Fabrication of steel-concrete-steel structures via wire and arc additive manufacturing: Performance evaluation and structural optimization

Steel-concrete-steel (SCS) composite structures are widely studied due to their high load-bearing capacity, impact resistance, and efficient construction. This study proposes a novel wire and arc additive manufacturing (WAAM)-based method for fabricating SCS structures with steel bar through-connectors, enabling cost-effective and automated construction while overcoming design constraints of traditional techniques. To address bond slip issues in SCS structures, a variable cross-section steel bar through-connector was designed based on WAAM and the beam on elastic foundation model. Push-out and three-point bending tests were conducted to evaluate the mechanical performance of SCS structures with both uniform and variable cross-section connectors. Results showed that WAAM-fabricated connectors exhibited excellent bonding with steel plates, providing superior composite strength for SCS structures. Specifically, the optimized variable cross-section design better aligned with the nonlinear shear force distribution, increasing the yield push-out load by 185 % and 53 % compared to optimized UC8 and same-volume UC12. In bending tests, UC8-SCS beams failed due to high bond slip, while VC-SCS beams suppressed slip, improving load capacity. A theoretical model was developed to predict failure modes, showing good agreement with experiments. This study provides a foundation for advancing WAAM-fabricated SCS structures.