On bond failure by splitting of concrete cover surrounding anchored bars

This study develops analytical expressions for the bond stress level surrounding a longitudinal steel bar that causes the cover concrete to fail in a splitting mode, with bar-to-surface cracks forming in the longitudinal direction parallel to the bar. The proposed models use as a foundation the fracture mechanics-based cohesive-elastic ring model, developed by Reinhardt & Van der Veen (1990 ) based on original work by Tepfers (1979 ). They propose formulations that better address the assumptions and simplifications made in the original model, namely the biaxial behavior of concrete in tension, the crack-opening displacement profile, and the material law governing post-cracking tension softening. The relative significance of the proposed model enhancements is established through their prediction of bond stress and the associated computational cost for a computational benchmark problem involving a steelbarpullout from a concrete cylinder. Finally, the robustness of the reference and proposed models, measured by their sensitivity to the uncertainty in their respective parameters is evaluated and compared using a deterministic sensitivity analysis. Based on such analysis, recommendations are given on the most suitable and practical enhancements of the original model.