Size-dependent model to predict the flexural strength of 3D printed engineered cementitious composites beams

This study developed a size-dependent model to predict the flexural strength of 3D printed engineered cementitious composites (ECC) beams with different beam spans. The proposed model relates the flexural strength of printed ECC beams to beam spans based on a stochastic tensile constitutive model of ECC, by taking the size effect into account. ECC beams with four spans (240 mm, 300 mm, 450 mm, and 1500 mm) were printed and tested by four-point bending. The results showed that the size-dependent model can predict the flexural strength with an approximate accuracy of 90%. Compared to the size-independent model, the proposed size-dependent model improved the prediction accuracy by approximately 27%. The force analysis of the shear strength of interlayers further revealed that interfacial bonding has a negligible impact on the simulated flexural strength. Consequently, the developed size-dependent model can potentially guide the structural design of 3D printed ECC beams.