An integrated computational framework for structural optimization of prestressed concrete structures with 3D-printed formwork

We present a novel, integrated computational framework for the optimal design of post-tensioned concrete structures assembled from 3D-printed stay-in-place formwork and complementary cast concrete. The framework combines shape optimization, explicit multi-phase material modeling that distinguishes between the 3D-printed formwork and the cast concrete, prestressing design, and fabrication-aware toolpath generation within a unified optimization formulation that accounts for both the load balancing and the service stages. Buildability is enforced through layer-by-layer stress constraints based on the evolving strength of fresh concrete, while geometric regularization ensures manufacturable toolpaths. Numerical examples demonstrate that incorporating buildability constraints directly into the optimization yields manufacturable designs that satisfy the prescribed structural and fabrication requirements. Comparisons to conventional solid prestressed members demonstrate the material reduction achieved by structural optimization. The proposed computational framework bridges optimal design and digital fabrication, paving the way toward a holistic design-for-manufacturing approach in 3D concrete printing.