Steel-Wire Mesh Reinforcement of Topology-Optimized 3D-Printed ECC Beams: Experimental and Numerical Investigation

Engineered cementitious composites (ECC) exhibit tensile strain hardening and multiple cracking, providing an inherent self-reinforcing capability that endows ECC with suitability for the complex forms enabled by topology optimization and 3D printing. To extend such optimized structures to a broader range of engineering applications, their structural capacity needs to be further enhanced through reinforcement. This study investigates two printable topology-optimized (TO) 3D-printed ECC beams in unreinforced and steel-wire-mesh-reinforced forms under four-point bending. For the single specimen tested in each configuration, steel-wire mesh increased the experimental peak loads of TO1 and TO2 by 53.7% and 81.2%, respectively. After normalization by the measured as-built retained-area ratio, the corresponding increases in normalized peak load were 46.3% and 56.2%. Reinforcement produced contrasting effects on energy absorption, decreasing it by 36.8% for TO1 but increasing it by 47.2% for TO2. A three-dimensional finite-element model was developed to reproduce the printable geometries, extrusion discontinuities, and inter-filament and interlayer interfaces. The simulations showed that increasing reinforcement shifted the failure mode from distributed lower-chord cracking to damage at diagonal-to-chord connections and support-side interfaces. Increasing the normal interface strength from 1.0 to 2.5 MPa markedly improved the load capacity of both beam configurations, while a further increase to 4.0 MPa had a slight influence. These findings extend topology-optimized 3DP-ECC beyond geometry-driven material reduction toward reinforcement-enabled structural performance enhancement, providing a basis for the broader application of lightweight, high-capacity, and material-efficient 3D-printed structural systems.