Nonlinear Finite Element Investigation of Steel–Concrete Interface Effects on the Cyclic Behavior of Steel-Reinforced Concrete (SRC) Columns

The cyclic response of Steel-Reinforced Concrete (SRC) columns is governed by the interaction between the embedded structural steel section and the surrounding concrete. However, most nonlinear finite element studies assume a perfect bond at the steel–concrete interface, neglecting interface slip that may considerably influence the structural response. This study investigates the effects of steel–concrete interface conditions on the cyclic behavior of SRC columns through three-dimensional nonlinear finite element analyses conducted in ABAQUS. The developed modeling approach was first validated against experimental results available in the literature and demonstrated excellent agreement with the measured global response. A comprehensive parametric investigation was subsequently performed by considering two interface conditions (perfect bond and frictional contact), three axial load ratios, four interface friction coefficients, and different structural steel ratios under displacement-controlled cyclic loading. Structural performance was evaluated in terms of hysteretic response, lateral load capacity, stiffness degradation, and cumulative energy dissipation. The results indicate that the perfect bond assumption consistently overestimates the seismic performance of SRC columns by predicting higher lateral strength, greater stiffness, and significantly larger energy dissipation than the frictional interface model. Depending on the axial load ratio, the cumulative energy dissipation capacity of the frictional model was 44.2–73.1% lower than that of the perfect bond model, while the influence of interface modeling became increasingly pronounced at higher axial load levels. Increasing the interface friction coefficient enhanced the composite action between steel and concrete, although its influence on peak lateral resistance remained relatively limited. The findings demonstrate that realistic steel–concrete interface modeling is essential for reliable nonlinear finite element simulations and provides practical guidance for the seismic assessment and design of SRC columns.