Design and Deployment of a Functionally Efficient 3D-Printed Concrete Bridge Developed by Form Optimization (2025-12)¶

Concrete 3D printing is emerging as a technology that can significantly impact the state of practice and overcome the limitations of conventional construction processes. Design and fabrication of a free-standing structure using a layer deposition process is demonstrated for a large-scale application. A 7.5 m pedestrian bridge is designed following the concept of form-specific structural optimization. A self-equilibrated system of a laterally restrained concrete compression form is used to develop the structural system of the bridge. The structural form, consisting of a lattice structure of constant width interconnected beams is developed within a compression form derived from the concept of a tied arch. Issues related to layer-induced orthotropy in the printed assembly are addressed in determining the configuration of the printed filaments that form the structure. The evolution of the structural system of the functionally efficient bridge that minimizes the use of material under the constraints of constant-width filaments and print-path continuity is presented. The final lattice form with interconnected beam members is arrived at by iterative analysis to minimize stress in members and deflection of the structure. A prototype 5.5 m bridge is load-tested for validation. The material testing, design development, off-site printing, and installation of the 7.5 m span printed, two-part pedestrian bridge are detailed.