Bond-Slip Model for Finite Element Analysis of Reinforced Recycled Aggregate Concrete Frames

The use of coarse recycled aggregate in structural concrete members is an alternative and beneficial way to reduce the consumption of natural materials. This is not only due to the limitation of resources of aggregates, but also due to the sustainability of concrete that can make construction industry more eco-friendly and consequently mitigate the global warming. The bond between recycled aggregate and reinforcing steel bars is one of the key factors that is interesting and significant in terms of the design and safety of reinforced concrete structures. Therefore, this paper develops and introduces a novel bond-slip model and frame element incorporating the bond-slip effect to analyze recycled aggregate concrete (RAC) structures under static loads. The proposed frame model is built on the Euler-Bernoulli kinematics beam theory and employs a fiber-discrete section model derived from the displacement-based formulation. Uniaxial material models are utilized to capture the nonlinear behaviors of RAC frames reinforced with steel bars. The bond-slip model is developed and refined through regression analysis of available experimental data on pull-out failure, enabling the assessment of bond interface slip between RAC and deformed bars. To validate the accuracy and efficiency of the proposed frame model, two numerical simulations are studied. The first simulation investigates the accuracy and convergence of the proposed model, while the second examines the impact of the bond-slip interface on the response analysis of RAC beams. Both simulations emphasize the significance of the bond-slip interface in analyzing RAC frame systems.