An efficient strategy for numerical implementation of 3D rebar-concrete interface element for integrating bond-slip behavior in RC structures simulation

Rational characterization of bond-slip behavior at the rebar-concrete interface constitutes a critical impact in evaluating the mechanical performance of reinforced concrete (RC) structures. This study presents a novel three-dimensional interface element using a user-defined element (UEL) subroutine, offering an advancement in realistically capturing nonlinear interfacial responses under diverse loading scenarios. A key innovation lies in the development of an efficient Python script for the insertion of interface elements within ABAQUS, addressing computational challenges in element deployment. The constitutive laws governing axial, radial, and coupled axial-radial interactions are elaborated to enhance the fidelity of bond-slip simulations. The numerical implementation of the interface element, based on the UEL subroutine, involves rigorous definitions of the element stiffness matrix, coordinate transformation matrix, and residual matrix, ensuring robust computational performance. Extensive validation against independent experimental results at both material and component levels demonstrates the accuracy of the interface element in predicting failure modes, damage evolution, and mechanical responses. The proposed approach represents a practical strategy for integrating bond-slip behavior into the nonlinear analysis of RC structures, offering a reliable solution for advancing structural engineering simulations.