CAD environment guided the choice of NURBS-based parametrization. Leveraging computational tools, finite element analysis, and parametric modeling, this research explores the intricate relationship between structure, process and material A constrained mass-minimization problem is formulated and solved with a penalty method. The analysis is applied in the particular case of 2K 3D printing and continuous fiber reinforcement through an original process called Flow-Based Pultrusion and highlights the potential for the design and construction of intricate geometries and custom structural elements. We show that the mechanical and process constraints shapes a continuum of solutions. Each of them comes with specific needs in terms of mechanical features at hardened state and process parameters. The findings of this study contribute to advancing construction methodologies, validating the workflow by manufacturing a shell prototype. These techniques hold promise for creating innovative, lightweight, and sustainable shell solutions, contributing positively to environmentally conscious construction practices.