An Equivalent Method for Bar Slip Simulation in Reinforced Concrete Frames

Abstract

An extreme loading on a reinforced concrete frame leads to severe increase in cracks in concrete as well as large strains in reinforcing bars. This, in turn, results in reduction of steel–concrete bond as well as an increase in the subsidiary effects of slip. In the current study, to include the slip effects in the numerical analyses, an indirect approach based on the results of pull-out test modeling is proposed. The proposed approach suggests a steel strength-reduction factor of 0.6 so as to apply to the bars prone to slip. This value is obtained based on the results of micro-modeling of available experimental pull-out tests using ABAQUS. To account for the bond-slip effect between concrete and rebar, adjacent nodes of concrete and rebar were connected using nonlinear springs. To estimate the length of slip prone zone, a sensitivity analysis on the collapse behavior of two reinforced concrete sub-frames from a 10-story building was conducted. The experimental data for the sub-frames were available. Corroborated with the experimental data revealed that if the length of the slip prone zone is considered to be twice the depth of the beam, the presented indirect approach will be capable of predicting the load–deformation response with a good accuracy. The obtained results showed the significance of considering slip effect in the analyses of reinforced concrete frames as well.