This research studies the impact of localized damage and deformed printing geometry on the structural failure of plastic collapse for 3D concrete printing (3DCP) using the lattice model. Two different approaches are utilized for buildability quantification: the (previously developed) load-unload method, which updates and relaxes the printing system after each analysis step and repeatedly applies the gravitational loading to the undeformed structure; and the incremental method, which keeps the load after each analysis step and applies the incremental loading to the deformed printing system. The former can consider the material yielding but cannot capture accurately the structural deformation during printing process. Compared to the load-unload method, the incremental method can not only consider deformed printing geometry but can also simulate the non-proportional loading conditions and disequilibrium force occurring during 3D printing. In this study, computational uniaxial compression tests are first conducted to compare two algorithms. The numerical results indicate the consideration of nonequilibrium force and deformed geometry affects the peak load and crack information for fracture analysis. Subsequently, the incremental method is incorporated into the lattice model to quantify buildability of 3DCP. The predictions are compared with previously published numerical results obtained using the load-unload method. The lattice model based on incremental method reproduces correct failure mode; better quantitative agreement about critical printing height also can be obtained. These numerical analyses demonstrate that the incremental solution is an approximate method for buildability quantification since it can account for the nonequilibrium force induced by the deformed printing geometry and localized damage.

本研究使用晶格模型研究了局部损伤和变形的打印几何形状对 3D 混凝土打印 (3DCP) 塑性坍塌结构失效的影响。可建造性量化采用了两种不同的方法：（以前开发的）加载-卸载方法，在每个分析步骤之后更新和放松打印系统，并重复地将重力加载到未变形的结构上；增量法，在每个分析步骤后保持加载，并将增量加载应用于变形的打印系统。前者可以考虑材料屈服，但不能准确捕捉打印过程中的结构变形。与加载卸载方法相比，增量法不仅可以考虑变形的打印几何形状，还可以模拟3D打印过程中发生的非比例加载条件和不平衡力。在这项研究中，首先进行了计算单轴压缩测试来比较两种算法。数值结果表明考虑非平衡力和变形几何会影响断裂分析的峰值载荷和裂纹信息。随后，增量方法被纳入晶格模型以量化 3DCP 的可构建性。将预测与使用加载卸载方法获得的先前公布的数值结果进行比较。基于增量法的晶格模型再现了正确的失效模式；还可以获得关于临界印刷高度的更好的定量一致性。