Reinforcement design and structural performance for the topology optimized 3D printed concrete truss beams

Abstract

Reinforced 3D printed concrete (3DPC) truss structure, owing to its ease of fabrication and light-weight configurations, is increasingly accepted as a popular load-bearing system. However, the understanding into its reinforcement design and structural performance is still scarce up to now, failing to guide the wide application efficiently and appropriately. To upgrade current design methods and improve structural performance, this study introduces a workflow for integrating the topology optimization, reinforcement design and structural performance evaluation into the design of reinforced 3DPC truss beams. In the proposed workflow, the topology optimization process considering the printing constraints was employed to produce the 3DPC truss configuration, incorporating only tension and compression struts to reduce structural weight and enhance stress transfer efficiency. The reinforcing bar characteristics in the struts were identified based on the proposed reinforcing bar selection criterion from the perspective of bond performance. The overall reinforcement strategies between the printed layers were designed based on the stress flow to endow the un-reinforced truss with load-bearing and ductile properties. The flexural performance of the topology optimization-based reinforced 3DPC truss beams was experimentally evaluated. A finite element model was afterwards developed to support a parametric study aimed at optimizing the flexural design. Significantly, the topology optimized 3DPC truss beams demonstrated to achieve a 94 % improvement in strength-to-weight ratio while preserving the same failure deflection-to-weight ratio as traditional reinforce concrete (RC) beams.