An integrated topology optimization method including manufacturing constraints for 3D printed fiber-reinforced concrete structures

The difficulty of achieving overall optimization design of concrete materials, structures, and performances has always been a bottleneck restricting the safety and comprehensive performance improvement of civil engineering structures throughout their life cycle. Driven by digital design, 3D concrete printing (3DCP) with a high degree of freedom and flexibility can achieve accurate distribution of materials and flexible construction, which is a favorable guarantee for the high-quality construction of high-performance structures. In this paper, an integrated design method of material-process-performance is developed by introducing both concrete material properties and printing process parameters into the optimization design. The nodal volume fraction and material orientation are selected as design variables to obtain lightweight structures, meanwhile the tensile capacity enhanced through fiber alignment is fully utilized. The minimum size control combined with the central axis algorithm is introduced to achieve integer multiple of nozzle size and also to improve the manufacturing quality. Structural compliance and stress are adopted as the objective function and constraint to improve structural stiffness and strength, respectively. Test results show that the strength-to-weight ratio of the optimized beam is 42 % higher than that of the cast-in-place one, and therefore the effectiveness of the proposed method is validated.