Prediction of the flexural strength of 3D printed SHCC beams based on a stochastic size-dependent model

Integrating reinforcement remains a challenge in 3D concrete printing (3DCP). Self-reinforced concrete materials, such as strain-hardening cementitious composites (SHCC), show great potential to address this challenge due to their enhanced tensile performance. However, the lack of a predictive method to link the material properties of SHCC and the structural strength of printed SHCC members impedes the engineering application of 3D printed SHCC. This work aims to establish a stochastic model for predicting the flexural strength of 3D printed SHCC beams based on the material performance and the beam span. In the modelling process, a printed beam is conceptualized as a multi-layered structure. The constitutive relationship of the tensile layers is derived based on a stochastic model, in which the impact of size effect on the tensile strength and strain capacity of SHCC is taken into account. The flexural strength of the printed SHCC beam can thus be determined by the cross-sectional analysis of force equilibrium. 3D printed SHCC beams with four spans (240 mm, 300 mm, 450 mm, and 1500 mm) were tested by four-point bending to measure the flexural strength for validation. Results show that the predictive accuracy of the proposed model is as high as 87.4%. The developed model can provide a guideline for predicting the flexural strength of 3D printed SHCC beams, and the findings can facilitate the structural design in 3DCP.