3D concrete printing (3DCP) offers many new possibilities. This technology could increase the productivity of the construction industry and reduce its environmental impact by producing optimised structures more efficiently. Despite significant developments in materials science, little effort has been put in developing reinforcement strategies compatible with 3DCP and on the characterisation of their structural behaviour. Consequently, 3DCD still lacks compliance with structural integrity requirements. This study presents an experimental investigation consisting of nine four-point bending tests on extrusion 3DCP beams reinforced with various types of reinforcement. As interlayer shear reinforcement, aligned end-hook fibres (0.3 and 0.6%) or steel cables (0.1%) placed between the layers of printed concrete were used. As longitudinal reinforcement, unbonded post-tensioning and conventional bonded passive reinforcement were explored. The crack patterns and their associated kinematics were tracked using digital image correlation. The results show that the post-tensioned beams failed in a brittle manner due to the crushing of concrete in bending, with deformations localised in a few bending cracks. In the beams with conventional bonded longitudinal reinforcement, both bending as well as shear cracks were generated, and the brittle failure of the interlayer shear reinforcement limited the ultimate load. Estimations based on the measured crack kinematics show that the interlayer shear reinforcement carried most of the applied shear force. Based on these results, a simple mechanical model is developed to understand the mechanical behaviour and to pre-design the required amount of interlayer shear reinforcement.

3D混凝土印刷（3DCP）提供了许多新的可能性。通过更有效地生产优化的结构，该技术可以提高建筑行业的生产率并降低其对环境的影响。尽管材料科学取得了长足的发展，但在开发与3DCP兼容的增强策略以及表征其结构行为方面所做的工作很少。因此，3DCD仍然缺乏结构完整性要求。这项研究提出了一项实验研究，包括对使用各种类型的增强件增强的挤压3DCP梁进行的九个四点弯曲测试。作为层间剪切增强，使用了在印刷混凝土层之间放置的对齐的尾钩纤维（0.3％和0.6％）或钢缆（0.1％）。作为纵向钢筋，探索了无粘结后张法和常规粘结被动补强。使用数字图像相关性跟踪裂缝模式及其相关的运动学。结果表明，由于混凝土在弯曲过程中的破碎，后张梁以脆性方式破坏，变形集中在一些弯曲裂纹中。在具有传统粘结纵向钢筋的梁中，既产生弯曲又产生剪切裂缝，并且层间剪切钢筋的脆性破坏限制了极限载荷。基于测得的裂纹运动学的估计表明，层间剪切增强承载了大部分施加的剪切力。根据这些结果，