Insights on the bond behavior between HS-ECC and steel bar: Experiment, 3D meso-scale numerical model and probabilistic predictions

Reliable bonding performance between steel bar and high-strength engineered cementitious composites (HS-ECC) is crucial for efficient structural members, the in-depth understanding of which, however, is still lacking. This study develops a 3D meso-scale numerical model to investigate the interfacial bonding characteristics between ribbed steel bars and HS-ECC, and the effectiveness of the proposed numerical model is verified. The failure modes, the matrix cracking pattern, the refined bond stress distribution and proportion of bond strength of HS-ECC specimens are vividly demonstrated. Parametric studies are further conducted to investigate the influence of matrix strength, fiber content, steel bar diameter, embedment length, and thickness of matrix cover on the bond behavior. Furthermore, utilizing a Bayesian updating approach, three probabilistic models are further proposed based on the numerical modelling results to predict the bond strength between ribbed steel bars and HS-ECC. The proposed probabilistic models achieve good prediction significantly reducing randomness by fully accounting for the uncertainty of geometric parameters of steel bar, geometry and strength parameters of ECC, offering a robust approach to evaluate the bond strength. This work provides a comprehensive understanding of the bond behavior between ribbed steel bars and HS-ECC based on meso-scale simulation, and establishes a design method based on probabilistic models for engineering applications.