Abstract
This report presents a comparative evaluation of local bond–slip models used to simulate the interaction between prestressing strands and concrete in post-tensioned structures, with a particular focus on the influence of grouting defects. Accurate modelling of bond–slip behaviour is essential for reliable finite element analysis (FEA), especially in assessing stress transfer, crack development, and long-term durability. The study reviews four key models: the fib Model Code 2010, Dörr’s (1980) cubic polynomial model, Guo et al.’s (2020) modified BEP model, and Ferretti et al. (2024) model based on experimental pull-out tests. Each model is assessed under conditions with and without grouting defects. Results show that Ferretti’s model provides the most realistic and resilient predictions, especially in defect scenarios, while Guo’s model offers conservative estimates suitable for safety-critical applications. The fib model remains appropriate for general design, and Dörr’s model serves as a simplified alternative. The report concludes with recommendations for model selection based on design objectives and highlights the need for further validation under varied environmental and loading conditions.