Experimental Study of a Funicular Concrete Beam Prototype (2024-08)¶

This work presents the design and construction of a concrete 3D-printed, post-tensioned funicular beam prototype as well as the experimental test results of subjecting the beam to four-point bending. The beam is designed as a combined compression and tension funicular system with minimized mass and optimized reinforcement. Periodic anticlastic surfaces are embedded within the thrust network to inherently increase geometric stiffness. In consideration of construction, sustainability, and recyclability, the beam is designed as a modular system, consisting of nine individual segments, where each segment is 3Dprinted using a multi-component concrete mix with a multi-axis industrial robot arm. Post-tensioning the nine individual segments together with ungrouted steel cables forms the beam. Beneficially, the beam can be readily disassembled and recycled since the concrete and steel can be separated easily from each other. To understand the structural performance, and how both the funicular load path and the geometric stiffness work in tandem, a four-point bending test was conducted. The experimental test provides insights on, and captures the complexities associated with, the overall design, fabrication, and construction, and reveals the flexural behavior and mode of failure. Design, fabrication, construction, and structural testing processes and setups are outlined and discussed. This study establishes a foundational basis that will be used to further develop and enhance such structural systems for more sustainable construction practices in the future.