Modeling Bar Slip in Nonductile Reinforced Concrete Columns

Bar slip deformations in reinforced concrete frame structures cause additional flexibility at the boundaries of beams and columns due to penetration of rebar strain into the joints and footings. There are several available analytical models that estimate bar slip deformations, many of which have difficulties capturing the bar slip deformations that occur after flexural-axial damage. A new methodology is proposed to effectively account for bar slip deformations within the existing elements of an analytical model, without increasing the complexity of the system. This new method shows good agreement with previous experimental results and was successfully used in large-scale hybrid simulations. A series of hybrid simulations were conducted involving full-scale concrete columns instrumented to measure the bar slip deformations. The results of these tests, along with previous experimental studies, are used to develop a new model for the slip of rebar embedded in concrete. The proposed bar slip model is developed for use in nonductile columns and is shown to achieve good agreement with experimental results.