Failure Mechanism of Reinforced 3D Printed Concrete Arches (2026-02)¶

Although 3D concrete printing (3DCP) enables complex structural forms, effective reinforcement remains a critical challenge, particularly for curved structures. This study focuses on the static behavior and failure mechanisms of steel-reinforced extrusion-based 3D printed concrete (3DPC) arches. Through systematic experiments on eight groups of arches and Finite Element Modeling (FEM), the interaction between steel reinforcement and the inherent layered interfaces was investigated. Results reveal a critical failure mechanism transition: unreinforced arches fail via brittle fracture, while steel-reinforced arches fail by a bond-governed failure dominated by steel-concrete interfacial slip. While increasing the cross-sectional width significantly enhanced the capacity (up to 268.5%) demonstrating the structural scalability of the printing process, reinforcement proved to be most effective, boosting the ultimate load by up to 307.9%. Crucially, FEM simulations revealed an optimal reinforcement ratio (approx. 2.33%), beyond which interfacial bond failure accelerates and capacity decreases. Based on this bond-governed mechanism, a novel prediction model is proposed. It innovatively incorporates a bond strength reduction factor to account for interlayer weakness, showing good agreement with experimental data and providing a theoretical basis for the design of steel-reinforced 3DPC arches.