Reinforcement slip in reinforced concrete columns

Reinforcement slip in footings and beam-column joint regions can make a significant contribution to the total lateral displacement of a reinforced concrete structure. In this paper, a model for the prediction of lateral deformation of a column due to reinforcement slip in the anchorage zone is presented. The model employs a stepped bond stress along the embedded length of the reinforcing bar that allows for efficient computation of displacements due to slip. A method for computing slip when a reinforcing bar is stressed to its unloaded end and a corresponding failure criterion are presented. Procedures for calculating slip in hooked bars are also outlined. The proposed model is compared with five other commonly-used models found in the literature against three independent sets of test data. Considering its simplicity and computational efficiency, the proposed model predicts slip displacements reasonably well.