In this work aspects of interaction between steel and concrete, for reinforced concrete structures, with particular interest in the mechanism of slip that occurs in the steel-concrete interface are presented. A nonlinear computational model which considers the bond-slip behavior between reinforcing steel and concrete for the nonlinear analysis of beams subjected to bending is developed. The finite element method is used to predict the behavior of reinforced concrete structures based on the properties of the concrete, the reinforcing steel, and the relationship of the steel-concrete interface. The concept about equivalent uniaxial stress-strain model proposed by [
] is used to describe the nonlinear behavior of reinforced concrete which incorporates tensile cracking at a limiting stress and the strain-softening phenomenon beyond the maximum compressive strength from an incremental load procedure with an iterative approach to obtain an equilibrium position of the structure for each increment. The bond is modeled with interface element (bond-zone element) connecting the steel and concrete elements. The interface element presented by [
] has its stiffness based on the stages of relationship between the local bond stress and the relative slip of the bar, for incremental load process. Several numerical examples comparing results of bending beams are presented.