Modified Steel Bar Model Incorporating Bond-Slip for Seismic Assessment of Concrete Structures

This paper presents a simplified model for describing the response of a longitudinal bar embedded in concrete taking into account the bond‐slip phenomenon. The model is developed by assuming a linear bond‐slip field along the bar anchorage length and provides a simplified stress‐strain relationship to assign to the longitudinal reinforcement. The analytical approach adopted makes the proposed model very convenient from a computational standpoint because, unlike many other refined models, it does not require a multi‐level iterative process. Moreover, the assumptions made are particularly appropriate for modeling bond‐slip of smooth bars generally used in older reinforced concrete buildings. The implementation strategy of the proposed bond‐slip model in a general‐purpose nonlinear structural analysis software and comparisons with experimental results are discussed in a companion paper.